Search Results (85)

Objective: Study the mechanism of ginsenoside Rg₁ in ameliorating hyperuricemia (HUA) induced by high-purine diet. Methods: Rats were randomly divided into groups, and the HUA model was established by administering a high-purine diet containing potassium oxonate combined with yeast. After the experiment, blood was collected via cardiac puncture, and the organ indices of the rats were calculated. Serum biochemical markers including aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), total cholesterol (TC), xanthine oxidase (XOD), creatinine (CREA), uric acid (UA), and blood urea nitrogen (BUN) were measured. Histopathological sections of the kidney and intestine were prepared. Western blot was used to assess the expression levels of intestinal occludin and zonula occludens-1 barrier proteins and key proteins in IL-17/NF-κB inflammatory pathways. After the experiment, fecal samples were collected from the rats. The gut microbiota of HUA-induced rats was analyzed via 16S rRNA sequencing, and the levels of short-chain fatty acids in the fecal samples were quantified using gas chromatography–mass spectrometry. Results: Ginsenoside Rg₁ significantly increased body weight and organ indexes as well as reduced serum levels of BUN, CREA, ALT, AST, XOD, and UA. Pathologic analysis showed that ginsenoside Rg₁ improved renal cell injury, glomerulosclerosis, and renal interstitial fibrosis while restoring intestinal barrier function. Ginsenoside Rg₁ down-regulated the expression of inflammatory proteins and up-regulated the levels of intestinal barrier proteins. The results of 16S rRNA sequencing showed that ginsenoside Rg₁ significantly increased the diversity index of gut microbiota and enhanced the number of beneficial bacteria in HUA rats. Short-chain fatty acids analysis demonstrated that ginsenoside Rg₁ markedly elevated the levels of acetate, propionate, butyrate, and valerate in HUA rats. Conclusions: Ginsenoside Rg₁ ameliorates and treats HUA by improving the composition of intestinal flora and inhibiting the IL-17/NF-κB signaling pathway to reduce inflammatory factors in the intestinal tract in HUA rats. Full article

In this study, nitrogen-doped TiO₂ heterojunction materials were successfully synthesized via a facile one-step solvothermal approach. A range of advanced characterization techniques were employed to thoroughly analyze the structural and compositional properties of the synthesized photocatalysts, and their application potential for tetracycline (TC) degradation under visible light was studied. The results indicated that N-doped TiO₂ exhibited a well-defined hierarchical micro/nanostructure and formed an efficient anatase/rutile homogeneous heterojunction. The photocatalytic performance of N-TiO₂ for TC degradation under visible light was significantly enhanced, achieving a degradation efficiency of up to 87% after 60 min of irradiation. This improvement could be attributed to the synergistic effects of optimal nitrogen doping, heterojunction formation, and the hierarchical micro/nanostructure, which collectively reduced the bandgap energy and suppressed the recombination rate of photogenerated carriers. Furthermore, density functional theory (DFT) calculations were conducted to systematically explore the impacts of substitutional and interstitial nitrogen doping on the energy band structure of TiO₂. Full article

A one-micron-thick pure zinc oxide (ZnO) and nitrogen-doped zinc oxide (N-ZnO) film were fabricated on p-type, pristine (non-porous), and porous gallium nitride (GaN) substrates using a radio frequency (RF) sputtering technique at room temperature. The doping medium was nitrogen gas, which has a flow rate that ranges from 0 to 10 sccm (0 sccm refers to pure ZnO). The photoelectrochemical etching process, using ultraviolet light, was employed to etch the wafer surface and create a porous GaN substrate. ZnO films were developed on GaN with ZnO powder as the target material under vacuum conditions. This research aimed to investigate how variations in substrate and doping influenced the structural, optical, and electrical characteristics of the resulting thin films. The SEM images indicated that the pores developed on the etched GaN surface had a spherical shape. The A₁ (LO) phonon peak at 750.2 cm⁻¹ was observed in the Raman spectrum of the etched porous GaN. The X-ray diffraction (XRD) analysis confirmed that the films grown on GaN possessed a hexagonal wurtzite structure and the observed peak shift of (101) in all N-ZnO films suggested interstitial nitrogen doping. For the N-ZnO films, the UV-visible cut-off wavelength shifted towards the blue region. The root mean square (RMS) roughness of the N-ZnO films, measured using atomic force microscopy (AFM), was found to decrease with an increasing N-doping concentration. The 10 sccm sample exhibited the lowest roughness value of 1.1 nm, whereas the pure ZnO film showed the highest roughness of 3.4 nm. The N-ZnO thin films were found to exhibit p-type conductivity, as computed by Hall measurements using the van der Pauw method, and the higher value of carrier concentration obtained for the nitrogen gas flow rate of 8 sccm was 5.29 × 10²¹ cm⁻³. Full article

This study investigates the impact of KNO₃-based salt bath nitriding on the microstructure, hardness, and corrosion resistance of 20MnCr5 steel. The nitriding process was conducted at 600 °C for 3 h and resulted in a nitrogen diffusion zone with a thickness that varied across the specimen, reaching a maximum of 70 μm. X-ray diffraction (XRD) analysis revealed no detectable nitrides, indicating nitrogen primarily occupied interstitial sites in the ferrite lattice and caused a lattice expansion of ~0.16%. Nanoindentation measurements showed an 80% increase in surface hardness (10.2 GPa) compared to the substrate (5.67 GPa), attributed to the solid solution strengthening mechanism. In contrast, however, an 18% decrease in Young’s modulus was observed near the surface, likely due to nitrogen-induced lattice distortions and crystal defects. Electrochemical tests in a 3.5 wt.% NaCl solution showed improved corrosion resistance, with the nitrided specimen exhibiting a 58% lower corrosion rate (1.275 mm/year) compared to untreated steel (3.04 mm/year). Despite a cathodic shift in corrosion potential, indicating localized susceptibility, the surface layer acted as a partial barrier to chloride ingress. The study demonstrates that KNO₃-based salt nitriding is an environmentally friendly alternative to cyanide-based processes that offers good surface hardness and corrosion resistance, but needs to be further optimized. Full article

Carbon materials have been employed in many applications in flue gas purification due to their high specific surface area, good chemical inertness, and tunable surface chemistry. However, traditional methods such as adsorption or metal-loaded catalysis can be financially burdensome. The surface of carbon materials contains abundant vacancies, interstitial atoms, boundaries, and other defects. These structural defects are often modified with saturated or unsaturated functional groups containing heteroatoms such as oxygen, nitrogen, etc., thus possessing a certain acid–base property and redox ability, which makes the carbon materials themselves have some catalytic activity. The metal-free carbon catalytic purification of flue gas pollutants offers a promising solution to improve removal efficiency while reducing costs significantly. This review examines the research on carbon materials for the removal of flue gas pollutants, presenting recent advancements in carbon catalysis purification of NO_x, SO₂, and VOCs. It analyzes the critical properties of carbon materials that govern carbon catalytic efficiency, such as surface functional groups, surface defects, and pore structure. Finally, it summarizes methods for regulating these properties to achieve higher efficiencies in the metal-free carbon-catalyzed purification of flue gas pollutants. Full article

The mechanical properties of High-Performance Self-Compacting Concrete (HPSCC) are strongly influenced by its pore structure, but the impact of varying water–binder ratios (W/C) on this relationship remains unclear. To address this, the present study investigates HPSCC with W/C ratios ranging from 0.19 to 0.23, aiming to elucidate the connection between pore structure, fractal characteristics, and mechanical performance. Through a combination of compressive strength testing, low-temperature nitrogen adsorption, and Scanning Electron Microscopy (SEM) observations, this study reveals key insights. First, compressive strength initially increases with a decreasing W/C ratio but plateaus beyond W/C = 0.21, identifying an optimal range for balancing strength and workability. Second, the pore structure of HPSCC is characterized by cylindrical, ink-bottle, and planar interstitial pores, with significant fractal characteristics. Notably, the fractal dimension decreases as the W/C ratio increases, indicating reduced pore complexity and improved homogeneity. Finally, a strong linear correlation (R² > 0.9) between the W/C ratio, fractal dimension, and compressive strength provides a predictive tool for assessing HPSCC performance. This study concludes that the internal pore structure is a critical determinant of HPSCC strength, and the identified optimal W/C ratio range offers guidance for mixture designs. Additionally, fractal dimension analysis emerges as a novel method to evaluate HPSCC’s microstructural quality, enabling predictions of long-term performance and durability. These findings contribute to the scientific basis for designing high-performance concrete materials with improved mechanical properties and durability. Full article

Objectives: This study primarily aimed to examine the optimal amount of carbohydrates in the effects of high-isomaltulose and high-sucrose ingestion compared with low-sucrose ingestion on blood glucose levels. The secondary objective was to assess the changes in blood glucose levels that may impact golf-related performance. Methods: This study included 29 healthy male competitive golfers playing 18 holes. These participants were randomly assigned to the low-sucrose (LSUC, 30.9 g/h of carbohydrates), high-sucrose (HSUC, 44.2 g/h of carbohydrates), and high-isomaltulose (HISO, 44.5 g/h of carbohydrates) groups. They were required to continuously consume the test food during the round. Assessment items included blood glucose, golf performance, urinary urea nitrogen, subjective ratings (concentration, fatigue, and relaxation), and anxiety ratings. A main effect of the test meal of changes in interstitial glucose concentration was determined. Results: The HSUC had significantly more interstitial glucose than the HISO and LSUC, while the HISO group had a much lower decrease in urine urea nitrogen than the LSUC group. In subjective fatigue, the main effect of the test diet was observed, and the HSUC and HISO showed significantly lower values than the LSUC after 18 h. Conclusions: Compared with low-carbohydrate intake, high-carbohydrate intake during a round of golf-maintained the blood glucose levels and prevented fatigue. Therefore, this study indicates that competitive golfers need a high-carbohydrate intake of approximately 44 g/h for energy intake during a round of golf. Full article

Tetrataenite is a promising candidate for rare earth-free permanent magnets due to its low cost and intrinsic magnetic properties. This work investigates the effect of combined milling at liquid nitrogen temperatures (cryomilling) and the addition of carbon as an interstitial element for promoting the formation of tetrataenite. Crystal structure, microstructure, and magnetic properties are investigated to understand the influence of mechanical processing and compositional modifications. No unambiguous evidence of the ordered phase of tetrataenite is found in the structural characterization. However, using Scanning Transmission Electron Microscopy (STEM) and powder X-ray diffraction (PXD) analyses, the occurrence of both twinning and stacking faults resulting from the high-energy milling process is observed, which is a relevant factor for identifying tetrataenite in FeNi alloys. The probability of a stacking fault and twinning occurring for a carbon-free FeNi sample before annealing is found to be 2% and 1.4%, respectively. After annealing, the stacking fault probability decreased to 1.2%, while that of twinning was 1.4%. By increasing the carbon concentration to 5 at.%, the stacking faults and twinning probabilities decrease slightly to 1.2% and 1.3%, respectively. The occurrence of stacking faults combined with small crystallite sizes was a hindering factor in identifying the presence of tetrataenite. Full article

Photocatalysis is a promising method for methylene blue (MB) degradation due to its effectiveness and environmental compatibility. Among the photocatalysts, titanium dioxide (TiO₂) has been widely used for MB degradation due to its exceptional photocatalytic activity. However, the wide bandgap limits the degradation efficiency of TiO₂ under visible light. Here, an interstitial nitrogen-doped TiO₂ (5%N_T/TiO₂) used thiourea as the N source was fabricated for visible light-derived MB degradation. The 5%N_T/TiO₂ exhibited an extended absorption range of visible light. Moreover, photoelectrochemical measurements showed an improvement in the photocurrent response and charge transfer behavior on N/TiO₂. Thus, 5%N_T/TiO₂ had enhanced photocatalytic activity compared with pristine TiO₂ and substitutive N-doped TiO₂ (5%N_AB/TiO₂). The accelerated photocatalytic MB degradation process on N/TiO₂ could be mainly attributed to the interstitial N doping, which caused the appearance of new energy states and extended optical properties. Through comparing the impact of interstitial and substitutive in TiO₂ activity, our work proposes a suitable form of element doping to enhance the optical properties and photocatalytic activity of TiO₂ and even other semiconductors, providing guidance for future work. Full article

Zinc oxide (ZnO) is a wide bandgap semiconductor that holds significant potential for various applications. However, most of the native point defects in ZnO like Zn interstitials typically cause an n-type conductivity. Consequently, achieving p-type doping in ZnO is challenging but crucial for comprehensive applications in the field of optoelectronics. In this work, we investigated the electrical and optical properties of ex situ doped p-type ZnO films. The p-type conductivity has been realized by ion implantation of group V elements followed by rapid thermal annealing (RTA) for 60 s or flash lamp annealing (FLA) on the millisecond time scale in nitrogen or oxygen ambience. The phosphorus (P)-doped ZnO films exhibit stable p-type doping with a hole concentration in the range of 10¹⁴ to 10¹⁸ cm⁻³, while antimony (Sb) implantation produces only n-type layers independently of the annealing procedure. Microstructural studies of Sb-doped ZnO show the formation of metallic clusters after ms range annealing and SbZn-oxides after RTA. Full article

A change in the growth mode from Stranski–Krastanov one, which is characteristic of MOCVD grown GaN, to the laterally grown BGaN in the Volmer–Weber growth mode is described. This change in growth is evidenced by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of BGaN grown on GaN at high temperatures. It is postulated on the basis of SIMS and XRD results that this change in growth is initiated by the transfer of boron atoms from gallium substitutional to interstitial. The proposed mechanism for the observed growth change is related to the generation of nitrogen interstitials and subsequent reactions with boron interstitials, which result in the formation of a BN layer at the growth front. The observed large change in the growth mode is due to a lattice mismatch between the grown BGaN and the atomic layer of BN and stays behind the change to the Volmer–Weber growth mode. The consequence of the Volmer–Weber growth mode is the textural layer of BGaN. The textural character of this material is associated with large voids between grown BGaN “plates”. These large voids are responsible for the termination of threading dislocations propagating in the c-direction. It is also postulated that the blocked threading dislocations from the GaN underlayer and laterally grown BGaN layers along the a-directions are responsible for the decrease in defect concentration within these layers. Full article

The formation of intrinsic point defects in the N-sublattice of semi-insulating Mg-doped GaN crystals grown by the ammonothermal method (SI AT GaN:Mg) was investigated for the first time. The grown-in defects produced by the displacement of nitrogen atoms were experimentally observed as deep traps revealed by the Laplace transform photoinduced transient spectroscopy in the compensated p-type crystals with the Mg concentrations of 6 × 10¹⁸ and 2 × 10¹⁹ cm⁻³ and resistivities of ~10¹¹ Ωcm and ~10⁶ Ωcm, respectively. In both kinds of materials, three closely located traps with activation energies of 430, 450, and 460 meV were revealed. The traps, whose concentrations in the stronger-doped material were found to be significantly higher, are assigned to the (3+/+) and (2+/+) transition levels of nitrogen vacancies as well as to the (2+/+) level of nitrogen split interstitials, respectively. In the material with the lower Mg concentration, a middle-gap trap with the activation energy of 1870 meV was found to be predominant. The results are confirmed and quantitatively described by temperature-dependent Hall effect measurements. The mechanism of nitrogen atom displacement due to the local strain field arising in SI AT GaN:Mg is proposed and the effect of the Mg concentration on the charge compensation is discussed. Full article

This paper investigates the effect of the element La on plasma nitriding of the CoCrCuFeNi high-entropy alloy (HEA) at 440 °C for 8, 16, and 24 h. The phase composition, morphology, and hardness distribution of the nitrided layer are characterized using XRD, optical microscopy, and a microhardness tester. Furthermore, the corrosion resistance is tested using an electrochemical workstation. The study evaluated the friction and wear performance using a testing machine and scanning electron microscope. The thickness of the effective hardening layer after 16 h of treatment with La was similar to that after 24 h of treatment without La. The addition of La significantly increased the growth rate constant of the effective hardening layer from 0.53 × 10⁻¹⁴ m²/s to 0.72 × 10⁻¹⁴ m²/s. In addition, an expanded FCC phase with greater interplanar spacing can be formed on the surface of the sample by introducing La into the plasma nitriding process. This indicates that the expanded FCC phase, with a higher concentration of interstitial nitrogen atoms, can effectively improve the corrosion resistance of the specimen surface. The corrosion rate of the specimen surface was reduced by 27.5% and the wear rate was reduced by 41.7% after 16 h of treatment with the addition of La compared to 24 h of nitriding without the addition of La. It has been shown that the addition of La to the plasma nitriding process results in a higher quality nitrided layer in a shorter time and also demonstrates that La has the potential to optimize the surface properties of plasma nitrided HEAs. Full article

Defects and impurities play a fundamental role in semiconductors affecting their mechanical, optical, and electronic properties. Nitrogen (N) impurities are almost always present in a silicon (Si) lattice, either unintentionally, due to the growth and processing procedures, or intentionally, as a result of implantation. Nitrogen forms complexes with intrinsic defects (i.e., vacancies and self-interstitials) as well as with other impurities present in the Si lattice such as oxygen and carbon. It is, therefore, necessary to investigate and understand nitrogen-related defects, especially their structures, their energies, and their interaction with intrinsic point defects and impurities. The present review is focused on nitrogen-related defects (for example N_i, N_s, N_iN_i, N_iN_s, N_sN_s); nitrogen–self-interstitial and nitrogen-vacancy-related complexes (for example N_sV, (N_iN_i)Si_i, (N_sN_s)V); nitrogen–oxygen defects (for example NO, NO₂, N₂O, N₂O₂); more extended clusters such as V_mN₂O_n (m, n = 1, 2); and nitrogen–carbon defects (for example C_iN and C_iNO). Both experimental and theoretical investigations are considered as they provide complementary information. Full article

Metal additive manufacturing is a developing technique with numerous advantages and challenges to overcome. As with all manufacturing techniques, the specific raw materials and processing parameters used have a profound influence on microstructures and the resulting behavior of materials. It is important to understand the relationship between processing and microstructures of Ti to advance knowledge of Ti-alloys in the additive field. In this study, a face-centered cubic (FCC) phase was found in grade 2 commercially pure titanium specimens, additively manufactured with directed energy deposition in an argon atmosphere. Two scanning speeds (500 and 1000 mm/min) and three scanning patterns (cross-hatched and unidirectional patterns) were investigated. Electron backscatter diffraction and energy-dispersive X-ray spectroscopy were used for microstructural and compositional analysis. Inverse pole figure, phase, and kernel average misorientation (KAM) maps were analyzed in this work. Larger amounts of the FCC phase were found in the unidirectional scanning patterns for the slower scanning speed, while the cross-hatched pattern for both scanning speeds showed a lower amount of FCC. Higher KAM averages were present in the faster scanning speed specimens. According to EDS scans, small amounts of nitrogen were uniformly distributed throughout the specimens, leading to the possibility of interstitial content as a contributing factor for development of the observed FCC phase. However, there is no clear relationship between nitrogen and the FCC phase. The formation of this FCC phase could be connected to high densities of crystalline defects from processing, plastic deformation, or the distribution of interstitials in the AM structure. An unexpected Kurdjumow–Sachs-type orientation relationship between the parent beta phase and FCC phase was found, as ${\left\{110\right\}}_{\mathrm{B}\mathrm{C}\mathrm{C}}\parallel {\left\{111\right\}}_{\mathrm{F}\mathrm{C}\mathrm{C}}$, ${⟨111⟩}_{\mathrm{B}\mathrm{C}\mathrm{C}}\parallel {⟨110⟩}_{\mathrm{F}\mathrm{C}\mathrm{C}}$. Full article