Hasil untuk "Materials of engineering and construction. Mechanics of materials"

Daniil Shirokiy, Andrey Bukaemskiy, Maximilian Henkes et al.

Abstract Cr-doped UO₂ fuels are increasingly adopted for their superior in-reactor performance compared to undoped UO₂, but their spent fuel behaviour, particularly potential Cr speciation and fission product reactivity, remains poorly understood. This investigation has used high energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy to examine speciation of Cr and Pr/Gd within 200 ppm Cr-doped (U4.4+ 0.7Pr3+ 0.3)O2-x and 200 ppm Cr-doped (U4.4+ 0.7Gd3+ 0.3)O2-x compounds. Despite both being UO2 soluble and undersaturated, analysis indicates that Cr3+ and Pr3+/Gd3+ form perovskite type (Pr3+/Gd3+)Cr3+O3 phases, consistent with classical “grey phases” of spent fuel. The radiation tolerance of these phases was examined via swift heavy ion irradiations of PrCrO3 and GdCrO3 compounds where electron microscopy and grazing incidence synchrotron diffraction indicate significant amorphization but retention of the crystal structure. The investigation highlights the pertinence of considering the chemistry of dopants used for nuclear fuel enhancements regarding their speciation during irradiation and subsequent occurrence within spent fuel.

Haoyu Wang, Sheng'e Su, Xin An et al.

Lipid metabolism imbalance combined with over-activated inflammation are two key factors for hepatic stestosis. However, on-demand anchoring inflammation and lipid metabolism disorder for hepatic stestosis treatment has yet to be realized. Here we propose a charge reversal fullerene based nano-assembly to migrate hepatic steatosis via inhibiting macrophage-mediated inflammation and normalizing hepatocellular lipid metabolism in obesity mice. Our nano-assembly (abbreviated as FPPD) is comprised of electropositive polyetherimide (PEI), charge-shielded dimethylmaleic anhydride (DMA), and poly(lactic-co-glycolic acid) (PLGA), which provides hydrophobic chains for self-assembly with anti-oxidative dicarboxy fullerene poly(ethylene glycol) molecule (FP). The obtained FPPD nano-assembly owns a charge reversal ability that switches to a positive charge in an acidic environment that targets the electronegative mitochondria both in pro-inflammatory macrophages and steatosis hepatocytes. We demonstrate that the anti-oxidative and mitochondria-targeting FPPD notably reduces inflammation in macrophages and lipid accumulation in hepatocytes by quenching excessive reactive oxygen species (ROS) and improving mitochondrial function in vitro. Importantly, FPPD nano-assembly reveals a superior anti-hepatic steatosis effect via migrating inflammation and facilitating lipid transport in obesity mice. Overall, the charge reversal nano-assembly reduces over-activated inflammation and promotes lipid metabolism that provides an effectiveness of a multi-target strategy for hepatic steatosis treatment.

Yingbin Song, Xiangping Zhang, Jinxia Xu et al.

The low pozzolanic activity of the silt in the Yellow River has always been the key factor that hinders its resource utilization as artificial stones. A high-speed ball-milling method was first attempted to pretreat the silt for enhancing its pozzolanic activity in this study. The artificial stones incorporating the ball-milled silt were prepared by the alkali-activation method. The changes in the basic physical and chemical properties and microstructures of the pre-treated silt and fabricated artificial stones were characterized. Also, the compressive strength, splitting tensile strength and water resistance of fabricated specimens were measured. The results show that the ball-milling treatment destroys the original crystal structure, and significantly enhances the potential pozzolanic activity of the silt. In addition, it improves the compressive strength, splitting tensile strength and water resistance of the artificial stones. The compressive strength of artificial stones incorporated with the ball-milled silt has a maximum value of 17.1 MPa, showing an increase by one time. It can be ascribed to the increase of C-S-H/C-A-S-H gel amount in specimens. Furthermore, compared to traditional mined bluestone, the carbon emission of the alkali-activated artificial stone incorporating ball-milled Yellow River silt is much lower. The production of 1 t of artificial stone only emits 1155.25 kg of CO2.

Giuseppe Misia, Maurizio Prato, Alessandro Silvestri

Abstract Efficient hydrogen peroxide (H2O2) detection is crucial for electrochemical and colorimetric sensors, making the hydrogen peroxide reduction reaction (HPRR) a key area of catalysis. In this context, molybdenum disulfide (MoS2) has emerged as a valuable HPRR catalyst. Here, we report the first experimental investigation comparing the electrocatalytic properties of MoS2 enriched with different phases (2H and 1T) and showcasing diverse morphologies toward HPRR. We provide unprecedented parameters (Tafel slope, constant, and exchange current density) describing the materials’ HPRR performance through state-of-the-art electrochemical techniques, including Tafel plots and EIS. Our findings reveal that 1T-enriched MoS2 outcompetes 2H-MoS2. Moreover, we show that the distinct morphologies of 1T-MoS2, such as exfoliated nanosheets and hydrothermally synthesized nanoflowers, strongly influence the kinetics of the catalytic reaction. This study bridges the gap between MoS2 structural properties and its electrocatalytic activity for HPRR, facilitating the selection of optimal MoS2 materials for high-sensitivity hydrogen peroxide sensors.

Nargis Fatima Khatoon, Zubair Aslam, Mohd Shoab et al.

Abstract In this manuscript, we report successful synthesis and investigation of structural, morphological, electrical, and optical properties of doped and undoped Sb2Se3. A significant enhancement in electrical and optical properties of Zn-doped Sb2Se3 is observed. The temperature dependence of direct current (dc) conductivity has been investigated in thin films of Sb2ZnxSe3-x (where x = 0 and x = 0.25) in the temperature range of 290–490 K to determine the conduction mechanism and examine the effects of doping. It shows that, in the temperature range (343–490 K), conduction is primarily due to thermally activated tunneling of charge carriers through the band tails of localized states. In the lower temperature range 293–343 K, conduction occurs via variable range hopping in the localized states near the fermi level. The decrease in the optical bandgap value as a result of Zn doping in Sb2Se3 has been correlated with the variation in density of states, increased electron–phonon interaction and steepness parameter.

Syed Waqas Ali Shah, Hao Yuan, Shaohao Quan et al.

Multidrug-resistant (MDR) bacterial infections in chronic wounds pose a serious clinical challenge, necessitating innovative, drug free therapeutic strategies. Here, we report a novel self-healing keratin-based cryogel (KGG), fabricated via cryo-polymerization using keratin (KR), gum arabic (GA) and glycerol (GC). Unlike conventional hydrogels requiring antibiotics or growth factors, KGG demonstrates intrinsic regenerative, antibacterial, antioxidant, and hemostatic properties. Its highly interconnected macroporous structure, shape-memory behavior, and superior absorbency enable efficient exudate management and cellular infiltration. The cationic KR network facilitates electrostatic interactions with bacterial membranes, providing strong antibacterial activity against Escherichia coli (E. coli) and Methicillin-Resistant Staphylococcus aureus (MRSA) without promoting resistance. Additionally, KGG scavenges reactive oxygen species (ROS), modulates immune responses, and promotes macrophage polarization creating a pro-healing environment. In vitro and in vivo studies confirm its non-cytotoxic, enhanced angiogenesis, accelerated re-epithelialization, and inflammation suppression. The cryogel also exhibits excellent hemostatic performance, making it suitable for hemorrhage control. These finding highlight KGG as a multifunctional, pharmaceutical free platform for treating MDR-infected chronic wounds, with added potential in trauma care applications.

Futing Shu, Hongchao Huang, Shichu Xiao et al.

Diabetic wounds, characterized by prolonged inflammation and impaired vascularization, are a serious complication of diabetes. This study aimed to design a gelatin methacrylate (GelMA) hydrogel for the sustained release of netrin-1 and evaluate its potential as a scaffold to promote diabetic wound healing. The results showed that netrin-1 was highly expressed during the inflammation and proliferation phases of normal wounds, whereas it synchronously exhibited aberrantly low expression in diabetic wounds. Neutralization of netrin-1 inhibited normal wound healing, and the topical application of netrin-1 accelerated diabetic wound healing. Mechanistic studies demonstrated that netrin-1 regulated macrophage heterogeneity via the A2bR/STAT/PPARγ signaling pathway and promoted the function of endothelial cells, thus accelerating diabetic wound healing. These data suggest that netrin-1 is a potential therapeutic target for diabetic wounds.

WANG Ruilin, QU Junhao, HUANG Haibo et al.

The oriented nanotubes reinforced styrene butadiene rubber (CNTs/SBR) composites were prepared by applying the mechanical shear induction method, and the laws of carbon tube content and orientation on the mechanical and tribological properties of the composite rubber materials were investigated. The mechanisms of these results were analyzed. The results show that the orientation of CNTs has a significant impact on the tribological properties of SBR composites. When CNTs-z are perpendicular to the friction interface and sliding direction, the mechanical and tribological properties of CNTs-z/SBR are superior to those of CNTs-x/SBR and CNTs-y/SBR. When CNTs are parallel to the friction interface, the mechanical properties of CNTs-x/SBR aligned with the sliding direction are better than those perpendicular to the sliding direction. CNTs-z can improve the shear resistance of rubber composites, reduce the magnitude of temperature rise and surface adhesion, and effectively improve the tribological properties of rubber materials. Under load and speed conditions, the friction coefficient and wear extent are negatively correlated. The friction coefficient decreases while the wear increases, and the effect of speed on tribological properties is greater than that of load. The research results can provide scientific references for improving the tribological properties and industrial application of CNTs composites tire rubber materials.

Ren-Gen Xiong, Han-Yue Zhang, Huan-Huan Jiang

Abstract Progesterone and its derivatives attracted widespread interest because of their applications in medicine, health care and birth control, which is the main active ingredient of contraceptive pills known as one of the five chemistry discoveries that changed human life. Although the research of pharmacological effects on contraceptive pill-related compounds has been around for decades, their ferroelectricity has long been overlooked. Here, we report that 4-androsten-3-one-5-ene-17-carboxylic acid, a derivative of progesterone, is an organic single-component ferroelectric, as confirmed by the polarization–electric field hysteresis loops. It crystallizes in the monoclinic space group P21 with a polar packing structure and undergoes a reversible structural phase transition at a high temperature of 489 K. Thermal analysis revealed that its ferroelectricity can persist up to 533 K, giving a wide working temperature range. As the first ferroelectric in steroid biomaterials, 4-androsten-3-one-5-ene-17-carboxylic acid shows great potential in applications for flexible devices, biomedical devices, bio-machines and so on.

Weirong Lin, Tong Wu, Chuanxi Wang et al.

This work reported a facile route for fabricating super-hydrophobic concrete via sizing sand grains. It was found that mixing the sands with a size ranging from 150–180 μ m into cement enabled the formation of a lotus-like surface with a papillary structure at micro-scale. SEM showed that the size of bumper was about 3 μ m. When spraying a fluorocarbon solution onto this surface, the porous nature of the cement matrix showed the advantage of taking the fluorocarbon into the internal structure of the concrete via capillary force. As a result, the sub surface up to a depth of ∼1.5 mm were transformed into a thick superhydrophobic layer directly. The contact angle (CA) of water droplets could reach 157° on this surface, and which could remain more than 150° after abrasion 100 cycles under a weight of 300 g at 360 grit sandpaper. This thick hydrophobic layer significantly reduced the corrosion rate of the steel the concrete at the Cl ^- environment by 620 times. The measurement of British pendulum number and compression strength revealed that this superhydrophobic layer was beneficial for maintaining the friction coefficient of the concrete surface in wet condition without altering the mechanical integrity of the concrete.

Xiaoqing Zhang, Wei Yuan, Honglin Huang et al.

The lithium-sulfur (Li-S) battery with an ultrahigh theoretical energy density has emerged as a promising rechargeable battery system. However, the practical applications of Li-S batteries are severely plagued by the sluggish reaction kinetics of sulfur species and notorious shuttling of soluble lithium polysulfides (LiPSs) intermediates that result in low sulfur utilization. The introduction of functional layers on separators has been considered as an effective strategy to improve the sulfur utilization in Li-S batteries by achieving effective regulation of LiPSs. Herein, a promising self-assembly strategy is proposed to achieve the low-cost fabrication of hollow and hierarchically porous Fe _3 O _4 nanospheres (p-Fe _3 O _4 -NSs) assembled by numerous extremely-small primary nanocrystals as building blocks. The rationally-designed p-Fe _3 O _4 -NSs are utilized as a multifunctional layer on the separator with highly efficient trapping and conversion features toward LiPSs. Results demonstrate that the nanostructured p-Fe _3 O _4 -NSs provide chemical adsorption toward LiPSs and kinetically promote the mutual transformation between LiPSs and Li _2 S _2 /Li _2 S during cycling, thus inhibiting the LiPSs shuttling and boosting the redox reaction kinetics via a chemisorption-catalytic conversion mechanism. The enhanced wettability of the p-Fe _3 O _4 -NSs-based separator with the electrolyte enables fast transportation of lithium ions. Benefitting from these alluring properties, the functionalized separator with p-Fe _3 O _4 -NSs endows the battery with an admirable rate performance of 877 mAh g ^−1 at 2 C, an ultra-durable cycling performance of up to 2176 cycles at 1 C, and a promising areal capacity of 4.55 mAh cm ^−2 under high-sulfur-loading and lean-electrolyte conditions (4.29 mg cm ^−2 , electrolyte/ratio: 8 µ l mg ^−1 ). This study will offer fresh insights on the rational design and low-cost fabrication of multifunctional separator to strengthen electrochemical reaction kinetics by regulating LiPSs conversion for developing efficient and long-life Li-S batteries.

Teunis van Manen, Shahram Janbaz, Kaspar M. B. Jansen et al.

Shape-shifting structures are important building blocks in the design of reconfigurable materials and devices with advanced functionalities. Here, versatile metamaterials with 3D-to-3D shape-shifting behavior upon thermal activation are fabricated by adapting a 3D printer to print on curved surfaces.

Toufik Fantous, Ammar Yahia

Yan Li Chen, Satoshk Ueharo

Glass fiber reinforced cement (GRC) is a new type of composite material formed by using alkali-resistant glass fiber as a reinforcing material and cement paste or cement mortar as a matrix. GRC is widely used in construction engineering. However, the durability of GRC is still a major problem in engineering applications, especially GRC materials have been in the hot and humid building engineering environment for a long time. The alkaline environment of the cement matrix will cause serious erosion of the glass fiber, and Will significantly reduce the mechanical properties such as flexural strength and toughness of GRC. In this paper, ordinary Portland cement is mixed with active mineral admixtures such as fly ash and silica fume to reduce the alkaline environment of GRC matrix, and to delay the erosion rate of glass fiber and increase the flexural strength and compressive strength of GRC; At the same time, the effects of different hot and humid building engineering environments on the mechanical properties of GRC were studied.

V. Guarino, V. Iannotti, G. Ausanio et al.

Small polymeric ducts incorporating a ribbon-shaped mat of densely packed magnetic nanofibers have been manufactured via electrospinning by using a cylindrical manifold, alternately under rotation or static. The magnetic nanofibers mat is located on the side of the tube and aligned to the longitudinal axis using the assistance of a magnetic field. The designed methodology ensures that the magnetic particles are completely wrapped into a protective polymer shell. Experimental results demonstrate that the innovative confinement of magnetic nanofibers, forming a longitudinal ribbon on a tube side, confers a high and reversible transverse strain under a moderate magnetic field stimulus: a magnetic field gradient ≤30 mT/mm, at a basic field intensity <0.04 T, induces a 40% decrement of the duct radius aligned with the magnetic force axis. In perspective, this is very attractive to fabricate magneto-active ducts suitable for microfluidic components, as well as biomedical devices to be applied in surgery and endoscopy.

Xiaodong Yu, Junling Zhao, Chengjiao Wu et al.

Antifogging coatings have tremendous application potential as they can prevent undesired fogging and blurring on transparent substrates when exposed to humid environment. However, most antifogging surfaces suffer from poor durability and tend to lose the antifogging property in the short term caused by airborne pollutant adsorption or environment weathering (e.g., UV irradiation). To address this issue, a series of zwitterionic and hydroxylated superhydrophilic coatings were prepared and their long-term antifogging properties under harsh conditions were systematically studied, including in a normal laboratory environment, under accelerated pollution test by exposing surfaces to acetic acid steam, and under UV irradiation. The prepared zwitterionic coatings showed significantly improved durability than the hydroxylated surfaces in all the test conditions, attributed to the chemical inertness and stability of the zwitterionic moieties. By incorporating zwitterionic coating and nanoscale roughness together, the longevity of antifogging surfaces can be further greatly improved, and eyeglasses treated with such nanostructured zwitterionic coating kept decent antifogging property even after storage for up to 210 days. The present nanostructured zwitterionic coatings are promising for real-world antifogging applications that can survive practical environmental fouling and weathering.

Wael Mahmood, Ahmed Mohammed, Kawan Ghafor

In this study, two types of polycarboxylate (PCE) polymer (DBC-21 and VK-98) were used as additives in the cement-based grout. The water-cement ratio (w/c) was fixed to 0.6 and 1.0 ​at temperature of 25° Celsius and 50° Celsius. Experimentalists were conducted to study the chemical composition of the cement-based grout, the mass loss, the rheology behavior, and the compressive strength. Numerical studies were performed to understand the shear strength, rheological properties and compressive strength by taking advantages of numerical models. The results show that the 0.16% PCE polymer additive leads to low cement weight loss at 800° Celsius, drastic increase of apparent and plastic viscosity, and significant improvement of compressive strength. Effects of polymer content, w/c, curing period and the temperature on the rheological properties and compressive strength (CS) of cement-based grout were investigated using a multiple nonlinear regression analysis.

吕安明

The die steel 4Cr5MoSiV1 was produced with the path of hot metal + scrap→100 t EAF→double LF→ double VD→ round billet continuous casting (section Φ 500 mm)→ step reheating furnace→ 950 rolling mill,in the special steel division new district of Shandong Steel. There are defects in the detection of individual batches die steel 4Cr5MoSiV1. By using the ultrasonic testing to locate the defect location, and analyzing with the way of Metallographic analysis and scanning electron microscopy (SEM) , finally confirmed the center defect and the rolling compression ratio small are the main reasons of the testing substandard batch of steel 4Cr5MoSiV1, and the corresponding improved measures are put forward.

ZHANG AYing, XU HongMing, CHEN Hao

Fastened joint repair is a main repair method for composite structure with advantages of easy disassembling,high load transferring capacity. It is important to evaluate the residual strength in repair design process. In this paper,the tensile load bearing capacity of metal riveted repair laminates were evaluated by numerical simulation using progressive failure analysis method. Laminate was modeled using shell element whereas the fasteners were modeled by beam elements. MPC technique was adopt to simulate the constraint between fastener and hole. The USDFLD subroutine was used to degrade material stiffness by multi-lever manner while damage occurred. The failure analysis results including failure mode,failure load are in good agreement with test results. The errors of predicted failure loads are with 6%,which shows the proposed method is helpful to composite fastened joint repair design.

Ngo Xuan Dinh, Tran Quang Huy, Le Van Vu et al.

In this work, a functional nanocomposite consisting of silver nanoparticles and multiwalled carbon nanotubes (MWCNTs-Ag) was successfully synthesized using a two-step chemical process. The MWCNTs-Ag nanocomposite has been studied as a surface-enhanced Raman scattering (SERS) sensing platform for detection of methylene blue (MB) dye in an aqueous medium. The obtained results reveal that the MWCNTs-Ag nanocomposite exhibits higher SERS detection activity than that of pure Ag-nanoparticles (Ag-NPs). The calculated enhancement factors are 1.51 × 106 for pure Ag-NPs and 4.68 × 106 for the MWCNTs-Ag nanocomposite. MB detection has been achieved as low as 1 ppm. The SERS enhancement of the MWCNTs-Ag nanocomposite can be attributed to the combination of both an electromagnetic (EM) effect and a chemical effect (CE). With exhibited properties, the MWCNTs-Ag nanocomposite can be effectively used for detection of various organic dyes in water solution.