bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimizing Stainless Steel Bearings: Enhancement of Stainless Steel Bearing Fatigue Life by Low-Temperature Forming
Authors: Bodewig Alexander Heinrich , Pape Florian , Poll Gerhard
Published: May 2024

A proposed low-temperature forging method is presented to enhance stainless steel bearings by creating a martensitic subsurface layer, significantly boosting bearing fatigue life due to increased surface hardness. This technique induces beneficial residual stresses, particularly in axial bearings, streamlining their construction and improving machine elements. Challenges persist, especially with radial bearings, but simplicity in axial bearing forging promotes compact, resource-efficient facility construction. Future research will focus on applying this technique to axial bearing washers, potentially replicating success in other bearing components. Despite the energy expenditure on cooling during forging, the substantial increase in bearing fatigue life offsets this, enhancing overall durability and reliability of critical machine components. Integration of this forging technique into bearing fabrication appears seamless, offering a promising trade-off between energy use and enhanced performance.
Improving Maraging Steel 350 Machinability via Wiper Insert-Enhanced Face Milling
Authors: Abbas Adel T. , Helmy Mohamed O. , Alqosaibi Khalid F. , Parvez Shahid , Hasan Ali S. , Elkaseer Ahmed
Published: May 2024

Despite the prevalent application of 18% Ni maraging steel in critical sectors such as aerospace and automotive due to its unique characteristics, including high ductility, yield strength, and hardenability, its machining presents enormous challenges, categorizing it as a difficult-to-machine material. The cutting tool’s geometry is crucial in machining, significantly affecting chip formation, cutting forces, power consumption, and obtainable surface quality. In particular, wiper insert technology, characterized by its multi-radius design, offers an increased contact area compared to conventional inserts, potentially enhancing the quality of the machined surface. This study explores the effectiveness of wiper inserts in the face-milling of maraging steel 350, conducting a comparative analysis across three distinct machining setups. These setups vary by alternating the number of wiper and conventional inserts within the same cutter, thereby examining the influence of insert configuration on machining outcomes. The research employs a reliable and well-established statistical approach to evaluate how different variables, such as cutting speed and feed rate, affect surface quality, power consumption, and material removal rate (MRR). It also sheds light on the material removal mechanisms facilitated by each type of insert. The findings reveal that incorporating a higher number of wiper inserts significantly enhances the surface finish but concurrently increases power consumption. Thus, the study successfully identifies an optimal set of process parameters that attain a balance between achieving superior surface quality and maintaining energy efficiency in the machining of maraging steel 350. This balance is crucial for optimizing manufacturing processes while adhering to the stringent quality and sustainability standards required in aerospace and automotive manufacturing.
Strip Casting of Sm2TM17-Type Alloys for Production of the Metastable SmTM7 Phase
Authors: Sheridan Richard , Gresle-Farthing Joseph , Appleby Alice , Brown Mangaliso
Published: May 2024

Conventional book casting of Sm2TM17-type alloys (where TM = Co, Fe, Cu, Zr) leads to a coarse, highly segregated microstructure, predominantly due to the slow, variable cooling rate from the mould surface towards the centre of the ingot. These cast alloys require a long homogenisation treatment to remove this segregation and develop a super-saturated, metastable SmTM7-type hexagonal phase. This SmTM7 phase is a vital precursor phase required during magnet production to develop the complex cellular structure responsible for high magnetic properties. In this work, strip casting was employed to facilitate rapid solidification to develop thin flakes (<0.5 mm thick) with a columnar grain structure. Rapid cooling has the potential to produce a homogenous microstructure consisting predominantly of the metastable SmTM7 phase. This could remove or significantly reduce the need for the energy-intensive homogenisation treatment usually required in conventional magnet manufacture. This paper investigates the effect of wheel speed (and hence cooling rate) on flake thickness, microstructure, and phase balance of the cast alloys. It was shown that for wheel speeds between 1.1 and 3.0 m/s, the microstructure showed large variation; however, in all cases, evidence of the columnar SmTM7 phase was presented. The adhesion between the melt and the wheel was deemed to be critical for the nucleation and subsequent columnar growth of SmTM7 grains, where the wheel speed controlled both the flow of the alloy onto the wheel and the thickness of the resultant flake. It was determined that in order to achieve a homogenous columnar SmTM7 structure, the maximum flake thickness should be limited to 270 μm to avoid the formation of equiaxed Sm2TM17 grains through insufficient cooling.
Mixing Time Prediction in a Ladle Furnace
Authors: Guo Xipeng , Liu Yun , Jojo-Cunningham Yasmeen , Silaen Armin , Walla Nicholas , Zhou Chenn
Published: May 2024

This paper presents a study on the effectiveness of two turbulence models, the large eddy simulation (LES) model and the k-ε turbulence model, in predicting mixing time within a ladle furnace using the computational fluid dynamics (CFD) technique. The CFD model was developed based on a downscaled water ladle from an industrial ladle. Corresponding experiments were conducted to provide insights into the flow field, which were used for the validation of CFD simulations. The correlation between the flow structure and turbulence kinetic energy in relation to mixing time was investigated. Flow field results indicated that both turbulence models aligned well with time-averaged velocity data from the experiments. However, the LES model not only offered a closer match in magnitude but also provided a more detailed representation of turbulence eddies. With respect to predicting mixing time, increased flow rates resulted in extended mixing times in both turbulence models. However, the LES model consistently projected longer mixing times due to its capability to capture a more intricate distribution of turbulence eddies.
Advances in Understanding the Evolution Mechanism of Micropore Defects in Metal Materials under External Loads
Authors: Liang Jianwei , Zhang Menghao , Peng Yan , Wang Jiapo
Published: May 2024

Micropores are one of the critical factors affecting materials’ performance and service life. As the need for a deeper understanding of micropore evolution and damage mechanisms grows, assessing the mechanical properties of materials containing micropores and predicting the lifespan of related metal structural components becomes increasingly complex. This paper focuses on the evolution process, regularities, and research methods of micropores in metal materials. Based on recent research and practical applications, the key stages of micropore evolution are discussed, encompassing nucleation, growth, coalescence, collapse, interaction, and the influence of other microstructures. Firstly, the advantages and limitations of commonly used characterization methods such as scanning electron microscopy, transmission electron microscopy, and X-ray computed tomography are introduced in the study of micropore evolution. Subsequently, critical theoretical models for micropore evolution, such as the Gurson model and its extensions, are summarized. By using a multiscale approach combining the crystal plasticity finite element method, dislocation dynamics, and molecular dynamics, the factors influencing the micropore evolution, such as external stress conditions, internal microstructures, and micropore characteristics, are specifically elaborated, and the basic physical mechanisms of micropore evolution are analyzed. Finally, a comprehensive review and summary of current research trends and key findings are provided, and a forward-looking perspective on future research directions is presented.
On the Link between Plastic Wake Induced Crack Closure and the Fatigue Threshold
Authors: Jones Rhys , Ang Andrew , Phan Nam D. , Nicholas Michael
Published: May 2024

This purpose of this paper is to examine the relationship between crack growth equations based on Elber’s original plastic wake induced crack closure concept and the fatigue threshold as defined by the American Society for Testing and Materials (ASTM) fatigue test standard ASTM E647-15el. It is shown that, for a number of conventionally manufactured metals, the function U(R), where R is the ratio of the minimum to maximum applied remote stress, that is used to relate the stress intensity factor ΔK to the effective stress intensity factor ΔKeff is inversely proportional to the fatigue threshold ΔKth(R). This finding also results in a simple closed form equation that relates the crack opening stress intensity factor Ko(R) to ΔK, Kmax, and the fatigue threshold terms ΔKth(R) and ΔKeff,th. It is also shown that plotting da/dN as function of ΔK/ΔKth(R) would appear to have the potential to help to identify the key fracture mechanics parameters that characterise the effect of test temperature on crack growth. As such, for conventionally manufactured metals, plotting da/dN as function of ΔK/ΔKth(R) would appear to be a useful addition to the tools available to assess the fracture mechanics parameters affecting crack growth.
Diffusion Nitride Surface Layers on Aluminum Substrates Produced by Hybrid Method Using Gas Nitriding
Authors: Tacikowski Michał , Słoma Jacek , Jakieła Rafał , Marciniak Szymon , Diduszko Ryszard , Wierzchoń Tadeusz
Published: May 2024

While gas nitriding of steel is currently used in industry, nitriding of aluminum alloys remains an open challenge. The main obstacle is aluminum’s high susceptibility to passivation. The oxide film provides an effective barrier to nitrogen diffusion. Attempts to overcome this problem have mainly focused on glow discharge nitriding using cathode sputtering of an oxide layer. The produced AlN layers exhibit no diffusion zone and show limited performance properties. In this work, the effect of hybrid treatment aimed at producing diffusion layers of nitrides other than AlN on aluminum alloys was investigated on the model system of iron nitride–aluminum substrate. Hybrid treatment combines an electrochemical process involving the removal of the aluminum oxide layer from the substrate, its subsequent iron plating, and a further gas nitriding in high-purity ammonia. The obtained results prove that the hybrid treatment allows the production, at 530 °C/10 h, of diffusion layers of Fe3N iron nitrides on aluminum substrates with a nitrogen diffusion zone range in aluminum of ca. 12 µm. In alloys containing magnesium, its unfavorable effect on the nitrogen diffusion and the functional properties of the layers was observed. An interesting direction for further research is hybrid treatment of precipitation-hardened alloys without magnesium.
Microstructure and Microhardness of High-Strength Aluminium Alloy Prepared Using High-Speed Laser Fabrication
Authors: Wu Yu , Chen Bingqing , Xu Peixin , Tang Pengjun , Du Borui , Huang Chen
Published: May 2024

As a recently developed high-strength aluminium alloy used specifically for laser additive manufacturing, AlMgMnSc alloy possesses superior mechanical properties and excellent processability. Extreme high-speed laser deposition (EHLD) is a novel surface-modification technique, which is characterised by high depositing speed, rapid cooling, rate and minimal dilution rate. To offer a new method for surface repairing high-strength aluminium alloys, an AlMgMnSc alloy coating, containing two deposition layers, is prepared on a 6061 aluminium-alloy axle using the EHLD technique. Meanwhile, the microstructure, composition distribution, and microhardness variation of the fabricated coating are studied. The results reveal that the coating is dense and crack-free, which is well-bonded with the substrate. Additionally, layer 1 is mainly composed of large columnar and equiaxed grains, while layer 2 consists of a fully equiaxed grain structure with an average grain size of about 4.5 μm. Moreover, the microhardness of the coating (about 104~118 HV) is similar to the substrate (about 105 HV), proving the feasibility of repairing high-strength aluminium alloys using AlMgMnSc alloy powders through the EHLD technique.
New Insight into Electric Force in Metal and the Quadratic Electrical Resistivity Law of Metals at Low Temperatures
Authors: Palenskis Vilius
Published: May 2024

Considering that Einstein’s relation between the diffusion coefficient and the drift mobility of free randomly moving charge carriers in homogeneous materials including metals is always valid, it is shown that the effective electric force acting on free electrons in metal depends on the ratio between the kinetic free electron energy at the Fermi surface to the classical particle energy 3 kT/2. The electrical resistivity of elemental metals dependence on very low temperatures has the quadratic term, which has been explained by electron–electron scattering. In this paper, it is shown that the quadratic term of the electrical resistivity at low temperatures is caused by scattering of the free randomly moving electrons by electronic defects due to linear effective free electron scattering cross-section dependence on temperature, but not by electron–electron scattering.
Ductile Fracture of Titanium Alloys in the Dynamic Punch Test
Authors: Skripnyak Vladimir V. , Skripnyak Vladimir A.
Published: May 2024

Estimates of physical and mechanical characteristics of materials at high strain rates play a key role in enhancing the accuracy of prediction of the stress–strain state of structures operating in extreme conditions. This article presents the results of a combined experimental–numerical study on the mechanical response of a thin-sheet rolled Ti-5Al-2.5Sn alloy to dynamic penetration. A specimen of a titanium alloy plate underwent punching with a hemispherical indenter at loading rates of 10, 5, 1, and 0.5 m/s. The evolution of the rear surface of specimens and crack configuration during deformation were observed by means of high-speed photography. Numerical simulations were performed to evaluate stress distribution in a titanium plate under specified loading conditions. To describe the constitutive behavior and fracture of the Ti-5Al-2.5Sn alloy at moderate strain rates, a physical-based viscoplastic material model and damage nucleation and growth relations were adopted in the computational model. The results of simulations confirm a biaxial stress state in the center of specimens prior to fracture initiation. The crack shapes and plate deflections obtained in the calculations are similar to those observed in experiments during dynamic punching.
Directed Energy Deposition of Metal Alloys
Authors: Andersson Joel
Published: May 2024

Directed energy deposition (DED) stands as an advancement in material utilization, facilitating the production of highly precise near-net shape components using wire and powders [...]
Cytotoxicity, Corrosion Resistance, and Wettability of Titanium and Ti-TiB2 Composite Fabricated by Powder Metallurgy for Dental Implants
Authors: Aljafery Ali Mohammad Ali , Fatalla Abdalbseet A. , Haider Julfikar
Published: May 2024

Objectives: Orthopedics and dentistry have widely utilized titanium alloys as biomaterials for dental implants, but limited research has been conducted on the fabrication of ceramic particle-reinforced Ti composites for further weight reductions. The current study compared titanium–titanium diboride metal composites (Ti-TiB2) with pure titanium (processed by powder metallurgy) in terms of toxicity, corrosion resistance, and wettability. Methods: First, cell lines of a primary dermal fibroblast normal human adult (HDFa) were used to test the cytocompatibility (in vitro) of the composite and pure Ti using an indirect contact approach. Corrosion testing was performed for the materials using electrochemical techniques such as potentiodynamic polarization in a simulated bodily fluid (SBF) in conjunction with a three-electrode electrochemical cell. The entire set of experimental tests was conducted according to the ASTM F746-04 protocol. The contact angles were measured during wettability testing in accordance with ASTM D7334-08. An X-ray diffractometer (XRD) was used to catalog every phase that was visible in the microstructure. A scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to determine the chemical composition. Results: The cytotoxicity tests revealed that there was no detectable level of toxicity, and there was no significant difference in the impact of either of the two materials on the viability of human fibroblasts. An increase in the corrosion resistance of the composite (0.036 ± 0.0001 mpy (millimeters per year)) demonstrated the development of a passive oxide coating. According to the findings, the composites showed a greater degree of hydrophilicity (contact angle 44.29° ± 0.28) than did the pure titanium (56.31° ± 0.47). Conclusions/Significance: The Ti-TiB2 composite showed no toxicity and better corrosion resistance and wettability than did pure Ti. The composite could be a suitable alternative to Ti for applications involving dental implants.
A Silicon-Based ROTE Sensor for High-Q and Label-Free Carcinoembryonic Antigen Detection
Authors: Sang Luxiao , Liang Haojie , Zhao Biao , Shi Runze , Jian Aoqun , Sang Shengbo
Published: May 2024

This paper presents a biosensor based on the resonant optical tunneling effect (ROTE) for detecting a carcinoembryonic antigen (CEA). In this design, sensing is accomplished through the interaction of the evanescent wave with the CEA immobilized on the sensor’s surface. When CEA binds to the anti-CEA, it alters the effective refractive index (RI) on the sensor’s surface, leading to shifts in wavelength. This shift can be identified through the cascade coupling of the FP cavity and ROTE cavity in the same mode. Experimental results further show that the shift in resonance wavelength increases with the concentration of CEA. The biosensor responded linearly to CEA concentrations ranging from 1 to 5 ng/mL with a limit of detection (LOD) of 0.5 ng/mL and a total Q factor of 9500. This research introduces a new avenue for identifying biomolecules and cancer biomarkers, which are crucial for early cancer detection.
Fluorescence-Based Image Analysis of Seepage Behavior in Drip Irrigation: Exploring Varied Fractal Grading in Media Permeability
Authors: Wang Xiaolong , Huang Junjie , Li Xiang , Yuan Wenbin , Liu Hongchang , Gan Min , Wang Jun , Zhang Yansheng
Published: May 2024

In the recycling of low-value metallic elements, heap leaching is commonly employed. The particle size distribution is a crucial parameter in heap leaching implementation, and the percolation behavior of a heap has always been a focal point in heap leaching technology. This paper utilizes a novel form of ultraviolet fluorescence image acquisition and fluorescence image analysis to investigate the percolation process with different fractal dimension particle size distributions, where the maximum particle diameter is 10 mm. The ore used was low-grade copper ore. The results indicate that the new fluorescence image analysis method can reveal different percolation regions during the heap leaching process, aiding in a better understanding of heap leaching behavior. The combined study found that under irrigation conditions of 10 mL/min, seepage was more uniform under the heap structure formed by a particle gradation with a fractal dimension of 2.2.
New Insights into the Role of Thiol Collectors in Malachite Flotation
Authors: Yang Congren , Chen Siying , Li Haodong , Qin Wenqing
Published: May 2024

Malachite is one of the most important copper-bearing oxide minerals; however, it shows poor floatability prior to sulfidization under the thiol collector system. This study investigated the reasons for the low recovery of malachite flotation without sulfidization. The results of adsorption capacity and contact angle test indicated that the malachite surface could adsorb a sufficient amount of the collector, obviously increasing the hydrophobicity of the malachite surface under static conditions. By measuring the amount of inorganic carbon in the flotation solution, it was found that the amount of inorganic carbon in the solution increased significantly when the thiol collectors were added into pulp, which could be attributed to the induced dissolution of the malachite surface by thiol collectors. Solubility tests further demonstrated that the copper ions released from the natural dissolution of malachite proved difficult in regard to reactions with thiol collector to form precipitates; however, the thiol collector induced the dissolution of malachite surface, and so the hydrophobic complexes’ copper-collector could not firmly adsorb on the mineral surface. Fourier transform infrared (FTIR) analysis revealed that thiol collectors do not adsorb stably on malachite surfaces. This was considered to be a substantial reason for the poor performance of malachite flotation without sulfidization.
Chitosan as a Bio-Based Ligand for the Production of Hydrogenation Catalysts
Authors: Paganelli Stefano , Brugnera Eleonora , Di Michele Alessandro , Facchin Manuela , Beghetto Valentina
Published: May 2024

Bio-based polymers are attracting increasing interest as alternatives to harmful and environmentally concerning non-biodegradable fossil-based products. In particular, bio-based polymers may be employed as ligands for the preparation of metal nanoparticles (M(0)NPs). In this study, chitosan (CS) was used for the stabilization of Ru(0) and Rh(0) metal nanoparticles (MNPs), prepared by simply mixing RhCl3 × 3H2O or RuCl3 with an aqueous solution of CS, followed by NaBH4 reduction. The formation of M(0)NPs-CS was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Analysis (EDX), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). Their size was estimated to be below 40 nm for Rh(0)-CS and 10nm for Ru(0)-CS by SEM analysis. M(0)NPs-CS were employed for the hydrogenation of (E)-cinnamic aldehyde and levulinic acid. Easy recovery by liquid-liquid extraction made it possible to separate the catalyst from the reaction products. Recycling experiments demonstrated that M(0)NPs-CS were highly efficient up to four times in the best hydrogenation conditions. The data found in this study show that CS is an excellent ligand for the stabilization of Rh(0) and Ru(0) nanoparticles, allowing the production of some of the most efficient, selective and recyclable hydrogenation catalysts known in the literature.
UVC Stokes and Anti-Stokes Emission of Ca9Y(PO4)7 Polycrystals Doped with Pr3+ Ions
Authors: Lemański Karol , Bezkrovna Olha , Rebrova Nadiia , Lisiecki Radosław , Zdeb Patrycja , Dereń Przemysław Jacek
Published: May 2024

The recent COVID-19 pandemic has made everyone aware of the threat of viruses and the growing number of antibiotic-resistant bacteria. It has become necessary to find new methods to combat these hazards. One tool that could be used is UVC radiation, i.e., 100–280 nm. Currently, the available sources of this light are mercury vapor lamps. However, the modern world requires more compact, mercury-free, and less energy-consuming light sources. This work presents the results of our research on a new material in which efficient UVC radiation was obtained. Here, we present the results of research on Ca9Y(PO4)7 polycrystals doped with Pr3+ ions prepared using the solid-state method. The absorption, excitation, emission, and emission decay profiles of praseodymium(III) ions were measured and analyzed. The upconversion emission in the UVC region excited by blue light was observed. Parameters such as energy bandgap, refractive index, and thermal stability of luminescence were determined. The studied phosphate-based phosphor possesses promising characteristics that show its potential in luminescent applications in future use in medicine or for surface disinfection.
Antibiofilm Activity of Combretum micranthum G. Don Catechin–Sugar Phytocomplex on Pseudomonas aeruginosa
Authors: Orlandi Viviana Teresa , Bolognese Fabrizio , Chiodaroli Luca , Armenia Ilaria , Caruso Enrico , Malacarne Miryam Chiara
Published: May 2024

Clinicians often have to face infections caused by microorganisms that are difficult to eradicate due to their resistance and/or tolerance to antimicrobials. Among these pathogens, Pseudomonas aeruginosa causes chronic infections due to its ability to form biofilms on medical devices, skin wounds, ulcers and the lungs of patients with Cystic Fibrosis. In this scenario, the plant world represents an important reservoir of natural compounds with antimicrobial and/or antibiofilm properties. In this study, an extract from the leaves of Combretum micranthum G. Don, named Cm4-p, which was previously investigated for its antimicrobial activities, was assayed for its capacity to inhibit biofilm formation and/or to eradicate formed biofilms. The model strain P. aeruginosa PAO1 and its isogenic biofilm hyperproducer derivative B13 were treated with Cm4-p. Preliminary IR, UV-vis, NMR, and mass spectrometry analyses showed that the extract was mainly composed of catechins bearing different sugar moieties. The phytocomplex (3 g/L) inhibited the biofilm formation of both the PAO1 and B13 strains in a significant manner. In light of the obtained results, Cm4-p deserves deeper investigations of its potential in the antimicrobial field.
Development of New Drugs to Treat Tuberculosis Based on the Dinitrobenzamide Scaffold
Authors: Delgado Tiago , Pais João P. , Pires David , Estrada Filipe G. A. , Guedes Rita C. , Anes Elsa , Constantino Luis
Published: May 2024

Tuberculosis (TB) continues to be a major global health challenge and a leading cause of death from infectious diseases. Inspired by the results from a previous work by our group on antimycobacterial N-alkylnitrobenzamides, which are structurally related to the nitrobenzamide family of decaprenylphosphoryl-β-d-ribose oxidase (DprE1) inhibitors, the present study explored a broad array of substituted benzamides. We particularly focused on previously unexplored 3,5-dinitrobenzamide derivatives. Starting with 3,5-dinitrobenzoic acid, we synthesized a diverse library of amides, incorporating both linear and cyclic amine moieties and also assessed the impact of terminal aromatic groups connected through ether, ester, or amide bonds on the bioactivity of the compounds. The synthesis primarily utilized nucleophilic addition/elimination, SN2, and Mitsunobu reactions. The activity was impacted mainly by two structural features, the addition of an aromatic moiety as a terminal group and the type of linker. The most interesting compounds (c2, d1, and d2, MIC = 0.031 μg/mL) exhibited activities against Mycobacterium Tuberculosis (Mtb) H37Rv comparable to isoniazid. Complementary computational studies helped elucidate potential interactions with DprE1, enhancing our understanding of the molecular basis of their action. Our findings suggest that the most active compounds provide a promising foundation for the continued development of new antimycobacterial agents.
Antimicrobial Effect of Honey Phenolic Compounds against E. coli—An In Vitro Study
Authors: Kassym Laura , Kussainova Assiya , Semenova Yuliya , McLoone Pauline
Published: May 2024

Growing concern over antimicrobial resistance in chronic wound patients necessitates the exploration of alternative treatments from natural sources. This study suggests that honey’s phenolic compounds may offer antimicrobial benefits, warranting further investigation for therapeutic development. The main aim of this study was to investigate the antimicrobial activity of phenolic compounds and to determine the effects of their sub-inhibitory concentrations against Escherichia coli (E. coli). 3-phenyllactic acid (PLA), p-coumaric acid (PCA), and phloretin were tested against the bacterial strain of E. coli ATCC 25922. Comparison of the antimicrobial activity of honey constituents in vitro was performed using a broth culture assay. Measurement of the inhibitory properties of constituents in vitro was conducted using disc and well diffusion assays. The effects of sub-inhibitory concentrations of PCA on the susceptibility of E. coli ATCC 25922 to penicillin–streptomycin were tested. The results demonstrated that PLA was the most efficient antimicrobial agent, followed by PCA, whereas phloretin, at lower (2 mg/mL) concentrations, led to an increase in the growth of E. coli. Various modifications of the agar diffusion assay did not reveal the antibacterial properties of the studied phytochemicals. The enhancing effect of a sub-inhibitory concentration of PCA in cooperation with penicillin–streptomycin was shown. These findings might be helpful for the further investigation and development of new antimicrobial agents for the treatment of skin infections and wounds.
Effect of Lampaya medicinalis Phil. (Verbenaceae) and Palmitic Acid on Insulin Signaling and Inflammatory Marker Expression in Human Adipocytes
Authors: Yuri Gabriela , Cifuentes Mariana , Cisternas Pedro , Paredes Adrián , Ormazabal Paulina
Published: May 2024

Background: Aging and obesity are associated with insulin resistance (IR) and low-grade inflammation. Molecularly, IR is characterized by a reduction in glucose uptake and insulin signaling (IRS-1/Akt/AS160 pathway), while inflammation may result from upregulated NF-κB pathway after low Tyr-IκBα phosphorylation. Upregulated phosphatase activity of PTP1B is associated with impaired insulin signaling and increased inflammation. Plasma levels of palmitic acid (PA) are elevated in obesity, triggering inflammation and disruption of insulin signaling. Traditional medicine in Northern Chile uses oral infusions of Lampaya medicinalis Phil. (Verbenaceae) to treat inflammatory conditions. Significant amounts of flavonoids are found in the hydroethanolic extract of Lampaya (HEL), which may account for its biological activity. The aim of this work was to study the effect of HEL and PA on insulin signaling and glucose uptake as well as inflammatory marker expression in human adipocytes. Methods: We studied HEL effects on PA-induced impairment on insulin signaling, glucose uptake and inflammatory marker content in human SW872 adipocytes. HEL cytotoxicity was assessed in adipocytes at different concentrations (0.01 to 10 g/mL). Adipocytes were incubated or not with PA (0.4 mM, 24 h) with or without HEL (2 h pre-incubation), and then stimulated with insulin (10 min, 100 mM) or a vehicle. Phospho-IRS-1, phospho-Akt, phospho-AS160, phospho-NF-κB and phospho-IκBα, as well as protein levels of PTP1B, were assessed using Western blotting, and glucose uptake was evaluated using the 2-NBDG analogue. Results: At the assessed HEL concentrations, no cytotoxic effects were observed. PA decreased insulin-stimulated phospho-Akt and glucose uptake, while co-treatment with HEL increased such markers. PA decreased phospho-IRS-1 and phospho-Tyr-IκBα. On the other hand, incubation with HEL+PA decreased phospho-AS160 and phospho-NF-κB compared with cells treated with PA alone. Conclusion: Our results suggest a beneficial effect of HEL by improving PA-induced impairment on molecular markers of insulin signaling, glucose uptake and inflammation in adipocytes. Further studies are necessary to elucidate whether lampaya may constitute a preventive strategy for people whose circulating PA levels contribute to IR and inflammation during aging and obesity.
Synthesis and Evaluation of 5-(Heteroarylmethylene)hydantoins as Glycogen Synthase Kinase-3β Inhibitors
Authors: Schneider Nicholas O. , Gilreath Kendra , Burkett Daniel J. , St. Maurice Martin , Donaldson William A.
Published: May 2024

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase which plays a center role in the phosphorylation of a wide variety of proteins, generally leading to their inactivation. As such, GSK-3 is viewed as a therapeutic target. An ever-increasing number of small organic molecule inhibitors of GSK-3 have been reported. Phenylmethylene hydantoins are known to exhibit a wide range of inhibitory activities including for GSK-3β. A family of fourteen 2-heterocycle substituted methylene hydantoins (14, 17–29) were prepared and evaluated for the inhibition of GSK-3β at 25 μM. The IC50 values of five of these compounds was determined; the two best inhibitors are 5-[(4′-chloro-2-pyridinyl)methylene]hydantoin (IC50 = 2.14 ± 0.18 μM) and 5-[(6′-bromo-2-pyridinyl)methylene]hydantoin (IC50 = 3.39 ± 0.16 μM). The computational docking of the compounds with GSK-3β (pdb 1q41) revealed poses with hydrogen bonding to the backbone at Val135. The 5-[(heteroaryl)methylene]hydantoins did not strongly inhibit other metalloenzymes, demonstrating poor inhibitory activity against matrix metalloproteinase-12 at 25 μM and against human carbonic anhydrase at 200 μM, and were not inhibitors for Staphylococcus aureus pyruvate carboxylase at concentrations >1000 μM.
Anti-Biofilm and Anti-Quorum-Sensing Activity of Inula Extracts: A Strategy for Modulating Chromobacterium violaceum Virulence Factors
Authors: Dimitrova Petya D. , Ivanova Viktoria , Trendafilova Antoaneta , Paunova-Krasteva Tsvetelina
Published: May 2024

The formation of microbial biofilm is a self-organizing process among bacterial cells, regulated by quorum-sensing (QS) mechanisms, contributing to development of infections. These processes, either separately or in combination, significantly contribute to bacterial resistance to antibiotics and disinfectants. A novel approach to addressing the challenge of treating infections due to antibacterial resistance involves the use of plant metabolites. In recent years, there has been increasing recognition of different phytochemicals as potential modulators. In our study, we evaluated the synergistic effect of chloroform and methanol extracts from Inula species against key virulence factors, including biofilm formation, violacein production, and swarming motility. Each of the 11 examined plant extracts demonstrated the ability to reduce biofilms and pigment synthesis in C. violaceum. Two of the extracts from I. britannica exhibited significant anti-biofilm and anti-quorum-sensing effects with over 80% inhibition. Their inhibitory effect on violacein synthesis indicates their potential as anti-QS agents, likely attributed to their high concentration of terpenoids (triterpenoids, sesquiterpene lactones, and diterpenoids). Scanning electron microscopy revealed a notable reduction in biofilm biomass, along with changes in biofilm architecture and cell morphology. Additionally, fluorescence microscopy revealed the presence of metabolically inactive cells, indicating the potent activity of the extracts during treatment. These new findings underscore the effectiveness of the plant extracts from the genus Inula as potential anti-virulent agents against C. violaceum. They also propose a promising strategy for preventing or treating its biofilm formation.
Potential Anti-Tumorigenic Properties of Diverse Medicinal Plants against the Majority of Common Types of Cancer
Authors: Albahri Ghosoon , Badran Adnan , Abdel Baki Zaher , Alame Mohamad , Hijazi Akram , Daou Anis , Baydoun Elias
Published: May 2024

Globally, cancer is one of the primary causes of both morbidity and mortality. To prevent cancer from getting worse, more targeted and efficient treatment plans must be developed immediately. Recent research has demonstrated the benefits of natural products for several illnesses, and these products have played a significant role in the development of novel treatments whose bioactive components serve as both chemotherapeutic and chemo-preventive agents. Phytochemicals are naturally occurring molecules obtained from plants that have potential applications in both cancer therapy and the development of new medications. These phytochemicals function by regulating the molecular pathways connected to the onset and progression of cancer. Among the specific methods are immune system control, inducing cell cycle arrest and apoptosis, preventing proliferation, raising antioxidant status, and inactivating carcinogens. A thorough literature review was conducted using Google Scholar, PubMed, Scopus, Google Patent, Patent Scope, and US Patent to obtain the data. To provide an overview of the anticancer effects of several medicinal plants, including Annona muricata, Arctium lappa, Arum palaestinum, Cannabis sativa, Catharanthus roseus, Curcuma longa, Glycyrrhiza glabra, Hibiscus, Kalanchoe blossfeldiana, Moringa oleifera, Nerium oleander, Silybum marianum, Taraxacum officinale, Urtica dioica, Withania somnifera L., their availability, classification, active components, pharmacological activities, signaling mechanisms, and potential side effects against the most common cancer types were explored.
Characterization, Biocompatibility and Antioxidant Activity of Hydrogels Containing Propolis Extract as an Alternative Treatment in Wound Healing
Authors: Ferreira Lindalva Maria de Meneses Costa , Modesto Yuri Yoshioka , Souza Poliana Dimsan Queiroz de , Nascimento Fabiana Cristina de Araújo , Pereira Rayanne Rocha , Converti Attilio , Lynch Desireé Gyles , Brasil Davi do Socorro Barros , da Silva Edilene Oliveira , Silva-Júnior José Otávio Carréra , Ribeiro-Costa Roseane Maria
Published: May 2024

Hydrogels consist of a network of highly porous polymeric chains with the potential for use as a wound dressing. Propolis is a natural product with several biological properties including anti-inflammatory, antibacterial and antioxidant activities. This study was aimed at synthesizing and characterizing a polyacrylamide/methylcellulose hydrogel containing propolis as an active ingredient, to serve as a wound dressing alternative, for the treatment of skin lesions. The hydrogels were prepared using free radical polymerization, and were characterized using scanning electron microscopy, infrared spectroscopy, thermogravimetry, differential scanning calorimetry, swelling capacity, mechanical and rheological properties, UV-Vis spectroscopy, antioxidant activity by the DPPH, ABTS and FRAP assays and biocompatibility determined in Vero cells and J774 macrophages by the MTT assay. Hydrogels showed a porous and foliaceous structure with a well-defined network, a good ability to absorb water and aqueous solutions simulating body fluids as well as desirable mechanical properties and pseudoplastic behavior. In hydrogels containing 1.0 and 2.5% propolis, the contents of total polyphenols were 24.74 ± 1.71 mg GAE/g and 32.10 ± 1.01 mg GAE/g and those of total flavonoids 8.01 ± 0.99 mg QE/g and 13.81 ± 0.71 mg QE/g, respectively, in addition to good antioxidant activity determined with all three methods used. Therefore, hydrogels containing propolis extract, may serve as a promising alternative wound dressing for the treatment of skin lesions, due to their anti-oxidant properties, low cost and availability.
Insulin Treatment Does Not Prevent EARLY Autonomic Cardiovascular and Diastolic Dysfunctions in Streptozotocin-Induced Diabetic Rats
Authors: Freitas Sarah C. F. , Dutra Marina R. H. , Dourado Paulo M. M. , Miranda Victor Hugo de Martins , dos Santos Camila P. , Sanches Iris C. , Irigoyen Maria-Cláudia , De Angelis Kátia
Published: May 2024

Recent studies have found increased cardiovascular mortality risk in patients with type 1 diabetes when compared to normoglycemic people, even when they were kept under good glycemic control. However, the mechanisms underlying this condition have yet to be fully understood. Using streptozotocin (STZ)-induced diabetic rats, we evaluated the effects of insulin replacement therapy on cardiac, autonomic, inflammatory, and oxidative stress parameters. Daily treatment with insulin administrated subcutaneously in the STZ-diabetic rats showed a reduction in hyperglycemia (>250 mg/dL) to normalized values. The insulin treatment was effective in preventing alterations in cardiac morphometry and systolic function but had no impact on diastolic function. Also, the treatment was not able to prevent the impairment of baroreflex-tachycardic response and systolic arterial pressure variability (SAP-V). A correlation was found between improvement of these autonomic parameters and higher levels of IL-10 and lower levels of oxidized glutathione. Our findings show that insulin treatment was not able to prevent diastolic, baroreflex, and SAP-V dysfunction, suggesting an outstanding cardiovascular risk, even after obtaining a good glycemic control in STZ-induced diabetic rats. This study shed light on a relatively large population of diabetic patients in need of other therapies to be used in combination with insulin treatment and thus more effectively manage cardiovascular risk.
Anticancer Potential and Molecular Targets of Pristimerin in Human Malignancies
Authors: Prabhu Kirti , Jessy Serah , Kuttikrishnan Shilpa , Mujeeb Farina , Mariyam Zahwa , Habeeba Ummu , Ahmad Nuha , Bhat Ajaz , Uddin Shahab
Published: May 2024

The growing global burden of malignant tumors with increasing incidence and mortality rates underscores the urgent need for more effective and less toxic therapeutic options. Herbal compounds are being increasingly studied for their potential to meet these needs due to their reduced side effects and significant efficacy. Pristimerin (PS), a triterpenoid from the quinone formamide class derived from the Celastraceae and Hippocrateaceae families, has emerged as a potent anticancer agent. It exhibits broad-spectrum anti-tumor activity across various cancers such as breast, pancreatic, prostate, glioblastoma, colorectal, cervical, and lung cancers. PS modulates several key cellular processes, including apoptosis, autophagy, cell migration and invasion, angiogenesis, and resistance to chemotherapy, targeting crucial signaling pathways such as those involving NF-κB, p53, and STAT3, among others. The main objective of this review is to provide a comprehensive synthesis of the current literature on PS, emphasizing its mechanisms of action and molecular targets with the utmost clarity. It discusses the comparative advantages of PS over current cancer therapies and explores the implications for future research and clinical applications. By delineating the specific pathways and targets affected by PS, this review seeks to offer valuable insights and directions for future research in this field. The information gathered in this review could pave the way for the successful development of PS into a clinically applicable anticancer therapy.
1H-NMR Metabolomic Study of the Mushroom Pleurotus djamor for the Identification of Nematocidal Compounds
Authors: Pineda-Alegría Jesús Antonio , Peña-Rodríguez Luis Manuel , Cardoso-Taketa Alexandre , Sánchez José E. , Torres-Acosta Juan Felipe de Jesús , Hernández-Bolio Gloria Ivonne , Ortiz-Caltempa Anabel , Villarreal María Luisa , Aguilar-Marcelino Liliana
Published: May 2024

Due to the increasing populations of anthelmintic-resistant gastrointestinal nematodes and as a consequence of the adverse effects of synthetic drugs, this study focuses on the search for secondary metabolites with nematocidal activity from the edible mushroom Pleurotus djamor using The proton nuclear magnetic resonance (1H-NMR) metabolomics. The highest activity was shown by the ethyl acetate fractions of mycelium (EC50 290.8 µg/mL) and basidiomes (EC50 282.7 µg/mL). Principal component analysis (PCA) and hierarchical data analysis (HCA) of the 1H-NMR metabolic profiles data showed that the ethanolic extracts, the ethyl acetate, butanol, and water fractions from mycelium have different metabolic profiles than those from basidiomes, while low polarity (hexane) fractions from both stages of fungal development show similar profiles. Orthogonal partial least squares discriminant analysis (OPLS-DA) allowed the identification of signals in the 1H-NMR metabolic profile associated with nematocidal activity. The signals yielded via OPLS-DA and bidimensional NMR analysis allowed the identification of uracil as a component in the ethyl acetate fraction from basidiomes, with an EC50 of 237.7 µg/mL. The results obtained showed that chemometric analyses of the 1H-NMR metabolic profiles represent a viable strategy for the identification of bioactive compounds from samples with complex chemical profiles.
Investigating the Antiviral Properties of Nyctanthes arbor-tristis Linn against the Ebola, SARS-CoV-2, Nipah, and Chikungunya Viruses: A Computational Simulation Study
Authors: Albiheyri Raed , Ahmad Varish , Khan Mohammad Imran , Alzahrani Faisal A. , Jamal Qazi Mohammad Sajid
Published: May 2024

Background: The hunt for naturally occurring antiviral compounds to combat viral infection was expedited when COVID-19 and Ebola spread rapidly. Phytochemicals from Nyctanthes arbor-tristis Linn were evaluated as significant inhibitors of these viruses. Methods: Computational tools and techniques were used to assess the binding pattern of phytochemicals from Nyctanthes arbor-tristis Linn to Ebola virus VP35, SARS-CoV-2 protease, Nipah virus glycoprotein, and chikungunya virus. Results: Virtual screening and AutoDock analysis revealed that arborside-C, beta amyrin, and beta-sitosterol exhibited a substantial binding affinity for specific viral targets. The arborside-C and beta-sitosterol molecules were shown to have binding energies of −8.65 and −9.11 kcal/mol, respectively, when interacting with the major protease. Simultaneously, the medication remdesivir exhibited a control value of −6.18 kcal/mol. The measured affinity of phytochemicals for the other investigated targets was −7.52 for beta-amyrin against Ebola and −6.33 kcal/mol for nicotiflorin against Nipah virus targets. Additional molecular dynamics simulation (MDS) conducted on the molecules with significant antiviral potential, specifically the beta-amyrin-VP35 complex showing a stable RMSD pattern, yielded encouraging outcomes. Conclusions: Arborside-C, beta-sitosterol, beta-amyrin, and nicotiflorin could be established as excellent natural antiviral compounds derived from Nyctanthes arbor-tristis Linn. The virus-suppressing phytochemicals in this plant make it a compelling target for both in vitro and in vivo research in the future.
The Application of Fluorescence In Situ Hybridization in the Prescreening of Veronica Hybrids
Authors: Park Hye-Wan , Sevilleno Samantha Serafin , Ha My Khanh Tran Thi , Cabahug-Braza Raisa Aone , Yi Ji-Hun , Lim Ki-Byung , Cho Wonwoo , Hwang Yoon-Jung
Published: May 2024

Fluorescence in situ hybridization (FISH), a molecular cytogenetic technique that enables the visualization and identification of specific DNA sequences within chromosomes, has emerged as a pivotal tool in plant breeding programs, particularly in the case of Veronica species. Veronica, a genus with a complex reproductive system, often poses challenges in accurately identifying hybrids because of its tendency to hybridize, which leads to intricate genetic variation. This study focused on the use of FISH as a prescreening method to identify true hybrids in Veronica breeding programs. FISH analysis was first performed on the parents to identify their 45S and 5S rDNA signals, along with their respective chromosome numbers. The signals were then compared with those of the twenty progenies with reference to their supposed parents. Five true hybrids, seven self-pollinated progenies, and eight false hybrids were identified through FISH. The findings highlight the significance of FISH as a screening method that contributes significantly to the efficiency of Veronica breeding programs by ensuring the preservation of desired genetic traits and minimizing the inadvertent inclusion of misidentified hybrids. To conclude, this study underscores the vital role of FISH in enhancing the precision and success of breeding programs and opens new avenues for improved breeding strategies and crop development.