HPU2 Journal of Science: Natural Sciences and Technology
Tạp chí của Trường Đại học Sư phạm Hà Nội 2
The existence and uniqueness of weak solutions to three-dimensional Kelvin-Voigt equations with damping and unbounded delays
There are many results involving PDEs in fluid mechanics with delays and many results about asymptotic behavior to PDEs. Navier-Stokes equations with delays have been studied extensively over the last decades, for their important contributions to understanding fluid motion and turbulence. In this paper we consider the modifications of the three dimensional Navier-Stokes equations: the three dimensional Kelvin-Voigt equations involving damping and unbounded delays in a bounded domain . The damping term is often introduced to model energy dissipation, which can stabilize the system. We show the existence and uniqueness of weak solutions by the Galerkin approximations method and the energy method.
Blockchain with IoT to enhance security, data integrity, and automation
The integration of Blockchain technology with the Internet of Things (IoT) presents a transformative approach to addressing critical challenges in security, data integrity, and automation. This paper explores the synergies between these technologies, proposing a framework that leverages the decentralized and immutable nature of Blockchain to enhance IoT ecosystems. By eliminating single points of failure, Blockchain ensures robust security for IoT devices and networks. Furthermore, its transparent and tamper-resistant data structure guarantees the integrity of data exchanged across IoT systems. The study also examines how smart contracts can automate processes within IoT environments, enabling real-time decision-making and reducing human intervention. Practical use cases, such as secure supply chain management, automated healthcare systems, and industrial IoT applications, are discussed to illustrate the effectiveness of the proposed framework. The results demonstrate significant improvements in system resilience, trustworthiness, and operational efficiency, highlighting the potential of Blockchain-enabled IoT to revolutionize diverse industries.
Harnessing the power of Big Data: transforming market prediction and supply chain optimization
In the rapidly evolving landscape of commerce and industry, the integration of Big Data analytics stands as a pivotal innovation driving transformation across market prediction and supply chain optimization. This paper delves into the methodologies and technologies underpinning behind the harnessing of Big Data to enhance predictive accuracy in market trends prediction and streamline supply chain processes. Through comprehensive analysis and case studies, we explore how advanced algorithms, machine learning techniques, and real-time data processing can be leveraged to forecast market dynamics with unprecedented precision. Furthermore, we examine the impact of Big Data on supply chain management, highlighting how data-driven strategies can optimize inventory management, reduce operational costs, and improve responsiveness to market demands. By synthesizing insights from various sectors, this study illustrates the profound potential of Big Data to revolutionize traditional business models, offering a roadmap for organizations aiming to achieve competitive advantage in a data-centric world. The findings underscore the necessity for businesses to adopt robust data infrastructure and analytical capabilities, ensuring sustained growth and adaptability in an increasingly complex marketplace.
Big Data and business network analysis: applications in management and optimization
Big Data has significantly transformed business operations, enabling deeper insights and more informed decision-making. Its impact is particularly evident in business network analysis, where companies can now dissect and understand complex supply chains and distribution systems like never before. Businesses can uncover hidden patterns and relationships by analyzing vast datasets, improving efficiency and decision-making processes. This paper explores the applications of Big Data in business network analysis, focusing on how it enhances supply chain visibility, risk management, and demand forecasting. It also addresses challenges like data privacy, security, and managing large datasets. Finally, the paper highlights potential future research directions, emphasizing areas for further development that could drive more innovation in using Big Data for business networks. Through this examination, the paper aims to clarify how Big Data is reshaping business networks and offer insights into this critical field’s continued evolution.
Cost-benefit analysis: utilizing mathematics to optimize economic project decisions
Cost-Benefit Analysis (CBA) is an essential tool for economic decision-making, providing a systematic way to evaluate the financial value of projects. It employs mathematical techniques to quantify benefits and costs, enabling decision-makers to compare various options. By translating potential gains and expenses into monetary values, CBA identifies projects that yield the highest net benefits. This method allows decision-makers to assess investment feasibility, optimize resource allocation, and prioritize projects based on their economic efficiency. The article emphasizes the importance of mathematical techniques in enhancing informed decision-making during project evaluations. It illustrates how Cost-Benefit Analysis (CBA) contributes to effective economic planning and resource management. By providing a structured framework to quantify benefits and costs, CBA helps decision-makers assess investment feasibility and prioritize projects. This ensures optimal resource allocation and maximizes net benefits, ultimately guiding stakeholders toward economically efficient choices.
The ammonium adsorption capacity of coffee husk‑derived activated carbon composite with MnFe2O4
In this study, a composite material between MnFe2O4 and activated carbon from coffee husks (MFO/AC) was synthesized using co-precipitate and hydrothermal methods to remove ammonium from aqueous solutions. The characteristics of MFO/AC were characterized and evaluated by scanning electron microscopy (SEM) and Fourier transform infrared spectra (FTIR). The ammonium adsorption process of MFO/AC was investigated through batch experiments, assessing parameters such as solution pH (3 ÷ 8), contact time (5 ÷ 120 min), material dosage (0.2 ÷ 3 g.L-1), and initial ammonium concentration (10 ÷ 60 mg.L-1). Results indicate that MFO/AC effectively adsorbs ammonium, which is attributed to the functional groups on the composite surface. The maximum ammonium adsorption capacity of MFO/AC was 15.97 mg.g-1 at an initial ammonium concentration of 20 mg.L-1, pH 7, material dosage of 1.5 g.L-1, and contact time of 80 min. The MFO/AC composite material has the potential to be an effective agent for ammonium removal from wastewater.
On the multiplicity of graded fiber cones with arbitrary dimensions
Let be a Noetherian local ring with maximal ideal , an -primary ideal, a finitely generated standard graded algebra over A and a finitely generated graded -module. Then is called the fiber cone of the graded module with respect to As we know, the concept of multiplicities in commutative algebra is an object that plays an important role in determining the properties and classifying the structure of rings and modules including the Cohen-Macaulay property. In this paper, we establish the multiplicity formula of the fiber cone with arbitrary dimensions. The concept we used to prove the results is filter-regular sequences of graded modules. Our approach is based on the formulas of multiplicities of fiber cones of graded modules in the case that the dimensions of those fiber cones equal 1 and by induction on dimensions of fiber cones of graded modules.
A Lagrange function approach to study second-order optimality conditions for infinite-dimensional optimization problems
In this paper, we focus on the second-order optimality conditions for infinite-dimensional optimization problems constrained by generalized polyhedral convex sets. Our aim is to further explore the role of the generalized polyhedral convex property, which is inspired by the findings of other authors. To this end, we employ the concept of Fréchet second-order subdifferential, a tool in variational analysis, to establish optimality conditions. Furthermore, by applying this concept to the Lagrangian function associated with the problem, we are able to derive refined optimality conditions that surpass existing results. The unique properties of generalized polyhedral convex sets play a crucial role in enabling these improvements.
Optimization of extraction of flavonoid and polyphenol from Camellia megasepala leaves and their anticancer activity
Camellia megasepala Hung T. Chang & Trin Ninh, found in Na Hang district, Tuyen Quang province, contains a significant amount of flavonoids and polyphenols, which are important phenolic compounds known for their various biological activities beneficial to human health, including antibacterial and anti-inflammatory effects. This study applied the response surface methodology (RSM) to examine the influence of extraction factors on the polyphenol and flavonoid content in golden tea leaves. The optimal conditions for extracting polyphenols and flavonoids were temperature at 60°C, 70% ethanol concentration, extraction time of 80 minutes, and a material/solvent ratio of 1/20 (w/v). The experimental values were: flavonoid = 1.42 ± 0.0172 mgQE/g extract; polyphenol = 4.29 ± 0.0348 g/100g extract. The extract from golden tea leaves was evaluated for its cytotoxic activity against HepG2 liver cancer cells and A549 lung cancer cells. The inhibitory concentration (IC50) for the ethanol 70% extract was recorded as IC50 = 74.11 ± 1.37 µg/ml and IC50 = 67.11 ± 1.57 µg/ml for HepG2 and A549 cells, respectively. The results of this study suggest the potential application of golden tea leaf extract in inhibiting the growth of liver and lung cancer cells.
The standard model-like higgs boson decay h→Zγ in the 3-3-1 simple model
The exact one-loop contributions to the decay amplitudes of the Standard model-like Higgs boson decays , as predicted by the simple 3-3-1 model, are presented in terms of using the Passarino-Veltman notations. In the unitary gauge, all triple couplings related to the decay amplitudes are determined and LoopTools package has been applied to the numerical investigation. The result shows that the 3-3-1 simple model predicts the largest value , which defines the signal strength of the decay channel . This result is still outside the range of the recent experimental constraint of , therefore explaining why this signal is still invisible at LHC.
Hybrid affine cipher and eigenvector methods for cryptography
This paper systematically presents a specific application of linear algebra in information security and cryptography, highlighting the crucial role of matrix operations and linear techniques in the design and analysis of encryption algorithms. Specifically, we focus on a method that utilizes linear algebra to enhance the security and efficiency of modern cryptographic systems. A detailed illustrative example is provided to help readers better understand how these mathematical tools are applied in practice. Furthermore, we review existing encryption techniques and propose a new matrix-based scheme that leverages linear algebra to improve data security, optimize the encryption-decryption process, and ensure the integrity and confidentiality of information throughout transmission and storage.
On the second-order sufficient optimality condition in nonconvex multiobjective optimization problems
The study of second-order optimality conditions is one of the most important topics in optimization theory and attracting the attention and interest of many authors. In this paper, we introduce a novel solution concept called “essential local efficient solutions of second-order” for nonconvex constrained multiobjective optimization problems. We then show that the new solution concept is stronger than the quadratic growth condition and under a mild constraint qualification, these solution concepts are equivalent. By using the second subderivative, we derive a sufficient optimality condition for a feasible solution to become an essential local efficient solution of second-order for the considered problem. Examples are provided to illustrate the obtained results.
On minimization of quadratic functions over closed convex sets in Hilbert spaces
Quadratic programming problems are of primary importance in various applications and arise as subproblems in many optimization algorithms. In this paper, we investigate quadratic programming problems in Hilbert spaces. By utilizing the Legendre property of quadratic forms and an asymptotically linear set with respect to a cone, we establish a sufficient condition for the existence of solutions to the considered problems through a Frank-Wolfe type theorem. The proposed condition is based on the special structure of Hilbert spaces, extending the applicability of quadratic programming methods. Finally, we provide a numerical example to illustrate the results obtained and demonstrate that existing approaches cannot be applied in certain cases.
Some data about endangered and rare plant species in Me Linh Station for Biodiversity, Vinh Phuc province
Me Linh Station for Biodiversity has an area of ​​170.3 hectares, near Tam Dao National Park. Although the area is not large, it has with high biodiversity and rich flora, including many rare and threatened plant species. So, this place not only preserves biodiversity but also organizes research and educational activities to protect biodiversity and the environment. Some research projects have been done on species diversity, ecosystem diversity, and forest biomass... This study identifies 38 endangered and rare plant species. Among them, 20 species in Vietnam Red Data Book 2007; 20 species belong to Decree No. 84/2021/ND-CP; 16 species belong to Appendix II of CITES (2024), and 4 species belong to IUCN (2024). Simultaneously, this study added summary information about the conservation status, life forms, geographical factors, and uses of 38 plant endangered and rare species in Me Linh Station for Biodiversity, Vinh Phuc province.
An investigation into the morphological and anatomical characteristics of three cassava (Manihot esculenta) varieties collected from the Northern provinces of Vietnam
Cassava (Manihot esculenta Crantz) is a crucial crop that sustains millions of people across tropical and subtropical regions, providing an essential source of carbohydrates and contributing significantly to food security. Morphologically, varieties KM94, 08SA06, and Ruột vàng exhibit distinct traits such as plant form, leaf structure, tuber shape, and starch content, which underline their adaptability and potential for high yield under diverse growing conditions. Anatomically, the stems of these varieties demonstrate unique structural features, including tightly packed epidermal cells with thick cuticle layers, varying layers of collenchyma and parenchyma, robust sclerenchyma rings, and well-organized vascular bundles. These features ensure efficient nutrient and water transport, structural integrity, and resilience against environmental stresses, essential for the growth and development of these cassava varieties. By highlighting these morphological and anatomical traits, this study emphasizes the importance of such detailed analyses for improving cassava cultivation practices.
The one-pot fabrication of green-emitting composites based on PMMA
Photoluminescent composites consisting of a photoluminescent material dispersed in a suitable matrix have been applied in many applications, such as light-emitting diodes, solar concentrators, and anti-counterfeiting inks. The traditional method for the fabrication of composites by blending an as-synthesized photoluminescent material and a matrix is very challenging as it is difficult to obtain homogeneous composites. In this study, we have demonstrated a one-step method to prepare homogeneous composites by inducing the formation of in-situ photoluminescent centers in a stable matrix. Poly(methyl methacrylate) (PMMA) coated with o-phenylenediamine (oPD) was thermally annealed at 165oC for a duration of 5 minutes in an extruder to obtain green-emitting composites. The composites exhibited a broad absorption peak at 425 nm and an absorption shoulder at 495 nm. The emission spectrum of the composite was broad, ranging from 400 nm to 700 nm, and reached the maximum at 525 nm. The photoluminescent maximum position was independent of the excitation wavelength. The photoluminescent excitation spectrum of the composite resembled the absorption near 425 nm. Time-dependent density functional theory (TD-DFT) calculations suggested that 2,3-diaminophenazine and 3-amino-2-hydroxyphenazine are the main molecular fluorophores accounting for the optical properties of the composites. The synthetic method demonstrated in this study is transferable for preparing numerous photoluminescent thermoplastics.
Algebraic method for image reconstruction in ultrasonic tomography
Ultrasound tomography is crucial due to its capability to deliver detailed, real-time, and non-invasive imaging. This is essential for early diagnosis, treatment planning, and guiding medical procedures. Its affordability, portability, and safety make it a versatile tool in medical and non-medical fields alike, driving ongoing advancements in technology and applications. The Distorted Born Iterative Method (DBIM) is an advanced technique used in ultrasound tomography to iteratively restore images, improving upon the standard Born approximation by addressing some of its limitations. However, the DBIM also has its own set of disadvantages when used for iterative image restoration, resulting in computational complexity, noise sensitivity, convergence issues, etc. In this paper, we introduce a new method for image reconstruction in ultrasound tomography by using the algebraic method. The numerical results indicate that this method has a shorter computational time and achieves high-resolution reconstructions and accurate solutions.
Stepwise grafting polyethyleneimine onto silica surface for Cu(II) removal
Polyethyleneimine (PEI) is a novel polymer that contains multiple amine groups that are suitable for chelation with many heavy metal ions (HMI). Anchoring PEI onto the surface of a solid substrate has been widely adopted to develop adsorbent materials with the hope of combining the HMI chelating ability of PEI with the heterogeneity of the substrate. Herein, the preparation of PEI grafted SiO2 (PEI/SiO2) has been demonstrated by a stepwise method in which SiO2 nanoparticles were functionalized with 3-glycidoxypropyltrimethoxysilane (KH560) followed by refluxing with PEI. The method could provide PEI/SiO2 material with 23.4% of PEI by weight. Studying the adsorption properties of PEI/SiO2 with Cu(II) revealed that the adsorption of Cu(II) ions on PEI/SiO2 followed Langmuir and Dubinin-Radushkevich models and included both chemisorption and physisorption. The adsorption capacity was about 25.3-27.3 mg/g. The stepwise method demonstrated in this study may be adopted to fabricated PEI based materials for HMI removal.
An ab initio calculation on the structural, electronic and magnetic properties of Ni-doped Bi0.5Na0.5TiO3
The first principle calculation was employed to investigate the formation energies and structural, electronic, and magnetic properties of intrinsic and Ni-doped sodium bismuth titanate Bi0.5Na0.5TiO3 (BNT). The obtained formation energies indicate that Ni atoms prefer to dope into Bi-sites in the lattice of BNT while the calculated band structure shows that the doping leads to the emergence of new mid-gap energy states in the bandgaps, reducing the bandgap value of doped materials. The PDOSs reveal that Bi-6p, O-2p and Ti-3d contribute major parts in BNT valence and conduction bands, while the Ni-3d and 4s play the main roles in the formation of new mid-gap states. The spin-resolved density of states, the integrated spin densities and the charge distributions suggest that all doped models exhibit magnetic behavior, mainly due to the interaction of Ni, O and Ti atoms. The study method of this research can be applied to predict new properties of BNT-based materials.
A probabilistic method to prove AM-QM inequality
Inequality is one of the interesting topics in mathematics that attracts the attention of both students and researchers. Solving inequalities often requires creativity, making it a challenging topic for many students. The inequality of arithmetic and quadratic means, or AM-QM in short, states that the arithmetic mean of a list of non-negative real numbers is less than or equals to the square root of the quadratic mean of the same list. There are many methods of proving the AM-QM inequality. In this paper, we will present a probabilistic method to prove the weighted general AM-QM inequality and show that the classical AM-QM inequality is a special case of the generalized AM-QM inequality with equal weights.
A non-existence result for higher-order Hardy-Hénon inequality on punctured balls
Let and be two positive integers such that . Let and be real such that and . In this note, we are mainly concerned with non-negative and classical solutions of the high-order harmonic inequality on the punctured ball . Using the method of test functions, the Hölder's inequality, and integral estimates, we will prove that this inequality has no positive solution satisfying some sufficient conditions. It should be mentioned that our result, see Theorem 1.1 in the next section, in the high-order setting is analogous to that of Laptev for the case .
Viscosity solutions of the augmented K-Hessian equations in exterior domains
This paper examines the Dirichlet problem for augmented -Hessian equations in exterior domains. Building upon our previous results on the viscosity solutions to the Dirichlet problems for augmented -Hessian equations in the bounded domain, and L. Dai, J. Bao's method to the -Hessian equations in exterior domains, a sufficient condition for the existence and uniqueness of viscosity solutions to the Dirichlet problem for the augmented -Hessian equations in exterior domains have been proven. During the process, a slight adjustment to the result on the existence and uniqueness of viscosity solutions to the problem in the bounded domains has been made for use in the present situation.
Essential oil of the leaves of Cinnamomum subpenninervium Kosterm. ex H. H. Pham and its antimicrobial activity
The current study first describes the chemical composition of the leaf essential oil of Cinnamomum subpenninervium Kosterm. ex H.H. Pham collected from Nghe An province, Central Vietnam. By the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrophotometry) analysis, more than thirty compounds were identified, representing 99.92%. The obtained essential oil from the fresh leaves was dominated by non-terpenic compounds (57.07%), monoterpene hydrocarbons (23.03%) and oxygenated monoterpenes (13.34%), as well as E-cinnamaldehyde (38.56%), linalool (12.20%), benzyl benzoate (11.33%), and α-pinene (8.12%). C. subpenninervium showed strong antimicrobial activity against the fungus Fusarium oxysporum ATCC 46591 with the MIC (minimum inhibitory concentration) value of 64 µg/mL.
A convergence enhancement approach for tomographic reconstruction in ultrasonic tomography
Ultrasound tomography is a non-invasive imaging technique that seeks to determine the internal distribution of acoustic properties within the body by analyzing measured ultrasound data. Based on the distorted Born iterative method (DBIM), this work suggests employing resolution-jumping and beamforming techniques for tomographic ultrasound imaging. The beamforming technique leverages multiple transmitting elements from the ultrasound probe, operating concurrently, to generate a focused and narrow beam. This targeted approach helps in reducing noise, thus enhancing the quality of the collected data. Meanwhile, resolution-jumping optimizes the imaging process by adjusting the resolution dynamically, thereby improving both the quality and speed of the reconstruction. The benefits of the proposed method are evident in the results of numerical simulations, which demonstrate a substantial improvement in the quality of image recovery. These simulations also highlight a significant reduction in the total runtime required for imaging, showcasing the efficiency of the approach. By combining these advanced methods, the work offers a promising pathway toward more accurate and faster tomographic ultrasound imaging, which could lead to better diagnostic capabilities in medical applications.
Right-angled Artin groups and representation liftings
The lifting problems are interesting problems of number theory. There are many mathematicians who study lifting problems with different classes of groups. They prove the lifting problems with different classes of groups using various methods. Recently, right-angled Artin groups have attracted much attention in number theory. They have nice structure and properties. Currently, we study right-angled Artin groups with different problems related to them. One of those problems is that we want to prove the lifting problem is associated with this class of groups. We have obtained a result for this problem. In this paper, we will show that a mod Heisenberg representations of a right-angled Artin group can be lifted to a mod representation.
Study on the adsorption L- and D- proline on MKN-MWCNT-P5000 carbon nanotubes from aqueous solutions
Carbon nanotubes (CNTs) are a new type of nano-adsorbent material with unique properties, which are promising adsorbents for the separation of enantiomers. Information regarding the interaction mechanism of enantiomers with carbon nanotubes has not yet been fully explored yet. In this work, we studied the adsorption of L and D-proline on carbon nanotubes in aqueous solution. Adsorption isotherms of enantiomers proline on multi-walled carbon nanotube MKN-MWCNT-P5000 from aqueous solution at 25℃ were constructed. The results of the experiments show that the adsorption capacity of the D-isomer is higher than that of the L-isomer. The separation coefficient of enantiomers on carbon nanotubes is in the range of 1.88–7.92. L-proline was adsorbed on CNTs as zwitterions and clusters of 62 molecules; and D-proline - in the form of zwitterions and clusters of 33 molecules. The results of quantum chemistry show that the adsorption energy of the D-proline monomer on carbon nanotubes is greater than that of the L-isomer. The nature of the bond between enantiomers and nanotubes was Van der Waals force.
A note on the existence of solutions to the semi-affine variational inequalities problems
The semi-affine variational inequality problem offers a general and versatile framework applicable to many problems in economics, mathematical physics, operations research, and mathematical programming. One of the important applications of the semi-affine variational inequality problem is quadratic programming. It is well-known that the first-order necessary optimality condition for a constrained optimization problem can be rewritten as a variational inequality. This paper investigates the existence of solutions for the semi-affine variational inequality problem in the finite-dimensional Hilbert spaces. Under suitable conditions, we show that the solution set of the semi-affine variational inequality problem is nonempty. The obtained results contribute to and complement the existing literature.
The decay of SM-like Higgs boson in a G221 model
The decay of SM-like Higgs boson in the G221 model which is one of all models beyond the SM (BSM) has been investigated. This decay channel has not been observed experimentally. In the framework, we indicate that new particles predicted by this model may significantly affect the previously mentioned decay channel of the SM-like Higgs boson. We will study the effects of the new heavy-charged boson, the charged Higgs boson was not included previously. We are namely, contributing from the diagram both Higgs boson and charged boson. The calculated results are expressed in terms of Passarino-Veltman functions, the numerical evaluation of which can be obtained using LoopTools. Our numerical investigation presents some details and properties of this decay. These may prove useful for comparison with future experimental results that could be detected.
Hydrothermal synthesis of CdTe quantum dots using ammonia as a reducing agent
Water-soluble CdTe quantum dots (QDs) have been applied in various fields, such as photoluminescent imaging, labeling agents in immune analysis, heavy metal ion sensing, and solar cells. The synthesis of CdTe QDs has relied vastly on reactions between Cd2+ and Te2- ions in the presence of mercapto ligands. Te2- ions are usually formed in situ in the synthetic solution by reducing tellurite ions with hydride salts, such as NaBH4 which gives rise to the emission of highly explosive hydrogen gas. Herein, we report a novel method to synthesize CdTe QDs by using ammonia as a reducing agent. We demonstrate that under hydrothermal conditions, ammonia can reduce tellurite forming telluride ions which react with cadmium ions in the presence of glutathione forming CdTe QDs. The resultant QDs exhibited high photoluminescence and resolvable absorption. The synthetic method demonstrated herein could reduce the cost of CdTe-based quantum dots for rapid deployment.
Structure, magnetic properties and magnetocaloric effect of Fe81-xCrx+4B2Zr10Nd3 rapidly quenched alloys
This paper presents, we present the structure, magnetic properties, and magnetocaloric effect of the Fe81-xCrx+4B2Zr10Nd3 (x = 0, 1, 2, and 3) alloy ribbons. The alloy ribbons were prepared by using the melt-spinning method. Structural analysis by X-ray diffraction shows that the obtained alloy ribbons are almost amorphous. Curie temperature of the alloy ribbons decreases from 310 to 275 K when x increases from 0 to 3. Under a magnetic field change of 12 kOe, the maximum magnetic entropy change (|DSm|max) of the Fe80Cr5B2Zr10Nd3 alloy ribbon is found to be 1.05 J.kg-1.K-1 at 302 K. In addition, the large refrigerant capacity (RC > 80 J∙kg-1 with DH = 12 kOe) at room temperature is obtained in the alloy ribbon. Thus, the alloy ribbons can be considered a potential magnetic refrigerant in the room temperature range.