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The potential for being the target of Denial of Service (DoS) attacks is one of the most severe security threats on the Internet. Attackers have been modifying their attack format over the years, damaging specific conditions of operating systems and protocols in an attempt to deny or diminish the quality of the service provided to legitimate users. Nowadays, attacks are stealthier and mimic legitimate user traffic in such a way that detection mechanisms against High-rate DoS attacks are no longer sufficient. This evolving type of attack, known as LDoS (Low-rate Denial of Service) attacks, has the potential to produce more damage than its predecessor due to its stealth nature and the lack of suitable detection and defense methods. This survey summarizes and complements previous studies and surveys related to this specific type of attack. First, we propose a taxonomy of the LDoS attacks, which were divided into three broad categories based on their modus operandi: QoS attacks, Slow rate attacks, and Service queue attacks. Next, we detail numerous detection mechanisms and counter-measures available against eight types of LDoS attacks. More specifically, we describe the methods used to throttle the attack traffic. Finally, we provide a feature comparison table for some existing attack tools. This survey aims at providing an extensive review of the literature for helping researchers and network administrators find up-to-date knowledge on LDoS attacks.

To increase situational awareness of maritime vessels and other entities and to enable their exchange of various information, the International Maritime Organization mandated the use of the Automatic Identification System (AIS) in 2004. The AIS is a self-reporting system that uses the VHF radio link. However, any radio-based self-reporting system is prone to forgery, especially in situations where authentication of the message is not designed into the architecture. As AIS was designed in the 1990s when cyberattacks were in their infancy, it does not implement authentication or encryption; thus, it can be seen as fundamentally vulnerable against cyberattacks. This paper demonstrates and evaluates the impact of multiple cyberattacks on AIS via remote radio frequency (RF) links using transmission-enabled software-defined radio (SDR). Overall, we implemented and tested a total of 11 different tests/attacks on 19 AIS setups, using a controlled environment. The tested configurations were derived from heterogeneous platforms such as Windows, Android, generic receivers, and commercial transponders. Our aim is to enhance the early discovery of new vulnerabilities in AIS to effectively address AIS attacks in the nearest future. The results showed that approximately 89% of the setups were affected by Denial-of-Service (DoS) attacks at the AIS protocol level. Besides implementing some existing attack ideas (e.g., spoofing, DoS, and flooding), we showed some novel attack concepts in the AIS context such as a coordinated attack, overwhelming alerts, and logical vulnerabilities, all of which have the potential to cause software/system crashes in the worst-case scenarios. Moreover, an implementation/specification flaw related to the AIS preamble was identified during the experiments, which may affect the interoperability of different AIS devices. The error-handling system in AIS was also investigated. Unlike the aviation sector’s Automatic Dependent Surveillance-Broadcast (ADS-B), the maritime sector’s AIS does not effectively support any error correction method, which may contribute to RF pollution and less effective use of the overall system. The consistency of our results for a comprehensive range of hardware-software configurations indicated the reliability of our approach, test system, and evaluation results.

Recently, the number of Internet of Things (IoT) networks has been grown exponentially, which results in more data sharing between devices without appropriate security mechanisms. Since huge data management is involved, maintaining the time constraints between the devices in IoT networks is another significant issue. To address these issues, an intelligent intrusion detection system has been adapted to recognize or predict a cyber-attack using Elite Machine Learning algorithms (EML), and a lightweight protocol is used to manage the time-constrained issue. The experimental analysis of work is done on a testbed setup with the hardware and sensors connected using a lightweight Message Queue Telemetry Transport (MQTT) protocol. This comprises three parts: (i) collection of data with the help of a sensor for three different scenarios called SEN-MQTTSET; (ii) multi-context feature generation using an ensemble statistical multi-view cascade feature generation algorithm from the SEN-MQTTSET dataset; and (iii) evaluating the dataset using ML algorithms. The SEN-MQTTSET dataset has been created from the three scenarios, such as normal, attack on a subscriber, and attack on a broker. The multi-context feature is generated from the raw dataset using an ensemble statistical multi-view cascade feature generation algorithm. The EML is proposed to select the best model for intrusion detection among ML algorithms such as Logistic Regression, K-Nearest Neighbour, Random Forest, Naive Bias, Support Vector Machine, Gradient Boosting, and Decision Tree by the performance metrics such as accuracy, prediction time, F1-score, and others. The proposed dataset is validated and the accuracy is found to be above 99% for the considered system model. Different quality parameters have been carried out for legitimate and attack traffic features to calculate the delay between the IoT-MQTT network.

Wireless sensor networks (WSNs) over the years have emerged as the enabling underlining infrastructure for new wireless technology trends such as Internet-of Things (IoT) and Fog Computing. Its application has spread across diverse fields such as agriculture, military, healthcare and home automation. Despite its promising attributes, it is characterized by its extremely limited resources such as battery energy and memory. Additionally, its deployment in hostile and unattended areas make it vulnerable to security attacks. One of such attacks is the denial of service (DoS) jamming attack that is perpetrated by malicious nodes emitting radio frequency signals to disrupt and interfere with the normal functions of the sensor nodes in the network. This eventually causes a denial of service in the network. Different routing protocols have been proposed over the years to guarantee reliable communication and maintain the network lifetime and functionality for a reasonable duration, notwithstanding DoS jamming attack. Therefore, in this work, we evaluate the effect of a constant jamming DoS attack on two key reactive routing protocols in WSN, ad hoc on-demand distance vector (AODV) and dynamic source routing (DSR). Metrics such as packet sending ratio (PSR), packet loss (PL) and transmitted packets are used to measure the impact of constant jamming DoS attack in the network. Simulation results using network simulation 2 (NS2) and trace graph show that, irrespective of the adopted reactive routing protocol, the impact of the jamming attack is the same. [ABSTRACT FROM AUTHOR]

This paper introduces the state-/output-feedback control for multi-channel nonlinear cyber–physical systems (CPSs). Many cyber-attacks are considered such as Denial-of-Service (DoS), replay and deception attacks. The deception cyber-attacks can be treated as measurement additive and multiplicative uncertainties. Both time-varying state-dependent and state-independent sensor additive attacks are considered. As DoS attack makes the CPS states unavailable, the standard modeling​ and control methods cannot be applied directly. Alternatively, as attackers in the replay attack re-transmit previous data and prevent the transmission of the more recent data, a delayed model is generated. To deal with these problems, a new observer at the controller side is proposed. It is used to perform two main tasks. The first is to estimate all system states at every time instant. The second is to exclude some unsecured transmitting channels from affecting the system response. Therefore, all attacks in these channels will have no effect on the system response. Using the estimated states, an anti-cyber-attacks state-feedback controller is investigated. Meanwhile, it is verified that the suggested approach certifies the convergence of all the CPSs states under different cyber-attacks. The effectiveness of the proposed secure control approach against different kinds of cyber-attacks is confirmed through two examples with simulation results. • A new model of DoS, replay, and deception attacks with degradation gain and state-dependent/-independent forms is proposed. • An asymptotic observer at the controller side is synthesized to reconstruct the system states at every time instant. • There is no need to design predictors for predicting the time of occurrence of the DoS attacks. • A new multi-channel transmission method in which some channels are excluded from affecting the system response is proposed. • For state and output feedback, controllers are designed such that asymptotic stability rather than boundedness is ensured. [ABSTRACT FROM AUTHOR]

Recently, fully π-functional two-dimensional (2D) materials have been reported for electronic device applications. Graphene is one of these 2D materials that is attributed to 2D electron confinement effects and exhibits an aromatic character; however, it is characterized by vanishing the bandgap energy. Hence, research was focused on the discovery of graphene-based 2D materials to reduce the bandgap energy. Herein, we investigate the silagraphene structures (SixCy) using DFT calculations to undertake and improve structural, physico-chemical, and electronic properties. Various types of 2D networks have been investigated by considering C–C and C–Si bonds in relative positions. Both conjugation and hyperconjugation phenomenon have been deeply examined and it seemed that they take advantage of each other depending on the C–C and C–Si bond positions. Localized orbital locator (LOL) and electron localization function (ELF) were also performed to examine the electronic densities in the investigated 2D networks and unveil the electronic properties of the studied materials. [ABSTRACT FROM AUTHOR]

For decades, researchers have struggled to determine the precise crystal structure of γ-Al 2 O 3 due to its atomic-level disorder and the challenges associated with obtaining high-purity, high-crystallinity γ-Al 2 O 3 in laboratory settings. This study investigates the crystal structure and electronic properties of γ-Al 2 O 3 coatings under the influence of an external electric field, integrating machine learning with density functional theory (DFT). A potential 160-atom supercell structure was identified from over 600,000 γ-Al 2 O 3 configurations and confirmed through high-resolution transmission electron microscopy and selected area electron diffraction. The findings indicate that γ-Al 2 O 3 deviates from the conventional spinel structure, suggesting that octahedral vacancies can reduce the system's energy. Under an external electric field, the material's band structure and density of states (DOS) undergo significant changes: the bandgap narrows from 3.996 to 0 eV, resulting in metallic behavior, while the projected density of states (PDOS) exhibits peak broadening and splitting of oxygen atom PDOS below the Fermi level. These alterations elucidate the variations in the electrical conductivity of alumina coatings under an electric field. These findings clarify the mechanisms of γ-Al 2 O 3 's electronic property modulation and offer insights into its covalent and ionic mixed bonding as a wide-bandgap semiconductor. This discovery is essential for understanding dielectric breakdown in insulating materials.

The spin-polarized electronic energy spectra of the ZnCrSe crystal were obtained based on calculations for a supercell containing 64 atoms. First, calculation is performed with an impurity of Cr atom, replacing the Zn atom. In the second variant, the Cr impurity and the vacancy at the Zn atom site are considered simultaneously. The results obtained in the first variant are as follows. It was found that the presence of the Cr atom leads to significant changes in the electronic energy bands, showing a large difference for different spin moments. The density curves of electronic states with opposite spins show an asymmetry, the consequence of which is the existence of a nonzero magnetic moment of the supercell. It was found that in the ZnCrSe crystal electronic 3d states with spin up are present at the Fermi level, i.e. the material is a metal. For spin-down states, the material is a semiconductor in which the Fermi level is inside the band gap. The value of the direct interband gap for electronic states with spin up is equal to 1.56 eV, and the magnetic moment of the supercell is 4.00 . The results obtained by the second variant of the calculation show a significant effect of the vacancy on the zinc site on the electronic structure of the ZnCrSe crystal. The Fermi level now intersects the dispersion curves of the upper part of the valence band for both spin orientations. The magnetic moment of the supercell is 2.74 .

Nowadays, the Internet of Things (IoT) concept plays a pivotal role in society and brings new capabilities to different industries. The number of IoT solutions in areas such as transportation and healthcare is increasing and new services are under development. In the last decade, society has experienced a drastic increase in IoT connections. In fact, IoT connections will increase in the next few years across different areas. Conversely, several challenges still need to be faced to enable efficient and secure operations (e.g., interoperability, security, and standards). Furthermore, although efforts have been made to produce datasets composed of attacks against IoT devices, several possible attacks are not considered. Most existing efforts do not consider an extensive network topology with real IoT devices. The main goal of this research is to propose a novel and extensive IoT attack dataset to foster the development of security analytics applications in real IoT operations. To accomplish this, 33 attacks are executed in an IoT topology composed of 105 devices. These attacks are classified into seven categories, namely DDoS, DoS, Recon, Web-based, brute force, spoofing, and Mirai. Finally, all attacks are executed by malicious IoT devices targeting other IoT devices. The dataset is available on the CIC Dataset website.

The sensitivity of pristine silicon carbide nanocage Si12C12 and their doping with n-type (SiP–Si11C12) and p-type (CB–Si12C11) were investigated for NO2, SO2, and NH3 gases using density functional theory (DFT). The reactivity of nanocages was examined through adsorption energy, charge transfer, the density of states (DOS), thermodynamic parameters, frontier molecular orbitals, molecular electrostatic potential, and nonlinear optical properties. The results revealed that doping with p-type has excellent sensitivity for SO2, NO2, and NH3 gases compared with pristine and n-type doped nanocages. [ABSTRACT FROM AUTHOR]

The present paper deals with design of silicon doped PS/SnS2 new composites to use in different nano-semiconductors devices include optic, electronic, photonic and electric approaches with individual characteristics contain few cost, high corrosion resistance, lightweight and good optical, thermal and electronic properties. Using the density functional theory (DFT), some of the electronic (energy band structure, density of states) and electronic characteristics of PS/SnS2/Si composites. S-vacancy could lead to strong n doping for the original SnS2, which largely influences its electronic structure. The obtained results indicated to the PS/SnS2/Si composites may be used for various optoelectronics devices with low cost and high flexibly. The energy band gap PS/SnS2/Si composites was found (Eg = 0.19 eV) which make it can be suitable in various nano-semiconductors devices. The calculated density of states (DOS) may interpret this magnitude of energy gap. [ABSTRACT FROM AUTHOR]

The use of Unmanned Aerial Vehicles (UAV) in every field is increasing rapidly. In order for UAVs to perform their duties correctly, they must be able to maintain continuous communication with ground stations. The use of WiFi wireless communication protocol has increased due to its high bandwidth. One of the most important threats that can threaten this type of communication is Denial of Service (DoS) attacks. In the event of such an attack, the UAV becomes inaccessible and may crash. Especially when the open port number is known, it becomes much easier to perform attacks that consume the resources of the drone. In this study, a mechanism is proposed to eliminate or at least mitigate the attack risk. This mechanism enables UAVs using wireless communication (WiFi) to communicate using TCP over UDP using middleware. In addition, by periodically changing the UDP open ports with a secret port number sequence known to both parties, it prevents the attacker from using the open port for a long time and renders the attack ineffective. In this study, the effects of the port hopping method on UAVs are evaluated. Test results on real systems shows that the proposed system makes the communication system of UAVs more resistant to DoS attacks by 91.2%. [ABSTRACT FROM AUTHOR]

Investigation of physicochemical and electronic properties of polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) blended solid polymer electrolyte incorporated with sodium perchlorate (NaClO4) as ion-conducting species has been carried out using first-principle Study. A proficient approach is proposed to analyse the conductive mechanism of electrolytes, based on density functional theory. Density of states (DOS) and projected density of states (PDOS) analysis provides a quantitative explanation of the electronic bandgap of the polymer–polymer (PEO-PVP) and polymer–salt (PEO-PVP-NaClO4) system. The bonding characteristic and charge distributions determined by charge density plot and crystal orbital overlap population analysis show to have a strong qualitative correlation with the ionic conductivity in solid polymer electrolyte. [ABSTRACT FROM AUTHOR]

The first principle calculation to investigate the structural, optoelectronic, and magnetic properties of the Y2FeSi Heusler alloy (HA) using the Wien2K code has been discussed in detail in the present manuscript. To estimate the physical properties of the HA, PBE-GGA and mBJ exchange–correlation functional were applied. The electronic charge density contour plot represents the dominant ionic character among the atomic configurations of Y2FeSi compound. Density of states (DOS) across the Fermi level (EF) exhibits the prominent role of Fe-3d electronic states along with Y-4d and Si-2p electronic states. Estimated spin polarization (SP ~ 75%) from the DOS profile suggests the metallic nature with magnetic (ferromagnetic having magnetic moment ~ 1.65 µB/cell for the HA) ordering of the compound. Phonon spectra represents the dynamical stability of the Y2FeSi compound. Additionally, the consequence of spin–orbit coupling (SOC) on material's physical properties was also explored. Band structure (BS) with SOC effect shows additional energy levels across the EF, due to splitting of Y-atoms' energy levels. A dielectric function was assessed with and without SOC to study the optical properties. Overall, Y2FeSi HA reveals interesting electronic, magnetic, and optical properties that have the potential for application in optical and spintronic devices. [ABSTRACT FROM AUTHOR]

• A new 3D Zn(II)-based MOF was synthesized and characterized. • The MOF was employed as a photocatalyst for antibiotic degradation. • MOF exhibited best photocatalytic degradation of nitrofurazone antibiotic. • Effect of NFZ concentration and MOF dosage on photocatalytic performance studied. Metal-organic frameworks (MOFs), a sub-class of coordination polymers, are versatile multidimensional materials that have the potential to serve as photocatalysts for the degradation of antibiotics found in wastewater. Herein, a new three dimensional (3D) Zn(II)-based MOF [Zn(TA)(bpyp)·3H 2 O] (1) (bypy = 2,5-bis(pyrid-4-yl)pyridine; H 2 TA = terephthalic acid) has been synthesized and characterized. The MOF 1 shows a 3D PCU -like topology and exhibits semiconducting properties with band gap of 3.34 eV and hence used as a photocatalyst for photodegradation of antibiotics viz. sulfasalazine (SLA), nitrofurazone (NFZ) and furazolidone (FZD) under simulated UV light irradiation. The photocatalytic results suggest that MOF 1 exhibits best photocatalytic activity for the photodegradation of nitrofurazone (NFZ) in 60 min time-span. The effects of initial concentration of NFZ, and photocatalyst dosage have been monitored for the photocatalytic performance of 1. The radical trapping experiments suggest that (holes) h + and superoxide radical (O 2 ·−) collectively catalyzes the photodecomposition of antibiotics. The possible mechanism for the antibiotic degradation by photocatalyst 1 have been proposed by integrating experiment with density of states (DOS) calculations and Hirshfeld surface analysis. A new Zn(II)-based MOF with PCU-like topology synthesized, characterized and used as photocatalyst for photodegradation of antibiotics. [Display omitted] [ABSTRACT FROM AUTHOR]

• Theoretical investigation of VOG has been done and optimized by DFT/B3LYP method. • The IR and UV–visible data has been compared with the experimental results. • The chemical reactivity and the stability of the compounds were also examined. • Mulliken charge investigation and MESP shows the reactive site of the compound. • Thermodynamic parameters were studied, which confirmed the stability of compound. In this paper, the computational investigation of Vat orange 7 has been studied. Vat dyes have high color fatness, due to which the investigation into the geometric properties should be studied and can be helpful in various applications, therefore the geometric parameters i.e., bond angles, bond length, energies, dipole moment, dihedral angles, Mulliken, atomic polar tensor (APT) atomic charges, and thermodynamics energies were calculated for the titled compound. The potential energy surface of vat orange dyes was computed at the quantum mechanical calculation level by using the Density functional theory, DFT/B3LYP/6311/6–311++ G) basic set. The molecular absorption and IR spectra of vat orange 7 were computed in both the gaseous state and various solvent environments i.e., water, ethanol, DMSO, heptane, and acetonitrile. A comparison was also made with the experimental spectra of UV/visible and FTIR studies. Computer programs such as Gaussian 16 W and Hyperchem are used to perform calculations. The line shape of the emission spectrum of the computed spectra is correlated with the experimentally observed spectra. The effect of solvent shift, protonic shift, and other parameters for different solvents according to their polarity and prototype were thoroughly investigated. By polarized continuum model (PCM) coupled with time-dependent density functional theory (TD-DFT) along DFT/B3LYP/6–311G++ basic sets were calculated, which shows perfect converges to excitation spectra and geometries. To understand the intermolecular and intramolecular interaction of compounds and the transfer of density from filled to unfilled orbitals, NBO analysis was performed. The analysis of the intramolecular charge transfer mechanism involved the determination of HOMO-LUMO energies. The calculations show that Vat Orange 7 exhibits higher reactivity in the medium with the smallest HOMO-LUMO gap. [Display omitted] Representation of energy levels and molecular orbital surfaces of Vat Orange 7 computed by DFT/B3LYP/6311++ G (d,p) method. [ABSTRACT FROM AUTHOR]

While effective targeted delivery is a challenge in nanomedicine for the delivery of anti-cancer drugs, this work focuses on the potential use of Bismuthene and antimonene nanosheets as nanocarriers for cisplatin anti-cancer using DFT methods. The results indicate that, compared to antimonene, bismuthene demonstrates significantly better physical stability, drug release rate, solubility, and biocompatibility, making it an excellent candidate for drug delivery systems. The parallel and perpendicular orientations of the anticancer drug were adsorbed on both nanosheets; the parallel configuration was the most energetically favored with an adsorption energy of −0.79 eV at the parallel site. A charge transfer from the drug to the bismuthene sheet is also revealed by the electronic charge analysis and DOS calculation, thus confirming efficient drug adsorption. Modeling a proton attack on the drug and the carrier surface near the adsorption sites was performed to model drug release, showing the stability and potential of bismuthene in this aspect of drug release mechanisms. Further, with an approach to studying its interactions with biomolecules, interactions of the drug molecule have been analyzed with amino acids, showing that drugs interact efficiently. Further assessments concerning work function, recovery time, electron localization function, and frontier molecular orbital analyses leave no doubt that bismuthene has beneficial features over antimonene. These thorough assessments present bismuthene as a more promising nanocarrier for the delivery of anti-cancer drugs and open a potential pathway to enhance the efficacy of strategies against cancer treatment. [ABSTRACT FROM AUTHOR]

Four new heteroleptic Ni(II)-dithiolates with general formula [Ni(dppf)(dithiolate)] (dithiolate = 2-cyano-2-(4-fluorophenyl)ethene-1,1-bis(dithiolate) (Ni-1); 2-cyano-2(2-(trifluoromethyl)phenyl)ethene-1,1-bis(thiolate) (Ni-2); 2-cyano-2(3-(trifluoromethyl)phenyl)ethene-1,1-bis(thiolate) (Ni-3) and 2-cyano-2(4-(trifluoromethyl)phenyl)ethene-1,1-bis(thiolate) (Ni-4); dppf = 1,1′-bis(diphenylphosphino) ferrocene) have been synthesized and characterized spectroscopically as well as by single crystal X-ray diffraction technique. Single crystal X-ray analyses for Ni-1 and Ni-2 reveal distorted square planar geometry around Ni(II) that are satisfied by two sulfur and two phosphorus centers of the dithiolate and dppf ligands, respectively. These complexes have been used as photosensitizers in TiO 2 -based dye-sensitized solar cells (DSSCs) which suggest that the performance of fluoro-substituted sensitizer Ni-1 is superior to that of the other three trifluoromethyl-substituted sensitizers. Ni-1 showcases an efficiency (η) of 5.47 %, open circuit potential (V oc) of 0.699 V, short circuit current (J sc) of 12.17 mA∙cm−2 and display 64 % incident photon-to-current conversion efficiency. The plausible reason for the variation in photovoltaic performances have been explained by integrated experimental methods and theoretical calculations. Results indicate that the small sized fluoro-group exhibits significant p -orbital overlap with the aromatic fragment of the dithiolate ligand, allowing facile photo-induced electron transfer from sensitizer to titania, thereby enhancing the electron donation from dppf→Ni(II)→dithiolate. Further, the cell fabricated with Ni-1 retains approximately 93 % of its initial conversion efficiency in 800 h time span. [Display omitted] • Four new dppf appended Ni(II)-dithiolates with F- and CF 3 groups synthesized and characterized. • The nature of weak interactions in one of the complexes explored using Hirshfeld surface analysis. • These dithiolates have been employed as sensitizers in dye-sensitized solar cells. • The observed differences in the photovolatic behavior of the complexes were justified by integrated experimental and computational approach. [ABSTRACT FROM AUTHOR]

Boron Nitride Nanotubes (BNNTs), 1-D nanomaterials, having extraordinary mechanical properties, are similar to carbon nanotubes. The structure of BNNT consists of alternative boron and nitrogen atoms, arranged in hexagonal lattice. In the current study, we have investigated the defected boron nitride nanotube (defBNNT) capability to capture CO 2 from a mixture of greenhouse gases such as CH 4 , CO 2 , CO, and H 2. The deep understanding of analytes@defBNNT complexation is acquired by interaction energies, quantum theory of atoms in molecules (QTAIM), noncovalent interaction (NCI), natural bond orbital (NBO), and frontier molecular orbital (FMO) analysis etc. It is evident from the results of interaction energies that all the analytes are physiosorbed over the defBNNT. The observed interaction energies are in the range of −2.09 to −6.43 kcal/mol. All the topological parameters, in QTAIM analysis, show that analyte@defBNNT complexes are stabilized through non-covalent interactions, particularly van der Waal's interactions. Results obtained from NCI analysis are strongly corroborated with the QTAIM analysis. The case of CO@defBNNT gives the highest charge transfer (0.031 e−), in natural bond orbital (NBO) analysis. Overall, there is a transfer of charge from analyte to the surface. Through electron density difference (EDD) analysis, the results of NBO charge transfer are also confirmed. We firmly believe that these findings could help experimentalists to design a well-suited surface for CO 2 capture using defective boron nitride nanotubes (defBNNTs). [Display omitted] • The highest interaction energy value is observed for CO 2 analyte (−6.43 kcal/mol). • QTAIM analysis reveals that analyte@defBNNT complexes are stabilized mainly through van der Waal's interactions. • defBNNT can act as a promising candidate for selective capture of CO 2. [ABSTRACT FROM AUTHOR]

The synthesized compound AlCuO2 was established and structurally characterized as the semiconductor. It is noted that there are no available data for theoretical studies, as well as computational studies. For developing theoretical studies on AlCuO2, this study has been designed by computational tools. Applying computational approaches, the electronic structure and optical properties were calculated for the AlCuO2 molecule, and computational tools of the CASTAP code from material studio 8.0 were used in this investigation. First of all, the band gap was recorded by 1.81 eV through the Generalized Gradient Approximation (GGA) based on the Perdew Burke Ernzerhof (PBE), and the density of state and the partial density of state were simulated for evaluating the nature of 3s2, 3p1 orbital for Al, 3d10, 4s1 orbital for Cu, 3d6, 4s2 orbital for Fe and 2s2, 2p4 orbital for O atom of AlCuO2. The optical properties, for instance, absorption, reflection, refractive index, conductivity, dielectric function, and loss function, were calculated. To develop the conducting nature, 4% Fe atom was doped by replacing the Cu atom on AlCuO2. As a result, the band gap was found at 0.00 eV having molecular formulation as AlCu0.96Fe0.04O2, as well as the optical conductivity and optical absorption was soared comparing with parent AlCuO2. From the analysis of the band gap and optical properties in AlCu0.96Fe0.04O2, it can be established that the semiconductor, AlCuO2, has converted into a superconductor due to 4% Fe atom doping. DOI: http://dx.doi.org/10.17807/orbital.v13i1.1533

Three-dimensional precise models of teeth are critical for a variety of dental procedures, including orthodontics, prosthodontics, and implantology. While X-ray-based imaging devices are commonly used to obtain anatomical information about teeth, optical devices offer a promising alternative for acquiring 3D data of teeth without exposing patients to harmful radiation. Previous research has not examined the optical interactions with all dental tissue compartments nor provided a thorough analysis of detected signals at various boundary conditions for both transmittance and reflectance modes. To address this gap, a GPU-based Monte Carlo (MC) method has been utilized to assess the feasibility of diffuse optical spectroscopy (DOS) systems operating at 633 nm and 1310 nm wavelengths for simulating light-tissue interactions in a 3D tooth model. The results show that the system’s sensitivity to detect pulp signals at both 633 nm and 1310 nm wavelengths is higher in the transmittance compared with that in the reflectance mode. Analyzing the recorded absorbance, reflectance, and transmittance data verified that surface reflection at boundaries can improve the detected signal, especially from the pulp region in both reflectance and transmittance DOS systems. These findings could ultimately lead to more accurate and effective dental diagnosis and treatment.