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Context: Airborne pathogens, defined as microscopic organisms, pose significant health risks and can potentially cause a variety of diseases. Given their ability to spread through diverse transmission routes from infected hosts, there is a critical need for accurate monitoring of these pathogens. This study aims to develop a sensor by investigating the vibrational responses of cantilever and bridged boundary-conditioned single-layer graphene (SLG) sheets with microorganisms, specifically SARS-CoV-2, attached at various positions on the sheet. The dynamic analysis of SLG with different boundary conditions and lengths was conducted using the atomistic finite element method (AFEM). Simulations were performed to evaluate SLG's performance as a sensor for biological entities. Altering the sheet's length and the mass of the attached biological object revealed observable frequency differences. This sensor design shows promise for enhancing the detection capabilities of graphene-based technologies for viruses. Methods: Finite element method (FEM) analysis is employed to model the sensor's performance and optimize its design parameters. The simulation results highlight the sensor's potential for achieving high sensitivity and rapid detection of SARS-CoV-2. Bridged and cantilever boundary conditions are applied at the ends of the SLG structure by using ANSYS software. Simulations have been conducted to observe how SLG behaves when used as sensors. In armchair graphene, under both boundary conditions, an SLG (5, 5) structure with a length of 50 nm displayed the highest frequency when a SARS-CoV-2 molecule with a mass of 2.6594 × 10−18 g was attached. Conversely, the chiral SLG (17, 1) structure exhibited its lowest frequency at a length of 10 nm. This insight is crucial for grasping detection limits and how factors such as size and boundary conditions influence sensor efficacy. These biosensors hold immense promise in biological sciences and medical applications, revolutionizing patient care by enabling early detection and accurate pathogen identification in clinical settings. [ABSTRACT FROM AUTHOR]

In the digital age, where data is a valuable commodity, securing sensitive information has become a growing concern. Image encryption techniques play an essential role in protecting visual data from unauthorized access and ensuring privacy. However, with limited computing capacity in Internet of Things (IoT) devices, standard encryption algorithms are not feasible, rendering lightweight methods mandatory. This study proposes a novel Corner Traversal algorithm, an alternative to existing pixel scrambling techniques. The proposed algorithm demonstrably outperforms its counterparts in both higher confusion and lower time complexity, making it remarkably efficient. Integrated with chaos-based diffusion methods, this algorithm forms a comprehensive encryption scheme. The proposed lightweight image encryption scheme utilizing the Corner Traversal algorithm successfully passed rigorous statistical and differential security analysis. Compared to similar schemes, the proposed encryption scheme employing the Corner Traversal algorithm in the confusion phase distinguishes itself through exceptional NPCR (99.6093 for Lenna) and UACI (33.4648 for Lenna) values. Combined with other evaluation criteria, this method demonstrably meets the stringent security requirements of IoT systems. [ABSTRACT FROM AUTHOR]

In engineering practice, the output performance of contact separation TENGs (CS‐TENGs) increases with the increase of tribo‐pair area, which includes increasing the size of single layer CS‐TENGs (SCS‐TENGs) or the number of units (zigzag TENGs). However, such two strategies show significant differences in output power and power density. In this study, to seek a universal CS‐TENG design solution, the output performance of a SCS‐TENG and a zigzag TENG (Z‐TENG) is systematically compared, including voltage, current, transferred charge, instantaneous power density, and charging power density. The relationship between contact area and output voltages is explored, and the output voltage equation is fitted. The experimental results reveal that SCS‐TENGs yield better performance than Z‐TENGs in terms of voltage, power, and power density under the same total contact area. Z‐TENGs show energy loss during the transfer of mechanical energy, and such loss is aggravated by the increasing number of units. The instantaneous peak power of the SCS‐TENG is up to 22 times that of the Z‐TENG (45 cm2). Furthermore, the power density of capacitor charging of SCS‐TENGs is 131% of that of Z‐TENGs, which are relatively close. Z‐TENG is a feasible alternative when the working space is limited. [ABSTRACT FROM AUTHOR]

Context: Iridoviruses, a group of double-stranded DNA viruses, pose a significant threat to various aquatic animals, causing substantial economic losses in aquaculture and impacting ecosystem health. Early and accurate detection of these viruses is crucial for effective disease management and control. Conventional diagnostic methods, including polymerase chain reaction (PCR) and virus isolation, often require specialized laboratories, skilled personnel, and considerable time. This highlights the need for rapid, sensitive, and cost-effective diagnostic tools for iridovirus detection. Single-layer graphene, a two-dimensional material with unique properties like high surface area, excellent electrical conductivity, and chemical stability, has emerged as a versatile platform for biosensing applications. This paper explores the potential of employing single-layer graphene in the development of a bionanosensor for the sensitive and rapid detection of iridoviruses. The aim of the present investigation is to develop a sensor by analyzing the vibrational responses of single-layer graphene sheets (SLGS) with attached microorganisms. Graphene-based virus sensors typically rely on the interaction between the virus and the graphene surface, which lead to changes in the frequency response of graphene. This change is measured and used to detect the presence of the virus. Its high surface-to-volume ratio and sensitivity to changes in its frequency make it a highly sensitive platform for virus detection. Methods: We employ finite element method (FEM) analysis to model the sensor's performance and optimize its design parameters. The simulation results highlight the sensor's potential for achieving high sensitivity and rapid detection of iridovirus. Bridged and simply supported with roller support boundary conditions applied at the ends of SLG structure. Simulations have been performed to see how SLG behaves when used as sensors. A single-layer graphene armchair SLG (5,5) with 50-nm length exhibits its highest frequency vibration at 8.66 × 106 Hz, with a mass of 1.2786 Zg. In contrast, a zigzag-SLG with a (18,0) configuration has its lowest frequency vibration at 2.82 × 105 Hz. This aids in comprehending the thresholds of detection and the influence of factors such as size, and boundary conditions on sensor effectiveness. These biosensors can be especially helpful in biological sciences and the medical field since they can considerably improve the treatment of patients, cancer early diagnosis, and pathogen identification when used in clinical environments. [ABSTRACT FROM AUTHOR]

It is necessary to maintain maneuverability for ship navigation in shallow water, such as channels, ports and other confined waters. In this study, a turning circle maneuver with 35° rudder deflection and a 20/5 zigzag maneuver for KVLCC2 in shallow waters are tested numerically to directly predict the maneuverability of the ship in shallow water. A viscous in-house CFD solver is applied with the dynamic overset grid approach. The impacts of the water depth on the ship's maneuverability in terms of turning and zigzag competence are evaluated, and the underlying mechanism is analyzed. The numerical method is validated by comparing it with experimental data on the turning indices, which shows good agreement. It is demonstrated that the turning capability become worse with a smaller depth–draft ratio, thus resulting in a lower yaw rate and a greater steady turning diameter. However, the drift angle and lateral speed are reduced with a smaller depth–draft ratio for zigzag maneuvers, but the overshoot angle and turn lag vary with the water depth non-monotonically. [ABSTRACT FROM AUTHOR]

As we know that all non-trivial permutation identities are not preserved under epimorphisms of partially ordered semigroups. In this paper towards this open problem, first we show that certain non-trivial identities in conjunction with the permutation identity z1z2 ... zn = zi1 zi2 ... zin (n ≥ 2) with in 6= n [i1 6= 1] are preserved under epimorphisms of partially ordered semigroups. Further, we extend a result of Ahanger and Shah which showed that the center of a partially ordered semigroup S is closed in S and show that the normalizer of any element of a partially ordered semigroup S is closed in S. [ABSTRACT FROM AUTHOR]

Distributed Acoustic Sensing (DAS) is an emerging sensing technology that records the strain-rate along fiber optic cables at high spatial and temporal resolution. This technique is becoming a popular tool in seismology, hydrology, and other subsurface monitoring applications. However, due to the large coverage (10’s of km) and high density of measurements (1m spacing at 100’s of Hz), a DAS installation could produce terabytes of data records per day. Because many DAS instruments are deployed in remote locations, this large data size poses significant challenges to its transfer and storage. In this paper, we explore lossless compression methods to reduce the storage requirement in both real-time and post-hoc scenarios. We propose a two-stage compression method to improve the compression ratio and compression speed. This two-stage compression method could reduce the storage requirement by 40%, which is 20% more than other lossless methods, such as ZSTD. We demonstrate that the compression method could complete its operation well before the DAS instrument needs to output the next file, making it suitable for real-time DAS acquisition. We also implement a parallel compression method for a post-hoc scenario and demonstrate that our method could effectively utilize a parallel computer. With 256 CPU cores, our parallel compression method achieves the speed of 26GB/second.

Decoration Features of Second Iron Age Pottery South of the Po The paper analyses on a chronological typological level the decorative syntax present on impasto pottery from the Late Iron Age (Ligure III period: 475–89 BC) in lower Piedmont (inner Piedmontese Liguria), where vessel forms and decorative elements appear largely in continuity with those of the Middle Iron Age (Ligure II period: 625–475 BC). Decoration is generally present on closed shapes (situliform vases, ollae). Compared to the Middle Iron Age, the percentage of decorated pottery increases and the decorative elements become more elaborate. The most characteristic elements are the horizontal rows of finger or tool impressions, the simple zigzags, at first continuous and then interrupted (the latter evolving over time from single to double and then to multiple, sometimes with the alternate insertion of triangular or circular impressions at the corners), the impressions with or without clay, are usually on the lower part of the vessel, sometimes in combination with the zigzag motif. Shapes and decorative syntax are not found in the funerary and settlement contexts of northern Pied mont and more generally in Cispadana, while they seem to have an identifying character for the Ligurian groups of inland Piedmont.

After the tremendous development and fast growth in communication systems and electronic devices, information security and preservation have become one of the most important procedures to be considered when transferring data between two parties. Encryption and data hiding are two of the most important techniques to protect the information sent over networks and the Internet. In this paper, a new technique of encryption and concealment is used through the following steps: First, the secret information is encrypted by using developed DNA to get (S1), second, by scrambling the encrypted data, the (S1) is diffused by using a zigzag method to get (S2), third, re-obfuscation the (S2) by using developed zigzag method through using Tinkerbell technique to get (S3), fourth, perform XoR operation between the (S3) and the Tinkerbell technique to get (S4), and fifth, the (S4) is hidden in the random locations of the cover image based on the LSB technique and the Tinkerbell technology, where the Tinkerbell has incredibly excellent characteristics and used to generate random sequence numbers twice with different initial and parameters value, once for the encryption process for scrambling secret information and once for the hiding process for determining hidden locations. Several metrics were used to evaluate the system's efficiency: histogram, PSNR, MSE, mean absolute error, bit error rate, encryption quality, Unified Average Changing Intensity, hamming distance, entropy, and correlation coefficient. The experimental results display that the suggested method has a good performance and reliability, high security, and greater embedding capacity and ensures higher image quality; also, the proposed method presented preferable outcomes when compared to other approaches. [ABSTRACT FROM AUTHOR]

The paper analyses on a chronological -typological level the decorative syntax present on impasto pottery from the Late Iron Age (Ligure III period: 475-89 BC) in lower Piedmont (inner Piedmontese Liguria), where vessel forms and decorative elements appear largely in continuity with those of the Middle Iron Age (Ligure II period: 625-475 BC). Decoration is generally present on closed shapes (situliform vases, ollae). Compared to the Middle Iron Age, the percentage of decorated pottery increases and the decorative elements become more elaborate. The most characteristic elements are the horizontal rows of finger or tool impressions, the simple zigzags, at first continuous and then interrupted (the latter evolving over time from single to double and then to multiple, sometimes with the alternate insertion of triangular or circular impressions at the corners), the impressions with or without clay, are usually on the lower part of the vessel, sometimes in combination with the zigzag motif. Shapes and decorative syntax are not found in the funerary and settlement contexts of northern Piedmont and more generally in Cispadana, while they seem to have an identifying character for the Ligurian groups of inland Piedmont. [ABSTRACT FROM AUTHOR]

Context: Graphene based nano sensors have huge potential in an era of sensor technology. The objective of this study is to create a sensor by investigating the vibration responses of cantilever and bridged boundary conditioned single layer graphene sheets (SLGS) with various attached microorganisms on the tip and at the centre of the sheet. The Parvoviridae, Flaviviridae, and Polyomaviridae biological substances have been comprehensively investigated here. For the Parvoviridae, Polyomaviridae, and Flaviviridae categories of targeted microbes, the sizes are 21nm, 40nm, and 45nm, respectively. The Parvoviridae family has a maximum frequency of 1.87x107 Hz with a cantilever condition and a mass of 4.2441 Zg, and for a bridged condition, it demonstrates a maximum frequency of 1.23x108 Hz with the same mass on armchair SLG (5 5). The data analysis shows that 3.0041 Zg mass of the Mimivirus has the lowest frequency. It demonstrates explicitly that the rate of frequency decreases as the value of mass increases. When compared to chiral SLG, the armchair single layer graphene sheet performs better. The research indicates that the dynamic properties are significantly influenced by the mass of various biological organisms. The application of this sensor will enable the detection of microorganisms or viruses that can be connected to SLG. Methods: In this research, the application of Single Layer Graphene (SLG) as a virus sensing device is explored. Atomistic finite element method (AFEM) has been used to carry out the dynamic analysis of SLG. Molecular dynamic analysis and simulations have been performed to see how SLG behaves when employed as sensors for biological entities and when they are exposed to bridged and cantilever boundary conditions. The frequency analysis was performed using ANSYS APDL software. SLG of various chirality has been utilised in the investigation. By altering the applied mass of a biological object, the difference in frequency observed. The idea behind mass detection employing nano biosensors is built on the concept that the stiffness of a biomolecule changes as its mass changes, making the resonant frequency extremely sensitive to that change. A shift in the resonance frequency results from a change in the associated mass on the graphene sheet. The main challenge in mass detection is estimating the variation in resonant frequency driven by the mass of the connected molecule. The SLG-based biosensor has a specific application in the early identification of diseases. The biosensor investigated in this article is novel, whereas the biosensors that are presently on the market operate using the ionization method. The simulations result shows SLG based biosensor's sensitivity considerably faster than an existing one. [ABSTRACT FROM AUTHOR]

It is necessary to maintain maneuverability for ship navigation in shallow water, such as channels, ports and other confined waters. In this study, a turning circle maneuver with 35° rudder deflection and a 20/5 zigzag maneuver for KVLCC2 in shallow waters are tested numerically to directly predict the maneuverability of the ship in shallow water. A viscous in-house CFD solver is applied with the dynamic overset grid approach. The impacts of the water depth on the ship’s maneuverability in terms of turning and zigzag competence are evaluated, and the underlying mechanism is analyzed. The numerical method is validated by comparing it with experimental data on the turning indices, which shows good agreement. It is demonstrated that the turning capability become worse with a smaller depth–draft ratio, thus resulting in a lower yaw rate and a greater steady turning diameter. However, the drift angle and lateral speed are reduced with a smaller depth–draft ratio for zigzag maneuvers, but the overshoot angle and turn lag vary with the water depth non-monotonically.

Based on doublet mechanics theory and various beam theories, this paper presents free vibration of axially loaded zigzag and armchair nanobeams. A two-noded higher order beam element is used to solve the problems of nanobeams with various boundary conditions. The verification studies in terms of fundamental frequencies and buckling loads are performed by comparing the results by the present model with Molecular Dynamic Simulations, Doublet Mechanics, and Eringen's nonlocal theory. The effects of material length scale parameter, slenderness ratio, nanotube model and boundary conditions on the fundamental frequencies of axially loaded nanobeams are investigated in details. Softening material behavior is detected for zigzag and armchair nanobeams. Having stiffer boundary conditions lead to the effect of material length scale parameter to be observed more prominently. [ABSTRACT FROM AUTHOR]

We have studied structures of single walled carbon nanotubes and metal semiconductor transition for the symmetric breaking. It was found that band gap existed for metallic armchair single walled carbon nanotubes. Calculations were made to analyse the meta-stability of the corrugated structures of armchair single walled carbon nanotubes. The corrugated single walled carbon nanotube structures are always lower in energy than the non corrugated nanotubes. The curvature effect was that the corrugated structure breaks the local symmetry between different carbon atoms. A true gap is created which does not vanish even when an external magnetic field is swept. The corrugation length and band gap gaps are decaying functions of the nanotubes radius and approached zero for carbon nanotube such as graphene. This was also true for zigzag and chiral single wall carbon nanotubes. The obtained results were found in good agreement with previously obtained results. [ABSTRACT FROM AUTHOR]

The electronic properties of zigzag and armchair SiC nanoribbons are studied using a theoretical method. The spin-unrestricted electronic behavior of an armchair and zigzag SiC nanoribbon containing Si and C vacancy in the supercell was investigated. Spin-polarized electronic structure calculations show that armchair SiC nanoribbon was classified as a nonmagnetic semiconductor while zigzag SiC nanoribbon presents a half-metallic electronic structure. Our results suggest that SiC nanoribbon containing point vacancy may be a good candidate for spintronics due to its half-metal properties. [ABSTRACT FROM AUTHOR]

Hydrocarbon belts have drawn great attention because of their unique structures and tantalizing properties. Although a few belts and heteroatom‐doped analogs have been synthesized, belt molecules containing non‐hexagonal rings remain rare. Herein we report the construction and application of unprecedented zigzag‐type hydrocarbon belts which contain functionalized eight‐membered rings. The synthesis features fourfold intramolecular acylation reactions of resorcin[4]arene‐derived intermediates, which affords C4‐symmetric tetrabenzobelt[4]arene[4]cyclooctatrienones. Stereoselective ketone reduction with LiAlH4 and nucleophilic addition with alkynyllithiums provide the corresponding tetrahydroxylated belts. The tetraol and its methyl ether are powerful and selective hosts to form 2 : 1 and 1 : 1 complexes with cesium ion, respectively, with binding constants up to (1.71±0.33)×1011 M−2 and (1.50±0.16)×106 M−1. In addition, enantiopure C4‐symmetric belts can emit CPL with |glum| being around 0.01. [ABSTRACT FROM AUTHOR]

The aim of this paper is to determine several saturated classes of structurally regular semigroups. First, we show that structurally (n , m) -regular semigroups are saturated in a subclass of semigroups for any pair (n , m) of positive integers. We also demonstrate that, for all positive integers n and k with 1 ≤ k ≤ n , the variety of structurally (0 , n) -left seminormal bands is saturated in the variety of structurally (0 , k) -bands. As a result, in the category of structurally (0 , k) -bands, epis from structurally (0 , n) -left seminormal bands is onto. [ABSTRACT FROM AUTHOR]

Context: Nanosensors and actuators are frequently made of graphene. Any defect in the graphene's manufacturing has an impact on its sensing performance and on its dynamic behaviour. Using a molecular dynamics technique, the influence of pinhole defects and atomic defects on the performance parameters of single-layer graphene sheets (SLGSs) and double-layer graphene sheets (DLGSs) with various boundary conditions and lengths is explored. In contrast to the perfect nanostructure of a graphene sheet, defects are described as holes formed by atomic vacancies. As the number of defects increases, the simulation results show that the presence of defects has the greatest impact on the resonance frequency of SLGSs and DLGSs. The influence of pinhole defect (PD) and atomic vacancy defect (AVD) on armchair, zigzag, and chiral SLGSs and DLGSs was investigated in this article using molecular dynamics simulation. The influence of both types of defects is largest when it is adjacent to the fixed support for all three different types of graphene sheets, i.e. armchair, zigzag, and chiral. Methods: The structure of the graphene sheet has been created using ANSYS APDL software. In the structure of the graphene sheet, atomic and pinhole defects have been generated. SLG and DLG sheets are modelled using a space frame structure that is identical to a three-dimensional beam. Dynamic analysis of single-layer and double-layer graphene sheets performed with different lengths using the atomistic finite element method. The interlayer separation in the form of Van der Waals interaction is modelled using characteristic spring element (Combin14). The upper and lower sheets of DLGSs are described as elastic beams connected by a spring element. With atomic vacancy defect for the bridged boundary condition, the highest frequency of 2.86 × 108 Hz was found for zigzag DLG (20 0) and with same boundary condition for pinhole defect 2.79 × 108 Hz frequency achieved. In a single-layer graphene sheet with an atomic vacancy and cantilever boundary condition, the maximum efficiency was 4.13 × 103 Hz for SLG (20 0), while in a pinhole defect, it produced 2.73 × 107 Hz. Moreover, the elastic parameters of beam components are calculated using the mechanical properties of covalent bonds between carbon atoms in the hexagonal lattice. The model has been tested against previous research. The focus of this research is to develop a mechanism for determining how defects affect graphene frequency band in application as nano resonators. [ABSTRACT FROM AUTHOR]

We show that all subvarieties of the variety of rectangular bands are closed in the variety of all bands. Further, we show that the variety of regular bands is closed. Next, we introduce the varieties of generalized left [right] regular semigroups and show that all such varieties are saturated and, subsequently, epis from generalized left [right] regular semigroups are surjective. [ABSTRACT FROM AUTHOR]

The effect of geometric parameters of the zigzag, rectangular, and serpentine channels on convective heat transfer coefficient and pressure drop was investigated using computational fluid dynamics (CFD). In all channels, the same boundary conditions were considered, and the number of steps was equal to 10. The simulations were performed for turbulent flows (liquid water as the operating fluid), and Reynolds number (Re) range between 20000 and 60000 was selected. The zigzag channel showed a best thermal performance and the serpentine channel showed the best hydraulic performance. The thermal-hydraulic performance (THP) factor was employed for comparing the channels. As the complexity of the channels surfaces increased, the two parameters of convective heat transfer coefficient (positive factor) and pressure drop (negative factor) increased simultaneously. Therefore, predictive correlations for friction factor and Nusselt number were presented using genetic algorithm (GA), and the multi-objective optimization was performed to obtain the most appropriate Nusselt number and minimum friction factor as the two basic objective functions. The resulting Pareto set, which includes the optimum geometric dimensions of the heat exchangers, allows a designer to choice the geometries based on higher heat transfer or lower pumping power.

• Exhibition of stationary as well as oscillatory regime is reported. • Possibility of secondary instabilities in various regimes is indicated. • Domains of the secondary instabilities of Eckhaus and zigzag are documented. • Parameters' space within which Benjamin–Feir instability manifests is depicted. Manifestation of stationary and oscillatory convection and secondary instabilities due to a chemical reaction in a two-component convective fluid system is reported in the paper by considering idealistic as well as physically realistic boundaries. Using a normal mode solution, analytical expression of the critical Rayleigh number for a stationary and oscillatory disturbances, and the natural frequency are reported. The range of parameters is identified where oscillatory motion happens. Further, the parameters' range for existence of oscillatory regime is found to be larger for rigid boundaries compared to that of free boundaries. Furthermore, for both the boundaries, parameters' range for this regime increases when the chemical reaction rate increases, leading to the conclusion that the oscillatory motion emerges as the most preferred mode in the two-component system due to the presence of a chemical reaction and the size of this domain is directly proportional to the chemical reaction rate. The marginal stability plots depict that the oscillatory and stationary regimes respectively correspond to Hopf and direct pitchfork bifurcations. The critical Rayleigh number and the wave number where codimension two bifurcation exists are documented in the paper for fixed values of parameters. It is shown that the codimension two bifurcation that arose in the problem is not a Takens–Bogdanov bifurcation. In a stationary regime, the domain for secondary instabilities of Eckhaus and zigzag is obtained using the spatio-temporal Newell–Whitehead–Segel equation. These instabilities grow with increasing chemical reaction rate. In the oscillatory regime, the complex Ginzburg–Landau equation is used to predict the appearance of the Benjamin–Feir instability. [ABSTRACT FROM AUTHOR]

Nowadays the E-bank systems witnessed huge growth due to the huge developments in the internet and technologies. The transmitted information represents crucial information that is exposed to various kinds of attacks. This paper presents a new block cipher technique to provide security to the transmitted information between the customers and the ebank systems. The proposed algorithm consists of 10 rounds, each round involves 5 operations. The operations involve Add round key, Sub bytes, Zigzag method, convert to vector, and Magic Square of order 11. The purpose of this algorithm is to make use of the complexity of the Magic Square algorithm, the speed of addition operation, the confusion provided by the zigzag, using these operations with Galois field 28 GF(28), and repeating these operations for several rounds to build fast high secure encryption algorithm. This algorithm is designed to provide fast with high complexity and security which is suitable to encrypt the data that is transmitted over the internet. Speed, complexity, and The National Institute of Standards and Technology Framework NIST suite tests were done. The complexity of the proposed algorithm is=((256)32)r+1∗((256)89)r+1+(256)121. The proposed technique gives higher speed and security in the encryption and decryption phases, according to the results of the experiments. The degree of randomness has grown by 31.8 percent. Due to a decrease in the time of encrypting and decrypting, as well as the usage of the central processing unit (CPU), efficiency is improved. The encryption process throughput is enhanced by 13%, while the decryption process throughput is increased by 11.6 percent with the recommended approach. [ABSTRACT FROM AUTHOR]

Based on systematic first-principles density-functional theory simulations, we predict that the zigzag GaN nanoribbons (ZGaNNRs) can be used both as highly efficient CO detectors as well as spin filters. Our calculations, performed both on infinitely long nanoribbons, and also on finite strands, suggest that: (a) CO binds strongly at the edges of ZGaNNRs, and (b) that several of the resultant configurations exhibit half-metallic behavior. We considered various edge-passivation sites and found that all the resultant structures are thermodynamically stable. The metallic, half-metallic, and semiconducting configurations are observed as a function of CO passivation coverage. We also compute the currentâ€"voltage (Iâ€"V) characteristics of various structures using the Landauer formalism, and find that the devices made up of half-metallic configurations act as highly-efficient spin filters. The effect of CO concentration is also investigated which suggests a viable way to not just tune the electronic band gap of ZGaNNRs, but also their half metallicity. Our simulations thus suggest a new direction of research for possible device applications of IIIâ€"V heterostructures. [ABSTRACT FROM AUTHOR]

CO2 gasification process on different active edges of a particular coke model surface has been explored computationally. It is observed that the adsorption through carbon and oxygen end of CO2 (CO‐mode) through formation of four‐ and five‐membered ring on the active sites is the favoured one. Our calculation also reveals that the strength of adsorption depends on nature and position of the active sites. The exergonic adsorption energy of CO‐mode drives the first CO release process and also makes it favoured compared to the adsorption mode where CO2 has been absorbed through its two‐oxygen end (OO‐mode). Among all the intermediates, intermediate having oxygen attached to the middle‐carbon of the coke (middle‐oxygenated coke) is found to be the most stable intermediate. The energy barrier for the second CO release also depends on the attachment sites of the oxygen on the coke surface. It is noteworthy that first principles investigations of coke gasification reactions with CO2 reported to date are found to consider different coke active sites separately on different coke model surfaces. In this context, our work is believed to be the first of its kind where complete characterization of CO2 gasification reactions has been performed considering all the active sites in a single coke model, thus providing a more coherent picture of it. [ABSTRACT FROM AUTHOR]

Graphene has been widely and extensively used in mass sensing applications. The present study focused on exploring the use of single-layer graphene (SLG) and double-layer graphene (DLG) as sensing devices. The dynamic analysis of SLG and DLG with different boundary conditions (BDs) and length was executed using the atomistic finite element method (AFEM). SLG and DLG sheets were modelled and considered as a space–frame structure similar to a 3D beam. Spring elements (Combin14) were used to identify the interlayer interactions between two graphene layers in the DLG sheet due to the van der Waals forces. Simulations were carried out to visualize the behavior of the SLG and DLG subjected to different BDs and when used as mass sensing devices. The variation in frequency was noted by changing the length and applied mass of the SLGs and DLGs. The quantity of the frequency was found to be highest in the armchair SLG (6, 6) for a 50 nm sheet length and lowest in the chiral SLG (16, 4) for a 20 nm sheet length in the bridged condition. When the mass was 0.1 Zg, the frequency for the zigzag SLG (20, 0) was higher in both cases. The results show that the length of the sheet and the various mass values have a significant impact on the dynamic properties. The present research will contribute to the ultra-high frequency nano-resonance applications. [ABSTRACT FROM AUTHOR]

Zigzag bilayer graphene nanoribbons are gapless, which is not good at the design of graphene field effect transistors. The edge line defects can open the band gap and the edge state localized on both sides may be tuned on one side, which provides theoretical support for the design of bilayer graphene nanodevices. The energy spectrum and lattice wave function of bilayer zigzag graphene nanoribbons are calculated by using the tight-binding model. The numerical results show that the hopping between edge line defects can open the AA stacking gap, and the on-site energy of edge line defects can open the AB stacking gap. The weak localization behavior in the bilayer zigzag graphene nanoribbons is different from that of single layer. The defect on-site energy and interlayer hopping can change the localized edge state, respectively. Appropriate defect on-site energy can make the electrons dominant in the upper layer (or lower layer). The electron transport of two-terminal bilayer zigzag graphene nanoribbons was investigated by using the non-equilibrium Green's function method, and the local state density and transmission probability of the system with edge defect were calculated. [ABSTRACT FROM AUTHOR]

In this paper we study epimorphisms, dominions and related properties for some classes of structurally (n,m)-regular semigroups for any pair (n,m) of positive integers. In Section 2, after a brief introduction of these semigroups, we prove that the class of structurallly (n,m)-generalized inverse semigroups is closed under morphic images. We then prove the main result of this section that the class of structurally (n,m)-generalized inverse semigroups is saturated and, thus, in the category of all semigroups, epimorphisms in this class are precisely surjective morphisms. Finally, in the last section, we prove that the variety of structurally (o, n)-left regular bands is saturated in the variety of structurally (o, k)-left regular bands for all positive integers k and n with 1 ≤ k ≤ n.

The aim of this paper is to determine several saturated classes of structurally regular semigroups. First, we show that structurally (n,m)-regular semigroups are saturated in a subclass of semigroups for any pair (n,m) of positive integers. We also demonstrate that, for all positive integers n and k with 1≤k≤n, the variety of structurally (0,n)-left seminormal bands is saturated in the variety of structurally (0,k)-bands. As a result, in the category of structurally (0,k)-bands, epis from structurally (0,n)-left seminormal bands is onto.

Understanding the long-term stability of MoS2 is important for various optoelectronic applications. Herein, we show that the long-term exposure to an oxygen atmosphere for up to a few months results in zigzag (zz)-directional line unzipping of the MoS2 basal plane. In contrast to exposure to dry or humid N2 atmospheres, dry O2 treatment promotes the initial formation of line defects, mainly along the armchair (ac) direction, and humid O2 treatment further promotes ac line unzipping near edges. Further incubation of MoS2 for a few months in an O2 atmosphere results in massive zz-directional line unzipping. The photoluminescence and the strain-doping plot based on two prominent bands in the Raman spectrum show that, in contrast to dry-N2-treated MoS2, the O2-treated MoS2 primarily exhibits hole doping, whereas humid-O2-treated MoS2 mainly exists in a neutral charge state with tension. This study provides a guideline for MoS2 preservation and a further method for generating controlled defects. [ABSTRACT FROM AUTHOR]

The zigzag (ZZ) classifier is a sorting and classification device with a wide range of applications (e.g. recycling, food industry). Due to the possible variation of geometry and process settings, the apparatus is used for various windows of operation due to the specifications of the separation (e.g. cut sizes from 100 µm to several decimetres, compact and fluffy materials as well as foils). Since the ZZ classifier gains more and more interest in recycling applications, it is discussed in this paper, with regards to its design, mode of operation, influencing parameters and the research to date. Research on the ZZ-classifier has been ongoing on for more than 50 years and can be divided into mainly experimental studies and modelling approaches. [ABSTRACT FROM AUTHOR]

Dislocations are a central concept in materials science, which dictate the plastic deformation and damage evolution in materials. Layered materials such as graphite admit two general types of interlayer dislocations: basal and prismatic dislocations, of which prismatic dislocations have been relatively less studied. Using density functional theory (DFT) calculations, we have examined different prismatic core structures in graphite and evaluated their structure, energetics and mobility. We find close energetic interplay between bonded and "free-standing" core structures in both zigzag and armchair directions, with a reconstructed stable zigzag core identified. We explore grain boundaries and prismatic dislocation pile-up, identifying metastable structures which may be important in energy storage. The role of interlayer stacking in core structure, dislocation glide and climb is also considered in-depth. Our calculations suggest that the prismatic dislocation core is stable up to high temperatures of approximately 1500 K in bulk graphite. Above this temperature, the breaking of bonds in the dislocation core can facilitate climb, grain-boundary motion, and the annealing of damage through prismatic dislocation glide. [Display omitted] [ABSTRACT FROM AUTHOR]

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Due to their simplicity and versatility of design, straight strip or rectangular pad anode structures are frequently used with micropattern gas detectors (MPGDs) to reconstruct high-precision space points for various tracking applications. The particle impact point is typically determined by interpolating the charge collected by several neighboring strips. However, to effectively extract the inherent positional information, the lateral spacing of the straight strips must be comparable to or preferably smaller than the full extent of the incident charge cloud. In contrast, highly interleaved anode patterns, such as zigzags, can adequately sample the incident charge with a pitch appreciably larger than the charge cloud. This has the considerable advantage of providing the same performance while requiring far fewer instrumented channels. Additionally, the geometric parameters defining such zigzag structures may be tuned to provide a near-uniform detector response along and perpendicular to the sensitive coordinate, without the need for so-called “pad response functions,” while simultaneously maintaining excellent position resolution. We have measured the position resolution of a variety of zigzag-shaped anode patterns optimized for various MPGDs, including gas electron multiplyer (GEM), Micromegas, and micro-resistive-well ($\mu $ RWELL) and compared this performance with the same detectors equipped with straight strips of varying pitch. We report on the performance results of each readout structure, evaluated under identical conditions in a test beam. [ABSTRACT FROM AUTHOR]

The effect of geometric parameters of the zigzag, rectangular, and serpentine channels on convective heat transfer coefficient and pressure drop was investigated using computational fluid dynamics (CFD). The same boundary conditions were considered in all channels, and the number of steps was equal to 10. The simulations were performed for turbulent flows (liquid water as the operating fluid), and the Reynolds number (Re) range between 20000 and 60000 was selected. The zigzag channel showed the best thermal performance, and the serpentine channel showed the best hydraulic performance. The thermal-hydraulic performance (THP) factor was employed for comparing the channels. As the complexity of the channel's surfaces increased, the two parameters of convective heat transfer coefficient (positive factor) and pressure drop (negative factor) increased simultaneously. Therefore, predictive correlations for friction factor and Nusselt number were presented using a genetic algorithm (GA), The multiobjective optimization was performed to obtain the most appropriate Nusselt number and minimum friction factor as the two basic objective functions. The resulting Pareto set, which includes the optimum geometric dimensions of the heat exchangers, allows a designer to chooce the geometries based on higher heat transfer or lower pumping power. [ABSTRACT FROM AUTHOR]

A novel one-dimensional zigzag chain-like CoII coordination polymer constructed from 4,4′-bipyridine (4,4′-bpy) and 2-hydroxybenzoate (2-OHbenz) ligands, namely, catena-poly[[(4,4′-bipyridine-κN)(μ-2-hydroxybenzoato-κ2O:O′)(2-hydroxybenzoato-κ2O,O′)cobalt(II)]-μ-4,4′-bipyridine-κ2N:N′-[aquahemi(μ-4,4′-bipyridine-κ2N:N′)(2-hydroxybenzoato-κO(2-hydroxybenzoato-κ2O:O′)cobalt(II)], [Co2(C7H5O3)4(C10H8N2)2.5(H2O)]n, has been synthesized by reacting cobalt(II) nitrate trihydrate, 4,4′-bpy and 2-hydroxybenzoic acid in a mixture of water and methanol at room temperature. There are two independent CoII centers, Co1 and Co2, in the asymmetric unit, revealing a distorted octahedral geometry with chromophore types of [CoN2O4] and [CoN2O3O′], respectively. The Co1 ions are doubly bridged by 2-OHbenz ligands with syn–anti coordination mode, generating a dinuclear unit. The bridging 4,4′-bpy ligands connect these dinuclear units and the mononuclear Co2 chromophores, providing a one-dimensional alternating zigzag chain-like structure. In the crystal, intermolecular hydrogen bonds, C—H...π and π–π stacking interactions are observed and these help to consolidate the packing. In addition, the physical properties of the title compound are reported.

Equivalent single layer theories for layered beams effectively and accurately predict global displacements and internal force and moment resultants using a limited number of displacement variables. However, they cannot reproduce local effects due to material architecture or weak/imperfect bonding of the layers, such as zigzag displacement fields, displacement jumps at the layer interfaces and complex transverse stress fields, nor can they simulate delamination damage growth. In this work we will present some applications and discuss advantages and limitations of a recently formulated zigzag model. The model, through a modification of the equilibrium equations of an equivalent single layer theory, which maintains the same number of variables, reproduces local effects and delamination fracture under mode II dominant conditions. The approach is based on a local enrichment of the displacement field of first order shear deformation theory, the introduction of cohesive interfaces and homogenization.

A Recurrent Neural Network (RNN) model is presented in this paper to predict the ship maneuvering motion. Inputs to the model are the orders of rudder angle and its variation as well as the propeller speed (ship speed) and also the recursive outputs velocities of surge, sway and yaw. The past values for the velocities are retained in the inputs to indicate the influence of historical state of motion on the maneuvering prediction. The KRISO Container Ship (KCS) is taken as the study object. The data obtained from a manoeuvring mathematical model and free-running model test are respectively used to train the neural network. Tactical circles and zigzags are simulated by the RNN, the prediction for maneuvers not involved in the training set shows that the RNN in this paper has good generalization performance. The concept of uncertainty is proposed to be considered in the further work through the analysis.

This article presents a new higher-order beam model. The present beam model is governed by differential equations that are similar to those present in some existing higher-order beam models; however, the present beam model makes use of a novel method of calculating the transverse shear stiffness, which facilitates the calculation of a shear-warping stiffness without the need for an assumed warping displacement field, and without introducing any additional kinematic variables. The present beam model also facilitates the recovery of the distributions of longitudinal normal stresses and transverse shear stresses. The authors postulate that the bending and shear terms in first-order shear deformation theory represent the first two terms in an infinite series that would constitute an ideal one-dimensional beam model, and it is suggested that the present beam model constitutes the first four terms in this hypothetical infinite series. The present beam model is solved for several example beams, and the results are compared with those of existing classical and higher-order beam models, as well as computational results from finite element analyses. It is shown that the present beam model is able to accurately represent deformed shapes and stress distributions pertaining to beams that exhibit non-trivial shear compliance as well as non-trivial shear-warping stiffness. In the case of laminated composite beams comprising a large number of laminae, the present beam model offers a level of analytical fidelity that is comparable to that of existing zigzag beam models; however, unlike zigzag beam models, the present beam model is equally well suited for the analyses of beams comprising any number of laminae. [ABSTRACT FROM AUTHOR]