Electronic and magnetic properties of the monolayer RuCl3_3: A first-principles and Monte Carlo study

Recent experiments revealed that monolayer $\alpha$-RuCl$_3$ can be obtain by chemical exfoliation method and exfoliation or restacking of nanosheets can manipulate the magnetic properties of the materials. In this present paper, the electronic and magnetic properties of $\alpha$-RuCl$_3$ monolayer are investigated by combining first-principles calculations and Monte Carlo simulations. From first-principles calculations, we found that the spin configuration FM corresponds to the ground state for $\alpha$-RuCl$_3$, however, the other excited zigzag oriented spin configuration has energy of 5 meV/atom higher than the ground state. Energy band gap has been obtained as $3$ meV using PBE functionals. When spin-orbit coupling effect is taken into account, corresponding energy gap is determined to be as $57$ meV. We also investigate the effect of Hubbard U energy terms on the electronic band structure of $\alpha$-RuCl$_3$ monolayer and revealed band gap increases approximately linear with increasing U value. Moreover, spin-spin coupling terms ($J_1$, $J_2$, $J_3$) have been obtained using first principles calculations. By benefiting from these terms, Monte Carlo simulations with single site update Metropolis algorithm have been implemented to elucidate magnetic properties of the considered system. Thermal variations of magnetization, susceptibility and also specific heat curves indicate that monolayer $\alpha$-RuCl$_3$ exhibits a phase transition between ordered and disordered phases at the Curie temperature $14.21$ K. We believe that this study can be utilized to improve two-dimensional magnet materials

Effects of intrathecal bupivacaine and bupivacaine plus sufentanil in elderly patients undergoing transurethral resection

Introduction: The present study compared the effect of bupivacaine and bupivacaine + sufentanil on hemodynamic parameters and characteristics of spinal anesthesia in elderly patients undergoing transurethral resection of the prostate (TURP) under spinal anesthesia.Technical Considerations: The study included 40 American Society of Anesthesiologists (ASA) I‑III patients scheduled to undergo TURP. Patients were blindly and randomly divided into two groups. Group B (n = 20) received 10 mg of intrathecal bupivacaine and group BS (n = 20) received 7.5 mg of bupivacaine + 5 μg of sufentanil. Sensory and motor block characteristics, hemodynamic changes, side effects, and time to first analgesic requirement were recorded. No differences in mean arterial pressure or heart rate, time for sensory blockade to reach the T10 level, and maximum sensory level were observed between the two groups. The time to first analgesic request was longer in group BS (P < 0.05). Motor block was significantly higher in group B (P < 0.05). In terms of side effects, no statistically significant differences occurred between the groups.Conclusions: Similar hemodynamic stability and sufficient level of sensory blockade were provided by bupivacaine and bupivacaine + sufentanil used for spinal anesthesia in patients undergoing TUR. Due to the fact that less motor block was observed and the time to first analgesic request was longer, the combination of bupivacaine + sufentanil might be appropriate for patients undergoing TUR.Key words: Bupivacaine, intrathecal, opioid, spinal, sufentani

Investigation of the effect of anti-fouling systems on meeting energy efficiency regulations

The operational efficiency of marine vessels should be kept as high as possible to achieve sustainable development goals in the maritime field. However, a lot of factors such as resistance components reduce the operational efficiency of the ship. Frictional resistance is the biggest resistance component for the power needed on ships and its coefficient increases due to the biofouling as long as the ship interacts with seawater. The increased total resistance of the ship causes extra power needed and excessive fuel consumption to reach service speed. The increase in both fuel consumption and power will create an obstacle to meeting the EEXI and CII reference values which became mandatory after January 1, 2023. That’s why the utilization of effective anti-fouling systems is quite critical in maritime applications. The purpose of this study is to reveal anti-fouling systems’ effect on EEXI, CII, and CII ratings by utilization of the container ship operated in liner shipping. That’s why, high, medium, and low effective anti-fouling system scenarios have been created since the effect of each anti-fouling will not be the same on the container ship. According to the results, the required EEXI and CII reference values will have been met respectively when the effect of ship biofouling is ignored. However, the reduction ratios and biofouling effect have created quite a challenge in meeting EEXI and CII in the following years. Although the required EEXI value has been met for 2024 and 2025 by the high-effective anti-fouling system and reference value has not been met by the low-effective anti-fouling system in the following years. Any anti-fouling system utilized in this paper won’t be sufficient to meet the reference value at the end of 2023 because attained CII of the container ship is very close to the reference value of CII in 2023. The CII rating of the container ship will have been at C level until the end of 2026 when the biofouling effect is ignored. However, it decreased to D and E levels in the following two years depending on the best and worst scenarios. This study will be a valuable resource for scientists, researchers, experts, and maritime stakeholders who want to investigate the effect of EEXI, CII, and CII rating of antifouling systems

Impacts of the Form Design and Operational Factors on the Energy Consumption of a Solar-Powered Boat: A System Dynamics Approach

This research paper aims to design a solar-powered boat and analyze the effects of environmental and form-related factors on power consumption and battery duration by utilizing a system dynamics approach-based simulation. The boat form is designed as the planing hull and its hull resistance analysis was ensured in Maxsurf package program. PV panels with 548 W power output and two battery packs with 4660 Wh capacity were placed on the hull body to employ an electric motor with a 10-kW nominal power output. Two MPPTs were implemented in the system to increase solar system efficiency. The relationships between all system components were modelled in Vensim software to observe battery endurance changes under different conditions. Results demonstrated that the ideal vessel speed is calculated to be around 7 knots with roughly 8 hours of battery duration for the designed boat. A critical stage of charge for sailing is 40% since 1.63 hours of cruising time may be achieved while maintaining a speed of 5 m/s (9.72 knots). Indeed, the boat’s rising trim angle shortens the battery discharge time; thus, navigation by no trim angle is the most effective usage for the vessel

Classification of Ship Propeller Types and Energy-Saving Devices Under Technology Developments

The propulsion system and its components need to be thoroughly analyzed and optimized for marine vessels to operate as efficiently as possible in applications where new builds or retrofitting are performed. Gearboxes, bearings, and other transmission equipment in the component of the power transmission from ship engine, which is the primary source of propulsion for most marine vessels, to propeller cause a variety of losses. To maximize propulsive efficiency, propeller selection should be performed precisely on the basis of ship type, operation mode, and area. Propulsion efficiency, fuel consumption, robustness, reliability, emissions, vibration, cavitation, complexity and cost are investigated in both conventional propellers and cutting-edge technology in propeller systems. This study will guide academicians, experts, and sector stakeholders in determining which propeller type will be more efficient for marine vessels since propulsion efficiency is critical for the sustainability of maritime transportation

The reliability evaluation of the deck machinery and galley equipment of a bulk carrier by utilizing the failure records

Among various modes of transportation, maritime transportation holds critical importance since it provides substantial carrying capacity with low unit costs. To perform seamless and efficient operations in maritime transportation plays a pivotal role in achieving sustainable development goals and the International Maritime Organization (IMO) targets. The execution of uninterrupted operations can only be carried out with the existence of reliable systems. Creating reliable systems onboard is possible through the implementation of planned and proactive maintenance strategies and leveraging experiences gained from past failures. 10-year failure records of bulk carriers have been scrutinized within the scope of system reliability to determine critical equipment and units. The data has been categorized into subgroups under four fundamental headings, and subsequent reliability analyses have been conducted on each subgroup. Within the subgroups, the reliability of navigation equipment should be improved since it has the highest failure rate and its malfunction can cause very serious marine accidents. This equipment is followed by fire-fighting systems, cargo equipment, and GMDSS instruments which are essential for ship operations based on reliability results. Therefore, regular failure records, planned and proactive maintenance strategies, and also extra efforts should be performed on this equipment to ensure sustainable and seamless operations in the maritime sector

Dynamic phase transition properties and hysteretic behavior of a ferrimagnetic core-shell nanoparticle in the presence of a time dependent magnetic field

We have presented dynamic phase transition features and stationary-state behavior of a ferrimagnetic small nanoparticle system with a core-shell structure. By means of detailed Monte Carlo simulations, a complete picture of the phase diagrams and magnetization profiles have been presented and the conditions for the occurrence of a compensation point $T_{comp}$ in the system have been investigated. According to N\'{e}el nomenclature, the magnetization curves of the particle have been found to obey P-type, N-type and Q-type classification schemes under certain conditions. Much effort has been devoted to investigation of hysteretic response of the particle and we observed the existence of triple hysteresis loop behavior which originates from the existence of a weak ferromagnetic core coupling $J_{c}/J_{sh}$, as well as a strong antiferromagnetic interface exchange interaction $J_{int}/J_{sh}$. Most of the calculations have been performed for a particle in the presence of oscillating fields of very high frequencies and high amplitudes in comparison with exchange interactions which resembles a magnetic system under the influence of ultrafast switching fields. Particular attention has also been paid on the influence of the particle size on the thermal and magnetic properties, as well as magnetic features such as coercivity, remanence and compensation temperature of the particle. We have found that in the presence of ultrafast switching fields, the particle may exhibit a dynamic phase transition from paramagnetic to a dynamically ordered phase with increasing ferromagnetic shell thickness.Comment: 12 pages, 12 figure

Stationary State Solutions of a Bond Diluted Kinetic Ising Model: An Effective-Field Theory Analysis

We have examined the stationary state solutions of a bond diluted kinetic Ising model under a time dependent oscillating magnetic field within the effective-field theory (EFT) for a honeycomb lattice $(q=3)$. Time evolution of the system has been modeled with a formalism of master equation. The effects of the bond dilution, as well as the frequency $(\omega)$ and amplitude $(h/J)$ of the external field on the dynamic phase diagrams have been discussed in detail. We have found that the system exhibits the first order phase transition with a dynamic tricritical point (DTCP) at low temperature and high amplitude regions, in contrast to the previously published results for the pure case \cite{Ling}. Bond dilution process on the kinetic Ising model gives rise to a number of interesting and unusual phenomena such as reentrant phenomena and has a tendency to destruct the first-order transitions and the DTCP. Moreover, we have investigated the variation of the bond percolation threshold as functions of the amplitude and frequency of the oscillating field.Comment: 8 pages, 4 figure

Neutrino Spectrum from SN 1987A and from Cosmic Supernovae

The detection of neutrinos from SN 1987A by the Kamiokande-II and Irvine-Michigan-Brookhaven detectors provided the first glimpse of core collapse in a supernova, complementing the optical observations and confirming our basic understanding of the mechanism behind the explosion. One long-standing puzzle is that, when fitted with thermal spectra, the two independent detections do not seem to agree with either each other or typical theoretical expectations. We assess the compatibility of the two data sets in a model-independent way and show that they can be reconciled if one avoids any bias on the neutrino spectrum stemming from theoretical conjecture. We reconstruct the neutrino spectrum from SN 1987A directly from the data through non-parametric inferential statistical methods and present predictions for the Diffuse Supernova Neutrino Background based on SN 1987A data. We show that this prediction cannot be too small (especially in the 10-18 MeV range), since the majority of the detected events from SN 1987 were above 18 MeV (including 6 events above 35 MeV), suggesting an imminent detection in operational and planned detectors.Comment: 9 pages, 4 figures; Matches version published in Phys. Rev.