Brazilian Journal of Physics最新文献_第10页

Effect of the Dust Size Distribution on the Rayleigh-Taylor Instability in Dusty Plasmas 尘埃粒径分布对尘埃等离子体中瑞利-泰勒不稳定性的影响

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-02-06 DOI: 10.1007/s13538-025-01706-z

Xin-Long Bing, Wei-Ping Zhang, Sabah Bibi, Wen-Shan Duan

引用次数: 0

Path Integral Analysis for a Damped Harmonic Oscillator with a Higher Derivative Term in the Damping 具有高阶阻尼项的阻尼谐振子的路径积分分析

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-02-05 DOI: 10.1007/s13538-025-01714-z

Albert C. R. Mendes, Everton M. C. Abreu

引用次数: 0

Propagation of Oblique Dust Ion Acoustic Solitons in a Warm Magnetized Plasma in the Presence of Electron Inertia and Negative Ions 倾斜尘埃离子声孤子在温暖磁化等离子体中电子惯性和负离子存在下的传播

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-31 DOI: 10.1007/s13538-025-01708-x

Muktarul Rahman, Satyendra Nath Barman

{"title":"Propagation of Oblique Dust Ion Acoustic Solitons in a Warm Magnetized Plasma in the Presence of Electron Inertia and Negative Ions","authors":"Muktarul Rahman, Satyendra Nath Barman","doi":"10.1007/s13538-025-01708-x","DOIUrl":"10.1007/s13538-025-01708-x","url":null,"abstract":"<div>The present paper studies the formation and characteristics of dust-ion-acoustic solitary waves of small amplitude in a multi-component warm magnetized plasma having inertial positive and negative ions together with negatively charged static dusts under the influences of inertial elections, considering a three-dimensional fluid dynamical model with the Poisson equation. We consider a uniform external magnetic field along the z-direction, and the wave propagation occurs obliquely to the direction of the magnetic field. Precisely, the reductive perturbation method is applied to derive the Korteweg-de Vries equations and obtained the solitary wave solution to investigate the variations in wave nature caused by different physical parameters. This theoretical study shows the coexistence of compressive and rarefactive dust-ion-acoustic solitons in the plasma. Depending on Q (=negative-to-positive ion mass ratio) and various ion temperatures, compressive solitons for (Q<1) and rarefactive solitons for (Q>1) are shown to exist. Additionally, the domination of different physical parameters of our plasma on the propagation of oblique dust-ion-acoustic solitary waves is numerically analyzed within the paper. The present study might be helpful for better understanding the propagation of nonlinear electrostatic waves in laboratory and space plasma environments.</div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Synthesis and Tailoring the Microstructure, Optical, and Dielectric Features of PVA/PVP/CeO2 Promising Nanocomposites PVA/PVP/CeO2纳米复合材料的合成与裁剪及其微观结构、光学和介电特性

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-30 DOI: 10.1007/s13538-025-01703-2

Ahmed Hashim, Mudhar A. Al-Obaidi, Hamed Ibrahim, Farhan Lafta Rashid, Aseel Hadi

{"title":"Synthesis and Tailoring the Microstructure, Optical, and Dielectric Features of PVA/PVP/CeO2 Promising Nanocomposites","authors":"Ahmed Hashim, Mudhar A. Al-Obaidi, Hamed Ibrahim, Farhan Lafta Rashid, Aseel Hadi","doi":"10.1007/s13538-025-01703-2","DOIUrl":"10.1007/s13538-025-01703-2","url":null,"abstract":"<div>This study aims to synthesize of new type of nanocomposites based on polyvinyl alcohol(PVA)-polyvinyl pyrrolidone(PVP) bend doped with cerium oxide(CeO2) nanoparticles to apply in various photonics and energy storage fields. The structural, optical, and electrical features of PVA/PVP/CeO2 nanocomposites were examined. The results indicated that the optical absorption of PVA/PVP blend enhanced of 94.9% when the CeO2 NPs concentration reached of 3 wt.% at wavelength of 260 nm. The energy gap of PVA/PVP blend decreased of 54.2% with rising CeO2 NPs concentration to 3 wt.%. The other factors of optical properties enhanced with increasing CeO2 NPs concentration. The electrical properties were investigated in frequency ranging from100 Hz to 5 MHz. The results showed that the dielectric constant and electrical conductivity are improved of 12.3% and 66%, respectively, at frequency of 1 kHz with rising CeO2 NPs concentration to 3 wt.%. The elaborated optical and electrical improvements of the PVA/PVP blend would definitely introduce the PVA/PVP/CeO2 nanocomposites as precious UV-shielding materials for a wide set of optoelectronics industry. The PVA/PVP/CeO2 nanocomposites included excellent UV-absorption, low energy gap, and good physical and chemical properties compared with other nanocomposites.</div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical Analysis of a Horizontal Flexible Rotor Supported by a Squeeze Film Air Bearing Based on Near-Field Acoustic Levitation 基于近场声悬浮的挤压膜气轴承支撑水平柔性转子数值分析

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-30 DOI: 10.1007/s13538-025-01711-2

Fernanda F. Rossi, Valder Steffen Jr, Aldemir A. Cavallini Jr

{"title":"Numerical Analysis of a Horizontal Flexible Rotor Supported by a Squeeze Film Air Bearing Based on Near-Field Acoustic Levitation","authors":"Fernanda F. Rossi, Valder Steffen Jr, Aldemir A. Cavallini Jr","doi":"10.1007/s13538-025-01711-2","DOIUrl":"10.1007/s13538-025-01711-2","url":null,"abstract":"<div>Acoustic levitation is a method through which an object is suspended at a stable position against gravity by means of an acoustic radiation force produced by intense sound waves. This technique encompasses two different approaches: standing wave acoustic levitation and near-field acoustic levitation. Over the last few decades, the application of near-field acoustic levitation in the development of squeeze film bearings has been investigated by a number of researchers. In most works, the bearings were experimentally tested on a vertical test rig that could be tilted to control the radial load applied to the bearings. Besides, the dynamic modeling of the rotor-bearing systems was performed by considering the rotor as a rigid body. In this context, the present work proposes to develop a finite element model to investigate the dynamic behavior of a horizontal flexible rotor supported by two bearings, one of them being a squeeze film air bearing based on near-field acoustic levitation. The numerical results demonstrate that due to its limited load capacity, low damping, and small radial clearance, this type of bearing is recommended for use in light rotating machines with low unbalance level.</div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Shock Structures in a Magnetized Nonthermal Plasma with Dust of Opposite Polarity 具有相反极性尘埃的磁化非热等离子体中的激波结构

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-30 DOI: 10.1007/s13538-025-01710-3

S. Sumaiya, S. Sultana, A A Mamun

引用次数: 0

Diabetes and Anemia Prognosis by 2-D Photonic Crystal Biosensor 二维光子晶体生物传感器对糖尿病和贫血的预测

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-30 DOI: 10.1007/s13538-025-01707-y

Esmat Rafiee

{"title":"Diabetes and Anemia Prognosis by 2-D Photonic Crystal Biosensor","authors":"Esmat Rafiee","doi":"10.1007/s13538-025-01707-y","DOIUrl":"10.1007/s13538-025-01707-y","url":null,"abstract":"<div>In the presented research, a 2-D optical structure made of photonic crystals is presented. It is based on 30*28 arrays of silicon in medium made of air. Designed system is made of linear media (no nonlinear rods) for overcoming nonlinearity and gain problems. Applicability of designed system can be studied through extracting photonic band gap and field distribution spectra. Latter diagrams would be obtained by utilizing PWE and FDTD techniques. After applying incident light wave, signal can be propagated along the waveguide reaching outputs 1 or 2 according to the resonant wavelengths. Output1 can be considered for diagnosis of glucose levels in blood with Quality factor (Q): (122.72 – 132.5), Sensitivity (S): 1730 nm/RIU, detection limit (DL): (7.01e-4 – 7.15e-4) RIU and Figure of merit (FOM): (134.4 –142.5) RIU−1. In another case, output2 can be considered for diagnosis of hemoglobin levels in blood with (Q): (106.56 – 112.8), (S): 1154.6 nm/RIU, (DL): (1.1e-3 – 1.2e-3) RIU, (FOM): (84.8–87.5) RIU−1. As a result, designed structure would effectively aid researchers in prognosis of diabetes (Output1) and anemia (Output2). Diagnosis of anemia and diabetes (fast and with high precision) in a simple and applicable configuration (made of only linear rods) with considerable characteristics (sensitivity, DL, FOM and Q-factor) are the most important features of the proposed device.</div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analysis of Surface Roughness and Conductivity Effects of Various Metals on a Gyrotron Cavity for Terahertz Communication System 太赫兹通信回旋管腔中不同金属的表面粗糙度和电导率效应分析

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-29 DOI: 10.1007/s13538-025-01695-z

Nahid-Al Mahmud, Farhana Bari Sumona, Sudipta Das, Li Shaofu, Torki Altameem, Mohammed EL Ghzaoui, Walid El-Shafai

{"title":"Analysis of Surface Roughness and Conductivity Effects of Various Metals on a Gyrotron Cavity for Terahertz Communication System","authors":"Nahid-Al Mahmud, Farhana Bari Sumona, Sudipta Das, Li Shaofu, Torki Altameem, Mohammed EL Ghzaoui, Walid El-Shafai","doi":"10.1007/s13538-025-01695-z","DOIUrl":"10.1007/s13538-025-01695-z","url":null,"abstract":"<div>In this article, the influence of the surface roughness (effective conductivity) on the open cavity of a gyrotron is analyzed and discussed theoretically. Based on electromagnetic field and wave theory, rough surface effects and metallic conductivity are analyzed considering terahertz cylindrical waveguides. The electromagnetic field distribution of a 360° cylindrical waveguide in TE48 mode is divided into eight parts, and every part is TE11 mode with 360/8° = 45° angle. The TE11 mode was designed by analyzing the TE48 mode. The electromagnetic field distribution of TE11 mode on the radial surface of the sector waveguide is as one-eighth (45° angle) of the surface of the cylindrical waveguide in TE48 mode. This cylindrical waveguide’s radius of TE48 mode is 1.375 mm, for which the operating frequency is 1 THz. MATLAB tool is used to analyze the cylindrical waveguide’s field distribution profile and electrical field characteristics. The characteristics of the effective conductivity of different cavity-cutting materials on smooth surfaces and rough surfaces are studied through numerical simulations. The results indicate that the attenuation coefficient (α) decreases with a rise in frequency considering enhancement in the surface roughness and metal conductivity. TE48 mode of the cylindrical waveguide and TE11 mode of the sector waveguide are discussed through MATLAB analysis. By optimizing through CST simulation, better numerical simulation results are obtained. Overall, this article contributes to attaining the design of the 1 THz gyrotron and a clear understanding of surface roughness improvement for the cylindrical waveguides.</div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Design and Construction of a Multi-Channel Logarithmic Analyzer for Extending Energy Measurement Range in Radioactive Radiation Spectroscopy 扩展辐射光谱学能量测量范围的多通道对数分析仪的设计与构建

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-27 DOI: 10.1007/s13538-025-01704-1

Mohammad Zaree, Hossein Tavakoli-Anbaran

{"title":"Design and Construction of a Multi-Channel Logarithmic Analyzer for Extending Energy Measurement Range in Radioactive Radiation Spectroscopy","authors":"Mohammad Zaree, Hossein Tavakoli-Anbaran","doi":"10.1007/s13538-025-01704-1","DOIUrl":"10.1007/s13538-025-01704-1","url":null,"abstract":"<div>In this research, we designed and constructed a multi-channel logarithmic analyzer capable of simultaneously measuring nuclear events in mixed fields with both high and low energies. This analyzer is essential for microdosimetry, where continuous spectra in the range of (varvec{10^{-2}}) keV to (varvec{10^3}) keV must be observed. As the energy measurement range increases, the pulse height analysis range also expands, necessitating improvements in the analyzer’s performance for pulse height analysis. The use of high-voltage amplifiers and block sampling in this multi-channel logarithmic analyzer enables pulse height analysis up to (varvec{10^5}) mV. We validated the analyzer using a signal generator, observing spectra corresponding to pulse heights of (varvec{3times 10^0}), (varvec{3times 10^1}), (varvec{3times 10^2}), (varvec{3times 10^3}), and (varvec{3times 10^4}) mV in channels 394, 1208, 2030, 2849, and 3666, respectively. In simultaneous gamma-ray spectroscopy using Am-241 and Co-60 sources and pulses from a pulse generator with an amplitude of 32,000 mV, the designed logarithmic analyzer detected all energy peaks, whereas the linear MCA detected only some peaks. The logarithmic analyzer, with a 16-bit conversion gain in the (varvec{10^5}) keV energy range, provides optimal energy resolution compared to lower conversion gains and linear MCA.</div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhanced Viability of Iron-Doped Titanium Dioxide Nanoparticles with Antibacterial Efficacy 铁掺杂二氧化钛纳米颗粒抑菌活性增强研究

IF 1.5 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2025-01-27 DOI: 10.1007/s13538-025-01702-3

N. G. Jitha, K. Deepa, N. Ayana

{"title":"Enhanced Viability of Iron-Doped Titanium Dioxide Nanoparticles with Antibacterial Efficacy","authors":"N. G. Jitha, K. Deepa, N. Ayana","doi":"10.1007/s13538-025-01702-3","DOIUrl":"10.1007/s13538-025-01702-3","url":null,"abstract":"<div>Titanium dioxide nanoparticles (TiO2NPs) exhibit optical, electrical, and magnetic properties and are potential candidates for biomedical uses. The cytotoxicity comparison among undoped as well as iron-doped TiO2NPs is supported by the current study. The antibacterial test was also conducted for five different bacteria. Pure and iron-doped TiO2NPs were synthesized using titanium isopropoxide and iron nitrate nonahydrate as precursors using the co-precipitation method. The synthesized TiO2NPs were characterized by XRD (X-ray diffraction), UV-Vis (UV-visible diffuse reflectance spectroscopy), EDAX (energy dispersive X-ray spectroscopy) analysis, and FTIR (Fourier transform infrared spectroscopy) analysis. XRD examination revealed a shift in peak when TiO2 is doped with iron. EDAX analysis verified that (Fe3+) iron particles were present in the TiO2 crystal structure. Band gap energy was calculated from UV-Vis, and it was confirmed that with an increase in doping concentration, band gap energy seems to decrease. FTIR analysis established the presence of different functional groups within TiO2NPs. The in-vitro cytotoxic effect was determined using the MTT assay method. The study showed that the iron-doped TiO2NPs are comparatively less cytotoxic than pure TiO2NPs.</div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0