V. Balasubramanian, Ginson P. Joseph, S. Sundaram, Sujay Chakravarty, V. N. Vijayakumar
{"title":"Synergistic Investigation of Binary Hydrogen Bond Liquid Crystal Complex: Experimental and Theoretical (DFT) Perspectives of Smectic Molecular Ordering via Molecular Dynamics","authors":"V. Balasubramanian, Ginson P. Joseph, S. Sundaram, Sujay Chakravarty, V. N. Vijayakumar","doi":"10.1007/s13538-024-01643-3","DOIUrl":"10.1007/s13538-024-01643-3","url":null,"abstract":"<div><p>Binary hydrogen bond liquid crystal (HBLC) complex is isolated from the combination of cholesteryl stearate (CHS) and 4-methoxycinnamic acid (4MCA) mesogenic compounds. Induced chiral smectic phases are observed and characterized using a polarizing optical microscope (POM). Enthalpy values and transition temperatures of liquid crystal (LC) phases and their thermal stability are reported using differential scanning calorimetry (DSC), and the same has been supported by the density functional theory (DFT) method. Observation of a strong peak at 3580 cm<sup>−1</sup> from the FTIR spectrum confirms the hydrogen bond (H-bond) between chiral (CHS) and non-chiral (4MCA) mesogenic compounds. Further, DFT calculation explores the molecular mechanism of the complexation (CHS + 4MCA). The calculated global reactivity parameters (GRP) values (DFT calculations) justify the stability of the synthesized binary HBLC complex (CHS + 4MCA). In addition, topological analysis of DFT confirms the intermolecular interaction in the title binary HBLC complex. Donor and acceptor interaction in the binary HBLC complex (CHS + 4MCA) is reported using molecular electrostatic potential (MEP) analysis. Further, the impact of increased H-bond length and bond angle on induced chiral smectic ordering has been discussed in the present communication. Quantum theory of atoms-in-molecules (QTAIM) study endorses the existence of linear H-bonding of O–H···O in the binary HBLC complex. In addition, the enhanced mesomorphic behaviour along with non-linear optical properties (NLO) is reported.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579509","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}
A. H. M. Iftekharul Ferdous, Zonaki Khaton, Dilip Kumar Sarker, Khalid Sifulla Noor, Jeneetha Jebanazer, Kannan Krishnan, Ganekanti Naresh, Ramachandran Thandaiah Prabu, Ahmed Nabih Zaki Rashed
{"title":"Next Generation Terahertz Biosensor Based Broadband Photonic Crystal Fiber for High Sensitivity Precision Kerosene Admixture Simultaneous Detection","authors":"A. H. M. Iftekharul Ferdous, Zonaki Khaton, Dilip Kumar Sarker, Khalid Sifulla Noor, Jeneetha Jebanazer, Kannan Krishnan, Ganekanti Naresh, Ramachandran Thandaiah Prabu, Ahmed Nabih Zaki Rashed","doi":"10.1007/s13538-024-01644-2","DOIUrl":"10.1007/s13538-024-01644-2","url":null,"abstract":"<div><p>A unique PCF detector is suggested that contains octagonal cladding and hexagonal core which is used for kerosene adulteration detection. The sensor performance was numerically investigated between the frequencies of 1.0 and 2.8 THz. The central hole has been full with kerosene. The strut size is adjusted to investigate This research as well as the detector’s functionality be carried out at THz frequencies. At 2.2 THz, the photonic crystal fiber sensor has a relative sensitivity of roughly 94.25%, EML 0.01106, and a confinement loss of 1.77 × 10<sup>−13</sup> of the order of 10<sup>14</sup>. This suggested detector can play a fine role in detecting kerosene admixture since it has high sensitivity and remarkable precision. This will be helpful for consumer to consume high-grade petroleum fuel without admixture of kerosene. Technologies related to extrude and 3D print might be utilized for the photonic crystal fiber detector.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142565955","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}
Weaam Alhejaili, Almas, Ata-ur-Rahman, S. A. El-Tantawy
{"title":"On the Oblique Propagation of Large Amplitude Dust-Acoustic Solitary Waves in Anisotropic Polarized Magnetoplasma","authors":"Weaam Alhejaili, Almas, Ata-ur-Rahman, S. A. El-Tantawy","doi":"10.1007/s13538-024-01635-3","DOIUrl":"10.1007/s13538-024-01635-3","url":null,"abstract":"<div><p>This study comprehensively investigates the oblique propagation of arbitrary dust-acoustic solitary waves (DASWs) in an anisotropic polarized complex magnetoplasma. The model consists of Maxwellian electrons and ions as well as inertial hot dust fluid. The hot dust is presumed to exhibit adiabatic behavior, distinguished by anisotropic thermal pressure. The linear dispersion relation (LDR) for both dust-cyclotron waves (DCWs) and dust-acoustic waves (DAWs) is obtained and investigated numerically using the plane wave approximation. The analysis applies Sagdeev’s pseudopotential theory to the fluid equations of the plasma model and simplifies them into the energy equation. Various factors, including polarization force, ions-to-electron temperature ratio, dust concentration, and dust pressure anisotropy, are considered to explore their influence on solitary waves’ existence and propagation characteristics (amplitude, width). The results reveal the presence of only rarefactive DASWs. This study provides valuable insights into wave phenomena in polarized magnetized plasmas and holds potential applications in space-dusty plasma environments like Saturn’s F rings.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142555248","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}
Hasan Tayfun Ay, Mehmet Fahri Sarac, Tuba Solakyildirim
{"title":"Effect of SnO2 Coating on the Structural, Optical, and Electrical Properties of TiO2 Nanowires Fabricated by a Two-Step Deposition Method","authors":"Hasan Tayfun Ay, Mehmet Fahri Sarac, Tuba Solakyildirim","doi":"10.1007/s13538-024-01639-z","DOIUrl":"10.1007/s13538-024-01639-z","url":null,"abstract":"<div><p>The photosensing properties of SnO<sub>2</sub>-coated TiO<sub>2</sub> NWs have been fabricated by a two-step sequential deposition method; a thermal oxidation method followed by a hydrolysis method. Pure TiO<sub>2</sub> NWs show vertically aligned and uniformly distributed NW arrays on Ti foil. It was observed that the SnO<sub>2</sub> coating accumulated on the TiO<sub>2</sub> NW surfaces with increasing Sn concentration. It filled the spaces between the NWs and finally covered the entire surface of the 100 mM SnO<sub>2</sub> concentrated sample. The presence of increased Sn concentration on the surface was qualitatively determined by EDS and XPS measurements. The PL intensity decreases as the SnO<sub>2</sub> coating increases, indicating recombination retardation. Coating thickness also decreases the band gap since electron excitation requires less energy. Since electrons are easily excited by the conduction band of TiO<sub>2</sub>, SnO<sub>2</sub> coatings can form an energy level within the band gap. The highest photosensitivity was 142.05% with 100-mM SnO<sub>2</sub>-coated TiO<sub>2</sub> NW arrays. An alternative approach to photosensitive UV devices can be made with 100-mM SnO<sub>2</sub>-coated TiO<sub>2</sub> NW arrays due to their excellent light absorption properties and efficient charge carrier generation.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142524501","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}
Pradanya A. Gajbhiye, Satya P. Singh, Madan K. Sharma
{"title":"Hybrid Optimization Framework for MIMO Antenna Design in Wearable IoT Applications Using Deep Learning and Bayesian Method","authors":"Pradanya A. Gajbhiye, Satya P. Singh, Madan K. Sharma","doi":"10.1007/s13538-024-01634-4","DOIUrl":"10.1007/s13538-024-01634-4","url":null,"abstract":"<div><p>The growing adoption of wearable Internet of Things (IoT) devices requires efficient wireless communication systems for applications like healthcare and fitness. Multiple-input multiple-output (MIMO) technology improves signal quality by using multiple antennas but presents challenges in compactness and low power consumption and offers minimal mutual coupling while interacting with the human body. Ensuring compliance with specific absorption rate (SAR) limits is also crucial. In this paper, we present a hybrid optimization framework for designing MIMO antennas for such wearable devices. We integrate deep learning with Bayesian optimization. We use artificial neural networks (ANNs) to model antenna performance and Bayesian optimization to explore the design space efficiently. The final optimized MIMO antenna has an overall size of 122.44 mm <span>(times )</span> 58.32 mm. The proposed MIMO antenna achieved minimized mutual coupling in free space, on hand, and leg with values of <<span>(-)</span>75.77 dB, <<span>(-)</span>46 dB, and <<span>(-)</span>37 dB, respectively. In every scenario, the antenna has a stable resonance at a 2.45 GHz frequency and maintains a SAR within the 1.6 W/kg safety limit. Additionally, our optimization reduced computational effort by about 30% compared to traditional methods. These results show the effectiveness of combining ANNs and Bayesian optimization in designing high-performance MIMO antennas, advancing wireless communication for wearable IoT devices.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518955","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}
C. A. M. dos Santos, M. S. da Luz, F. S. Oliveira, L. M. S. Alves
{"title":"On the Fermi Gas, the Sommerfeld Fine Structure Constant, and the Electron–Electron Scattering in Conductors","authors":"C. A. M. dos Santos, M. S. da Luz, F. S. Oliveira, L. M. S. Alves","doi":"10.1007/s13538-024-01611-x","DOIUrl":"10.1007/s13538-024-01611-x","url":null,"abstract":"<div><p>Electrical energy is revisited as a fundamental parameter for inclusion in Fermi gas theory, in addition to thermal energy. It is argued that electrical energy can move some electrons to above the Fermi level, providing free charges to carry the electrical current, even at absolute zero temperature. The Drude model, Ohm’s law, quantum resistance, and the electrical resistivity due to electron–electron scattering appear naturally as a consequence of the theoretical description, which is based on the quantization of the angular momentum and the Fermi–Dirac distribution, considering total energy as <span>(epsilon ={k}_{B}T+{Phi }_{0}I)</span>. The electrical and magnetic forces acting on an electron are related to the ratio between the Fermi velocity and the speed of light and show that the electron motion is due to helical paths. Considering the center of mass description for the Bohr atom, it was possible to show that the magnetic force is related to the electrical force as <span>({F}_{M}=(alpha /pi ){F}_{E})</span>, which demonstrates that the electrons move in helical paths along the orbit. The helical motion naturally provides for quantization of the magnetic flux, the spin of the electron, and the first correction term of the anomalous magnetic moment. Applying the model to describe the electron–electron scattering allows prediction of the behavior of the electrical resistivity of many metals at low temperatures, which is in excellent agreement with empirical observations.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518723","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}
Temur Mustafayev, Farkhad Akhmedjanov, Jurabek Abdiev, Shakhboz Khasanov
{"title":"An Exploration of Anisotropic Acoustic Wave Attenuation in Quartz Crystals","authors":"Temur Mustafayev, Farkhad Akhmedjanov, Jurabek Abdiev, Shakhboz Khasanov","doi":"10.1007/s13538-024-01638-0","DOIUrl":"10.1007/s13538-024-01638-0","url":null,"abstract":"<div><p>This study examines anisotropic acoustic wave attenuation in quartz crystals, utilizing Bragg light diffraction to investigate the phenomenon across a frequency range of 0.2 to 2.8 GHz. The research focuses on analyzing both real and imaginary elastic constants to develop models for acoustic attenuation. It reveals directional dependence in the attenuation parameters of sonic waves in quartz and highlights the role of the effective Gruneisen constant in wave vector orientation. The findings offer insights into quartz’s acoustic behavior with applications in fields like telecommunications, aerospace engineering, and geophysics. This research contributes to a deeper understanding of quartz crystals and encourages interdisciplinary exploration in this area.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518636","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}
{"title":"Synthesis and Characterization of Cadmium Tin Oxide for MEMS Substrates and Its Comparative Computational Study with Silicon and Silicon Carbide","authors":"Nicholas Ongwen","doi":"10.1007/s13538-024-01624-6","DOIUrl":"10.1007/s13538-024-01624-6","url":null,"abstract":"<div><p>The rising demand for semiconductor substrates for printing electronic circuits has been sparked by recent breakthroughs in electronics. The most popular substrate for printing these devices is silicon (Si), which is chosen over other substrates like silicon nitride because it is more widely accessible, and has better electrical and electronic properties. Despite the benefits above, Si has a number of disadvantages, including being brittle and only occasionally existing as a pure element. This study synthesized and characterized cadmium tin oxide (CTO) as potential substrates for MEMS manufacturing. A comparative computational study of the structural and mechanical properties with Si and silicon carbide (SiC) was also made. The experiments involved structural characterization of the synthesized samples at varied concentrations of cadmium, while the computations involved use of density functional theory within the generalized gradient approximation to investigate the structural and mechanical properties of the three materials. SiC was found to have better mechanical properties than both Si and CTO, but its brittleness prevents it from being used in the production of flexible MEMS. The manufacturing of flexible MEMS, including microbolometers and biomedical MEMS, can be made possible due to the soft and ductile character of CTO, especially the CTO 3, which was the most ductile.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"54 6","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142453132","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}
Humberto Araujo Machado, Danton José Fortes Villas Boas, Luis Eduardo Vergueiro Loures da Costa, Denis Guilgim Vieira
{"title":"Preliminary Thermal Analysis of the Sport Microsatellite","authors":"Humberto Araujo Machado, Danton José Fortes Villas Boas, Luis Eduardo Vergueiro Loures da Costa, Denis Guilgim Vieira","doi":"10.1007/s13538-024-01621-9","DOIUrl":"10.1007/s13538-024-01621-9","url":null,"abstract":"<div><p>This work presents the preliminary thermal analysis of the SPORT microsatellite, based on its initial configuration. A simplified analysis, using control volumes, is conducted, considering the power dissipated by the equipment and solar radiation as heat sources. Internal conduction and radiation processes between components, as well as radiation into space, are also taken into account. A system of ordinary differential equations is constructed and solved using a simple time-marching method. The results are presented as the average temperatures of the components over a 24-h period and are compared with the numerical simulation of the definitive configuration performed by CFD. The main objective is to apply a quick and simplified version of the thermal lumped method to identify which elements may exceed temperature limits during operation, using the results to adjust the design where those limits are not met. The results are compared with CFD data for the final configuration, showing that the overall temperature behavior is consistent, and that all elements remained below the temperature limits. This validates the use of the methodology in the early phases of nanosatellite design, though some improvements may still be required.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"54 6","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-024-01621-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142453052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Star-Shaped Molecules with a Triazine Core: (TD)DFT Investigation of Charge Transfer and Photovoltaic Properties of Organic Solar Cells","authors":"Nathália M. P. Rosa, Itamar Borges Jr.","doi":"10.1007/s13538-024-01636-2","DOIUrl":"10.1007/s13538-024-01636-2","url":null,"abstract":"<div><p>We investigate theoretically the design and application of nine triazine (Tr)-core star-shaped molecules built with thiophene (Th), phenyl (Ph), and carbazole (Cz) moieties in dye-sensitized solar cells (DSSCs) and bulk heterojunction (BHJ) organic solar cells. Density functional theory and time-dependent density functional theory are employed to rationalize the electronic structure, charge transfer properties, and photovoltaic performance of these systems. Tr-Th-Cz and Tr-Ph-<i>p</i>-Th-Cz display power conversion efficiency (<span>(text{PCE})</span>) values close to 30% due to a favorable alignment of the energy levels. Computed open-circuit voltage values show that lack of π-bridges, as in the Tr-Th and Tr-Cz, favor higher voltage generation. Systems containing thiophene (Th) and carbazole (Cz) present the most favorable values for efficient electron injection and dye regeneration. Furthermore, the incorporation of these Th and Cz donor substituents into the triazine core combined with π-bridges significantly impacts other optoelectronic properties of the organic solar cells. The computed high singlet–triplet gap values indicate limited potential of these molecules as thermally activated delayed fluorescence (TADF) emitters for applications in organic light-emitting diodes (OLEDs).</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"54 6","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142451065","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}