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Pixelated-polarization-camera-based polarimetry system for wide real-time optical rotation measurement
摘要： Chirality is an essential consideration in the field of life sciences and pharmaceutical industry because most biomolecules and pharmaceuticals are chiral, and optical rotation measurement is a simple and efficient means for identification, purity test and content detection of chiral materials. However, there are some drawbacks in existing methods, such as small measurement range, non-real-time performance, low measurement accuracy and resolution. This paper presents a novel system to implement optical rotation measurement, and pixelated polarization cameras and Stokes parameters are employed in the system. The polarization information of linearly polarized incident light can be recorded and extracted by a pixelated polarization camera and Stokes parameters respectively. Experiments demonstrate that the proposed system has the necessary advantages for optical rotation measurement, such as real time, wide range ( ?90 ° ～ +90 °), high accuracy ( ±4 ×10?6 °) and high resolution ( 6 ×10?11 °). Thus, this measurement system has great practical prospects in the hospital clinical diagnosis, chemical research, sugar production and pharmaceutical industry.
关键词： pixelated micropolarizer array,optical rotation,chiral drug,polarimetry,Stokes parameters
更新于2025-11-25 10:30:42
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Temperature-dependent phase transition in [001]-oriented 0.72Pb(MgNb)O-0.28PbTiO single crystals
摘要： Temperature-dependent dielectricity and polarization of [001]C-oriented 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 relaxor-based ferroelectric single crystals were studied by using a combined method of the X-ray di?raction, dielectric spectrum, polarization-electric (P-E) ?eld hysteresis loops, and the Landau-phenomenological theory. Results show that the room-temperature rhombohedral phase experiences a rhombohedral-monoclinic-tetragonal coexisting state, then transforms to tetragonal phase, and ?nally to cubic phase during the zero-?eld-heating process. The six-order Landau-type thermal expansion parameters for the tetragonal phase were determined by using the typical characteristics at the cubic-tetragonal phase transition in the temperature range from 91 °C to 113 °C. The calculated dielectric curve, polarizations, and P-E loops ?t well with the experimental results. The phase stability and piezoelectricity are further studied and compared with those of the PMN-0.36PT single crystal. The provided methods and obtained Landau parameters can be used for further studies on the relaxor-based ferroelectric single crystals.
关键词： PMN-PT single crystals,Phase transition,Double hysteresis loops,Landau expansion parameters
更新于2025-11-14 17:28:48
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Fluorescence and absorption studies of DNA-Pd(II) complex interaction: Synthesis, spectroanalytical investigations and biological activities
摘要： Novel palladium(II) complexes (7a–7e) of substituted quinoline derivatives were synthesized. The complexes were characterized using various techniques such as thermogravimetric analysis (TGA), elemental analysis, conductance measurement, mass, absorption, infra‐red (IR), 1H NMR, 13C NMR and energy‐dispersive X‐ray spectroscopy (EDX). Complexes for herring sperm DNA (HS DNA) binding were explored and absorption titration and the binding constant (Kb) as well as Gibb's free energy were evaluated. Complex 7d exhibited the highest binding constant, therefore the thermodynamic parameters of 7d at different temperatures were evaluated. To support the results of the absorption titration, fluorescence titration, viscosity measurement and molecular docking studies were performed. The fluorescence quenching data as evaluated from Stern–Volmer equation were used to calculate KSV, K f and the number of binding sites. The results of all these studies were in good agreement with the absorption study. DNA electrophoretic mobility was performed to explore the possible application of metal complexes as artificial metallonucleases. The antibacterial activity of the complexes was accessed against different pathogenic bacteria and cytotoxicity was measured using brine shrimp and S. pombe.
关键词： Stern–Volmer equation,absorption titration,thermodynamic parameters,cytotoxicity,fluorescence quenching,artificial metallonuclease
更新于2025-09-23 15:23:52
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Paracatadioptric camera calibration using sphere images and common self-polar triangles
摘要： Camera calibration is an indispensable step in achieving stratified three-dimensional reconstruction. In the imaging model of the unit viewing sphere of a central catadioptric camera, there exists a pair of common self-polar triangles between a pair of antipodal sphere images and the image of the great circle on the base plane, so the vertices of the common self-polar triangles can be obtained. According to the imaging characteristics of the sphere on the unit viewing sphere, the line connecting the two common poles outside the conics is a vanishing line, enabling the imaged circular points to be determined. Finally, the intrinsic parameters of the paracatadioptric camera can be found using constraints between the imaged circular points and the image of the absolute conic. Since the boundary points of the sphere image can be almost completely extracted, the curve fitting accuracy can be improved. Experiments with simulated as well as real data demonstrated that our method is feasible and effective.
关键词： Camera intrinsic parameters,Paracatadioptric camera,Imaged circular points,Sphere image,Common self-polar triangle
更新于2025-09-23 15:23:52
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A Numerical Study of Densification Behavior of Silicon Carbide Matrix Composites in Isothermal Chemical Vapor Infiltration
摘要： We studied the characteristics of two-scale pore structure of preform in the deposition process and the mass transfer of reactant gas in dual-scale pores, and observed the physiochemical phenomenon associated with the reaction. Thereby, we established mathematical models on two scales, respectively, preform and reactor. These models were used for the numerical simulation of the process of ceramic matrix composites densified by isothermal chemical vapor infiltration (ICVI). The models were used to carry out a systematic study on the influence of process conditions and the preform structure on the densification behaviors. The most important findings of our study are that the processing time could be reduced by about 50% without compromising the quality of the material, if the processing temperature is 950-1 000 ℃ for the first 70 hours and then raised to 1 100 ℃.
关键词： isothermal chemical vapor infiltration,fiber preform structure,densification behavior,ceramic matrix composites,process parameters
更新于2025-09-23 15:23:52
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Consideration of the Impact of the Environmental Conditions when Designing Heat-Receiving Systems of the Solar Cylindrical Parabolic Modules
摘要： The aerohydrodynamic and heat exchange characteristics in the cylindrical heat receiver of a solar cylindrical parabolic concentrating module are investigated. The mathematical model is based on the Navier-Stokes equation system for a laminar flow in a channel. The model is implemented using the control volume method. The created computer algorithm allows carrying out parametric studies and revealing the most rational geometric, dynamic, and power parameters of the process. The proposed model describes the general physical outlines of the heat exchange in a cylindrical heat receiver which allows estimating the influence of the environment—wind velocity, ambient temperature, etc.—on it.
关键词： cylindrical heat receiver,rational geometric, dynamic, and power parameters,solar cylindrical parabolic module,wind velocity,Navier-Stokes equation system,ambient temperature,control volume method
更新于2025-09-23 15:23:52
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Design and Analysis of Gate Engineered Dual Material Gate Double Gate Impact Ionization Metal Oxide Semiconductor
摘要： In this exposition, we have proposed the Dual Material Gate Double Gate Impact Ionization Metal Oxide Semiconductor (DMG DG IMOS) device with a gate engineered technique of Gate Stacking which is ordinarily used in MOSFET for performance augmentation. This paper compares the performance of four DG IMOS based devices i.e. Single Material Gate Double Gate IMOS (SMG DG IMOS), SMG Gate Stacked DG IMOS (SMG GS DG IMOS), DMG DG IMOS and DMG Gate stacked DG IMOS (DMG GS DG IMOS). The performance of all the devices has been investigated using 2-D simulations. The device structures of gate stacked devices have been developed with two gate oxides namely SiO2 and HfO2 and remaining parameters have been taken alike for all four devices. The doping concentration of source and drain regions for all four devices has been taken as 1020 cm?3 and the doping concentration of the intrinsic region has been taken as 1015 cm?3. The Gate Stacked devices showed better analog outcomes as compared to the other devices. The analog parameters evaluated include transconductance (gm), total gate capacitance (Cgg) and unity gain frequency (fT). The proposed design, DMG GS DG IMOS has been then analyzed for different channel lengths and dielectrics of gate oxide materials to optimize the gate engineered design for various applications.
关键词： Impact ionization MOS (IMOS),Analog and RF parameters,Dual Material Gate Double Gate IMOS,Gate engineering and gate stack
更新于2025-09-23 15:23:52
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Diffuser-assisted Photometric Follow-up Observations of the Neptune-sized Planets K2-28b and K2-100b
摘要： We present precision transit observations of the Neptune-sized planets K2-28b and K2-100b using the Engineered Diffuser on the Astrophysical Research Council Telescope Imaging Camera (ARCTIC) imager on the ARC 3.5 m Telescope at Apache Point Observatory. K2-28b is a Rp = 2.56 R⊕ mini-Neptune transiting a bright (J = 11.7) metal-rich M4 dwarf offering compelling prospects for future atmospheric characterization. K2-100b is an Rp = 3.45 R⊕ Neptune in the Praesepe Cluster and is one of few planets known in a cluster transiting a host star bright enough (V = 10.5) for precision radial velocity observations. Using the precision photometric capabilities of the diffuser/ARCTIC system allows us to achieve a precision of 365 ppm and 70 ppm in 30-minute bins for K2-28b and K2-100b, respectively. Our joint-fits to the K2 and ground-based light curves give an order-of-magnitude improvement in the orbital ephemeris for both planets, yielding a timing precision of 2 minutes in the James Webb Space Telescope (JWST) era. Although we show that the currently available broad-band measurements of K2-28b’s radius are currently too imprecise to place useful constraints on K2-28b’s atmosphere, we demonstrate that JWST/NIRISS will be able to discern between a cloudy/clear atmosphere in a modest number of transit observations. Our light curve of K2-100b marks the first transit follow-up observation of this challenging-to-observe transit, where we obtain a transit depth of 822 ± 50 ppm in the SDSS i′ band. We conclude that diffuser-assisted photometry can play an important role in the Transiting Exoplanet Survey Satellite (TESS) era to perform timely and precise follow-up of the expected bounty of TESS planet candidates.
关键词： techniques: photometric,planets and satellites: fundamental parameters
更新于2025-09-23 15:23:52
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Intensity modulation-based spectral polarization measurement method of coded aperture
摘要： This paper presents a spectral polarization measurement method for single-frame imaging. The method is based on intensity-modulated, coded aperture measurement, comprising a spectral polarization intensity modulation and a compressive sensing spectral imaging system. The incident light is modulated by two multistage phase retarders and a polarizer, and the spectrum's Stokes parameters are shifted to different frequency channels. The spectrum of the modulated light is obtained by a spectral imaging system composed of a coded aperture and a dispersive prism. The modulated spectral information is reconstructed using the TwIST algorithm, and the Stokes elements can be demodulated from it. Taking a pixel as an example, numerical simulations of the modulation of incident light intensity modulation, spectral reconstruction, and demodulation of Stokes parameters show that the method can acquire spectral polarization information of sparse images. This process needs only one measurement of the object and is therefore capable of high-speed acquisition.
关键词： Intensity modulation,Stokes parameters,Coded aperture
更新于2025-09-23 15:23:52
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An isogeometric analysis to identify the full flexoelectric complex material properties based on electrical impedance curve
摘要： In this paper, we present a new approach to identify all material parameters of flexoelectric materials based on electrical impedance curves. This approach combines an Isogeometric Analysis (IGA) formulation with a gradient-based optimization algorithm using the Method of Moving Asymptotes (MMA). The IGA formulation allows for efficient modeling of flexoelectricity taking advantage of the higher order continuity of IGA. The proposed methodology starts with determining preliminary real parts based on resonant modes in order to avoid local minima which gives the numerical impedance curves close to the experimental impedance curve. The results in the preliminary step are used as initial parameters of the refinement step to simultaneously determine both real and imaginary part by minimizing the difference between pseudo-experimental and numerical impedance curve. Some numerical examples are illustrated to show the good agreement between the numerical and pseudo-experimental impedance curves.
关键词： Complex parameters,Piezoelectric material,Flexoelectric material,Isogeometric analysis
更新于2025-09-23 15:23:52