Gap Width Research Articles

Geometric Parameter Effects on Bandgap Characteristics of Periodic Pile Barriers in Passive Vibration Isolation

To investigate the impact of the geometric parameters of periodic pile barriers on bandgap characteristics in passive vibration isolation, a two-dimensional, three-component unit cell was developed using the finite element method (FEM). This study analyzed the bandgap properties of periodic pile barriers and validated the effectiveness of the FEM through model testing. The FEM was then methodically applied to evaluate the effects of pipe pile thickness, periodic constant, arrangement pattern, and cross-sectional shape on the bandgap characteristics, culminating in the proposition of a novel H-shaped cross-section for the piles. The results demonstrated that the FEM-calculated bandgap frequency range, featuring steel piles arranged in a square pattern, closely aligned with the attenuation zone in the model tests. The lower band frequency (LBF) was primarily influenced by the pipe pile’s inner radius, while the upper band frequency (UBF) was predominantly affected by its outer radius. As the periodic constant increased, the LBF, UBF, and the width of band gap (WBG) all decreased. Conversely, changing the arrangement pattern from square to hexagonal led to increases in UBF and WBG, while the LBF diminished. Notably, the WBG of the H-section steel piles, possessing the same cross-sectional area, was 1.31 times greater than that of the steel pipe piles, indicating an enhanced vibration isolation performance. Additionally, the impact of transverse and vertical characteristic dimensions of the H-shaped pile on the band gap distribution was assessed, revealing that the transverse characteristic dimensions exerted a more significant influence than the vertical dimensions.

Kinetic simulation of uranium migration in granite fissure media of beishan, gansu, China: A case study based on the Laplace transform and inverse transform methods

Deep geological disposal is currently considered the most practical and feasible method for disposing high-level radioactive wastes (HLWs). One of its key scientific issues is the migration of nuclides in fissure media. However, studies on the migration of nuclides like U-238 are relatively limited. In this study, the granite rock masses in Beishan, Gansu were selected to construct a physical and mathematical model of U-238 migration using the Laplace transform and inverse transform methods. Based on the numerical methods, the kinetic migration of nuclide U-238 in the fissure media of granite was simulated, and the effects of parameters such as fissure width, hydraulic gradient, diffusible area ratio and rock porosity on the migration of U-238 were investigated. The following insights were obtained: (1) After 100,000 years, U-238 has a very limited diffusion depth in the matrix domain, with a diffusion range of only a few tens of millimeters, whereas it migrates relatively quickly in the fissure domain, with a maximum migration distance of about 1500 m. (2) Under the same migration time and distance, the relative concentration of nuclide U-238 in the fissure domain increases with larger gap width, hydraulic gradient, and diffusible area ratio, but decreases with higher rock porosity. (3) In the same time range, the rock masses with larger gap widths, hydraulic gradients, and diffusible area ratios have larger migration ranges, while those with higher porosities have smaller migration ranges. (4) While selecting a site for diposal of HLWs, it is recommended to choose rock masses in the granite area of Beishan with no fissures or few fissures; additionally, areas with smaller fissure widths, hydraulic gradients, and diffusible area ratios but higher rock porosity should be prioritized. This study can provide important theoretical support for understanding nuclide migration in the future geological disposal of HLWs.

Squeeze force of a Maxwell fluid between circular smooth surfaces with simple harmonic motion

The force and mechanical power required to maintain the simple harmonic motion (SHM) of the upper circular surface squeezing a viscoelastic fluid film is analyzed. The amplitude of the displacement of the upper surface is very small compared to the gap width as a function of time. The smoothness of the upper and lower surfaces is characterized by the slip model with two constant parameters, a slip length and a critical surface shear stress. The nonlinear convection terms in the momentum equation are neglected since the viscous forces dominate the inertial forces. The acceleration and deceleration terms are retained since the upper plate oscillates harmonically and the velocity in the fluid is strictly periodic. An exact solution of the governing equations is found as a function of the Deborah number, the Womersley number, the slip length, and the critical surface shear stress. A circular region without slip condition, bounded by a time-dependent radius, appears when the shear stress of the fluid does not exceed a critical surface shear stress. In addition, an annular region with slip up to the radius of the disk appears when the critical surface shear stress is exceeded. Our results show that viscoelastic and hydrophobic effects together with the Womersley number and a critical surface stress cause changes in the amplitude and phase lag of the waveform of the time-dependent radius and the force acting on the wall surface to maintain the SHM of the upper disk.

REFRACTIVE INDEX BASED DETECTION WITH A HIGH SENSITIVITY BIOSENSOR ENHANCED BY GRAPHENE

Over the past decade, optical sensors have made significant advances. An optical sensor examines the environmental impact through the change of an optical signal and offers advantages such as low cost and label-free detection. In this study, a sensor consisting of a single graphene layer and a slit positioned on the substrate is proposed. The strip gap made to improve the excitation of graphene plasmons allowed to achieve 96.2% high transmission resonance mode. This demonstrates the ability of the sensor surface to detect changing environmental conditions. The results show that the sensitivity of the sensor is 6282 nm/RIU when the sensor surface is exposed to analytes with different refractive indices. The use of a single graphene sheet eliminates the need for a metal resonator and achieves a higher sensitivity compared to some experiments recently published in the literature. Thus, the disadvantage of significant ohmic losses in metal resonators is avoided. Furthermore, a thorough discussion of various factors, including the modification of the strip gap width on the graphene layer and electrical tunability, led to the achievement of optimal sensitivity.

Effect of welding gap on electromagnetic pulse welding of a copper-aluminum alloy joint

ABSTRACT Electromagnetic pulse welding (EMPW) is commonly used for welding copper and aluminum alloy. The welding gap is important in the EMPW process. The research focused on the effect of welding gap on the welding process and the mechanical property of joints. During the EMPW experiments, the deformation, collision, and metal jet were recorded with a high-speed camera. The joint mechanical property was tested. SEM and EDS were employed to examine the bonding interface. Results indicated that the welding gap length did not significantly influence the aluminum alloy plate motion behavior when it was long enough. With the welding gap width increasing, the collision velocity initially increased and subsequently decreased, and the angle between the two plates when they first collided increased continuously. The intensity and duration of the metal jet and the joint mechanical properties also increased first and then decreased. The welding marks widened first and then narrowed.

Prediction of ferromagnetism in GaN:Ag and SiC:Ag nanotubes

Ferromagnetism in single-walled (6,0) GaN(SiC):Ag nanotubes were studied based on ab initio simulations within a pseudopotential method. For the GaN:Ag single-walled nanosystems, the width of the band gap reduces with the increase of dopant concentration. While Ag-doped SiC nanotubes, the band gap of majority-spin states decrease and these systems show metallic character. The first-principles results of total energies for SiC(GaN):Ag nanotubes predicted the stability of the ferromagnetic and antiferromagnetic phase, respectively. The obtained values of total magnetic moments of Ag-GaN and Ag-SiC systems are ∼2.0 and ∼3.2 μB, respectively. The analysis of the results of density of states show the significant contribution to the magnetization of both defected GaN:Ag and SiC:Ag systems come from three nitrogen and carbon atoms which are bonded with the dopant. First-principles investigation, suggest that the SiC(GaN):Ag nanotubes can be made into magnetic materials, and these are promising candidates for electronic, optoelectronic, and spintronic devices.

Analysis of fiber post–resin cement interfacial adaptation at different post regions using field emission scanning electron microscopy

Abstract Introduction: An ideal interfacial adaptation between fiber posts and resin cement is critical for optimum retention and good scenario. Therefore, this research was designed to estimate the interfacial adaptation at fiber post–resin cement interfaces using field emission scanning electron microscopy (FESEM) investigation. Materials and Methods: Forty-five extracted human lower premolars with sole and round canal were classified into three groups (n = 15) following the fiber post types. Each tooth was decoronated and implanted in acrylic resin-filled polyvinyl chloride mold. Roots were undergone endodontic management and post space preparations. Then, each group was classified into three subdivisions (n = 5) according to the resin cement types. After cementation, each post space was marked into apical, middle, and coronal thirds and sectioned horizontally into three 2 mm disc thickness for each third. After that, each disc in each sub-group was then subjected to FESEM analysis to evaluate the gaps width at fiber post–resin cement interface in µm. The data were recorded and statistically evaluated and compared using two-way analysis of variance and Duncan’s multiple range tests at P ≤ 0.05. Results: The everStick post with the RelyX U-200 cement group showed significantly the least gap width mean, while the glass fiber post with the TOTAL C-RAM cement has statistically the greatest gap width mean along the coronal, middle, and apical thirds of fiber post at P ≤ 0.05. The apical third of fiber post showed significantly the greatest mean of gap width, while the middle third showed the least gap width mean at P ≤ 0.05. Conclusion: Different brands of fiber post and resin cement can influence the interfacial adaptation at post–cement interface.

RSM-BASED STATISTICAL APPROACH TO ENHANCE THE COMPRESSIVE PERFORMANCE OF ABS P400 PARTS FABRICATED VIA FDM TECHNOLOGY

This research investigates the performance of ABS P400 parts under compressive loading. These ABS P400 parts are fabricated by fused deposition modeling (FDM) process using omnidirectional printing. The effects of three critical parameters, raster angle (A), air gap (B), and raster width (C), each at three different levels, were analyzed on three different performance measures, i.e. total deformation up to failure ([Formula: see text]) measured in %, maximum energy ([Formula: see text]) in MJ/m3 and break energy ([Formula: see text]) in MJ/m3. Results of experimentations were analyzed using analysis of variance (ANOVA), perturbation curve and 3D surface plots. The research established the anisotropic nature, durability and less brittleness of the FDM fabricated ABSP400 part, which leads to lower strength and also influence the energy absorbing behavior while deformation under compression. Complex relationships were exhibited between the chosen parameters and studied measures. It was also observed that [Formula: see text] is noticeable due to less brittleness of ABS P400 however, [Formula: see text] and [Formula: see text] vary in a contradictory fashion with changes in process parameters. The models were validated using normality plots. Multi-objective optimization was done using the desirability approach to determine the optimal combination of FDM process parameters for optimum responses. The desirability result showed that the optimized input parameter is [Formula: see text][Formula: see text]mm, and [Formula: see text][Formula: see text]mm which yield maximized optimum responses as [Formula: see text]%, [Formula: see text][Formula: see text]MJ/m3, and [Formula: see text][Formula: see text]MJ/m3. The work not only reflects the effect of three FDM parameters on the total deformation up to failure ([Formula: see text] in %) but, in addition, energy absorption behavior of FDM parts under compression is also investigated. The study on the behavior of energy at ultimate stress or ultimate load and breaking stress or breaking load were rarely investigated in earlier research which reflects the novelty of our research.

A first-principles investigation on a new group of diamond-like semiconductors Cu4-II-Ge2-VI7 (II = Zn, Cd and VI = S, Se) as photovoltaic absorbers

Many diamond-like semiconductors with tetrahedral bonds, such as Si, CdTe and Cu(In,Ga)Se2, have been utilized as absorbers in photovoltaics (PV). In this work, a novel group of diamond-like compounds, namely Cu4-II-Ge2-VI7 with II = Zn/Cd and VI = S/Se, have been explored by first-principles means. From the calculations of the electronic structures and related optical properties, we have demonstrated that all these quaternaries have direct-type band structures, while their band gap energies are not suitable for PV applications. By anionic alloying, however, the width of the band gaps can be tuned to the desired energy. For example, the Cu4ZnGe2S4Se3 alloy has a suitable band gap of 1.34 eV. Our work provides the support and perspective for further experimental research on this group of semiconductors and their alloys as potential candidates in PV technologies.

An analytical study of facemask performance to mitigate respiratory diseases transmission through coughs and sneezes

Upper respiratory infectious diseases are often transmitted through ejected droplets and aerosols at high velocity by coughs or sneezes. In its early stages, the rapid spread of the COVID-19 virus could not be fully controlled without face masks and social distancing, and the measures' effectiveness was in doubt due to the uncertainty of air leakage around the mask edges. This study aims to analytically investigate the effect of wearing face masks on the contamination distance around a coughing infected person in still air. The effect of mask design and the presence of gaps around the mask edges was also investigated in this study. A steady-state analytical model was developed to estimate the contamination distance as a function of mask properties and the gap width around the mask edges. The model was validated against experimental observations, showing good agreement. Results revealed that the effectiveness of a face mask in reducing contamination distances is highly dependent on the tightness of the mask fit around the wearer's face. Masks with high packing density, such as N95, were found to be ineffective with gap widths wider than 0.2 mm around the mask edges due to their high resistance, which diverts most of the flow to leak around the edges. For such wide gaps, more permeable cloth masks with packing densities below 1 % reduce the contamination distance more effectively, despite having a low filtration capacity, by impeding the inertia of the ejected particles.

Racetrack FAIMS for High-Resolution and High-Sensitivity Characterization of Peptide Conformers.

A racetrack field asymmetric waveform ion mobility spectrometry (r-FAIMS) device, which consists of both cylindrical FAIMS (c-FAIMS) and planar FAIMS (p-FAIMS) sections with a 1 mm gap width, was developed and applied for high-resolution and high-sensitivity exploration of conformational diversity for peptides. The optimal operating conditions of r-FAIMS were systemically studied, and the performance of the fully optimized r-FAIMS was compared to a previously developed p-FAIMS in detail by using pure nitrogen as the FAIMS carrier gas. Relying on the ion focusing effect in the c-FAIMS section, the intensity of the FAIMS spectrum for doubly charged bradykinin ions acquired by using r-FAIMS is ∼8.5-fold higher than that acquired by using p-FAIMS under the same resolving power/resolution condition, implying about an order of magnitude better sensitivity of r-FAIMS. In addition, the peak separation resolution of r-FAIMS was ∼1.70-fold higher than p-FAIMS under a similar sensitivity condition for doubly charged bradykinin ions. Due to a reduced gap width of the newly designed r-FAIMS (1 mm) as compared to the previously developed p-FAIMS (1.88 mm), r-FAIMS can operate at a much higher separation field with a similar FAIMS dispersion voltage (DV) to gain significantly higher resolving power. For triply charged syntide 2 ions, the resolving power of r-FAIMS can easily exceed 120 at -3.5 kV DV by using pure nitrogen as the FAIMS carrier gas as compared to 44.2 resolving power obtained by using p-FAIMS at -4.0 kV DV. All of the experimental results have confirmed that r-FAIMS can perform structural characterization of biomolecules with both high resolution and high sensitivity.

Prediction of noise generated by rod-airfoil configuration: An investigation based on experiments and machine learning

This study investigated the effects of various parameters on the SPL (Sound Pressure Level) levels of rod-airfoil configurations. An experimental study was performed to investigate the effects of the rod parameters, such as the configuration of the rod, the distance between the rod and the airfoil, the diameter effect of the rod, and the geometry of the rod, on the performance of the rod-airfoil configuration. An Artificial Neural Network (ANN) model was then developed and applied to accurately predict the SPL of rod-airfoil configurations. The results of the study revealed that the Levenberg-Marquardt (LM) algorithm with 2 hidden neurons produced the best performance in predicting the SPL level, with a training R-squared value of 0.9998 and a testing R-squared value of 0.998715. The findings also indicated that increasing rod diameter increases sound pressure level while reducing gap width increases SPL levels and decreases frequency values. This method offers a more precise and effective technique to forecast the SPL levels of rod-airfoil designs, allowing designers to enhance their creations and lower noise levels. The findings of this study can also be utilized to direct future research in this area and offer important information for a better understanding of the mechanism of rod-airfoil noise creation. To the best of the authors’ knowledge, this is the first study to look into rod-airfoil design predictions made using machine learning approaches.

Risk factors for delayed bone union in opening wedge high tibial osteotomy.

The purpose of this study was to investigate the relationship between patient demographics and potential intraoperative factors and delayed bone union in opening wedge high tibial osteotomy (OWHTO). A retrospective review of 65 patients (37 females, 28 males; mean age: 60.1±10.1 years; range, 44 to 77 years) who underwent OWHTO using an angle-stable implant with beta-tricalcium phosphate gap filling between September 2016 and October 2019 was conducted. The osteotomy site was divided into five zones from the lateral hinge on anteroposterior radiographs, and we defined the zone in which bone healing was observed. The bone union area was assessed according to this definition at three, six, nine, and 12 months after surgery, and bone union was defined as union at the fourth zone or greater. A generalized estimating equations approach was employed to investigate longitudinal data pertaining to bone union area as a dependent variable. In addition, the association of bone union at six months postoperatively and predictors were evaluated using cross-sectional statistical methods. The categorical predictors included in the models were smoking, diabetes, hinge fracture, and autologous osteophyte grafting. The continuous variables included in the models were age, body mass index, opening gap width, and plate position. Smoking (odds ratio [OR]=0.478, p<0.01), large opening gap width (OR=0.941, p=0.014), and anterior plate placement (OR=0.971, p<0.01) were significantly associated with decreased bone union area. Union rate at six months in smokers was significantly lower compared to nonsmokers (16.6% and 67.8%, respectively; OR=0.10, p=0.023). Area under the curve in the receiver operating characteristic analysis for bone union at six months was 0.60 for gap width and 0.63 for plate placement. Smoking, large opening gap width, and anterior plate placement are risk factors for delayed bone union after OWHTO. Surgeons should avoid anterior placement of the plate and carefully consider other options for smokers and those who require a large correction.

Исследование щелевой моды в структуре, включающей линию задержки и резонирующую пьезоэлектрическую пластину

The results of the experimental and theoretical study of a structure including a delay line based on a lithium niobate plate of Y-X cut with two interdigitated transducers for exciting and receiving an acoustic wave with the shear-horizontal polarization in the frequency range 1.5-2.2 MHz are presented. The plate thickness was 0.35 mm. A resonating lithium niobate plate was located above the delay line between the transducers with a certain gap. Resonating plates of Z-X, Y-X–140° and Y-X+155° crystallographic cuts were studied. When RF voltage was applied to the input transducer, pronounced resonant absorption peaks were observed on the frequency dependence of the insertion loss. It has been established that with increasing width of the gap between the plates, the depth of the resonance peaks monotonically decreases and the peaks smoothly disappears. Moreover, for most peaks, the quality factor decreases with increasing gap width. The theoretical analysis of such structures showed good agreement between the theoretical and the experimental results. The developed structure shows promise for its use for multiparameter analysis of various liquids

Investigation of the mechanism and stability of highly efficient photocatalytic degradation of Methylene blue using Ni doped CdS photocatalyst

Methylene blue (MB) is commonly utilized in chemical indicators, dyes, biological colors, and pharmaceuticals. Its aqueous solution is poisonous and carcinogenic, posing a significant threat to the ecological environment. The wurtzite-phase NixCd1−xS was synthesized using the hydrothermal technique in this study. Ni doped CdS enhanced its photocatalytic efficiency and resistance to photocorrosion, enabling its application in the photocatalytic destruction of MB. The incorporation of Ni did not change the crystal structure and microstructure of CdS, but increased the visible light absorption range and decreased the band gap width slightly, which promoted the migration of photogenerated electrons and reduced their recombination with holes, resulting in higher photogenerated carrier separation efficiency of NixCd1−xS. The photocatalytic decolorization rate of Ni0.06Cd0.94S for 100 mL of 10 mg/L MB at 240 min is 91.3 %, and the reaction rate constant is 0.01102 min−1, which is 4.42 times that of wurtzite-phase CdS. The photocatalytic mechanism of NixCd1−xS and its composite was analyzed using trap experiments in conjunction with the band structure of the sample. Additionally, the stability of NixCd1−xS was evaluated. The results indicated that the stability was superior to that of CdS. The findings demonstrate that Ni0.06Cd0.94S exhibits good catalytic activity and stability, making it a viable catalyst for the photocatalytic degradation of organic pollutants in water.

Topology Optimization of Hard-Magnetic Soft Phononic Structures for Wide Magnetically Tunable Band Gaps

Abstract Hard-magnetic soft materials, which exhibit finite deformation under magnetic loading, have emerged as a promising class of soft active materials for the development of phononic structures with tunable elastic wave band gap characteristics. In this paper, we present a gradient-based topology optimization framework for designing the hard-magnetic soft materials-based two-phase phononic structures with wide and magnetically tunable anti-plane shear wave band gaps. The incompressible Gent hyperelastic material model, along with the ideal hard-magnetic soft material model, is used to characterize the constitutive behavior of the hard-magnetic soft phononic structure phases. To extract the dispersion curves, an in-house finite element model in conjunction with Bloch’s theorem is employed. The method of moving asymptotes is used to iteratively update the design variables and obtain the optimal distribution of the hard-magnetic soft phases within the phononic structure unit cell. Analytical sensitivity analysis is performed to evaluate the gradient of the band gap maximization function with respect to each one of the design variables. Numerical results show that the optimized phononic structures exhibit a wide band gap width in comparison to a standard hard-magnetic soft phononic structure with a central circular inclusion, demonstrating the effectiveness of the proposed numerical framework. The numerical framework presented in this study, along with the derived conclusions, can serve as a valuable guide for the design and development of futuristic tunable wave manipulators.

Synergistic catalytic enhancement of chemical oxygen demand removal using Mn-Bi doped submicron fly ash carrier: Mechanistic insights and environmental adaptability

This study presents a novel approach to enhancing the removal efficiency of Chemical Oxygen Demand (COD) from water using a submicron fly ash carrier (MFA) doped with manganese (Mn) and bismuth (Bi). The synthesis process involved mechanical ball milling and alkali activation of original fly ash (FA) to obtain MFA, followed by impregnation calcination to prepare the Mn-Bi@MFA composite. The synergistic effect of Mn and Bi facilitated the formation of abundant oxygen vacancies on the catalyst surface, significantly reducing the band gap width. The Mn-Bi@MFA composite exhibited remarkable properties with a specific surface area and pore structure reaching 15.17 m2/g and 0.062 cm3/g, respectively, surpassing FA by 7.16 and 20.67 times, respectively. Utilizing the Mn-Bi@MFA/O3 system, the COD removal amount reached 562.73 mg/g under specific conditions (reaction time = 60 min, pH=7.0, catalyst dosage = 1.0 g/L, ozone dosage = 2.0 g/h), exceeding that of the ozone-alone system by 51.62 %. Moreover, Mn-Bi@MFA demonstrated excellent environmental adaptability and repeatability. An investigation into the contribution order of different free radicals revealed •OH>O2•- >1O2 in COD removal, elucidating the mechanisms of ozone oxidation, catalytic ozonation, and photocatalysis. This research provides valuable insights into the development of efficient and sustainable water treatment strategies employing advanced nano-material-based catalysts.

Severity of Rolling Reconstituted High Moisture Barley on Ensiling Characteristics and In Vitro Ruminal Fermentation

Barley grain sources with variable kernel sizes makes adequate and consistent processing of kernels challenging. This study evaluated how the severity of processing for reconstituted high moisture (65% on DM basis) barley (RHB) affects ensiling characteristics and in vitro ruminal fermentation. Three independent sources of light (<630 g/500 mL) and heavy (>670 g/500 mL) barley were blended to create 4 sources of variable kernel sized barley (646 g/500 mL). Reconstituted barley was rolled through a roller gap width of 1.40 (RHBF), 1.86 (RHBM), or 2.31 mm (RHBC) and ensiled for 1 or 5 mo with dry rolled barley (DRB; roller gap width 1.86 mm) used as a control. The 1-mo RHB and the DRB were further evaluated using the artificial rumen technique (RUSITEC) to investigate the effects of severity of processing for RHB on ruminal fermentation, and gas, methane, and microbial protein production. Using a randomized complete block design (n = 4), 16 fermenters from 2 RUSITEC apparatuses were used to assess the 4 sources and 4 processing treatments. The addition of water increased kernel width before rolling and resulted in increased kernel length, width, and thickness for RHB relative to dry rolled barley. Increasing processing severity for RHB linearly increased kernel width. The percentage of fine particles (<1.18 mm) was greater for DRB than RHBF, but did not differ by processing severity for RHB. Dry matter, organic matter, and starch disappearance were not different between DRB and RHBF, but linearly increased with increasing processing severity for RHB. Fermenter pH tended to be less for DRB relative to RHBF. In conclusion, the reduction in fine particles with the addition of water for RHB may prevent a decline in fermenter pH and when processed to achieve the same PI using a smaller roller gap width, yielded similar DM and OM disappearance suggesting a lesser risk for low ruminal pH without compromising digestibility.

Quantum Prism-Nano Source of Light with Dispersive Spectrum and Optical Upconversion.

A quantum prism, a new structure, consisting of many quantum wires with a diameter that gradually decreases from the base to the top, is the focus of our research. This distribution of quantum wires leads to a dispersive emitted spectrum. The red edge of the spectrum is determined by the band gap width of the bulk semiconductor, and the blue edge is determined by the quantum size of the excitons at the top of the prism. The PL spectrum of the silicon prismatic sample was excited by weak and strong light absorption. At weak absorption (hνex = 1.2 eV), the PL spectrum is located in the visible part of the spectrum, from 1.4 eV to 1.9 eV, with an energy higher than the band gap of the Si crystal. Such a "blue shift" of PL spectra by 0.7 eV is characteristic of the quantum confinement effect. It is a rainbow spectrum with an optical upconversion. The quantum prism is a new type of nano light source, as it replaces two elements in a conventional spectrometer: a light source and a dispersive element. These features enable to create a nano-spectrometer for measuring the absorption spectrum of individual molecules or viruses.

Infrared radiation and thermophysical properties of small band gap Cu-doped SrZrO3 perovskite ceramic

High infrared radiation materials have crucial applications in energy saving, heat conversion, and heat dissipation. SrZrO3 (SZO) is a potential material for high infrared radiation, however, its infrared emissivity still needs to be improved. To address this, in this study, Sr(Zr0.9375Cu0.0625)O3-δ (SZCO) perovskite ceramic with high infrared emissivity was prepared, and the impact of Cu ion doping on the electronic structure, infrared radiation characteristics, and thermal conductivity of SrZrO3 were explored. The findings reveal that SZO doped with Cu ions markedly decreases its band gap width from 5.658 eV to 1.467 eV. The infrared emissivity of the SZCO ceramic, sintered at 1200 °C, increases by 28 % in the 3–5 μm band compared to SZO at room temperature. This emissivity positively correlates with temperature, reaching up to 0.95 at 600 °C. The emissivities of SZCO are greater than that of SZO in the 8–14 μm and 1–22 μm band ranges over the test temperature range from room temperature to 600 °C, and both increase with increasing temperature, reaching 0.978 and 0.946 at 600 °C, respectively. Furthermore, the SZCO ceramic demonstrates thermal conductivities ranging from 1.90 to 3.2 W m−1 K−1 below 1400 °C. These results highlight the potential of Sr(Zr0.9375Cu0.0625)O3-δ ceramic as a high infrared radiation material.