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In this paper, an experimental setup composed of a color-mixing device, power supply, and spectrometer is developed. This setup is available for students to do hands-on color mixing with red, green, and blue light in undergraduate labs. LED volt-ampere and spectrum characteristics are investigated. The apparatus was used to perform additive color mixing, and visual colorimetric parameters such as color coordinates, dominant wavelength, and color purity were obtained. This will help students understand the physics of LEDs and chromaticity. In addition, this experiment is useful in introducing topics such as the CIE chromaticity diagram and human perception of colors.

A Cu2+ ion maintains coordination with two COOH groups, while a Fe3+ ion changes from coordination with three to two COOH groups after increasing the concentration of Cu2+/Fe3+ ions.

Using a substrate-directed molecular template to steer the synthesis of ordered polymers with a large area is reported.

As a new type of energetic material, cocrystal explosives demonstrate many excellent properties, such as high energy density and low sensitivity, due to the interaction between the molecules of the two components.

Cardiac troponin I (cTnI) is a specific biomarker of acute myocardial infarction (AMI). However, cTnI detection kits prepared with antibodies have many defects. Nucleic acid aptamers are sequences of single-strand DNA or RNA that can overcome the deficiency of antibodies. Herein, sandwich ELONA methods were established based on aptamers. Two selected ssDNA aptamers (Apt3 and Apt6) showed high binding affinity and sensibility (Apt3: Kd = 1.01 ± 0.07 nM, Apt6: k = 0.68 ± 0.05) and did not bind to the same domain of cTnI. Therefore, these two aptamers can be applied to the ELONA methods. The detection range of cTnI using the dual-aptamer sandwich ELONA method was 0.05-200 ng/mL, and the bioanalytical method verification results can meet the national standard of Chinese Pharmacopoeia (2020 Edition). There was no difference between results of the dual-aptamer sandwich ELONA method and the diagnostic results of serum obtained from 243 people (P = 0.39, P ˃ 0.05). The sensitivity and specificity of the ELONA with cTnI in serum were 96.46% and 93.85%, respectively. Compared with the FICA kit, which is clinically used, the consequences of ELONA method are closer to the diagnostic results. This study suggests that the aptamers Apt3 and Apt6 have high affinity and strong specificity and that the dual-aptamer sandwich ELONA method has a wide detection range and can be used to determine cTnI in serum, with potential applications in the diagnosis of AMIs.

Exploring and modifying the C-S-H structure at a micro–nano level is an effective solution to improve the performance of Portland cement. Compared with organics inserting C-S-H, the research on the performance of a polymer-binding C-S-H structure from nanoscale to macroscale is limited. In this work, the mechanical properties of a modified C-S-H, using hydroxyl-terminated polydimethylsiloxane (PDMS) as the binders, are evaluated. The PDMS-modified C-S-H structures are introduced into macro-defect-free cement to obtain stress–strain curves changes at a macro scale. The AFM–FM was adopted to measure the morphology and elastic modulus of C-S-H at a nano scale. The molecular dynamics (MD) simulation was performed to assess the toughness, tensile properties, and failure mechanism. The results show that the PDMS-modified C-S-H powders change the break process and enhance ductility of MDF cement. The elastic modulus of PDMS-modified C-S-H is lower than pure C-S-H. When PDMS molecules are located between the stacking crystal units, it can enhance the toughness of C-S-H aggregates. The PDMS-modified C-S-H stacking structure has better plasticity, and its tensile strains are higher than the pure C-S-H. PDMS molecules hinder the initial crack expansion, leading to the branching of the initial crack. In addition, the measurement of AFM–FM can identify and obtain the mechanical properties of basic units of C-S-H. This paper enhances the understanding of cement strength sources and modification methods.

Laser-induced damage threshold is the main limitation for fused silica optics in high-power laser applications. The existence of various defects near the surface is the key factor for the degradation of the threshold. In this work, the photoluminescence spectra at different regions of the damaged and recovered fused silica samples are recorded to analyze the correlation between photoluminescence of surface defects and laser-induced damage threshold. The experimental data concluded the inverse proportional correlation between fluorescence and laser-induced damage threshold value. The weak photoluminescence is the guarantee of the high laser-induced damage threshold, and then the higher local Si nanocluster concentration corresponds with the higher laser-induced damage threshold value for the fused silica optics after CO2 laser treatment. The investigation reveals that photoluminescence measurement can be employed to check the quality of pristine fused silica and evaluate the tendency of the laser-induced damage threshold value. The current results are helpful for understanding the evolution of interaction from CO2 laser treatment and fused silica optics and can provide the guide of process technology for the high quality of fused silica optics.

These arethe data for figures and code for machine learning

This is theresearch data for figures and the code for machine learning.

In this work, Ag@CdS nanowires (NWs) were fabricated via a facile hydrothermal route and magnetron sputtering. The structure and morphology of the Ag@CdS NWs were characterized by field emission sc...

A series of nucleobases guanine (G) and cytosine (C) pairing configurations have been fabricated on highly oriented pyrolytic graphite (HOPG) surface by controlling the molar ratio of G and C in water solution. Watson-Crick (WC) base pairing governs the association of C and G nucleobases when the molar ratio of C/G is adjusted to 1:1. Nucleobase-rich is preferentially hydrogen-bonded to the sites exposed around WC motifs with the adjustment of the C/G molar ratio. At a higher C/G molar ratio imbalance, the pairing configurations depend on the combination of interspace and sites of hydrogen binding between G and C bases. The systematic analysis of the high-resolution STM images and DFT calculations reveal that hydrogen bonding plays a dominant role in the formation of these pairing configurations and that the competition between the priority and diversity of hydrogen-bonded configurations bonding between G and C is the key for the pairing structural polymorphism.

Previous investigations had revealed that β-RDX facilely transforms to α-RDX due to the poor crystalline quality. This hindered obtaining insights into the β-RDX pressure behavior. In this work, ph...

The influence of sodium chloride (NaCl) on the hydration evolution of calcium aluminate cement (CAC) cured at 5°C, 20°C and 40°C was investigated by calorimetry, X-ray diffraction, differential scanning calorimetry–thermogravimetry, scanning electron microscopy and mercury intrusion porosimetry. The chloride binding capacity and compressive strength of the CAC were also determined. The results showed that the chloride binding capacities of all the CAC samples increased with an increasing sodium chloride content, but the trend of growth gradually slowed. The influence of sodium chloride on the hydration of CAC was found to be highly dependent on its dosage and the curing temperature. At 5°C and 20°C, the early hydration of CAC was accelerated by a small amount of sodium chloride, leading to greater amounts of CAH10. Additionally, the pore structure of hardened cement paste was optimised for a higher compressive strength. However, excessive sodium chloride was found to delay the early hydration to some extent. When the curing temperature was increased to 40°C, sodium chloride accelerated the phase conversion, accompanied with an increase of harmful pores and a sharp decrease in compressive strength. The findings indicate a potential application of CAC-based constructions made with sea sand, especially at temperatures below 20°C.

Calcium silicate hydrate (C–S–H) is the main product of cement hydration, which forms the microstructure of cement via the stacking of basic nanocrystals or gel units, and has a substantial influence on the mechanical performance of cement. Tetrahedron chains of silicon oxide form the main nanoscale structure of basic C–S–H units. Evaluation on the nanostructure of these tetrahedron chains facilitates to understand the source of cement strength. This article first introduced the atomic force microscopy-infrared spectroscopy (AFM-IR) technique into evaluating the nanostructure of C–S–H. The nano infrared spectroscopy of stacking C–S–H nanograins and tetrahedron spatial distribution mapping was obtained. The results demonstrate that the relative quantity of tobermorite-like and jennite-like units in C–S–H nanograins can be analyzed by AFM-IR. The stacking between C–S–H particles is facilitated to a large extent by silicate ( SiO 4 2 − {\text{SiO}}_{4}^{2-} ) tetrahedron chains formed of three tetrahedrons bridged by two oxygen atoms (i.e., Q2 chains), and there are Q2 chains acting as bridges between C–S–H particles. The proportions of different types of Q2 chains available for facilitating C–S–H particle stacking vary at the nanoscale. AFM-IR spatial mapping demonstrate that the orientations of these Q2 chains are not evenly distributed. These findings provide experimental information of the stacking C–S–H gaps.

The refinement of XRD patterns only provides the average structure parameters for the alloying materials because of the symmetric protection. Raman vibrational modes can append the detailed information about the bond length and structure. The refinements of XRD patterns for Bi alloying Cs2AgInCl6 revealed the strong structure distortion with the enlarged octahedron of In(Bi)Cl6 and the contracted octahedron of AgCl6 with the increasing Bi. Raman spectra supported the expanded octahedron of InCl6 and the reduced octahedron of AgCl6 but identified the anomalous shortening bond length of Bi-Cl with the increasing Bi. These distorting octahedrons break parity forbidden transition, modify Huang-Rhys factor, and result in the maximum values at 30% Bi alloying and the same variation trend for both photoluminescence and Huang-Rhys factor with the increasing Bi alloying.

The feasibility of selective laser melting (SLM) was investigated for manufacturing WC-20Co cemented carbide in this study. Both the microstructure analysis and finite element simulation were used ...

Here, a molecular switch using two metastable states of fullerene (C60) on Cu(111) as an information carrier was presented at 77 K. Density functional theory (DFT) calculations suggest that left-th...

Van der Waals (vdW) chemistry in simple molecular systems may be important for understanding the structure and properties of the interiors of the outer planets and their satellites, where pressures are high and such components may be abundant. In the current study, Raman spectra and visual observation are employed to investigate the phase separation and composition determination for helium-nitrogen mixtures with helium concentrations from 20 to 95% along the 295 K isothermal compression. Fluid-fluid-solid triple-phase equilibrium and several equilibria of two phases including fluid-fluid and fluid-solid have been observed in different helium-nitrogen mixtures upon loading or unloading pressure. The homogeneous fluid in helium-nitrogen mixtures separates into a helium-rich fluid (F

Knowledge of volatile cycling is vital to understanding the evolution of the planet and the life it supports. Although it has been gradually accepted that the mantle is a vast storehouse of H2O and other volatiles, the impact of coexisting volatiles on the thermal stabilities of OH and the lattice of the host mineral is still poorly understood. Phlogopite is one of the few hydrous minerals capable of carrying both water and halogens into the mantle. Previous observations from both experiments and textural relationships in natural samples have indicated that F-rich phlogopite can be stable under ultrahigh-temperature conditions. Here, the impact of F on the thermal stability of phlogopite was investigated via XRD, Raman, and IR spectroscopy from room temperature to 1000 to 1200 °C. Based on the experimental results from F-poor and F-rich natural phlogopites, we show that about 4 wt% F can increase the breakdown temperature of phlogopite by 100 °C under ambient pressure. The impact mechanism mainly involves preventing OH and lattice softening at high temperatures. This study reveals the links between F and the behavior of OH and phlogopite lattice, which is important for constraining volatile cycling, as well as the role of F in the physical and chemical properties of the upper mantle.

Thermal mechanical responses under high temperature and high pressure are basic information to understand the performance of energetic materials. In this work, the pressure effects on the thermal decay of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) are explored. Up to the initial pressure of 4.6 GPa, the pressure dependent decomposition boundary is built and no phase transition occurs until the decomposition of the LLM-105 crystal. The decomposition temperature is significantly lifted

Machining, especially dry machining of titanium alloys, has been one of the most significant challenges for carbide cutting tools. In this study, aluminum-rich AlTiN coating, as well as TiAlSiN nanocomposite coating, were successfully employed for dry milling of Ti–6Al–4V alloy with high efficiency and long tool life. At the cutting speeds of 150 m/min and 200 m/min, the tool life of the TiAlSiN-coated tool exceeds that of AlTiN-coated tool by 32 and 66%, respectively. The wear modes for both coated tools include the uniform flank wear, smooth wear, chipping, coating and substrate flaking, crater and notch wear, and the wear mechanisms include adhesion, diffusion, oxidation and crack. Among them, the wear mechanism is dominated by the adhesion and oxidation wear. As compared with AlTiN coating, TiAlSiN coating exhibits better mechanical properties and oxidation resistance, which contribute to a better cutting performance, fewer thermal cracks and smaller and uniform workpiece chips during the dry milling of Ti–6Al–4V alloy.