The Role of FveAFB5 in Auxin-Mediated Responses and Growth in Strawberries.

Auxin is a crucial hormone that regulates various aspects of plant growth and development. It exerts its effects through multiple signaling pathways, including the TIR1/AFB-based transcriptional regulation in the nucleus. However, the specific role of auxin receptors in determining developmental features in the strawberry (Fragaria vesca) remains unclear. Our research has identified FveAFB5, a potential auxin receptor, as a key player in the development and auxin responses of woodland strawberry diploid variety Hawaii 4. FveAFB5 positively influences lateral root development, plant height, and fruit development, while negatively regulating shoot branching. Moreover, the mutation of FveAFB5 confers strong resistance to the auxinic herbicide picloram, compared to dicamba and quinclorac. Transcriptome analysis suggests that FveAFB5 may initiate auxin and abscisic acid signaling to inhibit growth in response to picloram. Therefore, FveAFB5 likely acts as an auxin receptor involved in regulating multiple processes related to strawberry growth and development.

Preparation and Performance Characterization of Exploding Foil Initiator Based on ODPA-ODA Polyimide Flyer.

The exploding foil initiator (EFI) system has been extensively used in ignition and detonation sequences and proved to be of high safety and reliability. Polyimide is considered the ideal flyer material for EFI due to its excellent performance, including thermal stability, outstanding mechanical properties, high radiation resistance, and excellent dielectric properties. In this study, we prepared the EFI based on a polyimide (ODPA-ODA) flyer, which is spin-coated and solidified on patterned copper film in situ. The electric explosion test shows that the prepared EFI has good working performance, and the 4000 V working voltage drove the flyer to reach a maximum velocity of 5096 m/s. The polyimide morphology and chemical structure after the electric explosion was observed by microscope, SEM, XPS, and FTIR, which showed that the polyimide flyer underwent thermal deformation and complex chemical reactions during an electric explosion. A large number of polyimide bonds broke to form new carbonyl compounds, and the opening of aromatic rings was accompanied by the formation of aliphatic hydrocarbon chains. The morphology and chemical structure analysis after the electric explosion test will lay a foundation for us to further understand the working principle and evolution process of polyimide (ODPA-ODA) flyer.

Enhanced Photothermal Effect in Ultralow-Density Carbon Aerogels with Microporous Structures for Facile Optical Ignition Applications.

The exact mechanism responsible for the phenomenon known as photoignition with an enhanced photothermal effect in high-surface-area carbon with the addition of a metal catalyst is an open issue. Here, we report the first successful flash ignition of a pure carbon material in ambient air microporous carbon aerogels (CAs) with ultralow density and high surface area. Under flash exposure, the CAs show a strong local heat confinement effect near microporous structures (0.6-2 nm), and the graphite crystallite structures existing in single carbon nanoparticles (∼15 nm) are damaged. The local heat confinement effects are mainly derived from the low gaseous thermal conductivity in micropores and low solid thermal conductivity in low-density CAs. In addition, the limiting effects of the microporous structure on the vibration amplitude of free-state electrons in low-density CAs result in a dramatic increase in optical absorption. Numerical simulations of unsteady temperature fields of CAs with different densities and thicknesses are also performed, and the calculated maximum temperature of a 17 µm-thick 20 mg/cm3 CA bed is 1782 °C. CAs with higher density can also give rise to enhanced photothermal response and ignition with the addition of metal Fe nanoparticles. The metal catalyst increases both the light absorption capacity in the visible-light range and the heat accumulation capacity. These results are important for understanding the mechanism of flash ignition, especially the local high temperature and effects of metal catalyst in carbon materials during the photothermal process.

Probing the properties of size dependence and correlation for tantalum clusters: geometry, stability, vibrational spectra, magnetism, and electronic structure.

A comprehensive investigation on the equilibrium geometry, relative stability, vibrational spectra, and magnetic and electronic properties of neutral tantalum clusters (Ta n , n = 2-17) was performed using density functional theory (DFT). We perform a study of the size dependence and correlations among those descriptors of parameters, and showed these could provide a novel way to confirm and predict experimental results. Some new isomer configurations that have never been reported before for tantalum clusters were found. The growth behaviors revealed that a compact geometrical growth route is preferred and develops a body-centered-cubic (BCC) structure with the cluster size increasing. The perfectly fitted functional curve, strong linear evolution, and obvious odd-even oscillation behavior proved their corresponding properties depended on the cluster size. Multiple demonstrations of the magic number were confirmed through the correlated relationships with the relative stability, including the second difference in energy, maximum hardness, and minimum polarizability. An inverse evolution trend between the energy gap and electric dipole moment and strong linear correlation between ionization potentials and polarizability indicated the strong correlation between the magnetic and electronic properties. Vibrational spectroscopy as a fingerprint was used to distinguish the ground state among the competitive geometrical isomers close in energy. The charge density difference isosurface, density of states, and molecular orbitals of selected representative clusters were analyzed to investigate the difference and evolutional trend of the relative stability and electronic structure. In addition, we first calculated the ionization potential and magnetic moment and compared these with the current available experimental data for tantalum clusters.

Laser emission from flash ignition of Zr/Al nanoparticles.

We report the first laser emission from flash ignition of Zr/Al nanoparticles with the addition of strong oxidizer KClO4 using Nd: YAG as a laser medium. The mixture Zr/Al/Kp-45 (mass ratio = 33%Zr: 33%Al: 34%KClO4) has the highest brightness temperature Tb = 4615 K and the adiabatic flame temperature Tf = 4194 K with the duration of 20 ms. At 1064 nm we measured a maximum output energy of 702.5 mJ with the duration of nearly 10 ms by using only 100 mg mixture with an output coupler (transmission T = 10%). Further optimizing the concentration cavity and increasing the mixture content will yield much higher efficiency and output energy.

Preparation of core-shell structure KClO4@Al/CuO Nanoenergetic material and enhancement of thermal behavior.

In this paper, a solvent/non-solvent synthetic approach has been utilized in preparing a new nanoenergetic material KClO4@Al/CuO by coating Al/CuO nanocomposites particles with a layer of nanoscale oxidizer KClO4. The coating process and mechanism are discussed. The composites of Al/CuO are uniformly mixed by mechanical ball milling process and CuO acts as a catalytic metallic oxide. The ternary mixtures KClO4@Al/CuO were characterized by X-ray diffraction (XRD) and the results reveal that after ball-milling and chemical synthesis process, the phase compositions haven't changed. Scan electron microscopy (SEM) images show that these energetic nanocomposites consist of small clusters of Al/CuO that are in intimate contact with a continuous and clear-cut KClO4 layer (100-400 nm). In a Scanning transmission electron microscopy (STEM) elemental map, high K/Cl intensity on the perimeter of the nanoparticles and high Cu/Al content in the interior powerfully demonstrated the KClO4@Al/CuO core-shell nanostructure. Electrical ignition experiments and pressure cell test prove that these nanoenergetic composites are more sensitive to ignition with much higher burning rate than traditional formulations (conventional counterparts). To quantify the enhancement of thermal behavior, Thermogravimetry (TG) and Differential scanning calorimetry (DSC) were performed and the results show that the burning rate of these energetic nanocomposites nearly tripled.

Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate.

Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the "V"-shaped or "U"-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications.

Discrete Dipole Approximation Simulation of Nearly Touching Plasmonic Au Dimers and Influence of Particle Shape Assembly on Optical Response.

The method Discrete Dipole Approximation (DDA) is used to calculate the extinction spectra and field distribution of three types of dimers. In the paper we provide a systematic analysis of the optical response of different nanoscopic dimer structures with relatively small gap distances. A description is given about how the energy and excitation cross sections of dimer plasmons depend on nanoparticle separation. Resonance peaks of dimers show red-shift compared with single nanoparticle. Dimers formed by different single particle display distinct optical response. Interaction junctions in dimers can serve as hot spots for field enhancement. Field distribution in gaps made of two flat planes is nearly continuous. Changing gaps between two particles in dimers can tune the resonance wavelength effectively as well as different particle ensembles. Existence of sharp corners can attract and change field distribution. It is not effective volume but the effective cross-section that dominates the extinction efficiency.

[An Analysis of Combustion Emission Spectrum and Combustion Products of KClO4/Zr in the Quartz Tubes].

Aiming at understanding the light radiation properties of KClO4/Zr combusting under different conditions, emission spectrum and combustion products for KClO4/Zr combusting in open air and closed quartz tubes were studied respectively. Energy distribution of the light radiation signal and the emission intensity evolution with time were measured with fiber optic spectrometer, and photo-diode and oscilloscope. Spectral efficiency within (590±10), (750±10) and (808±10) nm were analyzed respectively according to the obtained flame emission spectrum. Morphology of the combustion products of KClO4/Zr were observed with scanning electronic microscopy (SEM). Results showed that the flame emission spectrum of KClO4/Zr distributed within the visible and near infrared width wave band, whiel the strongest radiation appeared within 730 nm to 820 nm band. When burning in closed quartz tubes, detected combustion emission spectrum intensity decreased significantly with the decrease in size of the tube. Also, the energy distribution of the emission spectrum showed different variation trends, and to deal with flame emission spectrum distribution, as the change of volume of quartz tubes, (590±10), (750±10) and (808±10) nm bands' spectral efficiency are also present different change rules. Generally, increasing the diameter of the quarts tube favored the increase of the effective light radiation energy detected outside of the tube, and decreasing the diameter of the quartz tubes favored the peak emission intensity of KClO4/Zr. With the increase of tube diameter, KClO4 burning more fully, the product particle size is smaller; the morphology is the rule of the globular. And the change of tube length is not too large effect in the reaction results.

Mesoporous gold sponges: electric charge-assisted seed mediated synthesis and application as surface-enhanced Raman scattering substrates.

Mesoporous gold sponges were prepared using 4-dimethylaminopyridine (DMAP)-stabilized Au seeds. This is a general process, which involves a simple template-free method, room temperature reduction of HAuCl4·4H2O with hydroxylamine. The formation process of mesoporous gold sponges could be accounted for the electrostatic interaction (the small Au nanoparticles (~3 nm) and the positively charged DMAP-stabilized Au seeds) and Ostwald ripening process. The mesoporous gold sponges had appeared to undergo electrostatic adsorption initially, sequentially linear aggregation, welding and Ostwald ripening, then, they randomly cross link into self-supporting, three-dimensional networks with time. The mesoporous gold sponges exhibit higher surface area than the literature. In addition, application of the spongelike networks as an active material for surface-enhanced Raman scattering has been investigated by employing 4-aminothiophenol (4-ATP) molecules as a probe.

Surface specific heats of metal nanocrystals at low temperatures.

In order to quantitatively explain the enhanced specific heat of metal nanocrystals measured from 4.2 K to 80 K, an analytical expression has been deduced to determine the surface specific heat in nanocrystals, which is proportional to T(2.5) at low temperatures. The consequently calculated specific heat and surface Debye temperature of copper nanocrystals are in good agreement with the experimental data. This explains why the experimental specific heat of copper nanocrystals is enhanced with respect to the bulk and why it exhibits a different feature as a function of temperature from that of the bulk at low temperatures. The first experimental evidence is presented that the spatial dimension of surfaces should be neither pure 2D nor 3D, but between 2D and 3D, due to the effect of atoms in the core of the nanocrystals.

The influence of edge and corner evolution on plasmon properties and resonant edge effect in gold nanoplatelets.

In this paper a simulation of the properties of surface plasmons on gold nanoplatelets with various cross-sections inscribed in a circle and an investigation of their field distributions to assign multiple SPRs are described. The manipulated propagation can be obtained through the evolution of edges and corners. Furthermore, the particle morphology and the associated spectral positions alone do not uniquely reflect the important details of the local field distribution or the resonance modes. The plasmon modes were investigated and found to be mainly excited along the edges and in the side and sloped side surfaces. The strong field distributions can generally be found around the corners and how the plasmons transmit through the corners to adjacent edges was also investigated. Besides the plasmons excited along the edges as were found for the triangular nanoplatelets, plasmons were excited in the interior region of the triangular surfaces and were also investigated. Despite this in the infrared region, plasmon modes were found to be along the edges for the hexagonal nanoplatelets. Also, it can be seen that the change of nanoplatelet thickness can support different plasmon modes ranging from dipolar resonance mode to quadrupole resonance mode. The thickness far below the skin depth can display complex plasmon modes along the edges and on the side and sloping side surfaces as well as the strong coupling between the top and bottom surfaces. The observed plasmon resonance modes in this simulation reflect the interference of all these contributions including the plasmons along the edges and on the side surfaces. This is an essential step towards a thorough understanding of plasmon modes and the effect of edge and corner evolution in polygonous nanoplatelets.

[Study of density functional theory for surface-enhanced Raman spectra of furfural].

In the present paper, DFT method at the B3LYP/6-31+G* * (C, H, O)/LANL2DZ(Ag) level was used to optimize molecular configurations of furfural. Based on the optimized structure, the normal Raman spectrum (NRS) of FUR and the surface-enhanced Raman spectrum (SERS) of FUR adsorbed on Ag, Ag2 and Ag4 were all calculated, which were compared with the experimental values. The calculation results indicated that a good conformity was found between the computed and the experimental results. The results of furfural adsorbed on Ag4 were more approximate to the ever reported experimental date than those of furfural adsorbed on Ag and Ag2. At the end, detailed analysis of the Raman spectrum and more comprehensive assignments of the vibration mode for furfural were studied by the software of GaussView. The data of the SERS by comparing with the one of NRS show that furfural molecule and Ag atoms interact with each other. And we suppose that the molecular plane with the ring of adsorbed furfural molecule is vertically orientated to the silver surface. The work in this paper offers a theory evidence for detection and trace analysis of drinks containing furfural.

[Study of density functional theory for surface-enhanced Raman spectra of p-aminothiophenol].

In the present paper, DFT method at the B3LYP/6-31++G** (C, H, N, S)/LANL2DZ(Ag) level was used to optimize molecular configurations of p-aminothiophenol. Based on the optimized structure, the normal Raman scattering (NRS) spectrum of PATP and the surface-enhanced Raman scattering(SERS) spectrum of PATP adsorbed on Ag and Ag2 were both calculated, and were compared with the results of other literatures values. The calculation results indicated that a good conformity was found between the computed and experimental results. The results of PATP adsorbed on Ag2 were more approximate to the ever reported experimental data than those of PATP adsorbed on Ag. At the end, detailed analysis of the Raman spectrum and more comprehensive assignments of the vibration mode for p-aminothiophenol were studied by the software of GaussView. In comparison with SERS spectrum and NRS spectrum of PATP molecule, the authors observed the stretching vibration bands in the SERS spectrum at about 213 cm(-1), which is due to Ag-S stretching vibration mode. The work in this paper has greatly directive value in understanding and explaining some experiment phenomenon, and helps to study the mechanism of surface-enhanced Raman scattering of PATP.

Correlations of the stability, static dipole polarizabilities, and electronic properties of yttrium clusters.

Static dipole polarizabilities for the ground-state geometries of yttrium clusters (Yn, n < or = 15) are investigated by using the numerically finite field method in the framework of density functional theory. The structural size dependence of electronic properties, such as the highest occupied molecular orbital-lowest occupied molecular orbital (HOMO-LUMO) gap, ionization energy, electron affinity, chemical hardness and softness, etc., has been determined for yttrium clusters. The energetic analysis, minimum polarizability principle, and principle of maximum hardness are used to characterize the stability of yttrium clusters. The correlations of stability, static dipole polarizabilities, and electronic properties are analyzed especially. The results show that static polarizability and electronic structure can reflect obviously the stability of yttrium clusters. The static polarizability per atom decreases slowly with an increase in the cluster size and exhibits a local minimum at the magic number cluster. The ratio of the mean static polarizability to the HOMO-LUMO gap has a much lower value for the most stable clusters. The static dipole polarizabilities of yttrium clusters are highly dependent on their electronic properties and are also partly related to their geometrical characteristics. A large HOMO-LUMO gap of an yttrium cluster usually corresponds to a large dipole moment. Strong correlative relationships of the ionization potential, softness, and static dipole polarizability are observed for yttrium clusters.