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The blood clam Tegillarca granosa is a commercial marine bivalve of economic value, accounting for approximately 50% of clam production in China. In recent years, the yield of blood clams has been threatened by bacterial infections caused by marine Vibrio species that thrive under a rising sea temperature. The transcription factor activating protein-1 (AP-1) is emerging as an important player in the innate immunity of marine bivalves against viral or bacterial infections. In this study, the full-length cDNA of a novel T. granosa AP-1 (TgAP-1) was cloned for the first time. The 1591-bp cDNA encoded a protein of 292 amino acid residues with a calculated molecular weight of 32.8 kDa. The TgAP-1 protein contained an N-terminal Jun domain and a C-terminal basic region leucine zipper domain typically found in Jun proteins (a subfamily of AP-1 proteins). TgAP-1 was ubiquitously expressed in T. granosa, with the highest expression detected in the gill and foot, followed by the mantle, hemolymph, and hepatopancreas. Exposure to Vibrio harveyi induced TgAP-1 expression in gill tissues and the expression levels of TgAP-1 of resistant blood clams were always lower than that of control population whether Vibro infection or not. A total of 18 single nucleotide polymorphisms (SNPs) of TgAP-1 were detected in T. granosa. SNP-typing and haplotyping of resistant and susceptible populations revealed that six SNPs (AG type of TgSNP-1, GA type of TgSNP-2, TG type of TgSNP-4, CT type of TgSNP-7, AG type of TgSNP-11, and GA type of TgSNP-12) and four haplotypes (fHap2, fHap3, fHap6, and fHap7) were significantly associated with V. harveyi resistance. Risk assessment showed that fHap2 (CG) and fHap7 (GA) were associated with an increased resistance, while fHap3 (CT) and fHap6 (AG) were associated with an increased susceptibility. The results from this study supported a potential role of TgAp-1 in the anti-Vibro immunity of T. granosa. The discovery of the genetic molecular markers and haplotypes related to Vibrio resistance can provide guidance for selective breeding of T. granosa in the future.

The technique of terahertz time-domain spectroscopy (THz-TDS) enables us to simultaneously determine the real and imaginary parts of optical parameters. However, it is still a challenge to extract the optical parameters of a two-dimensional (2D) material (or an ultra-thin film) on a substrate accurately and flexibly for an arbitrary incident angle and different polarization. By treating a 2D material as a conductive boundary without thickness, we propose an improved theoretical model to extract the optical conductivity of the 2D material on a substrate from THz transmission or reflection spectroscopy. Importantly, the effects of wave polarization, incident angle, and multiple reflections in the substrate are considered in our model and the analytical formulae associated with the optical conductivity of the 2D material are provided. Furthermore, we verify the validation of our model based on the THz transmission and reflection experiments for mono- and few-layer MoS2 on sapphire substrates. These results not only are of practical significance for investigating the THz properties of 2D materials but can also be extended to the situations of ultra-thin films and/or incoherent detection such as Fourier transform infrared spectroscopy.

The high-temperature annealing effect of a V2O5/Al2O3 bilayer on the reflectivity of visible band was studied in the present work. It was found that the V2O5 (200 nm)/Al2O3 (30 nm) sample (A-0) has a nano-granular surface morphology without a definite crystalline phase. The reflectance of A-0 overreaches 60% as the wavelength is larger than 650 nm, and its minimum reflectance (20%) occurs at the wavelength of ~500 nm. After in situ annealing treatment at 750 °C for 30 min, a triclinic AlVO4 phase appears while the nano-granular surface morphology remains (sample A-30). The reflectivity of A-30 is well suppressed in comparison with that of A-0 especially in the long wavelength range. Its minimum reflectivity approaches 5% at ~500 nm wavelength. It is speculated that the appearance of a new AlVO4 nanophase is the main reason for the decline of reflectivity. Extending the annealing time to 60 min, the reflectivity spectrum, as well as the surface morphology, are almost the same. These results can be helpful for applications of vanadium alumina nanocomposites in high-temperature environments.

The characteristic energies of elementary excitations and collective modes in many quantum materials lie mostly in the terahertz (THz) frequency range, which provides a wide space for the development of THz optical materials and devices. In particular, topological Weyl semimetal Mn3Sn is a noncollinear antiferromagnet with anomalous THz properties, which is strongly affected by thermal energy and external magnetic fields. Despite the explosive growth of the research on magnetic Weyl semimetals recently, its nanoscale structure for applications in THz optical devices remains to be explored. Here, we fabricated nanostructured Mn3+0.53Sn films with different crystal orientations, driven by Ostwald Ripening (OR) on (0001) c-Al2O3. A huge anisotropic THz response manifested a firm link between the optical properties of Weyl antiferromagnet Mn3Sn and its contrivable spin structures. The topological properties of Mn3Sn are robustly protected in its nanostructures. This work can provide a new horizon for the fabrication of a nanostructured magnetic Weyl alloy and for its potential applications in subwavelength high-performance THz devices.

Due to the potential application of DNA for biophysics and optoelectronics, the electronic energy states and transitions of this genetic material have attracted a great deal of attention recently. However, the fluorescence and corresponding physical process of DNA under optical excitation with photon energies below ultraviolet are still not fully clear. In this work, we experimentally investigate the photoluminescence (PL) properties of single-stranded DNA (ssDNA) samples under near-ultraviolet (NUV) and visible excitations (270 similar to 440 nm). Based on the dependence of the PL peak wavelength (lem) upon the excitation wavelength (lex), the PL behaviors of ssDNA can be approximately classified into two categories. In the relatively short excitation wavelength regime, lem is nearly constant due to exciton-like transitions associated with delocalized excitonic states and excimer states. In the relatively long excitation wavelength range, a linear relation of lem = Alex + B with A 0 or A < 0 can be observed, which comes from electronic transitions related to coupled vibrational-electronic levels. Moreover, the transition channels in different excitation wavelength regimes and the effects of strand length and base type can be analyzed on the basis of these results. These important findings not only can give a general description of the electronic energy states and transitional behaviors of ssDNA samples under NUV and visible excitations, but also can be the basis for the application of DNA in nanoelectronics and optoelectronics.

The solubility of Bi3+ in aqueous solution is an important factor that limits the fabrication of high-quality Bi2S3 thin films. In order to find a low-cost method to manufacture high-quality Bi2S3 thin films, we are reporting the preparation of the Bi2S3 thin films based on pulse-plating method in this paper for the first time. The nano-bismuth particles were obtained by electroplating on fluorine-doped SnO2 (FTO)-coated conducting glass substrates with saturated bismuth potassium citrate solution as the electroplating bath, and then it was put into a muffle furnace to oxidize. Finally, the thin films depositing on FTO glass substrates were put into the thioacetamide solution for vulcanization. In the end, the Bi2S3 thin films were successfully prepared on FTO glass substrates. Different characterization techniques were used to characterize the structure, morphology and photoelectrochemical properties of the prepared thin films. The test results revealed that we used this method to synthesize the high-quality Bi2S3 thin films, thus the Bi2S3 materials synthesized through this method are promising candidates in photoelectrochemical application.

The cuttings transport during well drilling was numerically simulated based on kinetic theory of granular flow in combination with sliding mesh for drill pipe rotation. The power-law model was implemented to describe the rheological behavior of drilling fluid. Numerical results were compared with available experimental data in the literature to validate the algorithm, and good agreement was found. Three distinguishable regions of cuttings flow pattern and swaying phenomenon of cuttings distribution were observed along the direction of drill pipe rotation. Increasing the fluid velocity results in a reduction in the height of cuttings bed and weakening of the swaying phenomenon. Higher apparent viscosity of drilling fluid contributes to a good performance of cuttings transport at a low annular velocity, but rising in pressure loss. There is critical inclination angle of the well θctr for cuttings transport ratio and θdp for pressure drop through the annulus. The most difficult of cuttings transport occurs in the well inclinations around 35°–65°. There is no additional contribution of drill pipe rotation to cuttings transport after reaching a critical rotation speed. Increasing the cutting size leads to a reduction in the cuttings transport ratio and an increase in pressure drop.

To realize broadband near-infrared (NIR) absorption, we theoretically propose a metamaterial absorber (MMA) comprised of periodic array of alternating Cu/Ge layers with graded apertures, whose widths are different in different layers. The calculations exploiting finite-element method (FEM) demonstrate that the rainbow trapping effect (RTE) induced by plasmonic resonances can result in NIR absorption with a broad bandwidth. The bandwidth is dependent with the number of layers and the width variation of the aperture between adjacent layers. Moreover, the effects of the structure parameters, incident angle, and light polarization on the operational bandwidth (OBW) and absorption efficiency ( η O B W ) of the MMA have also been investigated in detail. Interestingly, by optimizing the structure parameters, it is possible to achieve an absorbance of more than 90% over a broad band (OBW ∼ 0. 9 μ m ). Meanwhile, we also find that η O B W is nearly independent to the polarization of the NIR light when the incident angle θ is below ∼ 40°. These results can be applied to design broadband NIR devices including detectors and emitters.

Fusarium head blight is a severe wheat disease that affects yield and food safety. Chemical and biological methods are the main techniques for detection of the deoxynivalenol (DON) content, but despite being highly accurate, these techniques are destructive and time-consuming. A nondestructive, efficient and accurate method for estimating the DON content levels of scabs is required in post-harvest wheat processing. Hyperspectral imaging (HSI) systems have the capability of detecting subsurface defects and the contents or properties of organic substances. Because this method is nondestructive and fast and can be fully automated, the HSI technique was used in this study for detection of the wheat grain quality. Mycotoxins can destroy tissues, cells, and even molecules in cereals. Furthermore, the contents or properties of organic substances such as proteins, carbohydrates, and lipids in wheat infected by DON toxin undergo changes that can be reflected in their spectral characteristics. In this study, data for both wheat kernels and wheat flour obtained using two types of HSI systems, i.e., visible near-infrared (Vis-NIR) (ranging from 400 to 1000 nm) and short-wave infrared (SWIR) (ranging from 1000 to 2500 nm), were investigated. Ninety-six samples of wheat kernels and wheat flour samples were divided into two groups, and the multiplicative scatter correction (MSC) and standard normal variate (SNV) were used for spectral data pre-processing. A support vector machine (SVM) and a sparse autoencoder (SAE) network were used to the build classifiers with the extracted important wavelengths by genetic algorithm (GA). The results suggest that it is possible to detect wheat kernel samples in the Vis-NIR bands and to detect wheat flour samples from SWIR data with high accuracy. Moreover, for wheat kernel samples, the results of the SAE and SVM models were roughly the same. For all types of classification models for wheat kernel samples using the Vis-NIR, the MSC-GA-SAE model achieved the highest prediction accuracy (100% for both the training and test sets). In contrast to the wheat kernels samples, for the wheat flour samples, the SNV-GA-SAE models achieved better results with the SWIR data in terms of correctly classifying the samples (100% for the training set and 96% for the test set), which suggested that it is possible to detect wheat flour samples from SWIR data with high accuracy.

We have developed a sensitive chemiluminescent (CL) assay for cysteine. It is based on the use of water-soluble and fluorescent silver nanoclusters (Ag NCs) which are found to be able to strongly enhance the weak CL signal resulting from the redox reaction between Ce(IV) ion and sulfite ion. This enhancement is inhibited by cysteine under appropriate conditions. Taking advantage of this specific CL inhibition, a novel CL method for the sensitive and selective detection of cysteine was developed. This effect is interpreted in terms of an electronic energy transfer from excited state intermediate sulfur dioxide (originating from the CL reaction between Ce(IV) and sulfite ions) to the Ag-NCs. The latter become electronically excited and thus can act as a new source of emission. The method was applied to the determination of cysteine in the range from 5.0 nM to 1.0 μM, with a detection limit at 2.5 nM (S/N = 3).

We report on the first application of novel, water-soluble and fluorescent silver nanoclusters (Ag NCs) in a chemiluminescent (CL) detection system. A method has been developed for the determination of copper(II) ion that is based on the fact that the weak CL resulting from the redox reaction between Ce(IV) ion and sulfite ion is strongly enhanced by the Ag NCs and that the main CL signals now originate from Ag NCs. UV-visible spectra, CL spectra and fluorescent (FL) spectra were acquired to investigate the enhanced CL mechanism. It is proposed that the electronic energy of the excited state intermediate SO2* that originates from the CL reaction is transferred to Ag NCs to form an electronically excited NC whose emission is observed. In addition, it is found that copper(II) is capable of inhibiting the CL of the nanoclusters system, but not if other common metal ions are present. The detection of copper(II) is achieved indirectly by measuring the CL intensity of Ag NCs. Under the optimized experimental conditions, a linear relationship does exist between the intensity of CL and the concentrations of copper(II) in the range of 0.2 nM to 0.1 mΜ. The detection limit is 0.12 nM. The method is applied to the determination of copper(II) ion in tap water with satisfactory results.

A chemiluminescence (CL) method is presented for the flow injection determination of norfloxacin (NFLX). It is based on the fact that the weak CL of the Ce(IV)-Na2SO3 redox system is strongly enhanced in the presence of silver nanoparticles. UV-visible and fluorescence spectroscopy was carried out and showed that the energy of the intermediate SO2*, originating from the reaction of Ce(IV) with Na2SO3, was transferred to Tb3+ via NFLX, and that the silver nanoparticles (AgNPs) accelerate the process due to the electric activity of AgNPs. Norfloxacin was detected by measuring the CL intensity which increases linearly with the concentration of NFLX in the range from 10 nM to 50 μM. The detection limit is lowered to 2.0 nM. The method was successfully applied to the determination of NFLX in eyedrops.