Search

In this work, a theoretical model for the refractive index (RI) detection that employs phase modulation for absorption compensation based on the mechanism of coherent perfect absorption (CPA) is presented. Different from most sensors using frequency modulation, the proposed sensor measures RI with phase modulation in a narrow frequency range. Due to the fragility of CPA, the narrow absorption peak is highly sensitive to changes in RI values of the dielectric layers inserted in the structure. Benefiting from this, the proposed sensing method is a feasible scheme of high-precision and high-sensitivity detection. By filling the structure with the substance to be detected, the measurement and analysis of substances with RI of 3.510-3.565 and 1.45-1.52 can be accurately achieved, respectively. For the measurement of RI from 3.51 to 3.565, the maximum sensitivity (S) is up to 3749.79 °/RIU, and the limit of detection (LoD) is $2.4\times10$ −4 RIU on average. If this sensor is used to measure RI of 1.45-1.52, the maximum S is 2775.1 °/RIU, and the average LoD is $2.8\times10$ −4 RIU. The structure consists of ferrites and other conventional materials. The magnetic field applied to the ferrite layers is proved to provide a sensor calibration function. The effects of the thicknesses of the dielectric layers and the incident angle on the sensing performance are also discussed. The suggested theoretical model has a better performance compared with the conventional sensors. This theoretical study introduces a novel idea for RI sensing and expands on the use of CPA in sensors. [ABSTRACT FROM AUTHOR]

Porcine reproductive and respiratory syndrome virus (PRRSV) is considered an important economic pathogen for the international swine industry. At present, both PRRSV-1 and PRRSV-2 have been confirmed to be co-circulating in China. However, there is little available information about the prevalence or distribution of PRRSV-1 in Guangdong province, southern China. In this study, we performed molecular detection of PRRSV-1 in 750 samples collected from 50 farms in 15 major pig farming regions in this province. After RT-PCR testing, 64% (32/50) of farms were confirmed as PRRSV-1-positive. Surprisingly, PRRSV-1 was circulating on at least one pig farm in all 15 regions; of the 750 samples, 186 samples (24.8%) were positive for PRRSV-1. Furthermore, 15 representative PRRSV-1 ORF5 sequences (606 bp) (n = 1 per region) were obtained from those PRRSV-1-positive regions. Sequence alignment analysis indicated that they shared 81.8% ~ 100% nucleotide and 81.2% ~ 100% amino acid similarity with each other. Although all current PRRSV-1 sequences were divided into pandemic subtype 1, most of them had unique glycoprotein-5 amino acid sequences that are significantly different from other known PRRSV-1 isolates. To conclude, the present findings revealed wide geographical distribution of PRRSV-1 in Guangdong province, southern China. This study further extends the epidemiological significance of PRRSV-1 in China. [ABSTRACT FROM AUTHOR]

One reported compound [Co(PDA)(4,4′-bipy)]·nHO and one new compound [Co(PDA)(Im)(HO)]·nHO were prepared by the reactions of Co(NO)·6HO or Co(OH) with 1,4-phenylenediacetic acid (HPDA) in the presence of the ancillary ligands 4,4′-bipyridine (4,4′-bipy) or imidazole (Im), and their magnetic properties were investigated. The presence of 4,4′-bipy in [Co(PDA)(4,4′-bipy)]·nHO results in a μ-bridging mode of the PDA ligand with one μ-carboxylato group and one chelating carboxylato group and the construction of a 2D framework as reported in the literature. The introduction of Im ligand in [Co(PDA)(Im)(HO)]·nHO helps to construct a one dimensional chain with the two carboxylato groups of PDA ligand in monodentate coordination modes. The magnetic studies reveal the presence of dominant antiferromagnetic interaction in [Co(PDA)(4,4′-bipy)]·nHO with a field-induced magnetic transition due to spin-flop. Magnetically, [Co(PDA)(Im)(HO)]·nHO presents a mononuclear structure. This work reveals that the introduction of ancillary ligands in the Co(II)-PDA system adjusts the linking modes of PDA and therefore the resulting frameworks and their magnetic properties. [ABSTRACT FROM AUTHOR]