One-Step Exfoliation Method for Plasmonic Activation of Large-Area 2D Crystals.

Advanced exfoliation techniques are crucial for exploring the intrinsic properties and applications of 2D materials. Though the recently discovered Au-enhanced exfoliation technique provides an effective strategy for the preparation of large-scale 2D crystals, the high cost of gold hinders this method from being widely adopted in industrial applications. In addition, direct Au contact could significantly quench photoluminescence (PL) emission in 2D semiconductors. It is therefore crucial to find alternative metals that can replace gold to achieve efficient exfoliation of 2D materials. Here, the authors present a one-step Ag-assisted method that can efficiently exfoliate many large-area 2D monolayers, where the yield ratio is comparable to Au-enhanced exfoliation method. Differing from Au film, however, the surface roughness of as-prepared Ag films on SiO2 /Si substrate is much higher, which facilitates the generation of surface plasmons resulting from the nanostructures formed on the rough Ag surface. More interestingly, the strong coupling between 2D semiconductor crystals (e.g., MoS2 , MoSe2 ) and Ag film leads to a unique PL enhancement that has not been observed in other mechanical exfoliation techniques, which can be mainly attributed to enhanced light-matter interaction as a result of extended propagation of surface plasmonic polariton (SPP). This work provides a lower-cost and universal Ag-assisted exfoliation method, while at the same time offering enhanced SPP-matter interactions.

Characterization of Neoschoengastia gallinarum from subtropical China by rDNA and identification of two genotypes based on mitochondrial cox1.

Genetic variations in the 18S ribosomal DNA (18S), 28S ribosomal DNA (28S), second internal transcribed spacer of ribosomal DNA (ITS2), and mitochondrial cytochrome c oxidase subunit 1 (cox1) of Neoschoengastia gallinarum collected from subtropical China were examined. First, a portion of the 18S (p18S), a portion of the 28S (p28S), and the complete ITS2 were separately amplified from individual mites and sequenced. The lengths of the sequences of p18S, p28S, and ITS2 were found to be 1379 bp, 3465~3468 bp, and 200 bp, respectively. The intraspecific sequence variation was 0~0.1% for p28S and 0~1.6% for ITS2, though no variation was observed for p18S, suggesting conservation of rDNA sequences. Second, a portion of the mitochondrial cox1 gene (pcox1) of N. gallinarum was analyzed. The length of the pcox1 sequence is 460 bp, and two distinct groups were observed in N. gallinarum. All pcox1 sequences in group I were identical, and there was only one nucleotide transition observed in group II; however, 7.0~7.2% variations between the two groups were observed, suggesting that two genotypes of N. gallinarum: genotype I and genotype II. Phylogenetic analyses based on pcox1 sequences indicated that N. gallinarum isolates (genotype I or genotype II) clustered into one branch; according to cox1 sequence analysis of Trombiculidae, Walchia hayashii is the closest species. The present study shows that ITS2 rDNA sequence can act as marker for the identification of N. gallinarum samples. Furthermore, analysis of the mitochondrial pcox1 sequence suggests the existence of two genotypes, which has implications for further studies of the ecology and population genetic structures of N. gallinarum.

Epidemiological investigation of Mycoplasma Synoviae in native chicken breeds in China.

BACKGROUD: Mycoplasma synoviae (M. synoviae) is widely distributed around the world, and leads to serious economic losses in the world every year. Nevertheless, the incidence and epidemiology of M. synoviae infection in China have remained unclear. RESULTS: In this study we demonstrate that over 9773 broiler chicken flocks in 16 Chinese provinces were affected by M. synoviae between 2010 and 2015. Our epidemiological study revealed that M. synoviae was widely prevalent in multi-aged Chinese native breeder chickens, and the prevalence of M. synoviae in embryos of breeders reached up to 16.29%. In addition, our data showed that chickens aged 14 days or younger carried simultaneously high levels of maternal antibody against M. synoviae and high M. synoviae infection (10%), and low M. synoviae antibody levels in breeders and high proportion of M. synoviae infection in embryos could increase the chances of incidence in the offspring. Finally, our results also indicated that 3- to 7-week-old chickens might be most the susceptible to M. synoviae and, therefore, might play a key role in the horizontal transmission of M. synoviae. CONCLUSION: Our findings suggest that M. synoviae is widely circulating in Chinese native chickens, accordingly, effective control measures are urgently needed to control the spread.

Molecular characterization and phylogenetic analysis of infectious bursal disease viruses isolated from chicken in South China in 2011.

Infectious bursal disease virus (IBDV) is a double-stranded RNA virus that causes immunosuppressive disease in young chickens. Thousands of cases of IBDV infection are reported each year in South China, and these infections can result in considerable economic losses to the poultry industry. To monitor variations of the virus during the outbreaks, 30 IBDVs were identified from vaccinated chicken flocks from nine provinces in South China in 2011. VP2 fragments from different virus strains were sequenced and analyzed by comparison with the published sequences of IBDV strains from China and around the world. Phylogenetic analysis of hypervariable regions of the VP2 (vVP2) gene showed that 29 of the isolates were very virulent (vv) IBDVs, and were closely related to vvIBDV strains from Europe and Asia. Alignment analysis of the deduced amino acid (aa) sequences of vVP2 showed the 29 vv isolates had high uniformity, indicated low variability and slow evolution of the virus. The non-vvIBDV isolate JX2-11 was associated with higher than expected mortality, and had high deduced aa sequence similarity (99.2 %) with the attenuated vaccine strain B87 (BJ). The present study has demonstrated the continued circulation of IBDV strains in South China, and emphasizes the importance of reinforcing IBDV surveillance.

Retrospective study of adenovirus in autopsied pulmonary tissue of pediatric fatal pneumonia in South China.

BACKGROUND: Adenovirus are the important pathogen of pediatric severe pneumonia. The aim of this study is to analyze the infection, subtype and distribution of adenovirus in autopsied pulmonary tissue of fatal pneumonia in infants and children, and the relationships between adenovirus infection and respiratory illness in South China. METHODS: Nested PCR was performed on DNA extracted from autopsied lung tissue from patients who died of severe pneumonia, and the positive nested PCR products were cloned and sequenced. The adenovirus in autopsied pulmonary tissue was also analyzed by immunohistochemistry assay in a blind way. RESULTS: In the 175 autopsied pulmonary tissues, the positive percentage of adenovirus was 9.14% (16/175) and 2.29% (4/175) detected with nested PCR and immunohistochemistry, respectively. There are three cases of adenovirus serotype 3, twelve cases of adenovirus serotype 4 and one case of serotype 41 determined by sequencing of the cloned positive nested PCR products. CONCLUSION: Adenovirus is an important cause of severe pneumonia, and these data suggest that adenovirus serotype 4 might be an important pathogen responsible for the fatal pneumonia in Guangzhou, South China.

Retrospective analysis of Mycoplasma pneumoniae infection in pediatric fatal pneumonia in Guangzhou, South China.

The objective of this study is to investigate the infection and distribution of Mycoplasma pneumoniae in autopsied pulmonary tissue of pediatric severe pneumonia. Mycoplasma pneumoniae nested polymerase chain reaction and immunohistochemistry were done on autopsy pulmonary tissue from 173 patients who died of severe pneumonia. Mycoplasma pneumoniae was identified in 135/173 (78.03%) and 114/173 (65.89%) samples of autopsied pulmonary tissue of lethal severe pneumonia via nested polymerase chain reaction and immunohistochemistry, respectively. The coincidence of both assays was 92.4%. Mycoplasma pneumoniae associated fatal pneumonia has showed an increasing trend from 1988 to 2005 in South China, and the fatality rate of Mycoplasma pneumoniae associated fatal pneumonia in infants, 1 to 12 months, has risen to 66.9% (97/145). Mycoplasma pneumoniae is a significant cause of severe pneumonia, it is a universal event in infants, and children have died of severe pneumonia in South China. Mycoplasma pneumoniae might be an important pathogen responsible for fatal pneumonia in Guangzhou area, South China.