We present a detailed investigation on the effect of functional group modulation at the edges of carbon quantum dots (CQDs) on the fluorescence from the CQDs. The CQDs attached by N, S, and P elements are synthesized via pyrolysis of a mixture of citric acid and NH 3 H 2 O, H 2 SO 4 , and H 3 PO 4 , respectively. Thus, part of –COOH at the edges of CQDs can be converted into –C=O and functional groups such as –NH 2 , –SO 2 , –HSO 3 , and –H 2 PO 4 can connect to the carbon bonds. We find that the formation of the N/S/P-CQDs can reduce the amount of –COOH that attaches to the edges of sp 2 -conjugated π -domains located at centers of these CQDs. This effect can result in the reduction of the non-radiative recombination for electronic transition in these CQDs. As a result, the quantum yield (QY) for fluorescence from the CQDs can be efficiently enhanced. We demonstrate experimentally that the QYs for N/S/P-CQDs can reach up to 18.7%, 29.7%, and 10.3%, respectively, in comparison to 9% for these without functional group modulation. This work can provide a practical experimental approach in improving the optical properties of fluorescent CQDs.

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Temperature dependence of dark current (I d) and photocurrent (I ph) is reported for Si-based amorphous HgCdTe (a-MCT) infrared photoconductive detector at 80-300 K. It is indicated that an uncooled a-MCT infrared detector can be fabricated based on the Si-based a-MCT. To describe the transport process, the Mott and Davis model [Davis and Mott, Philos. Mag. 22, 903 (1970)] is proposed as the conducting model originally developed for amorphous silicon. A possible mechanism of the carrier transports is shown in the a-MCT materials. The transport transition between the localized and extended carriers leads to the maximal I ph /I d above 200 K. V

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Group B Streptococcus (GBS) is one of the major pathogens of severe newborn sepsis and meningitis. Understanding its regional molecular epidemiology is helpful for regulating efficient prevention practice. A total of 160 GBS strains were collected from colonized pregnant women in six hospital settings in Beijing, China. Polymerase chain reaction (PCR) assays were used to identify the pilus island (PI), alp genes profiling of the alpha-like protein family, and capsular polysaccharide (cps) serotyping. The clonal relationships between strains were investigated using multilocus sequence typing (MLST). All isolates carried at least one pilus island. The most frequently detected pilus island was PI-2a alone (70 isolates, 43.8 %). The most prevalent alp gene was rib (60 isolates, 37.5 %). Moreover, a strong association was noted between alp genes, serotyping, and pilus island profiles. The GBS isolates under study hinted similar molecular epidemical characteristics in Beijing to those reported worldwide, but having their regional distributional features.

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Type V collagen is a component of non-cartilaginous tissues and is important in the determination of fibril structure and matrix organization, although its functions are still poorly understood. In this report, RNA interference (RNAi) approaches were used to investigate the effects of knockdown of the schistosome type V collagen (SjColV) gene. In this study, three different short interfering (si) RNAs targeting different regions of the gene were designed to suppress the expression of SjColV in Schistosoma japonicum using a soaking method. By establishing controls for measuring off-target RNAi effects, we found that different siRNA sequences had different levels of effectiveness. Although all the siRNAs tested reduced SjColV transcript levels, the S1 siRNA consistently reduced SjColV expression to >99 % of the control. In the following experiments, S1 siRNA was adapted to inhibit SjColV expression, and the silencing effects were detected by real-time PCR and Western blot. The spawning and egg hatching of parasites were calculated, while the worms' morphology was taken by scanning electron microscopy. The results show that silencing the expression of SjColV significantly affects the spawning and egg hatching of S. japonicum, and it also affects the worms' morphology.

This study demonstrated that STRB combined with MALDI-TOF MS is a fast, sensitive, and accurate method for the identification of GBS-colonized pregnant women.