Ultrafine electro-optical frequency comb based on cascade phase modulation with cyclic frequency shifting.

An ultrafine electro-optical frequency comb (EOFC) with plentiful comb teeth is demonstrated. Adopting a single-frequency fiber laser as a light source, cascade phase modulation based on a sinusoidal signal and a frequency-time transformation (FTT) signal is executed to generate the EOFC with high fineness. Meanwhile, a cyclic fast frequency shifting strategy is introduced to boost the number of comb teeth and the bandwidth of the EOFC. As a result, an EOFC with 12600 comb lines covering a broad bandwidth from -6.3 GHz to 6.3 GHz is established, corresponding to an ultrafine comb space of 1 MHz. Moreover, the power fluctuation of a comb tooth is less than 0.5 dBm. This state-of-the-art EOFC has significant potential in the field of precision spectroscopy.

Biocompatible diameter-oscillating fiber with microlens endface.

Optical fibers have been widely applied to life science, such as laser delivering, fluorescence collection, biosensing, bioimaging, etc. To resolve the challenges of advanced multiphoton biophotonic applications utilizing ultrashort laser pulses, here we report a flexible diameter-oscillating fiber (DOF) with microlens endface fabricated by using Polydimethylsiloxane (PDMS) elastomers. The diameter of the DOF is designed to longitudinally vary for providing accurate dispersion management, which is important for near-infrared multiphoton biophotonics that usually involves ultrashort laser pulses. The variation range and period of the DOF's diameter can be flexibly adjusted by controlling the parameters during the fabrication, such that dispersion curves with different oscillation landscapes can be obtained. The dispersion oscillating around the zero-dispersion baseline gives rise to a minimized net dispersion as the ultrashort laser pulse passes through the DOF - reducing the temporal broadening effect and resulting in transform-limited pulsewidth. In addition, the endface of the DOF is fabricated with a microlens, which is especially useful for laser scanning/focusing and fluorescence excitation. It is anticipated that this new biocompatible DOF is of great interest for biophotonic applications, particularly multiphoton microscopy deep inside biological tissues.

Copper Doped Carbon Dots for Addressing Bacterial Biofilm Formation, Wound Infection, and Tooth Staining.

Oral infectious diseases and tooth staining, the main challenges of dental healthcare, are inextricably linked to microbial colonization and the formation of pathogenic biofilms. However, dentistry has so far still lacked simple, safe, and universal prophylactic options and therapy. Here, we report copper-doped carbon dots (Cu-CDs) that display enhanced catalytic (catalase-like, peroxidase-like) activity in the oral environment for inhibiting initial bacteria (Streptococcus mutans) adhesion and for subsequent biofilm eradication without impacting the surrounding oral tissues via oxygen (O2) and reactive oxygen species (ROS) generation. Especially, Cu-CDs exhibit strong affinity for lipopolysaccharides (LPS) and peptidoglycans (PGN), thus conferring them with excellent antibacterial ability against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), such that they can prevent wound purulent infection and promoting rapid wound healing. Additionally, the Cu-CDs/H2O2 system shows a better performance in tooth whitening, compared with results obtained with other alternatives, e.g., CDs and clinically used H2O2, particularly its negligible enamel and dentin destruction. It is anticipated that the biocompatible Cu-CDs presented in this work are a promising nano-mouthwash for eliminating oral pathogenic biofilms, prompting wound healing as well as tooth whitening, highlighting their significance in oral health management.

[A cross-sectional survey on human immunodeficiency virus infection in a former commercial blood donating community, Shanxi Province].

OBJECTIVE: To determine the sero-prevalence of and the risk factors for human immunodeficiency virus infection among residents in a former commercial blood donating community, Shanxi Province. METHODS: A community-based cross-sectional survey was conducted among all residents aged 18 - 64 years in 4 villages in a rural county of Shanxi Province. A standardized structured questionnaire was administered to collect socio-demographic, medical and risk behavioral information. Venous blood was collected for HIV antibody testing. Generalized estimating equation with logistic regression was used to analyze the risk factors for HIV infection. Population attributable fraction was used to evaluate the role of public health in the risk factors for the incidence of HIV. RESULTS: A total of 3062 villagers participated in the study and provided their blood samples for HIV antibody testing. 29.5% of the participants had a history of selling blood and/or plasma. Among the subgroup of former blood donors (FBDs), 71.9% sold whole blood only, 4.1% sold plasma only and 24.0% sold both. Forty HIV infected persons were identified in the four villages. HIV prevalence was 1.3%, overall, 4.1% in FBDs and 0.1% in non-FBDs in the community. Amongst the subgroup of FBDs, HIV prevalence was 1.5% for whole blood only, 21.6% for plasma only and 8.8% for both. Univariate analysis showed that village of residence, education, marital status, gender, plasma/blood donation were statistically associated with HIV seropositivity in the villagers. Other variables, such as gender, age, occupation, number of sexual partners, drug use, histories of tooth extraction, acupuncture, surgical operation and medical injection were not found to be statistically associated with HIV seropositivity. Multivariate analysis found that selling whole blood only (adjusted OR = 13.25, 95% CI: 3.02 - 58.25) and selling plasma or both (adjusted OR = 87.85, 95% CI: 22.22 - 347.27) were significantly associated with HIV seropositivity, and the additive population attributable fraction (PAF) was 89.8%. Villagers in village 03 were more likely to be HIV positive than those in village 04 (adjusted OR = 12.26, 95% CI: 1.46 - 103.00). CONCLUSION: At present, HIV epidemic in the former commercial blood donating community has a low prevalence in Shanxi Province and the majority of HIV infections should be related to the blood and plasma donation. This study reveals the existence of HIV second-generation transmission from the infected blood donors to the general population. However, HIV had not been evidently extended from the blood/plasma donors to general population.