Intrinsic Blue Fluorescence of 2.0G PAMAM-DCM Polymer Dots and Its Applications for Fe3+ Sensing.

A typical and environment-friendly fluorescent polyamine-amine (PAMAM) features good compatibility and unique surface modification, while it is restricted by a low fluorescence property performance and an unclear fluorescence mechanism. In this work, we prepared blue fluorescent PAMAM polymer dots (PDs) via a simple hydrothermal method based on dichloromethane (DCM) and 2.0G PAMAM. The quantum yield achieved was 32.1%, which was 25 times stronger than that of 2.0G PAMAM due to the lone-pair electron leap of the amine groups, the aggregation of carbonyl groups, as well as the crosslinking induced by DCM inside the PAMAM. In addition, the fluorescent 2.0G PAMAM-DCM PDs show a great Fe3+ sensing property with the detection limit of 56.6 nM, which is much lower than the safety limits (5.36 µM) in drinking water, indicating its great potential for Fe3+ detection in aqueous media.

Elliptical-spiral elliptical-hole photonic crystal fiber with high birefringence, large nonlinearity, and two zero dispersion.

This paper presents a soft-glass (SF-57) elliptical-spiral photonic crystal fiber with elliptical air holes for achieving high birefringence, large nonlinearity, and tailoring two zero-dispersion wavelengths (ZDWs) in the near-infrared region. A full-vector finite-element method with perfectly matched boundary layer is used to characterize the properties of the photonic crystal fiber for different ellipticity ratios. The designed fiber has a birefringence 4 times higher than the circular-spiral structure. There are two ZDWs at around 1.2 µm and 2.8 µm which can be finely tuned depending on the ellipticity ratios along with a large nonlinearity. Due to the superior guiding properties, the proposed structure can be used for polarization control and broadband supercontinuum generation.

IKULDAS: An Improved kNN-Based UHF RFID Indoor Localization Algorithm for Directional Radiation Scenario.

Ultra high frequency radio frequency identification (UHF RFID)-based indoor localization technology has been a competitive candidate for context-awareness services. Previous works mainly utilize a simplified Friis transmission equation for simulating/rectifying received signal strength indicator (RSSI) values, in which the directional radiation of tag antenna and reader antenna was not fully considered, leading to unfavorable performance degradation. Moreover, a k-nearest neighbor (kNN) algorithm is widely used in existing systems, whereas the selection of an appropriate k value remains a critical issue. To solve such problems, this paper presents an improved kNN-based indoor localization algorithm for a directional radiation scenario, IKULDAS. Based on the gain features of dipole antenna and patch antenna, a novel RSSI estimation model is first established. By introducing the inclination angle and rotation angle to characterize the antenna postures, the gains of tag antenna and reader antenna referring to direct path and reflection paths are re-expressed. Then, three strategies are proposed and embedded into typical kNN for improving the localization performance. In IKULDAS, the optimal single fixed rotation angle is introduced for filtering a superior measurement and an NJW-based algorithm is advised for extracting nearest-neighbor reference tags. Furthermore, a dynamic mapping mechanism is proposed to accelerate the tracking process. Simulation results show that IKULDAS achieves a higher positioning accuracy and lower time consumption compared to other typical algorithms.

Multi-channel optical fiber refractometer based on tree topology structure.

A multi-channel optical fiber refractometer based on S fiber taper (SFT) cascaded with fiber Bragg grating (FBG) is proposed and experimentally demonstrated. The compact SFT acts as an in-line Mach-Zehnder interferometer (MZI) to be used as a band-pass filter (BPF) to tailor the FBG reflection, whose transmission spectrum is sensitive to the surrounding refractive index (SRI). Thus, the peak power of the FBG reflection is modulated by the SRI. The three-channel SRI monitor can be achieved by discriminating the different center wavelength and peak power variation of the FBG reflections. Experimental results show that the RI sensitivities of Channels 1, 2, and 3 are 345.54, 349.57, and 463.60 dB/RIU, respectively. Moreover, the temperature cross-sensitivity can be solved by interrogating the center wavelength of the FBG reflection.

Elucidating the causal association between gut microbiota and intrahepatic cholangiocarcinoma through Mendelian randomization analysis.

Background: Intrahepatic cholangiocarcinoma (ICC) is an aggressive liver cancer with poor prognosis. The gut microbiota has been linked to ICC, but evidence for causality is lacking. Elucidating causal gut microbiota-ICC links could inform prevention and treatment strategies. Materials and methods: We performed a bidirectional two-sample Mendelian randomization (MR) study to investigate causal associations between gut microbiota and ICC risk. Genome-wide significant single nucleotide polymorphisms (SNPs) associated with gut microbiota abundances were utilized as instrumental variables (IVs). Multiple methods assessed causality and sensitivity analyses evaluated result robustness. Bioinformatics analysis of genetic loci linked to gut microbiota and ICC examined potential mechanisms. Results: Genetically predicted increases in Veillonellaceae, Alistipes, Enterobacteriales, and Firmicutes were suggestively associated with higher ICC risk, while increases in Anaerostipes, Paraprevotella, Parasutterella, and Verrucomicrobia appeared protective. Bioinformatics analysis revealed differentially expressed genes near gut microbiota-associated loci may influence ICC through regulating pathways and tumor immune microenvironment. Conclusion: Our findings provide suggestive evidence for causal links between specific gut microbiota and ICC risk.

Thermo-/pH-Dual-Sensitive PEG/PAMAM Nanogel: Reaction Dynamics and Plugging Application of CO2 Channeling.

Smart hydrogels, owing to their exceptional viscoelastic and deformable capacity in response to environmental stimulation involving temperature and pH, have been successfully applied in oilfields for purposes such as water and/or gas shutoff treatments. However, the CO2 breakthrough problem in low permeability reservoirs has not been well solved. In this work, a rheological method-based Avrami dynamics model and Dickinson dynamics model were employed to investigate the dynamic gelation process of thermo-/pH-dual-sensitive PEG/PAMAM nanogels to further our understanding of the microstructure of their gelation and pertinence plugging application. Plugging experiments were performed by alternating injections of CO2 and hydrogel solution in a slug type on three fractured low permeability cores with a backpressure of 13 MPa. The nanogels presented a secondary growth pattern from three to one dimension from micrometer to nanometer size with a morphological transformation from a sphere to an irregular ellipsoid or disk shape. The phase transition temperature was 50 °C, and the phase transition pH was 10. If both or either were below these values, the hydrogel swelled; otherwise, it shrank. Plugging results show that the plugging efficiency was higher than 99%. The maximum breakthrough pressure was 19.93 MPa, and the corresponding residual pressure remained 17.64 MPa for a 10 mD core, exhibiting great plugging performance and high residual resistance after being broken through by CO2.

A facile and green preparation of high-quality CdTe semiconductor nanocrystals at room temperature.

One chemical reagent, hydrazine hydrate, was discovered to accelerate the growth of semiconductor nanocrystals (cadmium telluride) instead of additional energy, which was applied to the synthesis of high-quality CdTe nanocrystals at room temperature and ambient conditions within several hours. Under this mild condition the mercapto stabilizers were not destroyed, and they guaranteed CdTe nanocrystal particle sizes with narrow and uniform distribution over the largest possible range. The CdTe nanocrystals (photoluminescence emission range of 530-660 nm) synthesized in this way had very good spectral properties; for instance, they showed high photoluminescence quantum yield of up to 60%. Furthermore, we have succeeded in detecting the living Borrelia burgdorferi of Lyme disease by its photoluminescence image using CdTe nanocrystals.