Background Accurate quantification of infection intensity is essential to estimate infection patterns of avian haemosporidian parasites in order to understand the evolution of host-parasite associations. Traditional microscopy is cost-effective but requires high-quality blood smears and considerable experience, while the widely used semi-quantitative qPCR methods are mostly employed with ideal, laboratory-based golden samples and standard curves, which may limit the comparison of parasitemia from different laboratories. Methods Here we present a digital droplet PCR (ddPCR) protocol for absolute quantification of avian haemosporidians in raptors. Novel primers were designed that target a conserved fragment of a rRNA region of the mitochondrial genome of the parasites. Sensitivity and repeatability were evaluated compared to qPCR and other assays. Results This ddPCR assay enables accurate quantification of haemosporidian parasites belonging to Plasmodium , Haemoproteus and Leucocytozoon with minimum infection quantities of 10 −5 (i.e. one parasite copy in 10 5 host genomes) without the use of standard curves. Quantities assessed by ddPCR were more accurate than qPCR using the same primers through reduction of non-specific amplification in low-intensity samples. The ddPCR technique was more consistent among technical duplicates and reactions, especially when infection intensities were low, and this technique demonstrated equal sensitivity with high correspondence ( R 2 = 0.97) compared to the widely used qPCR assay. Both ddPCR and qPCR identified more positive samples than the standard nested PCR protocol for the cytb gene used for barcoding avian haemosporidians. Conclusions We developed a novel ddPCR assay enabling accurate quantification of avian haemosporidians without golden samples or standard curves. This assay can be used as a robust method for investigating infection patterns in different host-parasite assemblages and can facilitate the comparison of results from different laboratories.

The intensity distribution of four-petal Gaussian vortex (FPGV) beams through a focused optical system and the radiation force acting on a Rayleigh dielectric sphere is obtained based on the extended Huygens–Fresnel principle and the Rayleigh scattering theory. We mainly study the trapping of high and low refractive index Rayleigh particles by FPGV beams and the effect of the topological charge m on the radiation force. The results show that the specific distribution of the incident beam can be controlled by a reasonable choice of topological charge m . The multiple locations in a beam of light where particles of different refractive indices can be captured will be found. On the other hand, when m changes, the number of particles captured and the locations where they can be captured change accordingly. Therefore, the flexibility to simultaneously capture multiple Rayleigh particles with different refractive indices with a single beam at different locations in the focal plane can be achieved using the FPGV beam.

The control of the liquid crystal (LC) alignment is an important factor for practical applications. The conventional method typically used is the rubbing of the polyimide (PI) layer. However, it is difficult to obtain intermediate pretilt angles by employing such a method. In this paper, control of the pretilt angle of the LC is achieved by modifying the surface wettability of the PI films via oxygen plasma treatment. A new mode for guest–host liquid crystal (GHLC) smart windows is achieved with intermediate initial transmittance by controlling the pretilt angle, which can turn from the initial state to either the transparent or dark states. Different modes for the GHLC-based smart windows can be fabricated that are dependent on the environmental conditions.

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In this study, a novel, to the best of our knowledge, dye-doped dual-frequency liquid crystal multi-stable smart window is proposed. A chiral dopant with appropriate content was introduced into dye-doped dual-frequency liquid crystals to achieve an initial 180° twisted state. These liquid crystals can be switched to a nematic phase or a 360° twisted state by controlling the magnitude and frequency of the applied voltage. These nematic phase and 360° twisted states can exist stably for a long time because of the backflow effect and the anisotropic nature of the dual-frequency liquid crystal material. Due to the optical waveguide effect of dye-doped liquid crystals in the long-pitch state, the transmittance was different in nematic phase, 180°, and 360° twisted three zero-field stabilized absorption states. Finally, a multi-stable smart window is developed to switch between three zero-field stabilized absorption and scattering states.