Subunit vaccines with a saponin-based adjuvant boost humoral and cellular immunity to MERS coronavirus.

Middle East respiratory syndrome coronavirus (MERS-CoV) outbreaks have constituted a public health issue with drastic mortality higher than 34%, necessitating the development of an effective vaccine. During MERS-CoV infection, the trimeric spike protein on the viral envelope is primarily responsible for attachment to host cellular receptor, dipeptidyl peptidase 4 (DPP4). With the goal of generating a protein-based prophylactic, we designed a subunit vaccine comprising the recombinant S1 protein with a trimerization motif (S1-Fd) and examined its immunogenicity and protective immune responses in combination with various adjuvants. We found that sera from immunized wild-type and human DPP4 transgenic mice contained S1-specific antibodies that can neutralize MERS-CoV infection in susceptible cells. Vaccination with S1-Fd protein in combination with a saponin-based QS-21 adjuvant provided long-term humoral as well as cellular immunity in mice. Our findings highlight the significance of the trimeric S1 protein in the development of MERS-CoV vaccines and offer a suitable adjuvant, QS-21, to induce robust and prolonged memory T cell response.

Polarization beam splitter based on extremely anisotropic black phosphorus ribbons.

Properly designed black phosphorus (BP) ribbons exhibit extreme anisotropic properties, which can be used to fabricate a high-efficiency transmitter or reflector depending on the linear polarization of excitation. In this study, we design a highly efficient and broad-angle polarization beam splitter (PBS) based on extremely anisotropic BP ribbons around the mid-infrared frequency region with an ultra-thin structure, and study its performance by using transfer matrix calculation and finite element simulation. In the broad frequency range of 80.4 terahertz - 85.0 terahertz (THz) and an wide angle range of more than 50°, the reflectivity and transmissivity of the designed PBS are both larger than 80% and the polarization extinction ratios are higher than 25.50 dB for s-polarization light and 20.40 dB for p- polarization light, respectively. Furthermore, the effect of incident angle and device parameters on the behavior of the proposed PBS is examined. Finally, we show that the operation frequency of this PBS can be tuned by the electron concentration of BP, which can facilitate some practical applications such as tunable polarization splitters or filters, and mid-infrared sensors.

Tunable THz reflection-type polarizer based on monolayer phosphorene.

We demonstrate a tunable reflection-type polarizer in the terahertz (THz) regime formed by inserting a monolayer phosphorene in a Fabry-Perot cavity composed of a metal substrate and a distributed Bragg reflector. The physical mechanism of the polarizer is analyzed through the reflection spectrum, the electric field distribution, the energy flow, and the power dissipation density calculated by transfer-matrix method and finite-difference time-domain method. The results show that the polarization-selected reflection is caused by the in-plane anisotropic absorption of the phosphorene due to its special atomic lattice, and the polarization selection is further enhanced by the cavity resonator. A polarized reflection light can be obtained with a polarizing extinction ratio of more than 20 dB and a total reflectivity around 50% in the designed THz frequency. The operation frequency of the polarizer can be tuned by the angle of the incident light, the doping electron concentration, and the uniaxial strains of the phosphorene. The refection-type polarizer provides many applications such as filters, detectors, and biosensors.

Multi-Attribute Fusion Algorithm Based on Improved Evidence Theory and Clustering.

In most of the application scenarios of industrial control systems, the switching threshold of a device, such as a street light system, is typically set to a fixed value. To meet the requirements for a smart city, it is necessary to set a threshold that is adaptive to different conditions by fusing the multi-attribute observations of the sensors. This paper proposes a multi-attribute fusion algorithm based on fuzzy clustering and improved evidence theory. All of the observations are clustered by fuzzy clustering, where a proper clustering method is chosen, and the improved evidence theory is used to fuse the observations. In the experiments, two-dimensional observations for the street light illumination and for the ambient illumination are used in a campus-intelligent lighting system based on a narrowband Internet of things, and the results demonstrate the effectiveness of the proposed fusion algorithm. The proposed algorithm can be applied to a variety of multi-attribute fusion scenarios.

Designing a nearly perfect infrared absorber in monolayer black phosphorus.

Black phosphorus (BP) is a type of 2D layered material with a direct bandgap that displays high carrier mobility and strong in-plane anisotropy; it also exhibits potential as a promising optoelectronic material for IR applications. In this paper, we propose a nearly perfect IR absorber composed of a metal film, a spacer with a monolayer BP inside, and a distributed Bragg reflector (DBR). The electric field is confined inside the resonator generated by the metal film and DBR, and the absorption can be enhanced up to nearly 100%, owing to the strong interaction of BP with the confined field. Our results show that the absorption performance of the proposed structure is not only critically dependent on the electron density but also relies on the position of the BP within the spacer. This dependence can be mitigated because the absorption peak wavelength can be tuned by adjusting the angle of the light and the parameters of the DBR. Moreover, the absorber can be served as a reflective linear polarizer based on the anisotropic absorption properties. Our work can be helpful in designing a narrow perfect absorber and polarization-sensitive devices for IR waves.

Multiple adjustable optical Tamm states in one-dimensional photonic quasicrystals with predesigned bandgaps.

We proposed an approach to get multiple and adjustable optical Tamm states (OTSs) by constructing a structure consisting of a metal layer and one-dimensional photonic quasicrystals with preassigned bandgaps. In the structure, multiple OTSs excited simultaneously in each bandgap were observed. We explored the physics mechanism of the multiple OTSs by analyzing the electric field intensity distribution in the structure. Besides, the results also show that the thickness of the top layer gives one more degree of freedom in designing multiple OTSs. Finally, we demonstrated that one additional OTS can be obtained independently by adding another bandgap to the proposed structure.

Bioavailability and foam cells permeability enhancement of Salvianolic acid B pellets based on drug-phospholipids complex technique.

This study investigated phospholipids complex (PC) loaded pellets of poorly permeable Salvianolic acid B (SalB), in which PC was to improve the liposolubility and permeability of SalB. Transmission electron microscopy observation, differential scanning calorimetry measurement, infrared spectroscopy analysis, n-octanol/water partition coefficient study, and foam cell permeability research were employed to prove the complex formation. Pellets containing SalB phospholipids complex (SalB-PC) were prepared via extrusion/spheronization technique. The optimal pellets obtained with 30% SalB-PC, 15% Kollidon®CL-SF, 15% Flowlac®100, and 40% MCC exhibited a very homogeneous size distribution, the shortest disintegration time, highest crushing force, appreciable spherical shape, and a fast drug release behavior. Following hydration, the droplet size distribution of SalB-PC pellets was nearly same to its PC (85.4±16 and 73.5±12nm). In vivo performance showed SalB-PC pellets presented significantly larger AUC(0-)(t), which was 0.58 times more than that of physical mixtures (PMs) and 1.57 times more than that of SalB pellets. C(max) of SalB-PC pellets were also increased by 0.26-fold and 0.80-fold as that of PMs and SalB pellets, respectively. In conclusion, extrusion/spheronization could be a suitable technique to prepare PC loaded pellets, which could effectively preserve the properties of PC to improve the permeability and bioavailability of highly water-soluble drug.

Release behavior of tanshinone IIA sustained-release pellets based on crack formation theory.

The objective of this study was to investigate the drug release mechanism and in vivo performance of Tanshinone IIA sustained-release pellets, coated with blends of polyvinyl acetate (PVAc) and poly(vinyl alcohol)-poly(ethylene glycol) (PVA-PEG) graft copolymer. A formulation screening study showed that pellets coated with PVAc-PVA-PEG at a ratio of 70:30 (w/w) succeeded in achieving a 24 h sustained release, irrespective of the coating weight (from 2% to 10%). Both the microscopic observation and mathematical model gave further insight into the underlying release mechanism, indicating that diffusion through water-filled cracks was dominant for the control of drug release. In vivo test showed that the maximum plasma concentration of sustained-release pellets was decreased from 82.13 ± 17.05 to 40.50 ± 11.72 ng mL as that of quick-release pellets. The time of maximum concentration, half time, and mean residence time were all prolonged from 3.80 ± 0.40 to 8.02 ± 0.81 h, 4.28 ± 1.21 to 8.18 ± 2.06 h, and 8.60 ± 1.59 to 17.50 ± 2.78 h, compared with uncoated preparations. A good in vitro-in vivo correlation was characterized by a high coefficient of determination (r = 0.9772). In conclusion, pellets coated with PVAc-PVA-PEG could achieve a satisfactory sustained-release behavior based on crack formation theory.

Novel Tanshinone II A ternary solid dispersion pellets prepared by a single-step technique: in vitro and in vivo evaluation.

Novel Tanshinone II A (TA) ternary solid dispersion (tSD) pellets with the combination of polyvinylpyrrolidone and poloxamer 188 as dispersing carriers were prepared by a single-step technique. A formulation screening study showed that the addition of poloxamer 188 to binary TA-PVP system could remarkably promote the dissolution rate of TA from 60% to 100% after 60 min. Scanning electron microscopy study revealed a smooth surface and a tightly packed coating structure. Differential scanning calorimetry analysis confirmed the formation of solid dispersions. In vivo test showed that TA tSD pellets presented significantly larger AUC(0-)(t), which was 0.76 times more than that of binary solid dispersion (bSD) pellets, 2.87 times more than that of physical mixtures (PMs) and 5.40 times more than that of TA. C(max) of TA tSD pellets also increased by 1.82-8.97-fold as that of bSD pellets, PMs and TA. TA tSD pellets generated obviously shortened T(max) of (3.80 ± 0.398)h, compared to bSD pellets with (4.15 ± 0.456)h, PMs with (4.65 ± 0.226)h and TA with (5.52 ± 0.738)h. In conclusion, the addition of poloxamer 188 to pellets containing PVP-based solid dispersions could achieve complete dissolution, accelerated absorption rate and superior oral bioavailability. The fluid-bed technique becomes an alternative approach to obtain solid dispersion-coated pellets.