New Broad-Spectrum Viral Fusion Inhibitors Act by Deleterious Effect on the Viral Membrane through the Production Singlet Oxygen Molecules

Chitosan oligosaccharides (COS), the degraded products of chitosan, have been demonstrated to have versatile biological functions. In primary studies, it has displayed significant adjuvant effects when mixed with other vaccines. In this study, chitosan oligosaccharides with different deacetylation degrees were prepared and conjugated to porcine circovirus type 2 (PCV2) subunit vaccine to enhance its immunogenicity. The vaccine conjugates were designed by the covalent linkage of COSs to PCV2 molecules and administered to BALB/c mice three times at two-week intervals. The results indicate that, as compared to the PCV2 group, COS-PCV2 conjugates remarkably enhanced both humoral and cellular immunity against PCV2 by promoting lymphocyte proliferation and initiating a mixed T-helper 1 (Th1)/T-helper 2 (Th2) response, including raised levels of PCV2-specific antibodies and an increased production of inflammatory cytokines. Noticeably, with the increasing deacetylation degree, the stronger immune responses to PCV2 were observed in the groups with COS-PCV2 vaccination. In comparison with NACOS (chitin oligosaccharides)-PCV2 and LCOS (chitosan oligosaccharides with low deacetylation degree)-PCV2, HCOS (chitosan oligosaccharides with high deacetylation degree)-PCV2 showed the highest adjuvant effect, even comparable to that of PCV2/ISA206 (a commercialized adjuvant) group. In summary, COS conjugation might be a viable strategy to enhance the immune response to PCV2 subunit vaccine, and the adjuvant effect was positively correlated with the deacetylation degree of COS.</p

Stress background and rock fractures revealed by ultrasonic borehole television in the Fankou Lead-Zinc Mine

The stress background and rock fractures are essential factors affecting the stability of mines. In order to better understand the in situ stress background and rock fractures in the Guangdong Fankou Mine, we use ultrasonic borehole television scanning to measure rock fractures. The results indicate that rock fractures are intensively distributed at depths of −360 m to −450 m below the surface, suggesting the effect of intensive mining activities. The present maximum horizontal principal stress direction is NWW, which is consistent with the regional tectonic stress field direction. Systematic measurement of rock fractures is fundamental for further three-dimensional geological modeling and is significant for mining engineering

Operational performance of a novel fast-responsive heat storage/exchanging unit (HSEU) for solar heating systems

In order for a solar heating system to provide heat immediately after sunrise, a fast response is needed to the heat demand of a serviced space. The majority of existing solar heating systems have a slow response time due to the large volume of water stored in the heat storage/exchanger unit (HSEU). This leads to a slow heat delivery cycle, which results in discomfort for the occupants and thus creates a huge barrier to the wide deployment of solar heating systems. To overcome this critical issue, a novel interactive heat storage/exchanging unit (HSEU) employing a double-tank configuration was developed. Unlike conventional HSEUs, which have a single tank acting as the heat storage and exchanging unit, the new HSEU is comprised of a small tank for heat exchange combined with a large tank for heat storage. The small tank enables fast transfer of solar heat to the heating loop fluid without having to heat up the large volume of water in the entire HSEU tank, whilst the large tank is used to store and exchange heat between itself and the small tank using a temperature-oriented control mechanism. To test the proposed design, the heat transfer between the first (solar loop) and second (heating loop) fluids, the heat and mass transfer between the small and large tank and the associated operational strategy were investigated experimentally and theoretically for comparison. A conventional single tank HSEU requires around 120 min to deliver heat to a served space, whilst the new interactive double-tank HSEU can provide heat to the served space in around 20 min, thus creating a heating system which can respond significantly faster than traditional systems. The investigation of the heat exchange effect between the solar and heating loop fluids showed that the new HSEU achieved a convective heat transfer coefficient of as high as 391 W/m2·K, which is 551% higher than that of a conventional tank. As a result, the solar thermal efficiency of the solar panel-array in the new HSEU based system was increased by 7.5% compared to conventional HSEU based systems

Conjugation of chitosan oligosaccharides via a carrier protein markedly improves immunogenicity of porcine circovirus vaccine

Porcine circovirus type 2 (PCV2)-associated diseases have led to huge economic losses in pig industry. Our laboratory previously found that conjugation of chitosan oligosaccharides (COS) enhanced the immunogenicity of PCV2 vaccine against infectious pathogens. In this study, an effective adjuvant system was developed by covalent conjugation of COS via a carrier protein (Ovalbumin, OVA) to further increase the immunogenicity of vaccine. Its effect on dendritic cells maturation was assessed in vitro and its immunogenicity was investigated in mice. The results indicated that, as compared to the PCV2 and COS-PCV2, COS-OVA-PCV2 stimulated dendritic cells to express higher maturation markers (CD80, CD86, CD40 and MHC class II) and remarkably promoted both humoral and cellular immunity against PCV2 by enhancing the lymphocyte proliferation and inducing a mixed Th1/Th2 response, including the increased production of PCV2-specific antibodies and raised levels of inflammatory cytokines. Furthermore, it displayed better immune-stimulating effects than the physical mixture of vaccine and ISA206 (a commercialized adjuvant). In conclusion, conjugation of COS via a carrier protein might be a promising strategy to enhance the immunogenicity of vaccines

Conjugation of chitosan oligosaccharides enhances immune response to porcine circovirus vaccine by activating macrophages

Porcine circovirus type 2 (PCV2)-associated diseases have led to great economic losses to the pig industry. Our lab previously found that conjugation of chitosan oligosaccharides (COS) or via a carrier protein enhanced the immunogenicity of PCV2 vaccine against infectious pathogens. However, precise mechanisms and signal transduction pathways underlying the efficacy of COS conjugation remains poorly defined. In this study, to better understand the effects and mechanism of COS conjugates maintain the adjuvant potential in vivo, we investigated its augmentation of macrophage function, including cell activation, NO production, cytokine production and phagocytosis. Additionally, the role of Toll-like receptors (TLR) proteins in this process was also assessed. The results indicate that, as compared to the PCV and PCV/COS, conjugation of COS effectively enhanced the NO production, cytokines generation and phagocytosis activity of macrophages. Noticeably, the generation of NO and proinflammatory cytokines was closely related to the TLR2/4 signaling pathways, strongly suggesting that conjugation of COS regulates innate and adaptive immunity by activation of macrophages, resulting in immune enhancement. In summary, the present study provides a potential mechanism of COS conjugation as a novel adjuvant to improve immune responses against various diseases.</p

A Dual-Polarized Printed Antenna Based on a Tapered Slot SICL Balun for Airborne Radar Application

The substrate-integrated coaxial line (SICL) is a potential transmission line due to its good characteristics of high efficiency, nondispersive, and single operational mode. A tapered slot SICL balun is proposed, which can realize the impedance transformation from the microstrip line to the coplanar strip line (CPS). At the same time, the proposed balun can transform the quasi-TEM mode of the microstrip line to the TEM mode of CPS. A printed dipole radiator is designed and is fed by the proposed SICL balun to achieve the impedance matching. The dual-polarized radiation mode is realized by employing two orthogonal printed dipoles. For each polarization radiator, the CPS is bended to avoided the occlusion of two polarization ports and realize the direct assembling of two orthogonal printed circuits. What is more, the assembling method is advantageous to improve the port isolation degree and decrease the cross polarization level. To improve the ratio of front to back (F/B) of the radiation pattern, a cylindrical metal cavity is adopted. According to the results of simulation and experiments, the VSWR of each port is lower than 2, the isolation degree between two polarization ports is higher than 20 dB, and the cross polarization level at the boresight is lower than −20 dB at the operational frequency. The patterns of two ports are almost symmetric, and high radiation efficiency is obtained. The experimental results of the principle prototype verify the design schemes of the balun and the dual-polarized antenna. The proposed dual-polarized antenna fed by the tapered slot SICL balun is suitable for the airborne radar application