Ultralow lattice thermal conductivity induced high thermoelectric performance in the δ-Cu2S monolayer.

Motivated by the recent experimental exfoliation of ß-Cu2S thin films and the theoretical finding of a new phase labeled the δ-Cu2S monolayer, we carried out extensive studies on thermal conductivity and thermoelectric properties of the new phase using first principles combined with Boltzmann transport theory, focusing on the analysis of group velocities, Gruneisen parameters, three-phonon scattering rates, and the scattering phase space. Our results show that the δ-Cu2S monolayer exhibits an intrinsically ultralow lattice thermal conductivity of 0.10 W m-1 K-1 at 800 K. Such an ultralow lattice thermal conductivity leads to a high thermoelectric figure of merit ZT = 1.33 at 800 K in an optimum p-type doping concentration, which is not only larger than the value of 1.23 in In2S3 doped Cu2S at 850 K but also comparable with the value of 1.7 in Cu1.97S at 1000 K, exhibiting good potential in thermoelectric applications.

High Thermoelectric Figure of Merit Achieved in Cu2S1- xTe x Alloys Synthesized by Mechanical Alloying and Spark Plasma Sintering.

Chalcogenides have been considered as promising thermoelectric materials because of their low cost, nontoxicity, and environmental benignity. In this work, we synthesized a series of Cu2S1- xTe x (0 ≤ x ≤ 1) alloys by a facile, rapid method of mechanical alloying combined with spark plasma sintering process. The Cu2S1- xTe x system provides an excellent vision of the competition between pure phase and phase transformation, entropy-driven solid solution, and enthalpy-driven phase separation. When the Te concentration increases, the Cu2S1- xTe x system changed from the pure monoclinic Cu2S at x = 0 to monoclinic Cu2S1- xTe x solid solution at 0.02 ≤ x ≤ 0.06 and then transforms to hexagonal Cu2S1- xTe x solid solution at 0.08 ≤ x ≤ 0.1. The phase separation of hexagonal Cu2Te in the hexagonal Cu2S matrix occurs at 0.3 ≤ x ≤ 0.7 and finally forms the hexagonal Cu2Te at x = 1. Owing to the changed band structure and the coexisted Cu2S and Cu2Te phases, greatly enhanced power factor was achieved in all Cu2S1- xTe x (0 < x < 1) alloys. Meanwhile, the point defect introduced by the substitution of Te/S atoms strengthened the phonon scattering, resulting in a lowered lattice thermal conductivity in most of these solid solutions. As a consequence, Cu2S0.94Te0.06 exhibits a maximum ZT value of 1.18 at 723 K, which is about 3.7 and 14.8 times as compared to the values of pristine Cu2S (0.32) and Cu2Te (0.08), respectively.

Detection of Clonorchis sinensis circulating antigen in sera from Chinese patients by immunomagnetic bead ELISA based on IgY.

BACKGROUND: Clonorchiasis, caused by Clonorchis sinensis, is widely distributed in Southeast Asia including China. Clonorchiasis is included in control programs of neglected tropical diseases by World Health Organization (WHO) because it is one of the major health problems in most endemic areas. Diagnosis of clonorchiasis plays a key role in the control programs. However, so far, there is no satisfactory method for clonorchiasis because of low sensitivity, poor practicality and high false positivity of available diagnostic tools. METHODOLOGY/PRINCIPAL FINDINGS: We developed an immunomagnetic bead enzyme-linked immunosorbent assay (ELISA) based on IgY (egg yolk immunoglobulin) against cysteine proteinase of C. sinensis for detection of circulating antigen in serum samples of patients infected with C. sinensis. The polyclonal IgY, coated with magnetic beads, was used as a capture antibody and a monoclonal IgG labeled with horseradish peroxidase as a detection antibody in the IgY-based immunomagnetic bead ELISA system (IgY-IMB-ELISA). The results showed that the sensitivity of IgY-IMB-ELISA was 93.3% (14 of 15) in cases of heavy infection (5000 to 9999 eggs per gram feces, i.e, EPG 5000-9999), 86.7% (13 of 15) in cases of moderate infection (EPG 1000-4999) and 75.0% (9 of 12) in cases of light infection (EPG <1000) of clonorchiasis. Together 36 of total 42 (85.7%) serum samples of human clonorchiasis gave a positive reaction. There was a significant correlation between ELISA optical density and egg counts (EPG) with a correlation coefficient of 0.83 in total 42 patients. There were no positive results in patients with trichinosis (n = 10) or cysticercosis (n = 10). Cross-reactivity was 6.7% (2 of 30) with schistosomiasis japonica and 10.0% (3 of 30) with paragonimiasis, respectively. No positive reaction was found in 20 healthy persons. CONCLUSIONS: Our findings suggest that IgY-IMB-ELISA appears to be a sensitive and specific assay for detection of circulating antigen in human clonorchiasis.

Effect of Trichinella spiralis infection on the immune response to HBV vaccine in a mouse model.

Vaccination is the most effective and cost-effective way to treat hepatitis B virus (HBV) infection. Collective data suggest that helminth infections affect immune responses to some vaccines. Therefore, it is important to reveal the effects of helminth infections on the efficacy of protective vaccines in countries with highly prevalent helminth infections. In the present work, effects of Trichinella spiralis infection on the protective efficacy of HBV vaccine in a mouse model were investigated. This study demonstrated that the enteric stage of T. spiralis infection could inhibit the proliferative response of spleen lymphocytes to hepatitis B surface antigen (HBsAg) and lead to lower levels of anti-HBsAg antibodies, interferon-γ, and interleukin (IL)-2, along with higher levels of IL-4 and IL-5. However, these immunological differences are absent in the muscle stage of T. spiralis infection. The results suggest that the muscle stage of T. spiralis infection does not affect the immune response to HBV vaccination, while the enteric-stage infection results in a reduced immune response to HBsAg.