Rational Passivation of Sulfur Vacancy Defects in Two-Dimensional Transition Metal Dichalcogenides

Structural defects vary the optoelectronic properties of monolayer transition metal dichalcogenides, leading to concerted efforts to control defect type and density via materials growth or postgrowth passivation. Here, we explore a simple chemical treatment that allows on-off switching of low-lying, defect-localized exciton states, leading to tunable emission properties. Using steady-state and ultrafast optical spectroscopy, supported by ab initio calculations, we show that passivation of sulfur vacancy defects, which act as exciton traps in monolayer MoS₂ and WS₂, allows for controllable and improved mobilities and an increase in photoluminescence up to 275-fold, more than twice the value achieved by other chemical treatments. Our findings suggest a route for simple and rational defect engineering strategies for tunable and switchable electronic and excitonic properties through passivation.

Sensitive and rapid detection of Clonorchis sinensis infection in fish by loop-mediated isothermal amplification (LAMP)

The fish-borne clonorchiasis caused by the oriental liver fluke Clonorchis sinensis is endemic in a number of countries with over 35 million people being infected globally. Rapid and accurate detection of C. sinensis in its intermediate host fish is important for the control and prevention of clonorchiasis in areas where the disease is endemic. In the present study, we established a loop-mediated isothermal amplification (LAMP) approach for the sensitive and rapid detection of C. sinensis metacercariae in fish. The specificity and sensitivity of primers designed from the C. sinensis cathepsins B3 gene were evaluated, and specific amplification products were obtained with C. sinensis, while no amplification products were detected with DNA of related trematodes, demonstrating the specificity of the assay. The LAMP assay was proved to be 100 times more sensitive than a conventional polymerase chain reaction for detection of C. sinensis. The established LAMP assay provides a useful tool for the rapid and sensitive detection of C. sinensis in fish, which has important implications for the effective control of human clonorchiasis.

[Study on the expression of pig zona pellucida-3 beta excluding N-terminus signal peptide and C-terminus transmembrance-like domain in Escherichia coli]

Pig oocytes are surrounded by an acellular translucent envelope-zona pellucida(pZP), which is comprised of three biochemically and immunologically distinct glycoproteins(pZP1, pZP3 alpha and pZP3 beta). Due to the cross-reactivity of anti-pZP3 beta antibodies with human ZP in vitro, pZP3 beta has been considered as potential one of immunogens for developing human contraceptive vaccine. In order to express pZP3 beta directly in E. coli; we amplified the core fragment of pZP3 beta cDNA by PCR that was deleted 5'- and 3'-terminal sequences of coding for signal peptide and transmembrane-like domain. The DNA sequenced EcoRI and SalI restriced core fragment was cloned in a frame downstream of PRPL promoter in the pBV221 vector. SDS-PAGE analysis showed that pZP3 beta protein was expressed especially in E. coli after thermal induction, which the expression band displayed the molecular weight of about 38 kD matching with its deduced molecular weight(36.5 kD). In addition, the specially expressed protein band on SDS-PAGE gel showed specific immunological reaction with anti-pig ZP IgGs of rabbit in Western blot.