Synthesis of alkynyl sulfides via base-promoted nucleophilic ring-opening of α-bromostyrene sulfonium salt.

An efficient method for the synthesis of alkynyl sulfides via a C(sp3)-S bond cleavage of α-bromostyrene sulfonium salts has been developed. This base-promoted nucleophilic ring-opening pathway allows the preparation of diverse alkynyl sulfide compounds using tetramethylene sulfoxide as the sulfur source. The reaction proceeds with good functional group tolerance and could be applied to the late-stage functionalization of bioactive molecules and drugs. Furthermore, the synthetic utility of this method was demonstrated by a one-pot synthesis, scale-up reaction and further modification of various alkynyl sulfide products.

Investigation and development of transient production process for porcine circovirus Type-2 (PCV2) capsid protein in HEK293F cells.

Porcine circovirus type-2 capsid protein contains a major immunodominant epitope used as a subunit vaccine. Transient expression in mammalian cells is an efficient process for producing recombinant proteins. However, there is still a lack of research on the efficient production of virus capsid proteins in mammalian cells. Here we present a comprehensive study to investigate and optimize the production process of a model "difficult-to-express" virus capsid protein, PCV2 capsid protein in HEK293F transient expression system. The study evaluated the transient expression of PCV2 capsid protein in the mammalian cell line HEK293F and investigated the subcellular distribution by confocal microscopy. In addition, the RNA sequencing (RNA-seq) was used to detect the differential expression of genes after cells transfected with pEGFP-N1-Capsid or empty vectors. The analysis revealed that the PCV2 capsid gene affected a panel of differential genes of HEK293F cells involved in protein folding, stress response, and translation process, such as SHP90ß, GRP78, HSP47, and eIF4A. An integrated strategy of protein engineering combined with VPA addition was applied to promote the expression of PCV2 capsid protein in HEK293F. Moreover, this study significantly increased the production of the engineered PCV2 capsid protein in HEK293F cells, reaching a yield of 8.7 mg/L. Conclusively, this study may provide deep insight for other "difficult-to-express" virus capsid proteins in the mammalian cell system.

[Raman Enhancement of a Dipolar Molecule on CVD Graphene].

The CVD graphene was chosen as the Raman enhancement substrate, graphene-enhanced Raman scattering(GERS) of dipolar molecule DREP were explored with a laser wavelength λ = 532 nm of micro-Raman spectroscopy. Upon comparison of the raman signal of DREP molecular latched to a graphene/SiO2 substrate and to a bare SiO2substrate, we found that the Raman signal of pure DREP molecule basically does not exist at low concentrations, until it reaches a certain concentration of 1 x 10⁻5 mol · L⁻¹, its Raman signal emerging and as the increasing of the concentration, Raman signal and fluorescence signal all increase. However, the raman signal of DREP molecular on the grapheme occur at the concentration of 1 x 10⁻7 mol · L⁻¹ and as the increasing of concentration, the raman signal increasing quickly but the fluorescence signal is not obvious. The studies were shown that graphene can achieve the Raman signal of DREP molecule enhancement, and can quench fluorescent backing off, increase the ratio of Raman signal and fluorescence signals. Comparing the GERS of DREP and DR1P molecules with different molecular dipole moment, indicating that the greater the dipole moment, the greater the enhancement factor, the degree of enhancement is stronger. Finally, we analyze the mechanism of Raman enhancement about DREP molecule on the grapheme. The dipole molecular is a pyrene terminal tethered a azobenzene molecular that was modified. There will happen the electron transfer of the pyrene terminal on the graphene interface through π-π interactions, changing the energy level of grapheme and leading to a p-doping. The mechanism of Raman enhancement are chemical mechanisms. The study of GERS of DREP molecular can help the comprehension of grapheme and the mechanism of grapheme enhanced raman scattering, for example the transfer of grapheme electron, the theory of chemical enhancement mechanism and how to separate the chemical enhancement mechanism from electromagnetic enhancement mechanism.

Effects of Steel Slag Powder Content and Curing Condition on the Performance of Alkali-Activated Materials Based UHPC Matrix.

The accumulation of steel slag and other industrial solid wastes has caused serious environmental pollution and resource waste, and the resource utilization of steel slag is imminent. In this paper, alkali-activated ultra-high-performance concrete (AAM-UHPC) was prepared by replacing ground granulated blast furnace slag (GGBFS) powder with different proportions of steel slag powder, and its workability, mechanical properties, curing condition, microstructure, and pore structure were investigated. The results illustrate that the incorporation of steel slag powder can significantly delay the setting time and improve the flowability of AAM-UHPC, making it possible for engineering applications. The mechanical properties of AAM-UHPC showed a tendency to increase and then decrease with the increase in steel slag dosing and reached their best performance at a 30% dosage of steel slag. The maximum compressive strength and flexural strength are 157.1 MPa and 16.32 Mpa, respectively. High-temperature steam or hot water curing at an early age was beneficial to the strength development of AAM-UHPC, but continuous high-temperature, hot, and humid curing would lead to strength inversion. When the dosage of steel slag is 30%, the average pore diameter of the matrix is only 8.43 nm, and the appropriate steel slag dosage can reduce the heat of hydration and refine the pore size distribution, making the matrix denser.

Synthesis of 1,2-Diamines from Vinyl Sulfonium Salts and Arylamines.

A procedure for the synthesis of 1,2-diamines from vinyl sulfonium salts and arylamines under mild conditions was developed. This present synthetic protocol not only obviates the need for a transition-metal catalyst and an oxidizing reagent but also features a broad substrates scope. The practicability of this protocol is demonstrated by the one-pot synthesis, a scale-up reaction, and transformations of the products to diverse N-heterocyclic compounds. Mechanistic studies indicate that the formation of aziridine plays a key role during this diamination process.