Spin-valley locking and bulk quantum Hall effect in a noncentrosymmetric Dirac semimetal BaMnSb2.

Spin-valley locking in monolayer transition metal dichalcogenides has attracted enormous interest, since it offers potential for valleytronic and optoelectronic applications. Such an exotic electronic state has sparsely been seen in bulk materials. Here, we report spin-valley locking in a Dirac semimetal BaMnSb2. This is revealed by comprehensive studies using first principles calculations, tight-binding and effective model analyses, angle-resolved photoemission spectroscopy measurements. Moreover, this material also exhibits a stacked quantum Hall effect (QHE). The spin-valley degeneracy extracted from the QHE is close to 2. This result, together with the Landau level spin splitting, further confirms the spin-valley locking picture. In the extreme quantum limit, we also observed a plateau in the z-axis resistance, suggestive of a two-dimensional chiral surface state present in the quantum Hall state. These findings establish BaMnSb2 as a rare platform for exploring coupled spin and valley physics in bulk single crystals and accessing 3D interacting topological states.

Dual-targeting non-viral vector based on polyethylenimine improves gene transfer efficiency.

Polyethylenimine (PEI) is the polymer most commonly used for transferring plasmids into eukaryotes, but its gene-transfer efficiency is lower compared to viral vectors. Receptors targeting PEI combined with ligands can enhance efficiency of gene transfer into the corresponding receptor-positive cells. Using the double-receptor-mediated pathway of viral infection, in this study we synthesized a novel non-viral vector based on PEI combined with two peptides recognizing FGF receptors (peptide YC25) and integrins (peptide CP9) on the cell surface. The dual targeting vector showed a physicochemical character similar to that of PEI, such as pDNA formation, particle size, zeta potential and lower toxicity. In vitro gene transfer showed that the dual-receptor targeted vector (YC25-PEI-CP9) exhibited a markedly higher transgene efficiency in cell lines with positive expression of FGF receptors and integrins, compared with single-peptide-modified PEI or unmodified PEI. In the cells with only integrin-positive expression, YC25-PEI-CP9 mediated a higher transgene expression than PEI but lower than CP9-PEI. The corresponding free peptides could inhibit the transgene efficiency of the peptide-coupled PEI. In vivo gene transfer in tumor-bearing nude mice also demonstrated that the dual-targeting vectors showed a significantly enhanced transfection efficiency in tumors with positive expression of FGF receptors and integrins. The synthesized polymer YC25-PEI-CP9 has the prospect to act as a novel kind of non-viral vector in gene therapy.

Spermatophores and Plug Substance of the Marine Shrimp Trachypenaeus similis (Crustacea: Decapoda: Penaeidae): Formation in the Male Reproductive Tract and Disposition in the Inseminated Female.

Sperm are packaged into many small spermatophores of variable size in the median vas deferens (MVD) of the male. A substance is intermixed with sperm in the proximal coils of the MVD, separating groups of sperm that will be ejaculated as spermatophores. Most of the ejaculatory duct is occupied by a chamber filled with a transparent, viscous fluid termed the "plug substance." When males are artificially ejaculated, spermatophores are emitted, followed by plug substance that quickly solidifies. This latter material fills and stoppers a space on the female, the median pocket, which serves as an antechamber to the apertures of the internalized seminal receptacles, where sperm from ruptured spermatophores are stored. The slit-like openings to the receptacles are functionally divided into a posterior aperture, stoppered by plug substance after insemination, a closed mid-section, and an anterior exit for sperm release during spawning. Direct insemination by an everted male gonopore is considered more likely than transmission of spermatophores and plug substance via the male gonopod (petasma). In addition to its hypothesized roles during insemination and sperm release, the mass of plug substance (mating plug) may act as a paternity assurance device that prevents subsequent inseminations by other males.