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Lead-free ferroelectric ceramics (1-x) BaTiO3–xBi(Mg1/2Ti1/2)O3(x = 0.0–0.07) were synthesized by conventional solid state reaction method and the correlation of structure, dielectric, ferroelectric and impedance properties were investigated. It was found that Tmand εmshowed decreasing trend with the increase of BMT content. The high-temperature dielectric relaxation behaviour was observed in all the samples. The activation energy calculated from impedance (Ea) and conductivity (Econd), which revealed that the relaxation behaviours were linked with the migration of OVs. The values of Eawere almost equivalent to Econd. It was concluded that the short-range hopping of oxygen vacancy contributed to the dielectric relaxation and long-distance movement of doubly ionized oxygen vacancies contributed to the conduction. On the other hand, with increasing BMT contents, it was found that P-Eloops became slimmer and slimmer, which indicated the increase of relaxor behaviour. The temperature dependence of P-Eloops for 0.98BT–0.02BMT ceramic clearly showed the transition process from ferroelectric to relaxed ferroelectrics. more...

The arm system is the central part in the design of a portable crane. The purpose of this program is to assure that the load moves approximately along the path of the horizontal direction in the process of luffing, through the optimization of the bars’ length of the arm system. Using vectors in the mathematical model, we figured out the coordinates of the bottom point of the truck-beam according to the geometric relationships of the four-bar linkage. With the appliance of proper algorithm and the idea of visualization, we calculated the reasonable length of the bars in MATLAB and transformed the results into software ultimately. The design is suitable for different types of portable cranes, and the software is very convenient and can be used in engineering. more...

Wound healing has become one of the basic issues faced by the medical community because of the susceptibility of skin wounds to bacterial infection. As such, it is highly desired to design a nanocomposite hydrogel with excellent antibacterial activity to achieve high wound closure effectiveness. Here, based on ultrasound-triggered piezocatalytic therapy, a multifunctional hydrogel is designed to promote bacteria-infected wound healing. Under ultrasonic vibration, the surface of barium titanate (BaTiO3, BT) nanoparticles embedded in the hydrogel rapidly generate reactive oxygen species (ROS) owing to the established strong built-in electric field, endowing the hydrogel with superior antibacterial efficacy. This modality shows intriguing advantages over conventional photodynamic therapy, such as prominent soft tissue penetration ability and the avoidance of serious skin phototoxicity after systemic administration of photosensitizers. Moreover, the hydrogel based on N-[tris(hydroxymethyl)methyl]acrylamide (THM), N-(3-aminopropyl)methacrylamide hydrochloride (APMH) and oxidized hyaluronic acid (OHA) exhibits outstanding self-healing and bioadhesive properties able to accelerate full-thickness skin wound healing. Notably, compared with the widely reported mussel-inspired adhesive hydrogels, OHA/THM-APMH hydrogel due to the multiple hydrogen bonds from unique tri-hydroxyl structure overcomes the shortage that catechol groups are easily oxidized, giving it long-term and repeatable adhesion performance. Importantly, this hybrid hydrogel confines BT nanoparticles to wound area and locally induced piezoelectric catalysis under ultrasound to eradicate bacteria, markedly improving the therapeutic biosafety and exhibits great potential for harmless treatment of bacteria-infected tissues. more...

Nucleotide sequence comparisons of thepolgene among 47 retroelements identified two very conserved regions, separated by a span of approximately 640 bp, that have not been previously reported. A set of mixed oligonucleotide primers, 5′-MOP-2 and 3′-MOP-2, homologous to these two conservedpolregions was constructed for use in detection of retroelements. When MOPs-2 were employed in PCR amplification studies, products of about 0.64 kb in size were amplified from human and mouse genomic DNAs and from HIV-1 proviral DNA, but not from negative control plasmid DNAs. The PCR products amplified with MOPs-2 from human LuC-1 teratocarcinoma cell DNA were subcloned and sequenced. Five clones of approximately 0.64 kb in size were identified, and sequence comparisons with all entries in GenBank indicated that these five clones have highest homology, in a range of 64.31 to 98.65%, with the correspondingpolregion of HERV-K10 and HM-16 of the human endogenous retrovirus-K (HERV-K) family. Southern hybridizations at high stringency demonstrated that these five clones are present in all human DNAs tested. The evolutionary relationships of these clones with the equivalentpolregion of other retroelements were defined by phylogenetic analyses that placed three clones into the HERV-K family and two clones into a new family of human endogenous retroelements. In addition, clone HERV-(K)73 contains the smaller PV1bpolsegment that was reported to be selectively expressed in blood leukocytes of patients with polycythemia vera. more...

Northern hybridization with five HERV-K family members, previously cloned from human teratocarcinoma genomic DNA, indicated that two (HERV-(K)27 and -(K)67) of the five clones are expressed in these teratocarcinoma cells. These two clones are closely related (98.49%), however, and Northern blot hybridization lacks the specificity to distinguish between their respective mRNAs. Therefore, PCR analysis with mixed oligonucleotide primers homologous to conserved retroviral polgene regions was employed to amplify cDNA synthesized from teratocarcinoma cell RNA. This amplification scheme yielded two novel HERV-K family members, HERV-(K)55 and HERV-(K)91. Clone HERV-(K)55 has approximately 98% nucleotide sequence identity to clones HERV-(K)27 and -(K)67. Subsequent RNase protection assays confirmed the expression of HERV-(K)55 and indicated that clones HERV-(K)27 and -(K)67 were not expressed in these cells. One interpretation is that the HERV-(K)27 and -(K)67 probes detected transcripts of clone HERV-(K)55 or other closely-related elements because of their high homologies. In addition, clone HERV-(K)91, which has approximately 81% nucleotide sequence identity to clones HERV-(K)27, -(K)67, and -(K)55, was obtained only from teratocarcinoma 2102E-Pr cells, but the RNase protection assay showed that this clone is also expressed in other human teratocarcinoma cell lines. more...