DNA Phase Transition in Charge Neutralization and Comformation Induced by Trivalent-Hydrolysed Metal Ions

It is well known that common trivalent counter ions can induce DNA compaction or condensation but are unable to invert DNA surface charge in a normal aqueous solution. In the present study, we found that trivalent-hydrolysed metal ions (Fe3+, Al3+) are not only capable of inducing DNA condensation, but they also invert the electrophoretic mobility of DNA by electrophoretic light scattering and single molecular techniques. In comparison with neutral trivalent cations, hydrolysed metal ions such as Fe3+ can induce DNA condensation at a much lower concentration of cations, and its corresponding morphology of condensed DNA was directly observed by atomic force microscopy (AFM). The condensing and unravelling forces of DNA condensates were measured by tethering DNA by magnetic tweezers (MT) measurements at various concentration of Fe3+ and Al3+. We found that a coil–globule transition of DNA by hydrolysed metal ions not only was observed in DNA-complex sizes, but also in the curve of electrophoretic mobility of DNA in solution. In contrast, the transition was not observed in the case of neutral trivalent cations such as La3+ and Co3+. We attribute the transition and charge inversion to the ion-specific interaction between hydrolysed metal ions and phosphates of DNA backbone

A Rapid Self-Assembly Peptide Hydrogel for Recruitment and Activation of Immune Cells

Self-assembly peptide nanotechnology has attracted much attention due to its regular and orderly structure and diverse functions. Most of the existing self-assembly peptides can form aggregates with specific structures only under specific conditions and their assembly time is relatively long. They have good biocompatibility but no immunogenicity. To optimize it, a self-assembly peptide named DRF3 was designed. It contains a hydrophilic and hydrophobic surface, using two N-terminal arginines, leucine, and two c-terminal aspartate and glutamic acid. Meanwhile, the c-terminal of the peptide was amidated, so that peptide segments were interconnected to increase diversity. Its characterization, biocompatibility, controlled release effect on antigen, immune cell recruitment ability, and antitumor properties were examined here. Congo red/aniline blue staining revealed that peptide hydrogel DRF3 could be immediately gelled in PBS. The stable β-sheet secondary structure of DRF3 was confirmed by circular dichroism spectrum and IR spectra. The observation results of cryo-scanning electron microscopy, transmission electron microscopy, and atomic force microscopy demonstrated that DRF3 formed nanotubule-like and vesicular structures in PBS, and these structures interlaced with each other to form ordered three-dimensional nanofiber structures. Meanwhile, DRF3 showed excellent biocompatibility, could sustainably and slowly release antigens, recruit dendritic cells and promote the maturation of dendritic cells (DCs) in vitro. In addition, DRF3 has a strong inhibitory effect on clear renal cell carcinoma (786-0). These results provide a reliable basis for the application of peptide hydrogels in biomedical and preclinical trials

A Repetitive Control Scheme Aimed at Compensating the 6k + 1 Harmonics for a Three-Phase Hybrid Active Filter

The traditional repetitive controller has relatively worse stability and poor transient performance because it generates infinite gain at all the integer multiples of the fundamental frequency, and its control action is postponed by one fundamental period (T0). To improve these disadvantages, many repetitive controllers with reduced delay time have been proposed, which can selectively compensate the odd harmonics or 6k ± 1 harmonics with delay time reduced to T0/2 and T0/3, respectively. To further study in this area, this paper proposes an improved repetitive scheme implemented in a stationary reference frame, which only compensates the 6k + 1 harmonics (e.g., −5, +7, −11, +13) in three-phase systems and reduces the time delay to T0/6. Thus compared with the earlier reduced delay time repetitive controllers, the robustness and transient performance is further improved, the waste of control effort is reduced, and the possibility of amplifying and even injecting any harmonic noises into the system is avoided to a great extent. Moreover, the proposed repetitive scheme is used in the control of a three-phase hybrid active power filter. The experimental results validate the effectiveness of the proposed repetitive control scheme

A distributed decentralized cooperative control scheme for microgrids

Abstract A hybrid series‐parallel microgrid structure and its distributed decentralized cooperative control strategy are introduced in this paper. In the hybrid series‐parallel microgrids, the distributed generators (DGs) are concatenated in parallel to form a paralleled‐connected generation (PCG) module. Further, the hybrid series‐parallel microgrids consist of multiple PCG modules in series. For the considered microgrids, a distributed decentralized cooperative control strategy is proposed. For DGs in the same PCG module, low‐bandwidth communications are applied to obtain convergence control of the system. Meanwhile, different PCG modules realize autonomous synchronization in a communication‐free manner. Thus, the proposed distributed decentralized cooperative control method is a low‐bandwidth communication approach. Moreover, it is immune to single‐point fault and communication failure. Finally, the feasibility of the proposed controller for the considered microgrids is verified by stability and simulations

Teacher-student relationships and mental disorders of undergraduate and graduate students in online education: A moderated mediation model of mobile phone addiction and hometown setting

To solve the problem of distance education and cope with emergencies, online education has become one of the common educational methods in recent years. Objects: This study aimed to explore the relationship between the teacher-student relationship (TSR) and mental disorders of university students in online education. Measures: 2032 full-time undergraduate and graduate students from a comprehensive university in China participated in the online survey. The Chinese version of the Depression, Anxiety, Stress Scale-21 Items, the Chinese version of the Mobile Phone Addiction Index (MPAI), and the 7-item Teacher-Student Relationship Perception Questionnaire were administered to the students. Results: We found that higher quality of perceived TSR and a lower level of mobile phone addiction were associated with better mental health among undergraduate and graduate students during online education. Mobile phone addiction mediated the relationship between TSR and mental disorders, and hometown setting moderated the relationship between TSR and mobile phone addiction. Specifically, a higher quality of perceived TSR was associated with a lower level of mobile phone addiction. In addition, for students with low-quality perceived TSR, those who came from rural areas had a higher level of mobile phone addiction than those who came from urban areas. In contrast, when students had high-quality perceived TSR, the differences between students from urban and rural areas in mobile phone addiction were insignificant. Conclusion: The results of this study are of great significance in improving the mental health and mobile phone addiction of undergraduate and graduate students during online education and reveal the urban-rural differences in the impact of TSRs during online education

Changes in cerebral glucose metabolism in patients with mild-to-moderate Alzheimer's disease: A pilot study with the Chinese herbal medicine fuzhisan

National Natural Science Foundation of China [30670726]; Nature Science Foundation of HeiLongjiang [ZJY03-5]The aim of this study was to investigate the effects of fuzhisan (FZS, 10 mg/day), a Chinese herbal medicine, on cerebral glucose metabolism and neuropsychological metrics in patients with mild-to-moderate Alzheimer's disease (AD). This was a 12-week, randomized, double-blind, placebo-controlled pilot study. Twenty-two subjects were randomly assigned to groups that received FZS (n = 12) or placebo (n = 10). Positron emission tomography (PET) was used to study the regional cerebral metabolic rate of glucose consumption (rCMRglc) at baseline and week 12. We evaluated the clinical efficacy of FZS on cognition and behavioral functions using the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) and the Neuropsychiatric Index (NPI), respectively. Compared with placebo, FZS significantly improved ADAS-Cog scores and NPI scores at week 12. Moreover, FZS treatment favorably improved rCMRglc in the bilateral temporal and parietal cortices, hippocampus, and posterior cingulate gyrus. These results suggest that FZS treatment may have a positive effect on cognition, behavioral functions, and rCMRgIc in mild-to-moderate AD patients. (C) 2011 Elsevier Ireland Ltd. All rights reserved