Fabrication of Asymmetric Polysaccharide Composite Membranes as Guided Bone Regeneration Materials

Periodontal regeneration can be achieved by guided tissue and guided bone regeneration (GTR/GBR) membranes, which act as a physical barrier to exclude migration of connective and epithelium, favoring the repopulation of periodontal ligament cells. Asymmetric polysaccharide GBR membranes with two different surfaces were developed in this study. Positive chitosan (CS), negative hyluronaic acid (HA) and konjac glucomannan (KGM) were composited by electrostatic interaction, forming smooth and dense membranes as upper surface to inhibit the ingrowth of cells from gingiva. The lower porous and coarse surface was obtained by gel freeze-drying and mineralization to improve the regeneration of the bone tissue. The performance of the membranes was characterized by Infrared Radiation (IR), X-ray diffraction (XRD), scanning electron microscope (SEM), tensile strength and biological evaluation. It was found that the composite membranes with chitosan content of 56.7 wt%in the dry state possess the highest tensile strength, with elongation 10 times more higher than that of the pure CS ones. Additionaly, open pores with diameter of 10-100 µm and homogenouse distributed nano-hydroxyapatite (HAP) were investigated on the coarse part. Cell studies demonstrated that the porous surface promoted the growth of the preosteoblast. Overall, the composite membranes may be useful for regeneration of periodontal regeneration

Active Load-Sensitive Electro-Hydrostatic Actuator for More Electric Aircraft

In the flight control system, using an electro-hydrostatic actuator (EHA) instead of the currently used relatively mature electro-hydraulic valve-controlled actuator, there are three prevailing concerns, namely heating, size, and stiffness. This paper proposes a novel principle EHA, called active load-sensitive EHA (ALS-EHA), which can actively realize the adaptive adjustment of pump displacement with load pressure. Its principle analysis and mathematical modeling based on the direct load-sensitive EHA (DLS-EHA) configuration is done to obtain the relationship between motor current and hydraulic reduction ratio. Then, its stiffness characteristics are analyzed, especially the influence of hydraulic reduction ratio on impedance at low frequencies combined with investigating the power matching of ALS-EHA. A comparative experiment between the developed ALS-EHA and the EHA with fixed pump displacement and variable motor speed (EHA-FPVM) was carried out. The results reveal that the proposed ALS-EHA can reduce the motor heating and its displacement tracking error is smaller near zero speed owing to its higher impedance from the lower hydraulic reduction ratio under heavy load conditions

Urban Public Health: Is There a Pyramid?

Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000–2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development

<span style="font-variant: small-caps">Ponder</span>: Enabling Balloon-Borne Based Solar Unmanned Aerial Vehicle’s Take Off Diagnosis under Little Data

Balloon-borne based solar unmanned aerial vehicle (short for BS-UAV) has been researched prevalently due to the promising application area of near-space (i.e., 20–100 km above the ground) and the advantages of taking off. However, BS-UAV encounters serious fault in its taking off phase. The fault in taking off hinders the development of BS-UAV and causes great loss to human property. Thus, timely diagnosing the running state of BS-UAV in taking off phase is of great importance. Unfortunately, due to lack of fault data in the taking off phase, timely diagnosing the running state becomes a key challenge. In this paper, we propose Ponder to diagnose the running state of BS-UAV in the taking off phase. The key idea of Ponder is to take full advantage of existing data and complement fault data first and then diagnose current states. First, we compress existing data into a low-dimensional space. Then, we cluster the low-dimensional data into normal and outlier clusters. Third, we generate fault data with different aggression at different clusters. Finally, we diagnose fault state for each sampling at the taking off phase. With three datasets collected on real-world flying at different times, we show that Ponder outperforms existing diagnosing methods. In addition, we demonstrate Ponder’s effectiveness over time. We also show the comparable overhead