Design and Stiffness Analysis of a Bio-inspired Soft Actuator with Bi-direction Tunable Stiffness Property

The ability to modulate the stiffness of soft actuators plays a vital role in improving the efficiency of interacting with the environment. However, for the unidirectional stiffness modulation mechanism, high lateral stiffness and a wide range of bending stiffness cannot be guaranteed at the same time. Therefore, we draw inspiration from the anatomical structure of the finger, proposing a soft actuator with bi-direction tunable stiffness property (BTSA). BTSA is composed of air-tendon hybrid actuation (ATA) and bone-like structure (BLS). The bending stiffness can be tuned by ATA from 0.2 N/mm to 0.7 N/mm, about a magnification of 3.5 times. The lateral stiffness with BLS is enhanced up to 4.2 times compared to the one without BLS. Meanwhile the lateral stiffness can be tuned decoupling within a certain range of stiffness (e.g. from 0.35 N/mm to 0.46 when the bending angle is 45 deg). The BLS is designed according to a simplified stiffness analysis model. And a lost-wax based fabrication method is proposed to ensure the airtightness. The experiments about fingertip force, bending stiffness, and lateral stiffness are conducted to verify the property

Proteomic analysis of mismatch repair-mediated alkylating agent-induced DNA damage response

BACKGROUND: Mediating DNA damage-induced apoptosis is an important genome-maintenance function of the mismatch repair (MMR) system. Defects in MMR not only cause carcinogenesis, but also render cancer cells highly resistant to chemotherapeutics, including alkylating agents. To understand the mechanisms of MMR-mediated apoptosis and MMR-deficiency-caused drug resistance, we analyze a model alkylating agent (N-methyl-N’-nitro-N-nitrosoguanidine, MNNG)-induced changes in protein phosphorylation and abundance in two cell lines, the MMR-proficient TK6 and its derivative MMR-deficient MT1. RESULTS: Under an experimental condition that MNNG-induced apoptosis was only observed in MutSα-proficient (TK6), but not in MutSα-deficient (MT1) cells, quantitative analysis of the proteomic data revealed differential expression and phosphorylation of numerous individual proteins and clusters of protein kinase substrates, as well differential activation of response pathways/networks in MNNG-treated TK6 and MT1 cells. Many alterations in TK6 cells are in favor of turning on the apoptotic machinery, while many of those in MT1 cells are to promote cell proliferation and anti-apoptosis. CONCLUSIONS: Our work provides novel molecular insights into the mechanism of MMR-mediated DNA damage-induced apoptosis

A Newly Discovered Late Pleistocene Lower Third Premolar and the High Frequency Occurrence of Tomes’ Root in the Human Fossil Record from China

Dental remains provide crucial evidence for interpreting a populations’ affinity as well as human evolution. Recent studies of fossil human teeth have enriched our current view of morphological variation during the Pleistocene in East Asia. In the present paper, we describe a newly discovered late Pleistocene human tooth, a lower third premolar from the Weijiadong cave in Bijie in south-western China, which is dated around 18-20Ka BP using AMS Carbon 14 dating. The tooth is identified as belonging to an early modern human based on its morphology and size. The Tomes’ root is present in this lower third premolar, one of the non-metrical dental traits developed genetically. Moreover, we examine most of the fossil lower third premolars collected from China, as well as material from several Neolithic and historical human assemblages. We find that the Tomes’ root is very common in Chinese human fossils and occurs in high frequency in Neolithic and historic human remains from China. We suggest the high frequency of Tomes’ root may serve as a non-metric dental trait to support inferences regarding regional continuity of human evolution in East Asia

Dynamics in direct two-photon transition by frequency combs

Two-photon resonance transition technology has been proven to have a wide range of applications,it's limited by the available wavelength of commercial lasers.The application of optical comb technology with direct two-photon transition (DTPT) will not be restricted by cw lasers.This article will further theoretically analyze the dynamics effects of the DTPT process driven by optical frequency combs. In a three-level atomic system, the population of particles and the amount of momentum transfer on atoms are increased compared to that of the DTPT-free process. The 17% of population increasement in 6-level system of cesium atoms has verified that DTPT process has a robust enhancement on the effect of momentum transfer. It can be used to excite the DTPTs of rubidium and cesium simultaneously with the same mode-locked laser. And this technology has potential applications in cooling different atoms to obtain polar cold molecules, as well as high-precision spectroscopy measurement.Comment: 7 pages, 7 figure