No abstract

In this work we reported a novel graphite doped conductive magnetorheological plastomer (GMRP) with magnetic field dependent electro-conductivity. The conductivity of the GMRPs increased by increasing the content of the graphite particles, while it decreased with the graphite size. When the graphite content reached 15 wt%, the conductivity of GMRPs is approximately 10 000 times higher than the non-doped MRP. Because the iron particles in the GMRPs were magnetic, the conductivity of the GMRPs was magnetically sensitive. Upon applying a 780 mT magnetic field, the electric conductivity could increase about 1000 times larger than the one under zero magnetic field. A particle-particle resistance model was developed to investigate the influence of the magnetic field and graphite doping on the conductivity, and the fitting curve matched the experimental results very well. Finally, a magnetically controllable on-off switch based on GMRPs was proposed and its working mechanism was discussed.

. Purpose:  To evaluate the effect of collagen cross‐linking induced by genipin in porcine sclera. Methods:  Porcine cadaver eyes were treated with genipin at concentrations (by w/v) of 0.01%, 0.03%, 0.1%, 0.3%, 1.0% for 15 and 30 min. Riboflavin/ultraviolet A(UVA)‐treated and untreated samples were used as controls. After treatment, scleral strips of 4.0 × 10.0 mm were cut. Twenty‐four hours later, the stress‐strain parameters of the strips were measured using a biomaterial microtester. The stress and Young’s modulus at 8% strain were evaluated. Results:  Compared with untreated groups, after treatment with genipin for 15 min, the stress was increased by 66–246%, depending on the concentration of genipin. As for the 30‐min groups, the stress was 171–444% higher than that of the control. The difference of the Young’s modulus between genipin 15‐min groups, except the 0.01% groups (p = 0.095), also had statistical significance (p < 0.05). The Young’s modulus had significant difference between the untreated group and the genipin 30‐min groups (all p < 0.05). Of 0.3% genipin for 15 min or 0.01% genipin for 30 min had a similar stress‐strain curve with those of eyes treated with the riboflavin/UVA group. The sclera exhibited a bluish colour which became deeper with increase concentration and cross‐linking time. Conclusions:  Collagen cross‐linking induced by genipin could increase the biomechanical strength in porcine sclera. The effect depends on the concentration and treatment time of genipin.

Respiratory syncytial virus (RSV) is the leading cause of acute respiratory tract viral infection in infants, causing bronchiolitis and pneumonia. The host antiviral response to RSV acts via retinoic acid-inducible gene I (RIG-I). We show here that RSV infection upregulates major histocompatibility complex class I (MHC-I Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection in infants and young children, causing bronchiolitis and pneumonia in infants and young children worldwide. Due to the highly infectious nature of the virus, roughly two-thirds of children are infected by their first birthday, and this reaches essentially 100% by the age of 2 (1, 2). RSV infection is a leading cause of infant hospitalization due to bronchiolitis (2, 3). In the United States alone, an estimated 2.1 million children under 5 years of age with RSV infection require medical attention each year (4). Importantly, lower respiratory tract infection by RSV early in life is a risk factor for persistent wheezing and asthma in later life (5, 6). There are no RSV vaccines available to prevent childhood infection. These factors create an urgent need to understand the mechanisms of RSV disease, the molecular mechanisms associated with immunoregulation, and the downstream association between RSV infection and allergic asthma.RSV belongs to the subfamily Pneumovirinae of the paramyxoviruses. A negative-sense, single-stranded RNA virus with a genome of approximately 15,000 nucleotides (7), the virus can infect a broad range of cells. In patients, however, infection is normally highly restricted to the superficial cells of the respiratory epithelium, the ciliated cells of the small bronchioles, and pneumocytes in the alveoli (8-10). Infection is initiated by cell surface binding via proteoglycans (11), followed by nucleolin-mediated fusion for RSV cell entry (9, 12) and infection. In response, the host initiates an early innate immune response at the site of infection. Receptors of innate immune recognition, like Toll-like receptors (TLRs) and retinoic acid-inducible gene I (RIG-I), which are involved in detection of viral RNA, promote the activation of antiviral immunity and cytokine production, as well as the recruitment of proinflammatory cells (10,(13)(14)(15)(16). This increased expression of inflamma-

Magnetorheological elastomers (MREs) are a type of soft magneto-active rubber-like material, whose physical or mechanical properties can be altered upon the application of a magnetic field. In general, MREs can be prepared by mixing micron-sized magnetic particles into nonmagnetic rubber-like matrices. In this chapter, the materials, the preparing methods, the analytical models, and the applications of MREs are reviewed. First, different kinds of magnetic particles and rubber-like matrices used to prepare MREs, as well as the preparing methods, will be introduced. Second, some examples of the microstructures, as well as the microstructure-based analytical models, of MREs will be shown. Moreover, the magnetic field-induced changes of the macroscopic physical or mechanical properties of MREs will be experimentally given. Third, the applications of MREs in engineering fields will be introduced and the promising applications of MREs will be forecasted. This chapter aims to bring the reader a first-meeting introduction for quickly knowing about MREs, instead of a very deep understanding of MREs.

Magnetorheological elastomers (MREs) are intelligent materials consisting of a rubber matrix filled with magnetizable particles. In many engineering applications, MREs are usually pre-confined and work with constraint-induced prestress. The prestress can significantly change the mechanical properties of MREs. In this work, the influence of prestress on the mechanical response of MREs is studieds both experimentally and theoretically. The storage modulus as well as the magneto-induced modulus change non-linearly with increasing prestress and three regions can be found in the non-linear change. In the non-full contact region, the MREs present poor mechanical properties at small prestress due to the unevenness of the sample surface. In the full contact region, the MREs are under suitable prestress, thus they present good mechanical properties. In the overload region, the pre-configured microstructure of the MREs is destroyed under the large prestress. Moreover, an analytical model is proposed to study the prestress-dependent mechanical properties of MREs. It is revealed that the prestress can change the inter-particle distance, thus further affecting the mechanical response of MREs.

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Genipin induced crosslinking of collagen can increase its biomechanical behavior by direct strengthening of the extracellular matrix in rabbit sclera, with no α-SMA expression seen in the myofibroblasts. As there is no evidence of cytotoxicity in the scleral, choroidal, and retinal cells, genipin is likely a promising agent to strengthen the weakened sclera to prevent myopic progression.