Knotted Artificial Muscles for Bio-Mimetic Actuation under Deepwater.

Muscles featuring high frequency and high stroke linear actuation are essential for animals to achieve superior maneuverability, agility, and environmental adaptability. Artificial muscles are yet to match their biological counterparts, due to inferior actuation speed, magnitude, mode, or adaptability. Inspired by the hierarchical structure of natural muscles, artificial muscles are created that are powerful, responsive, robust, and adaptable. The artificial muscles consist of knots braided from 3D printed liquid crystal elastomer fibers and thin heating threads. The unique hierarchical, braided knot structure offers amplified linear stroke, force rate, and damage-tolerance, as verified by both numerical simulations and experiments. In particular, the square knotted artificial muscle shows reliable cycles of actuation at 1Hz in 3000m depth underwater. Potential application is demonstrated by propelling a model boat. Looking ahead, the knotted artificial muscles can empower novel biomedical devices and soft robots to explore various environments, from inside human body to the mysterious deep sea.

Secondary bone grafting for alveolar cleft in children with cleft lip or cleft lip and palate.

BACKGROUND: Secondary alveolar bone grafting has been widely used to reconstruct alveolar cleft. However, there is still some controversy. OBJECTIVES: To compare the effectiveness and safety of different secondary bone grafting methods. SEARCH STRATEGY: The final electronic and handsearches were carried out on 11 February 2011, and included the Cochrane Oral Health Group's Trials Register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Chinese Biomedical Literature Database and WHO International Clinical Trials Registry Platform. All the Chinese professional journals in the oral and dental field were handsearched and conference proceedings consulted. There was no language or time restriction. SELECTION CRITERIA: Only randomized clinical trials were selected. Patients with the diagnosis of cleft lip and alveolar process only, unilateral cleft lip and palate and bilateral cleft lip and palate involving the alveolar process and greater than 5 years of age were included. DATA COLLECTION AND ANALYSIS: Two review authors extracted data and assessed the quality of included studies independently. Disagreement between the two review authors was resolved by discussion in the review team. The first authors of the included studies were contacted for additional information, if necessary. MAIN RESULTS: Two of 582 potential studies met the inclusion criteria and were included. One trial compared alveolar bone grafting using artificial materials (InFuse bone graft substitute impregnated with BMP-2) with a traditional iliac graft. The other trial investigated the application of fibrin glue to the bone graft. Both trials were small with 21 and 27 patients and were assessed as being at high risk of bias. Any apparent differences between the interventions for outcomes in either study must therefore be treated with great caution and are not highlighted here. AUTHORS' CONCLUSIONS: Due to the high level of risk of bias in the two included trials there is insufficient evidence to conclude that one intervention is superior to another.

Optimal enamel conditioning strategy for rebonding orthodontic brackets: a laboratory study.

OBJECTIVE: To compare the conventional etching and primer method (CEP) and the self-etching primer method (SEP) in rebonding brackets. METHODS: Forty human maxillary second premolars extracted for orthodontic purpose were randomly divided into 4 equal groups. Group 1 and Group 2 were bonded using the CEP method; Group 3 and Group 4 using the SEP method. All the brackets were debonded and 40 new brackets were rebonded with four different protocols after surface cleaning: Group 1: CEP + adhesive; Group 2: CEP without etch step + adhesive; Group 3: SEP + adhesive; Group 4: non-acidic primer + adhesive. Then, the shear bond strength (SBS) of each group was tested and the measurements of adhesive remnant index scores (ARI) and SEM examination were performed. RESULTS: The mean SBSs for Group 1, 2, 3 and 4 were 14.18, 6.57, 11.90, 5.91 MPa, respectively. Statistical differences of the SBS existed between Group 1 and 2 (P < 0.05) and between Group 3 and 4 (P < 0.05). No difference was found between Group 1 and 3, or Group 2 and 4. CONCLUSION: Omission of the acid-etching step in rebonding orthodontic brackets may be adequate for the clinical requirement. No differences in SBS and ARI of the rebonded brackets were showed between CEP and SEP methods.

Oxide nanowires for solar cell applications.

Oxide nanowire arrays were studied for their applications to solar cells. It was demonstrated that the nanowires could provide direct pathways for electron transport in dye-sensitized solar cells and therefore, while forming photoelectrode films, they offered better suppression of charge recombination than nanoparticles. However, the photoelectron films consisting of nanowires suffered a disadvantage in giving large surface area for dye adsorption. Such a shortcoming of nanowires had been exemplified in this paper illustrating that it could be well compensated by incorporating with nanoparticles to form a nanoparticle-nanowire array hybrid photoelectrode film. The oxide nanowires were also demonstrated to be able to enhance the performance of inverted structure polymer solar cells as a cathode buffer layer by establishing a large interface with the polymers so as to facilitate the transport of photogenerated electrons from the polymer to the electron collecting electrode. Such an enhancement effect could be further boosted while the nanowires were replaced with nanotubes; the latter may build up larger interface with the polymers than the former and therefore facilitates the electron transport more efficiently.

A potential therapeutic method for conductive hearing loss in growing children-orthodontic expansion treatment.

Conductive hearing loss, the second most common type of hearing loss, happens when there is a problem transmitting sound waves into inner ear, which will bring a lot of inconvenience to the patient in life and put the impaired person at a competitive disadvantage. Although conductive hearing loss could be relieved by hearing aids, the inconvenience of using these removable aids or the surgery trauma of the implanted ones should not be overlooked. Transversal maxillary deficiency and high palatal arches are often found in patients with conductive hearing loss. Some researchers have reported that there is close relationship between the maxillary contraction and hearing damage. Luckily, rapid maxillary expansion (RME) has been proved to be an effective treatment method for the transversal maxillary deficiency in clinical orthodontics for more than 40 years. Thus, we hypothesized that RME treatment would be a potential therapeutic method for conductive hearing loss in growing children with maxillary constriction.