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Fibrous tissue is often formed in delayed healing of tendon bone insertion (TBI) instead of fibrocartilage. Extracorporeal shockwave (ESW) provides mechanical cues and upregulates expression of fibrocartilage-related makers and cytokines. We hypothesized that ESW would accelerate fibrocartilage regeneration at the healing interface in a delayed TBI healing model. Partial patellectomy with shielding at the TBI interface was performed on 32 female New Zealand White Rabbits for establishing this delayed TBI healing model. The rabbits were separated into the control and ESW group for evaluations at postoperative week 8 and 12. Shielding was removed at week 4 and a single ESW treatment was applied at week 6. Fibrocartilage regeneration was evaluated histomorphologically and immunohistochemically. Vickers hardness of the TBI matrix was measured by micro-indentation. ESW group showed higher fibrocartilage area, thickness, and proteoglycan deposition than the control in week 8 and 12. ESW increased expression of SOX9 and collagen II significantly in week 8 and 12, respectively. ESW group showed a gradual transition of hardness from bone to fibrocartilage to tendon, and had a higher Vickers hardness than the control group at week 12. In conclusion, ESW enhanced fibrocartilage regeneration at the healing interface in a delayed TBI healing model.

A new, fast and low cost method to produce Cu-doped ZnO nanosheets is reported for the first time in this paper. Zinc foil specimens were immersed into CuSO4 aqueous solutions with various concentrations for 3 seconds and then dried at ambient condition. The immersed specimens were characterized with a scanning electron microscope, an X-ray diffractometer and a transmission electron microscope. The results show that Cu-doped ZnO nanosheets with a multilayer structure on a cupper layer are formed. Cu-doped ZnO nanosheets show hexagonal crystalline structure and comprises polycrystalline grains with diameters of 5∼10 nm. A physical modal is suggested to explain the prepared Cu-doped ZnO nanosheet structure, based on the chemical reactions and a metallurgical cell.

Mollusks such as snail and mussels adopt hard shells to protect their vulnerable bodies. Recent studies on biomaterials have revealed that these shells especially the nacre layers exhibit excellent mechanical properties, inspiring a number of biomimetic endeavors. Nevertheless, in nature, there is a species of fish called Mylopharyngodon piceus or black carp, whose main diet is exactly snails and mussels. Does such unique diet imply that the pharyngeal teeth of black carp, its major masticatory apparatus, are superior to the mollusk shells in mechanical properties? In this paper, structural and mechanical characterizations are conducted on the pharyngeal teeth of black carp, showing that enameloid, the outermost layer of black carp teeth, possesses similar elastic modulus and hardness in comparison to those of the pond snail shells. To shed light on the mechanics underlying the capability of pharyngeal teeth to crush mollusk shells, parametric studies on the geometry of the shells are conducted by means of finite element method. It is found that whether a mollusk shell is crushable or not, for given pharyngeal teeth, depends on the radius (R) and thickness (t) of the shell. A predation map for black carp teeth is constructed by delimiting the t–R plane into three phasic regions corresponding to three possible consequences of the mechanical competition between pharyngeal teeth and shells. It is interesting to notice that all the freshwater shells chosen at random fall in the crushable regime while the seashells do not necessarily. This feature of black carp teeth can be speculated as a result of evolution in response to its freshwater diet.

We demonstrated a characterization method of entropy-change measurement for the study of the electrocaloric effect (ECE). After the specific heat capacity was measured under different applied fields using a differential scanning calorimeter (DSC) accompanied with DC power supply, the electrocaloric ΔS was calculated from the temperature integral of specific heat capacities based on the basic definition of entropy. The ΔS–T curve of BaTiO3 single crystal showed a sharp peak around Tc, which increased gradually and shifted to higher temperature with the rise of applied field. A high ECE with ΔS = 1.9 J/kg K and ΔT = 1.6 K is achieved under a quite low field of 10 kV/cm. The results agreed with the thermodynamic calculation. It provides a direct, precise, and time-efficient method for the electrocaloric studies.

Current oscillation will occur when a piezoelectric ceramic vibrator is driven by a high electric field. The mechanism of current oscillation is discussed, based on the results of the present experiment. Ring-shaped lead zirconate titanate (PZT) piezoelectric vibrators are driven by a 5.65 V electric field with a fixed frequency of slightly less than resonance, to form an oscillating current. The sample current, temperature, and phase between the driven electric field and sample current are recorded. The resonance frequency of PZT rings shifts in the direction of low frequency under a high electric field due to the heat produced by dissipated power, and then shifts back due to the effects of aging, which results in current oscillation. The oscillation phenomenon is explained according to the production of strong internal stresses due to abrupt change in temperature, and then, aging process through the rearrangement of domains to relieve various stresses.

In this paper, the effect of Zn element addition on martensitic transformation and damping capacity of Mn–20Cu–5Ni–2Fe (at%, M2052) alloy has been investigated systematically by using X-ray diffraction, optical microscopy, and dynamic mechanical analyzer. The results show that martensitic transformation and damping capacity have a crucial dependence on the addition of Zn element. It not only can markedly enhance the damping capacity of M2052 alloy at room temperature (internal friction Q−1 increases by ≈23% compared to M2052 without Zn as strain amplitude reaches 4 × 10−4), but also reduces the attenuation of damping capacity effectively at elevated temperatures. This is mainly because the addition of Zn element can evidently increase the Gibbs free energy difference between γ parent phase and γ' phase produced by face centered cubic to face centered tetragonal (f.c.c-f.c.t) phase transformation, and then raises the martensitic transformation and its reverse transformation temperatures, eventually leading to the apparent increase of amount of f.c.t γ' phase micro-twins as damping source and the significant enhancement of damping capacity. It will be of great value for design and optimization of high-performance M2052 damping alloy toward practical applications.

SAM is needed to reduce the leakage current through the gate and dielectric. Some of the SAMs would require relatively long preparation time [ 12–14 ] and usually the functional head groups of SAMs is dielectric specifi c. It is challenging to develop a universal SAMs suitable for different dielectric insulators. More importantly, the SAM also modifi es the surface energy of the dielectric and affects the crystallinity of the organic semiconductors. It is necessary to employ a suitable SAM to achieve high crystallility and carrier mobility in the OFETs. [ 14 ] To date, it is still a great challenge in the research fi eld to develop a universal highk material which does not require SAM, and can be processed at moderate temperature, ambient air environment, and adjustable surface energy for both thermal evaporation and solution processing of organic semiconductors. To address these challenges, we recently reported a highk (e r = 11) barium strontium titanate (BST) thin fi lm treated by UV-Ozone and deposited by multi-layer spin coating deposition. [ 15 ] The highk fi lms are spin coated in ambient air and heated to a temperature of around 85 °C during the UV-Ozone process. The UV emits at 184.9 nm and 253.7 nm under ambient air conditions converting oxygen into reactive O species, which then diffuse into the amorphous BST thin fi lm and reacts with the oxygen vacancies to form lattice oxygen. The reactive oxygen also removes the organic impurities in the fi lm, which results in a high quality amorphous BST thin fi lm with better stoichiometry. [ 16 ] The compatibility with ambient air environment, low processing temperature, and no SAM requirement suggest the BST dielectric has extremely high potentials to be applied in developing low cost OFETs on plastic fl exible substrates and have advantages over other polymers and inorganic materials. In the current study, we investigate the surface energy modifi cation effect by varying the storage environment and time of the BST thin fi lm in order to achieve a universal highk material for OFET fabrications without using SAM. Based on the contact angle measurements, we calculated the surface energy and the wetting envelope of the BST highk dielectric stored under different fi ve different conditions. The fresh BST with hydrophilic surface is suitable for spin coating or drop casting of organic semiconductor deposition where surface wetting is needed for the alignment of organic molecules. On the other hand, the BST thin fi lms stored under different conditions show different surface energy, which will directly affect the crystallinity of the organic semiconductors. On the current BST highk dielectric without SAM and further optimization, dinaphtho[2,3-b:2′,3′-f ] thieno[3,2-b] thiophene (DNTT) and 6,13-Bis (triisopropylsilylethynyl) pentacene (TIPS-pentacene) organic transistors with average mobility of 1.51 cm 2 V −1 s −1 and 0.11 cm 2 V −1 s −1 are formed by thermal evaporation and droplet-pinned crystallization (DPC) method (one of the solution processing methods). DOI: 10.1002/admi.201300119 Z. R. Wang, X. C. Ren, Y.-H. Chang, Prof. S.-P. Feng, Prof. P. K. L. Chan Department of Mechanical Engineering The University of Hong Kong Hong Kong E-mail: pklc@hku.hk Z. R. Wang, Prof. S. Q. Shi Department of Mechanical Engineering The Hong Kong Polytechnic University Hong Kong C. C. Fan, Prof. H. Y. Li, Prof. H. Z. Chen State Key Laboratory of Silicon Materials, MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering Zhejiang University China As the essential building blocks in the new generation of organic electronic devices such as fl exible pressure sensors, memories, radio frequency identifi cation (RFID), and display, [ 1–5 ] high performance organic fi eld effect transistors (OFETs) are attracting great interests from the research community, especially in the battery-powered and portable application where the low operating voltage OFETs are required. Different high dielectric constant (highk ) gate materials, including polymers, inorganic oxides and hybrid stacks thin fi lms with self-assembly monolayers (SAMs) have been proven to reduce the operating voltage of the OFETs. Relatively high annealing temperatures of the commonly used highk polymer materials, such as poly(vinylidenefl uoride-co-trifl uoroethylene) (P(VDF–TrFE)) (160 °C)-polyvinyl phenol (PVP) (175°C), [ 6 ]