A Novel Damage Indicator Based on the Electromechanical Impedance Principle for Structural Damage Identification.

This paper presents a novel structural damage detection indicator, i.e., fourth-order voltage statistical moment (FVSM) based on the electromechanical impedance (EMI) principle, and then proposes a two-step damage detection method based on the novel indicator and a differential evolution algorithm (DEA). In this study, several lead zirconate titanate (PZT) sensors bonded to an experimental steel beam were utilized to acquire the time-domain voltage responses. On this basis, the fourth-order voltage statistical moments (FVSMs) of the voltage responses are computed to locate the damage element in the detected structure, and the proposed damage detection method is utilized to quantify the damage. In addition, theoretical PZT voltage responses are also calculated based on the piezoelectric theory and the spectral element method (SEM). Experimental results verify the accuracy of the theoretical voltage values and the effectiveness of the proposed damage indicator. Results indicate that the FVSM is effective in locating the damage element. Integrated with DEA, the proposed technique is capable of quantifying damage.

Seroprevalence of Dirofilaria immitis in Cats from Liaoning Province, Northeastern China.

The present study was performed to investigate the seroprevalence and risk factors for Dirofilaria immitis infection in cats from Liaoning province, northeastern China. From October 2014 to September 2016, sera of 651 cats, including 364 domestic cats and 287 feral cats (332 females and 319 males) were assessed. They were tested for the presence of D. immitis antigen using SNAP Heartworm RT test kit. In this population, the average prevalence was 4.5%. Age and rearing conditions (feral or domestic) were found to be associated with the prevalence of D. immitis. The prevalence was significantly higher in feral cats compared with domestic cats (8.4% vs 1.4%, P<0.01). There was no significant difference between males and females (4.7% vs 4.2%, P>0.05), but older cats (≥3 years old) showed a statistically higher prevalence compared with younger cats (<3 years old) in feral populations (16.8 vs 2.4%, P<0.01), while the difference between the age groups was not statistically significant in domestic cats (2.4% vs 0.51%, P>0.05), all these results suggest that outdoor exposure time may be one of the most important factors for D. immitis prevalence in cats. Results reveal that D. immitis are prevalence in domestic and feral cats in northeastern China, which indicates that appropriate preventive measures should be taken to decrease the incidence of feline heartworm disease in Liaoning province, northeastern China.

Experimental Study on Damage Detection in Timber Specimens Based on an Electromechanical Impedance Technique and RMSD-Based Mahalanobis Distance.

In the electromechanical impedance (EMI) method, the PZT patch performs the functions of both sensor and exciter. Due to the high frequency actuation and non-model based characteristics, the EMI method can be utilized to detect incipient structural damage. In recent years EMI techniques have been widely applied to monitor the health status of concrete and steel materials, however, studies on application to timber are limited. This paper will explore the feasibility of using the EMI technique for damage detection in timber specimens. In addition, the conventional damage index, namely root mean square deviation (RMSD) is employed to evaluate the level of damage. On that basis, a new damage index, Mahalanobis distance based on RMSD, is proposed to evaluate the damage severity of timber specimens. Experimental studies are implemented to detect notch and hole damage in the timber specimens. Experimental results verify the availability and robustness of the proposed damage index and its superiority over the RMSD indexes.

A study of concrete slab damage detection based on the electromechanical impedance method.

Piezoelectric lead zirconate titanate (PZT) is being gradually applied into practice as a new intelligent material for structural health monitoring. In order to study the damage detection properties of PZT on concrete slabs, simply supported reinforced concrete slabs with piezoelectric patches attached to their surfaces were chosen as the research objects and the Electromechanical Impedance method (EMI) was adopted for research. Five kinds of damage condition were designed to test the impedance values at different frequency bands. Consistent rules are found by calculation and analysis. Both the root mean square deviation (RMSD) and the correlation coefficient deviation (CCD) damage indices are capable of detecting the structural damage. The newly proposed damage index Ry/Rx can also predict the changes well. The numerical and experimental studies verify that the Electromechanical Impedance method can accurately predict changes in the amount of damage in reinforced concrete slabs. The damage index changes regularly with the distance of damages to the sensor. This relationship can be used to determine the damage location. The newly proposed damage index Ry/Rx is accurate in determining the damage location.

[Experimental studies on chitosan blend membrane as scaffold carriers for cultivating rabbit corneal endothelial cells in vitro].

Un-transfected rabbit corneal endothelial cells (RCECs) were cultivated, using chitosan blend membrane 4ha (chitosan-hyaluronic acid), 631ha (chitosan-hyaluronic acid) and 631s (chitosan-chondroitine sulfate) as scaffold carriers. Their biocompatibilities were studied in regard to cell adherence, morphological changes, growth status and monolayer forming abilities. The results indicated that RCECs cultivated on 4ha and 631ha carriers tended to be aggregated and even desquamated to some extent in local areas, and even more severely on 631ha carrier. And the RCECs cultivated on 631ha carrier could form almost a monolayer 48h later, and those on 4ha carrier could not. Contrarily, the RCECs cultivated on 631s carrier were evenly distributed and were in good status of growth with a good adherence and fibroblast-like morphology which could form almost a monolayer 48h later. And a complete monolayer was formed and was tightly attached to the 631s carrier 72h later. From the above results, it can be concluded that 631s carrier is most probably an ideal scaffold carrier for RCEC cultivation. 631s carrier may have the potential for use in the development of tissue-engineered rabbit corneal endothelium.

Establishment and characterization of a novel untransfected corneal endothelial cell line from New Zealand white rabbits.

PURPOSE: To establish and characterize a novel untransfected corneal endothelial cell line from New Zealand white rabbits (NRCE cell line) for studies on corneal endothelial cells. METHODS: Primary culture was initiated with a pure population of NRCE cells from corneal endothelia by successive detachment and reattachment procedure of different durations, and cultured in 20% fetal bovine serum-containing DMEM/F12 media with several supplements. The cell line was characterized by chromosome analysis, fluorescence immunoassay and reverse transcription PCR. The tumorigenic potency of the cell line was examined by subcutaneous inoculation to nude mice. The biocompatibility of the cell line to denuded amnions was examined with routine microscopic and electron microscopic techniques. RESULTS: NRCE cells in primary culture proliferated to confluency in 25 days and has been subcultured to passage 227 to date. The novel NRCE cell line, with a steady growing rate in 20% bovine calf serum (BCS)-containing DMEM/F12 medium and a population doubling time of 40.32 h at passage 191, has been established. NRCE cells exhibited chromosomal aneuploidy but their modal chromosome number was still 44. The results of gene expression patterns of marker proteins and membrane transport proteins, combined with immunofluorescent localization patterns of cell junction proteins, indicated that NRCE cells retained normal corneal endothelial characteristics and normal expression pattern of functional proteins. Furthermore, these cells, without any tumorigenic potency, had excellent biocompatibility to denuded amnions in 20% BCS-containing DMEM/F12 medium, and formed confluent cell sheets attached tightly to denuded amnions. CONCLUSIONS: These results suggest that a novel untransfected NRCE cell line established here maintains normal corneal endothelial characteristics and potencies to form normal cell junctions and perform normal functions of transmembrane transport.