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Oxidation of graphite and subsequent exfoliation leads to single layer graphene oxide (GO). One of the key structural features of GO is the presence of different kinds of defects that dictates their various physical and chemical properties. Molecular dynamics simulations with ReaxFF force fields have been widely used to generate realistic models of GO. In these simulations, the extent and distribution of the defects are varied by changing the initial oxygen (O)/carbon (C) ratio while the defect density is often measured by the total number of non-graphitic carbon (non-gC) atoms. Our calculations suggest that this parameter overestimates the defect densities at low O/C ratio. Herein, we employ the relative area of the defects as an alternative metric to gauge the defect density. Being exclusive to the defects and sensitive to the structural irregularities, this metric works well at both low and high defect densities. In another example, we consider the reduction of GO to reduced graphene oxide (rGO) for different O/C ratios, where the decrease in the number of non-gC atoms is associated with the formation of comparatively larger defects. Hence, it is unclear whether the extent of reduction in the defect density (if at all) should vary monotonically with the O/C ratio. The defect area, unlike the count of the non-gC atoms, mirrors this ambiguity and the change with respect to O/C ratio is not strictly monotonic. Additionally, we also investigate the dependence of the defect distribution and defect area on the size of the simulation cell.

Objective: Study the repair effect of tilapia collagen on acute wounds, and the effect on the expression level of related genes and its metabolic direction in the repair process.Materials and methods: After the full-thickness skin defect model was constructed in standard deviation rats, the wound healing effect was observed and evaluated by means of characterization, histology, and immunohistochemistry. RT-PCR, fluorescence tracer, frozen section and other techniques were used to observe the effect of fish collagen on the expression of related genes and its metabolic direction in the process of wound repair.Results: After implantation, there was no immune rejection reaction, fish collagen fused with new collagen fibers in the early stage of wound repair, and was gradually degraded and replaced by new collagen in the later stage. It has excellent performance in inducing vascular growth, promoting collagen deposition and maturation, and re-epithelialization. The results of fluorescent tracer showed that fish collagen was decomposed, and the decomposition products were involved in the wound repair process and remained at the wound site as a part of the new tissue. RT-PCR results showed that, without affecting collagen deposition, the expression level of collagen-related genes was down-regulated due to the implantation of fish collagen.Conclusion: Fish collagen has good biocompatibility and wound repair ability. It is decomposed and utilized in the process of wound repair to form new tissues.

The goal of this research is to investigate the correlation between the piezomagnetic field and the defect size in ferromagnetic steels. Specimens of 30Cr steels were machined into standard bars with circular holes of different sizes in the centre. Tensile tests were carried out to measure the piezomagnetic field on the surface of the defective specimens. The variations of the piezomagnetic parameters with the tensile loads were studied and two evaluation parameters were defined to characterise the defect area. Analysis results showed that the evaluation parameters vary exponentially with the defect area. Quantitative algorithms were proposed to characterise the correlation between the evaluation parameters and the defect area. The results obtained in this research provide a method to quantitatively identify the defect size in ferromagnetic steels based on the piezomagnetic field measurement. [ABSTRACT FROM AUTHOR]

Purse‐string suture (PSS) and full‐thickness skin graft (FTSG) are two different approaches to the closure of circular skin defects. In this study, we compare the feasibility and the aesthetic outcome of these two techniques in high operatory risk non‐melanoma skin cancer (NMSC) patients. We performed a retrospective study on 65 patients, treated with PSS or FTSG, and evaluated after a minimum follow‐up of 6 months. The post‐surgery assessment was based on the Vancouver scar scale (VSS) and differences in terms of defect areas, operative and healing times were performed both with parametric and nonparametric tests. Operative times in PSS were significantly lower than those needed for FTSG, without perioperative adverse events; PSS required a waiting time before removing the suture greater than FTSG. After surgery, PSS resulted in a median defect area reduction of 73%. No significant differences were found in the median value for VSS in the two groups. Based on our clinical experience, the PSS advantages in terms of feasibility, rapidity of execution, and mean defect area reduction were confirmed. So, this technique seems to be appropriate for fragile patients affected by NMSC, that cannot hold long surgical sessions. [ABSTRACT FROM AUTHOR]

A novel method for positioning and operating needle-like cryo-surgical probes in 2D convex target areas is presented. The method is based on the recorded dynamic performance of a single probe, termed "unit circle," (UC) embedded in a semi-infinite, tissue-like medium. Up to 15 cryo-probes, inserted into the same depth, are operated uniformly for 2-5?min. A predetermined number of probes are rearranged inside the target area until a "tight configuration" is obtained. The probes are initially arranged inside the target area such that the "lethal temperature" circles produced by them are tangent to its contour and to both adjacent lethal temperature circles. Subsequently, all probes are repositioned inwardly, each at a specific distance that depends on the local radius of curvature of the target area. Resulting total "defect areas"--internal and external--for a number of demonstrated cases, amounted to between 2.5% and 7.6% of the target area. The lower values of the defect areas were obtained with increasing numbers of inserted probes coupled with shorter operating times. Possible freezing damages to regions beyond the target area were reduced by up to about 30% for these cases. Similar results were obtained for a case of combined convex-concave target area, treated with additional, externally inserted, heating probes. [ABSTRACT FROM AUTHOR]

A soft and highly directive, proximity-coupled split-ring resonator fabricated with a liquid alloy, copper and polydimethylsiloxane (PDMS) is presented. The same was designed for sensing osteogenesis of calvarial bone. As dielectric properties of bone grafts in ossifying calvarial defects should change during the osteogenesis process, devices like this could monitor the gradual transformation of the defect into bone by differentiating changes in the dielectric properties as shifts in the resonance frequency. Computational Software Technology (CST) Microwave Studio®-based simulation results on computational head models were in good agreement with laboratory results on head phantom models, which also included the comparison with an in-vivo measurement on the human head. A discussion based on an inductive reasoning regarding dynamics’ considerations is provided as well. Since the skin elasticity of newborn children is high, stretching and crumpling could be significant. In addition, due to typical head curvatures in newborn children, bending should not be a significant issue, and can provide higher energy focus in the defect area and improve conformability. The present concept could support the development of soft, cheap and portable follow-up monitoring systems to use in outpatient hospital and home care settings for post-operative monitoring of bone healing after reconstructive surgical procedures.

A comprehensive numerical analysis for a lead‐free perovskite solar cell (PSC) has been carried out using device simulation software. Various factors affecting the solar cell's performance have been investigated for device optimisation; more specifically optimisation of device buffer and the absorber layer. Different design strategies for optimising the power conversion efficiency (PCE) through solar cell capacitance simulator numerical simulation have been proposed. Enumerated study of the effects of thickness, band gap, light illumination and defect area on the PCE is carried out. In this study, two types of configurations (La0.7 Sr0.3 MnO3 /zinc oxide and La0.7 Sr0.3 MnO3 /Nb:SrTiO3) are simulated which gives highest conversion efficiency of 11% at 600 nm and 32% at 350 nm wavelength. The impact of defect density has also been addressed to analyse the performance of cell module. The optimisation of device parameters pinpoints enormous potential for the enhancement of conversion efficiency of high‐efficient PSC. [ABSTRACT FROM AUTHOR]

Background: It is an acceptable concept that the ventral hernia defect area will increase with a rise in intra-abdominal pressure (IAP). The literature lacks the evidence about how much this increase is in vivo. The aim of this study was to objectively measure the change in the ventral hernia defect area with increasing intra-abdominal pressure.Methods: In a prospective study of laparoscopic ventral hernia repair, the area of hernia defect was measured from inside the abdomen using a sterile paper ruler. The horizontal (width) and vertical (length) measurements of the defect were taken at two pressure points: (IAP = 8 mmHg) and (IAP = 15 mmHg). The hernia defect area was calculated as an oval shape using a standard formula.Results: Eighteen consecutive patients with a ventral hernia were included in this study (8 males: 10 females). Median age was 60 years (30-81), body mass index (BMI) was 29.9 (22.6-37.6). Changing the IAP significantly, (P < 0.001) changed the values of horizontal and vertical measurements, and the calculated area of the ventral hernia defect. The median calculated defect area, as an oval shape, was 5.6 cm(2) (Q1-Q3 = 3.5-15.5) and 6.9 cm(2) (Q1-Q3 = 4.5-18.7) at 8 and 15 mmHg IAP, respectively. The calculated area of mesh required to cover the defect with a 5 cm overlap increased by a median of 5% (Q1-Q3 = 3-6%). The change in defect area did not differ significantly between obese and non-obese patients (P = 0.5).Conclusions: Dynamic, rather than static, measurements of ventral hernia area during laparoscopy provide a simple way of in vivo objective measurement that helps the surgeon choose the appropriate area of mesh. When choosing mesh area, we support the trend toward a larger overlap of at least 5 cm if less precise methods of measuring defect area are been used. [ABSTRACT FROM AUTHOR]

The fishtail in head and tail of the slabs was studied during V-H hot rolling process. With the application of ANSYS/LS-DYNA, simulation analysis was used to research this process. The various factors which have a great influence on fishtail shapes were analysed, such as initial width, initial thickness, radius of the edger roll and horizontal roll, edging draught, horizontal reduction rate, and friction coefficient of the surface. Then the curves that can describe the shapes were obtained. After a certain time of self-learning, the optimized curves were given out. At last, through the fitting of the simulation test results, the math models for the area of fishtail defect changing with the presented factors were received. The experimental results show that the accuracy of the prediction for the fishtail shapes is more than 95%. With the application of the prediction for the fishtail shapes and the area of the fishtail defect, the loss rate of the slab is decreased by about 0.1%. [ABSTRACT FROM AUTHOR]

Objectives: It was our aim to evaluate whether the defect area plays a crucial role in successful device closure of atrial septal defects (ASDs). Methods: The long and short diameters of the defect were measured on en-face images. The defect area was then measured by planimetry. The device size compared to the defect length and defect area was analyzed in each group. Results: There were 22 patients in the circular group and 45 patients in the noncircular group. The defect area did not differ between the groups (201.6 ± 107.1 vs. 245.6 ± 127.6 mm2). Although the length between the device size and the long diameter differed between the groups (3.4 ± 2.0 vs. 0.8 ± 3.7 mm; p = 0.003), there was no difference in the ratio of the device area compared to the defect area, which was constant even in the noncircular defect (1.73 ± 0.41 vs. 1.72 ± 0.53 mm2; p = 0.947). The device size was positively correlated with the defect area (p < 0.01). Conclusion: The defect area measured by planimetry on en-face images might be useful in selecting the device size for transcatheter closure of ASDs. © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Guided wave tomography is a very attractive technique for online nondestructive inspection and structural health monitoring (SHM). RAPID (Reconstruction Algorithm for the Probabilistic Inspection of Damage) is an effective tomography algorithm for detecting, locating and imaging defect in plate-like structures. However, it is not complete for evaluating a damage area, because of the insufficient guideline for the shape factor called β. The work presented here introduces the calculation of shape factor for the evaluation of a damage area, as well as the variable β parameter technique to correct a damage shape. Experiment is performed using the guided wave pulse-echo method to find the length of damage on a ray path. In the images resulting from the advanced RAPID algorithm, the defect area and shape showed good agreement. The different shapes of the defect require further study. [ABSTRACT FROM AUTHOR]

A radiographic study was conducted to evaluate the effect of pelvic rotation and of simulated dorsal acetabular rim (DAR) remodeling on the radiographic appearance of the dorsal acetabular edge (DAE). The DAE is the line connecting the cranial and caudal rims of the acetabulum when viewing a pelvic radiograph made with the dog in the ventrodorsal position with the hind limbs extended. In this study, it was hypothesized that the DAE would change with pelvic rotation and simulated DAR damage. Ventrodorsal radiographs of eight canine pelves were made at 0°, 5°, and 10° of left and right pelvic rotation over its longitudinal axis. These radiographs were repeated following removal of 2, 4, and then 6 mm of bone from the right DAR of each pelvis. The ratio of acetabular width to maximum depth of the DAE was calculated. The area between the DAE and a straight line connecting the cranial and caudal acetabular rims was measured digitally. The DAE depth and area changed with pelvic rotation, and with increasing simulated DAR damage. A linear relationship between the obturator foramina width ratio and pelvic rotation allowed estimation of the degree and direction of pelvic rotation. Equations were developed from the data to assist with the estimation of the amount of DAR remodeling on a clinical radiograph. [ABSTRACT FROM AUTHOR]

This paper exploits a resistance–capacitance (RC) model of transient heat conduction for estimation of defect depth, and more significantly of the defect area, from single point surface temperature evolutions over the defect and non-defect regions of material subjected to step heating. For the initial time behaviour of the surface temperature, a distributed RC model has been presented and analysed for estimation of defect depth and area. In contrast, a lumped RC model forms the basis for obtaining an analytical expression for defect area from the later part of the surface temperature evolution. The derived analytical expression estimates the defect area from the defect depth, the saturation value of the absolute thermal contrast and the slopes of the initial and final surface temperature evolution. The presented method does not require knowledge of material thermal properties or the value of the incident heat flux for estimation of defect parameters. The method has been validated by estimating the parameters of defects of various sizes and at different depths from experimental and simulated surface temperature evolutions. [Copyright &y& Elsevier]

The influence of processing parameters in laser engineered net shaping (LENS) on the properties of 316L stainless steel and titanium carbide (TiC) composite coating was studied. The key processing parameters were laser power, scanning speed, TiC powder ratio, and powder feed rate. Mathematical models were developed to investigate the micro-hardness, wear volume, and defect area of the coating. The accuracy of the models was examined by analysis of variance and experimental validation. Results showed that micro-hardness was positively correlated with TiC powder ratio. Increasing TiC powder ratio could reduce the wear volume. In addition, the wear volume displayed an increase then decrease with increasing laser power and decreasing scanning speed. Both scanning speed and TiC powder ratio showed a recognizable impact on the defect area. Reducing the scanning speed and TiC powder ratio can effectively reduce the defect area. The targets for the processing parameters optimization were set to maximize micro-hardness, minimize wear volume, and defect area. The difference between the model prediction value and experimental validation result for micro-hardness, wear volume, and defect area were 0.46%, 4.54%, and 8.82%, respectively. These results provide guidance for the LENS processing parameters optimization in controlling and predicting of 316L/TiC composite coating properties. [ABSTRACT FROM AUTHOR]