Bending Of Film Research Articles

Safety and efficacy of sublaminar bands and Ponte osteotomies in rigid deformity: preliminary results in a prospective series of 20 neuromuscular scoliosis patients.

This prospective cohort study investigated radiographic outcomes and complications over time in patients with rigid neuromuscular scoliosis treated with sublaminar bands and Ponte osteotomies. Twenty consecutive patients with neuromuscular scoliosis were treated with sublaminar bands in addition to Ponte osteotomies at and around the apex of the deformity and prospectively included. All curves were rigid, with less than 30% reduction on preoperative bending films. Cobb angle, pelvic obliquity, and shoulder obliquity were significantly corrected (P<0.01). Normal thoracic kyphosis was achieved for 85% of patients at the last follow-up. No intraoperative complications were observed. The association between Ponte osteotomies and sublaminar bands appears to be efficient for the management of rigid neuromuscular deformities in children and adolescents. No death and no permanent neurological impairment, as well as no sublaminar bands associated events were recorded.

Rigorous derivation of active plate models for thin sheets of nematic elastomers

In the context of finite elasticity, we propose plate models describing the spontaneous bending of nematic elastomer thin films due to variations along the thickness of the nematic order parameters. Reduced energy functionals are deduced from a three-dimensional description of the system using rigorous dimension reduction techniques, based on the theory of Γ-convergence. The two-dimensional models are non-linear plate theories, in which deviations from a characteristic target curvature tensor cost elastic energy. Moreover, the stored energy functional cannot be minimised to zero, thus revealing the presence of residual stresses, as observed in numerical simulations. Three nematic textures are considered: splay-bend and twisted orientations of the nematic director, and a uniform director perpendicular to the mid-plane of the film, with variable degree of nematic order along the thickness. These three textures realise three very different structural models: one with only one stable spontaneously bent configuration, a bistable model with two oppositely curved configurations of minimal energy, and a shell with zero stiffness to twisting.

Do the disc degeneration and osteophyte contribute to the curve rigidity of degenerative scoliosis?

BackgroundThe factors associated with lateral curve flexibility in degenerative scoliosis have not been well documented. Disc degeneration could result in significant change in stiffness and range of motion in lateral bending films. The osteophytes could be commonly observed in degenerative spine but the relationship between osteophyte formation and curve flexibility remains controversial. The aim of the current study is to clarify if the disc degeneration and osteophyte formation were both associated with curve flexibility of degenerative scoliosis.MethodsA total of 85 patients were retrospectively analyzed. The inclusion criteria were as follow: age greater than 45 years, diagnosed as degenerative scoliosis and coronal Cobb angle greater than 20°. Curve flexibility was calculated based on Cobb angle, and range of motion (ROM) was based on disc angle evaluation. Regional disc degeneration score (RDS) was obtained according to Pfirrmann classification and osteophyte formation score (OFS) was based on Nanthan classification. Spearman correlation was performed to analyze the relationship between curve flexibility and RDS as well as OFS.ResultsModerate correlation was found between RDS and curve flexibility with a Spearman coefficient of −0.487 (P = 0.009). Similarly, moderate correlation was observed between curve flexibility and OFS with a Spearman coefficient of −0.429 (P = 0.012). Strong correlation was found between apical ROM and OFS compared to the relationship between curve flexibility and OFS with a Spearman coefficient of −0.627 (P < 0.001).ConclusionsBoth disc degeneration and osteophytes formation correlated with curve rigidity. The pre-operative evaluation of both features may aid in the surgical decision-making in degenerative scoliosis patients.

Effects of silver nanowire concentration on resistivity and flexibility in hybrid conducting films

Silver nanowires (AgNWs) are attracting much attention for their potential use in flexible or stretchable conducting film applications and in printed and wearable electronics devices. In this study, we fabricated flexible hybrid conducting films using different concentrations of composite silver ink prepared by mixing AgNW and silver nanoparticle (AgNP) materials, which we synthesized, for flexible interconnects and electrodes. These films had low resistivities at low sintering temperatures. Furthermore, they were also stable to tensile bending in comparison with a pure AgNP film. We found that there is an optimum concentration of AgNWs in the composite silver ink for the hybrid conducting film to have a lower resistivity even with sintering below 100 °C. We also found that the reason why hybrid conducting films are stable to repeated tensile bending is that AgNWs maintain functional conducting paths by making bridges that compensate for cracks between AgNPs during film bending.

High quality transparent conductive Ag-based barium stannate multilayer flexible thin films

Transparent conductive multilayer thin films of silver (Ag)-embedded barium stannate (BaSnO3) structures have been deposited onto flexible polycarbonate substrates by magnetron sputtering at room temperature to develop an indium free transparent flexible electrode. The effect of thicknesses of Ag mid-layer and barium stannate layers on optical and electrical properties were investigated, and the mechanisms of conduction and transmittance were discussed. The highest value of figure of merit is 25.5 × 10−3 Ω−1 for the BaSnO3/Ag/BaSnO3 multilayer flexible thin films with 9 nm thick silver mid-layer and 50 nm thick barium stannate layers, while the average optical transmittance in the visible range from 380 to 780 nm is above 87%, the resistivity is 9.66 × 10−5 Ω · cm, and the sheet resistance is 9.89 Ω/sq. The change rate of resistivity is under 10% after repeated bending of the multilayer flexible thin films. These results indicate that Ag-based barium stannate multilayer flexible thin films can be used as transparent flexible electrodes in various flexible optoelectronic devices.

Discretely Supported Dry Adhesive Film Inspired by Biological Bending Behavior for Enhanced Performance on a Rough Surface.

Biologically inspired dry adhesion has recently become a research hot topic because of its practical significance in scientific research and instrumental technology. Yet, most of the current studies merely focus on borrowing the concept from some finer biological contact elements but lose sight of the foundation ones that play an equally important role in the adhesion functionality. Inspired by the bending behavior of the flexible foundation element of a gecko (lamellar skin) in attachment motion, in this study, a new type of dry adhesive structure was proposed, wherein a mushroom-shaped micropillar array behaving as a strongly adhesive layer was engineered on a discretely supported thin film. We experimentally observed and analytically modeled the structural deformation and found that the energy penalty could be largely reduced because of the partial shift from pillar bending to film bending. Such behavior is very analogous in functionality to the lamellar skin in a gecko's pads and is helpful in effectively limiting the damage of the contact interface, thus generating enhanced adhesion even on a rough surface.

Structure-property relationships in ZnO:Al-hydroquinone films grown on flexible substrates by atomic and molecular layer deposition

ZnO:Al-hydroquinone (AZO-HQ) films were grown on poly(ethylene terephthalate) (PET) substrates by atomic and molecular layer deposition (ALD/MLD). Organic contents in the films varied from 0 to ≈4vol%. Structural and electrical investigations of the films were carried out. Electrical measurements were performed under film bending. The piezoresistive effect in the films with different organic contents was observed and described. Critical bend radius, critical strain, and piezoresistive coefficient values were related to the film microstructure. The piezoresistivity was found to be enhanced for the deformations of ZnO crystallites along the a-axis whereas higher critical strain was influenced by long crystallites oriented in the deformation direction. AZO-HQ films having 2vol% of the organic content are characterized by the lowest critical bend radius and the highest critical strain among the films under study.

Predictors for Postoperative Shoulder Balance in Lenke 1 Adolescent Idiopathic Scoliosis: A Prospective Cohort Study

Study DesignProspective cohort. ObjectivesTo determine the predictors of the shoulder balance after main thoracic (MT) fusion in patients with Lenke 1 adolescent idiopathic scoliosis (AIS). Summary of Background DataImbalanced shoulders are a major cause of dissatisfaction in AIS patients. In Lenke 1 curves, MT curve fusion is supposed to lead to spontaneous correction of the proximal thoracic (PT) curve and thereby promote shoulder balance. However, this is not always observed. MethodsFifty-two Lenke 1 AIS patients who underwent MT fusion by a posterior approach were prospectively evaluated preoperatively, immediately postoperatively and two years after the surgical procedure. The shoulder balance was determined using the biacromial angle. The clinical results were examined for their correlation with several radiographic measurements. ResultsSpontaneous correction of the PT Cobb angle after MT fusion was noted in 52% of cases, similar to that observed on preoperative bending films. A total of 51% of patients had unbalanced shoulders before surgery (right side higher). Two years after surgery, 30.77% showed unbalanced shoulders (p < .001). However, 17.1% of patients presented with a higher left shoulder, a reversion of the initial deformity. This phenomenon was more common among the patients with mild or no shoulder asymmetry (biacromial angle inferior to 1°) before surgery (p < .001). It was also determined that for each degree measured for the clavicle angle, there was an elevation of 0.14° for the ipsilateral shoulder. ConclusionsIn Lenke 1 cases with higher right shoulder and absence of abnormalities in the sagittal plane view, the correction of the main right thoracic curve could be enough to balance the shoulders. No correlation was found between shoulder balance and the amount of correction of the PT and MT curves.

Out-of-plane bending of carbon nanotube films

Carbon nanotube (CNT) films are easily bent in their applications because the dimension in thickness is much smaller than the other two dimensions. Therefore, it is of great importance to understand the bending mechanisms and to predict the bending stiffness of CNT films. In this paper, the out-of-plane bending stiffness of CNT films is studied based on energy analysis and validated by finite element simulations. It is found that the pure bending of CNT films consists of two types of deformation, i.e., the out-of-plane deformation and the in-plane deformation, which both contribute to the bending stiffness. Moreover, the bending stiffness threshold of CNT films, i.e., the critical CNT concentration to judge whether or not the film can bear bending load, is revealed. This threshold is different from the in-plane stiffness threshold but equivalent to the electrical percolation threshold because the inter-tube interactions can only transfer out-of-plane moment. The bending stiffness threshold as well as the two in-plane stiffness thresholds divide the bending stiffness behavior of CNT films into four stages, which is described by a simple piecewise analytical expression based on the energy theorems and superposition method. Besides, this study shows that the CNT curliness and inter-tube connection saturation can influence the bending stiffness by affecting the thresholds. The method and results of this study can be extended to other networks constructed by nanotubes and/or nanowires as well.

A flexible and wearable terahertz scanner

Imaging technologies based on terahertz (THz) waves have great potential for use in powerful non-invasive inspection methods. However, most real objects have various three-dimensional curvatures and existing THz technologies often encounter difficulties in imaging such configurations, which limits the useful range of THz imaging applications. Here, we report the development of a flexible and wearable THz scanner based on carbon nanotubes. We achieved room-temperature THz detection over a broad frequency band ranging from 0.14 to 39 THz and developed a portable THz scanner. Using this scanner, we performed THz imaging of samples concealed behind opaque objects, breakages and metal impurities of a bent film and multi-view scans of a syringe. We demonstrated a passive biometric THz scan of a human hand. Our results are expected to have considerable implications for non-destructive and non-contact inspections, such as medical examinations for the continuous monitoring of health conditions. A flexible and wearable terahertz scanner based on carbon nanotubes is demonstrated at room temperature over a frequency range 0.14 THz to 39 THz. The terahertz photothermoelectricity is enhanced by using different electrode materials.

Simultaneous retardation compensation during bending of plastic film coated with a polymer layer of opposite birefringence.

We proposed a method of eliminating the bending-induced retardation of a plastic film by coating it with a polymer layer with an opposite birefringence. We coated a polystyrene (PS) or a poly(methyl methacrylate) (PMMA) layer on a polycarbonate (PC) plastic film. The bare PC film is composed of main-chain-type polymers and showed an increase in retardation with bending. The main-chains of the PC polymer are reoriented along the circular arc direction during bending, resulting in a positive birefringence. In contrast, the 11 wt. % PS-coated and the 19 wt. % PMMA-coated PC films showed minimal change in the retardation regardless of the radius of curvature. The PS and the PMMA polymers are of the side-chain-type, and the side-chains were aligned perpendicular to the circular arc direction during bending, resulting in a negative birefringence. Consequently, the bending-induced retardation of the PC film can be compensated by the PS or the PMMA layer during bending of the film. This method of compensating for the bending-induced retardation of the plastic film can be useful for flexible display applications.

Analysis of the rate of orthopaedic contribution of strong halo-femoral traction in the treatment of severe rigid idiopathic scoliosis

Objective To analyze the rate of orthopaedic contribution of strong halo-femoral traction in the treatment of severe rigid idiopathic scoliosis and discuss its meaning. Methods All of 27 cases of severe rigid idiopathic scoliosis patients treated with strong halo-femoral traction, hospitalized in our department from December 2008 to August 2010, were retrospectively analyzed. All patients underwent preoperative Halo-femoral traction. After 2-4 weeks' traction, one-stage posterior instrumentation and fusion was performed with intraoperative traction. The Cobb angles in coronal plane of the major curve before surgery, on bending film, on fulcrum film, after traction and immediately after surgery were measured. The rate of absolute and relative contribution of every orthopaedic element (Bending, fulcrum, traction, surgery) were compared. Results The duration of follow-up was (51.8±7.7) months on average (range, 40-68 months). The mean coronal Cobb angle of major curve were 105.1°±11.1°(88°-131°), the mean coronal Cobb angle of major curve on Bending film were 84.6°±12.6°(69°-115°), and the mean coronal Cobb angle of major curve on fulcrum film were 75.8°±10.5°(62°-97°). The mean coronal Cobb angle of major curve after traction were 66°±11.7°(50°-90°). The mean coronal Cobb angle of major curve after posterior surgery were 43.1°±8.8°(23°-58.1°). The mean correction rate after traction was 37.5%±6.4%(28.6%-54%) ,the correction rate after surgery was 57.2%±6.7% (51.5%-67.7%) on the aver-age. The rate of absolute and relative contribution of Bending were 19.8%±4.4%(12.2%-28.1%) 、33.8%±7.6%(21.4%-46.2%). The rate of absolute and relative contribution of fulcrum were 8.2%±4.3%(2.9%-24.8%) 、13.3%±6.9%(1.1%-35.5%). The rate of absolute and relative contribution of traction were 9.5%±4.7%(2%-20%) 、16.2%±8.2%(3.4%-36.5%). The rate of absolute and relative contribution of surgery were 21.7%±7.0% (5.9%-37.2%) 、36.7%±10.7%(11.6%-55.6%). In the process of traction one patient had the right little finger numb and two other patients experienced stiff knee and hip, there were no other related complications occurring in the process of traction. No death or respiratory failure or paralysis occurred intra- and post-operatively. No screw or rod fracture was found during the follow-up. Conclusion The study indicates that the XiangYa gradual strong halo-femoral traction makes relatively prominent role in the treatment of severe rigid idiopathic scoliosis, meanwhile makes the correction diversification, reduces the risk of operation, effectively avoids many unnecessary VCR, and is a safe and effective way for the treatment of severe rigid idiopathic scoliosis. Key words: Scoliosis; Traction; Spinal Fusion

Prediction of delamination of steel-polymer composites using cohesive zone model and peeling tests

This study reports on the prediction of the delamination of steel-polymer composites. To characterize the adhesive properties from peeling tests, a simple model was derived based on peeling mechanics, in particular considering plastically dissipated energy of polymer film due to bending. Peeling tests were performed at two angles so that the adhesive properties were determined in both normal and tangential directions. Then, peel strength at arbitrary angle was predicted and compared with experiments, showing that the peel strength at only two angles and peeling mechanics considering the bending of polymer film can accurately describe the adhesive properties of steel-polymer interface. Finally, finite element simulations based on the cohesive zone model were performed to predict the delamination between steel-polymer sandwich composites, demonstrating the validity of cohesive zone model equipped with necessary properties determined using peeling tests and the developed model in this study.

Mechanical Characterization of Ultralow Interfacial Tension Oil-in-Water Droplets by Thermal Capillary Wave Analysis in a Microfluidic Device.

Measurements of the ultralow interfacial tension and surfactant film bending rigidity for micron-sized heptane droplets in bis(2-ethylhexyl) sodium sulfosuccinate-NaCl aqueous solutions were performed in a microfluidic device through the analysis of thermally driven droplet interface fluctuations. The Fourier spectrum of the stochastic droplet interface displacement was measured through bright-field video microscopy and a contour analysis technique. The droplet interfacial tension, together with the surfactant film bending rigidity, was obtained by fitting the experimental results to the prediction of a capillary wave model. Compared to existing methods for ultralow interfacial tension measurements, this contactless, nondestructive, all-optical approach has several advantages, such as fast measurement, easy implementation, cost-effectiveness, reduced amount of liquids, and integration into lab-on-a-chip devices.

VOC-Induced Flexing of Single and Multilayer Polyethylene Films As Gas Sensors.

The differential swelling and bending of multilayer polymeric films due to the dissimilar uptake of volatile organic compounds (VOCs; n-hexane, limonene) in the different layers was studied. Motions of thin polyethylene films triggered by the penetrant were investigated to learn more about how their deformation is related to VOC absorption. Single layers of metallocene or low-density polyethylene, and multilayers (2-288 layers) of these in alternating positions were considered. Single-, 24-, and 288-layer films displayed no motion when uniformly subjected to VOCs, but they could display simple curving modes when only one side of the film was wetted with a liquid VOC. Two-layer films displayed simple bending when uniformly subjected to VOCs due to the different swelling in the two layers, but when the VOC was applied to only one side of the film, more complex modes of motion as well as dynamic oscillations were observed (e.g., constant amplitude wagging at 2 Hz for ca. 50 s until all the VOC had evaporated). Diffusion modeling was used to study the transport behavior of VOCs inside the films and the different bending modes. Finally a prototype VOC sensor was developed, where the reproducible curving of the two-layer film was calibrated with n-hexane. The sensor is simple, cost-efficient, and nondestructive and requires no electricity.

Selection of Lowest Instrumented Vertebra in the Management of Thoracolumbar and Lumbar Adolescent Idiopathic Scoliosis using Pedicle Screw Instrumentation

Introduction The aim of surgical treatment for adolescent idiopathic scoliosis (AIS) is correction of the three dimensional deformity, achievement of stability and preservation of as many distal motion segments as possible. In Thoracolumbar/ Lumbar adolescent idiopathic scoliosis (TL/L AIS) correction of C-shaped coronal curve into S-shaped saggital curve is a considerable challenge to a spine surgeon. In this regard, selection of Lowest Instrumented Vertebra (LIV) is of particular importance and remains controversial in literature. We conducted a retrospective study involving Lenke V patients to determine the exact distal fusion level (LIV) in the management of thoracolumbar/lumbar adolescent idiopathic scoliosis (TL/L AIS) using pedicle screw instrumentation. Material and Methods Analysis of radiographic parameters of 32 TL/L AIS was done. The patients were grouped according to the Lowest Instrumented Vertebra; Group I (fusion to L3, n = 25) and Group II (fusion to L4, n = 7). The Group I was subdivided into Group IA (L3 crosses the mid-sacral line with rotation of less than grade II on bending films, n = 14) and Group IB (L3 does not cross the mid-sacral line or rotation is grade II or more on bending films, n = 11). All of the patients in the Group II had the same location and rotation of L3 in bending films as that of patients in the Group IB. Patients with lowest instrumented vertebral tilt (LIVT) of more than 10° or coronal balance of more than 15 mm were considered to have unsatisfactory results. Results In these 3 groups, there was a significantly lesser correction in the TL/L curve and LIVT in the Group IB. Unsatisfactory results were obtained in 1 patients (7.1%) of the Group IA, in 7 patients (63.3%) of the Group IB, and in 1 patient (12.5%) of the Group II, which was found to be statistically significant. Conclusion In TL/L AIS patients undergoing treatment with pedicular screw instrumentation, the curve can be fused to L3 with good radiographic outcomes when L3 crosses the mid-sacral line with rotation of less than grade II on bending films. Otherwise, L4 should be selected as the Lowest Instrumented Vertebra.

Electrical Stabilities of In2O3-ZnO-SnO2 (IZTO) Films Against the External Stresses

ABSTRACTThe (In2O3)77.34(ZnO)x(SnO2)22.66-x (denote to IZTO-2) films with x = 13, 15, 17, 19 wt.% were prepared on PET film with a 100-nm-thick SiO2 buffer layer by using RF-magnetron sputtering method, and their electrical stabilities were tested under various external stresses such as moist heat, temperature fluctuations and bending of substrate films. The lowest resistivity of 4.8 × 10−4 Ω•cm was observed in the IZTO-2 film of x = 17 wt.% which also had such good properties as high electrical stability, surface uniformity, and high conductivity as compared with those of another (In2O3)90(ZnO)7(SnO2)3 (IZTO-1) film. These results suggest that the optimum starting composition for IZTO film with high quality as a flexible transparent conducting oxide(TCO) film is In2O3 : ZnO : SnO2 = 77.34 : 17 : 5.66 wt.%. The electrical stability of the optimum IZTO-2 film was greatly improved because the SiO2 buffer layer introduced between IZTO thin film and PET substrate acted as a blocking barrier to water vapour and organic solvents diffusing from the PET film and also as a buffer layer withstanding the bending damage.

Flexibility of the Indium Tin Oxide Transparent Conductive Film Deposited onto the Plastic Substrate

In this study, we utilize the RF magnetron sputtering system to deposit the indium tin oxide (ITO) conductive transparent film with low resistivity and high light transmittance to the polyethylene tetephthalate (PET) plastic substrate and measure the film's bending property and reliability at different tensile/compressive strain bending curvatures as well as the flexibility after cycling bending. The results show that the critical curvatures corresponded to the significant increase in the resistance of the 150 nm-thick ITO film deposited onto the PET substrate under tensile and compressive stress areO 14.1 mm and 5.4 mm, respectively. By observing the film's surface crack and morphology, we can further discover that the critical curvature of the crack generated when the film is bent is quite consistent with the critical curvature at which the conductivity property degrades, and the film can withstand a higher compressive strain bending. In addition, the resistance and adhesion behavior of the film almost is unchanged after cycling bent for 1000 times with the curvature below the critical curvature.

Faulty radiographs: A cross-sectional analysis among dental college students in Namakkal District, Tamil Nadu, India.

Aim:The aim of this study was to assess the ability of taking and processing of intraoral periapical radiographs (IOPA) by the dental college undergraduate students and also to evaluate the impact of teaching on their skills.Materials and Methods:This study was conducted in the OMRD department. Final year students (52) and interns (41) of 2014 were included in this study. In this 1 year study, 13104 IOPAs were taken and manually processed by these students. These radiographs were evaluated by two senior faculties of the department separately. To check variability between two examiners, ANOVA test was performed and all data were analyzed using WINDOW’S SPSS version 12 (Microsoft, USA).Results:Of 13104 IOPAs, 3538 were considered as faulty radiographs, of this 26.1% cone cut which occupies the first position and was followed by improper vertical angulation (25.2%), film position error (23.2%), improper horizontal angulation (13.1%), processing errors (9.5%), and miscellaneous such as reversed film, film bending (2.9%).Conclusion:Considering the statistical analysis by increasing experience, students make fewer numbers of errors.

In situ study of the electronic structure of atomic layer deposited oxide ultrathin films upon oxygen adsorption using ambient pressure XPS

APXPS was used to investigate the effect of oxygen adsorption on the band bending and electron affinity of ALD Al2O3, ZnO and TiO2 ultrathin films.