Mylar Film Research Articles

Transmittance jump in a thin aluminium layer during laser ablation

A jump in the transmittance (from to for ) of an optical gate on a Mylar film (a thin aluminium layer on a Lavsan substrate) irradiated by nanosecond pulses of a neodymium laser with an intensity up to has been recorded. The mechanism of a fast increase in the transmittance of the aluminium layer upon its overheating (without boiling) to the metal – insulator phase-transition temperature is discussed.

Laser plasma influence on the space-time structure of powerful laser radiation

This paper deals with the influence of laser plasma on the structure of the radiation field of a powerful Nd-glass laser with pulse energy up to 30 J and with the diameter of the output beam 45 mm. Laser plasma is generated by focusing the laser radiation on a low-density target such as nylon mesh and teflon or mylar films. Temporal profile of the laser pulse with a total duration of 25 ns consists of a several short pulse train. Duration of each pulse is about 2 ns. Notable smoothing of spatially non-uniform radiation structure was observed in the middle of the laser pulse.

Electrical Instability in Pentacene Transistors with Mylar and PMMA/Mylar Gate Dielectrics Transferred by Lamination Process

This study deals with electrical instability under bias stress in pentacene-based transistors with gate dielectrics deposited by a lamination process. Mylar film is laminated onto a polyethylene terephthalate (PET) substrate, on which aluminum (Al) gate is deposited, followed by evaporation of organic semiconductor and gold (Au) source/drain contacts in bottom gate top contact configuration (Device 1). In order to compare the influence of the semiconductor/dielectric interface, a second organic transistor (Device 2) which is different from the Device 1 by the deposition of an intermediate layer of polymethyl methacrylate (PMMA) onto the laminated Mylar dielectric and before evaporating pentacene layer is fabricated. The critical device parameters such as threshold voltage (VT), subthreshold slope (S), mobility (μ), onset voltage (Von) and Ion/Ioff ratio have been studied. The results showed that the recorded hysteresis depend on the pentacene morphology. Moreover, after bias stress application, the electrical parameters are highly modified for both devices according to the regimes in which the transistors are operating. In ON state regime, Device 1 showed a pronounced threshold voltage shift associated to charge trapping, while keeping the μ, Ioff current and S minimally affected. Regardless of whether Device 2 exhibited better electrical performances and stability in ON state, we observed a bias stress-induced increase of depletion current and subthreshold slope in subthreshold region, a sign of defect creation. Both devices showed onset voltage shift in opposite direction.

A drift chamber with a new type of straws for operation in vacuum

A 2150×2150mm2 registration area drift chamber capable of working in vacuum is presented. Thin-wall tubes (straws) of a new type are used in the chamber. A large share of these 9.80mm diameter drift tubes are made in Dubna from metalized 36µm Mylar film welded along the generatrix using an ultrasonic welding machine created at JINR. The main features of the chamber and some characteristics of the drift tubes are described. Four such chambers with the X, Y, U, V coordinates each, containing 7168 straws in total, are designed and produced at JINR and CERN. They are installed in the vacuum volume of the NA62 setup in order to study the ultra-rare decay K+→π+vv¯ and to search for and study rare meson decays. In autumn 2014 the chambers were used for the first time for the data taking in the experimental run of the NA62 at CERN׳s SPS.

An experimental study on the effect of temperature on the acoustic properties of cranial bone

Transcranial focused ultrasound is increasingly being used as an alternative non-invasive treatment for various brain disorders, including essential tremor, Parkinson's disease, and neuropathic pain. These applications necessitate an understanding of the complex relationship between temperature and acoustic properties of cranial bone. In particular, the longitudinal speed of sound and attenuation coefficients will be investigated. In this study, ex vivo skull caps were heated to temperatures ranging from 20 to 50 °C, and ultrasound pulses were transmitted through the skull caps using a spherical transducer of 5 cm diameter and 10 cm focal length, at clinically relevant frequencies of 0.836 and 1.402 MHz. A thin Mylar film was placed at the focus, and a laser vibrometer was used to receive the ultrasound pulse transmitted through the skull. It was found that there was a measurable change in the phase and amplitude of the received signal, implying a change in both the speed of sound and attenuation of the bone at different temperatures. It was also found that these changes were completely reversible. These results imply that at sufficiently high cranial bone temperatures, the assumption of temperature-independent acoustic properties of bone may become invalid.

선형 등가모델을 이용한 유연날개 구조해석

Aircraft needs high lift-to-drag ratio and weight reduction of the structure for long endurance flight with a small power. Generally high aspect ratio wing is applied to HALE(High Altitude Long Endurance) aircraft. Also high modulus, and high strength CFRP(Carbon Fiber Reinforced Plastic) has been used in primary structures. and thin mylar(membrane material) film has been applied to skin of wing. As a result, wing is more flexible than the other structures. and the stiffness of thin mylar film has an affect on dynamic stability. In this study, the membrane characteristic of mylar film has been simulated using nonlinear gap elements. And equivalent modeling method using shell elements is presented using the nonlinear simulation result. The linear equivalent model has verified using the results of nonlinear membrane method. Proposed linear equivalent shell model has applied to mode analysis for estimate the effect of mylar mechanical properties on natural frequency.

A high-voltage, long-pulse generator based on magnetic pulse compressor and Blumlein-type rolled strip pulse forming line

AbstractIn this paper, a new technical scheme of high-voltage, long-pulse generator, mostly based on solid-state power devices, including magnetic pulse compressor, Blumlein-type rolled strip pulse-forming line (RSPFL) and inductive voltage adder (IVA), is proposed and investigated numerically and experimentally. The generator has potential advantages of high average power level, high repetitive rate capability, long lifetime, and long pulse achievability, which meet the requirements of military and industrial application of the pulsed power technology. Specifically, a two-stage magnetic pulse compressor was set up with iron-based amorphous cores. Total compression ratio of the device is approximately 12 and the achieved voltage efficiency is up to 92%. Low impedance, long-duration Blumlein-type RSPFL was established with characteristic impendence and electrical length of 3 Ω and 100 ns, respectively. Mylar film was selected as the solid-state dielectric. Increased by a four-stage IVA, typical quasi-square pulse was obtained with peak current of 2.3 kA and duration over 200 ns. As the resistance of the dummy load was measured to be 60 Ω, the peak voltage was approximately 138 kV. Experiments show reasonable agreement with numerical analysis.

Preliminary Experiments Using a Passive Detector for Measuring Indoor 220Rn Progeny Concentrations with an Aerosol Chamber.

This paper describes preliminary experiments using a passive detector for integrating measurements of indoor thoron (²²⁰Rn) progeny concentrations with an aerosol chamber. A solid state nuclear detector (CR-39) covered with a thin aluminum-vaporized polyethylene plate (Mylar film) was used to detect only alpha particles emitted from ²¹²Po due to ²²⁰Rn progeny deposited on the detector surfaces. The initial experiment showed that Mylar film with area density of more than 5 mg cm⁻² was suitable to cut off completely alpha particles of 7.7 MeV from ²¹⁴Po of ²²²Rn progeny decay. In the experiment using the passive detector, it was observed that the net track density increased linearly with an increase of time-integrating ²²⁰Rn progeny concentration. As a result of dividing deposition rates by atom concentrations, the deposition velocity was given as 0.023 cm s⁻¹ for total ²²⁰Rn progeny. The model estimates of deposition velocities were 0.330 cm s⁻¹ for unattached ²²⁰Rn progeny and 0.0011 cm s⁻¹ for aerosol-attached ²²⁰Rn progeny using Lai-Nazaroff formulae. These deposition velocities were in the same range with the results reported in the literature. It was also found that the exposure experiments showed little influence of vertical profiles and surface orientations of the passive detector in the chamber on the detection responses, which was in good agreement with that in the model estimates. Furthermore, it was inferred that the main uncertainty of the passive detector was inhomogeneous deposition of Rn progeny onto its detection surfaces.

Effect of process variables on the drying rate of mango pulp by Refractance Window

Refractance Window (RW) process is considered a novel and promising drying method, which uses hot water in contact with a polyester film (Mylar) at its bottom face to heat up and dry out a solution spread on the film surface. The aim of this study was to investigate the effect of process variables on the RW drying of mango pulp: water temperature (75, 85 and 95°C), product thickness (2, 3 and 5mm) and radiant source (transparent and painted Mylar film). Films' transmissivities to infrared radiation were determined and the drying kinetics of mango pulp with the nine possible pairs of layer thickness and water temperature were assessed. Mylar film was partially transparent to infrared radiation, while the black film (Mylar painted) blocked all infrared radiation emitted from the hot water. RW evaporation capacity was up to 10kgm−2h−1 (pulp with 2mm, water at 95°C), indicating a very efficient drying process. RW is more efficient than black film process for pulp thickness up to 3mm. In fact, this study clearly established that radiative heat transfer contributes to less than 5% of the total amount of energy delivery to food during the RW drying process.

Preliminary Evidence That Bioactive Cements Occlude Artificial Marginal Gaps.

The objective of this preliminary laboratory study was to explore whether bioactive dental cements have the ability to seal marginal gaps as compared with other classes of dental cements. Tooth discs (dentin/enamel) were positioned adjacent to a second disc of one of five possible dental cements (two bioactive and three conventional) and separated by a 50-μm Mylar film, creating a controlled gap between the two discs. The edges of the tooth segments were abraded to expose dentin such that the dentin interface was positioned opposite the cement. The artificial gap assembly was stabilized with adhesive and composite resin. Artificial gap assemblies for each cement type were immersed in a phosphate-containing, simulated body fluid (phosphate buffered saline) for up to 8 months. Occlusion of artificial marginal gaps (including deposition of crystal-like, mineralized deposits within the gaps) was observed and scored categorically during the observation period. Deposition of radiodense material within the artificial marginal gap space was confirmed by micro-computerized tomography analysis. There was no evidence of marginal gap occlusion for the three conventional control cements, whereas both bioactive, surface apatite-forming cements demonstrated occlusion of the artificial marginal gaps. The preliminary findings of this initial study suggest the possible capability of surface apatite-forming, calcium-based, bioactive dental cements to seal or reseal artificial marginal gaps in simulated aqueous physiological conditions. The results of this laboratory study, although preliminary in nature, suggest a new functional property for bioactive dental materials, namely the ability to significantly improve marginal stability with tooth/restorative material interface. Such behavior in a restorative material could improve the survival and serviceability of dental restorations.

Hierarchical opal grating films prepared by slide coating of colloidal dispersions in binary liquid media

There are active researches on well ordered opal films due to their possible applications to various photonic devices. A recently developed slide coating method is capable of rapid fabrication of large area opal films from aqueous colloidal dispersion. In the current study, the slide coating of polystyrene colloidal dispersions in water/i-propanol (IPA) binary media is investigated. Under high IPA content in a dispersing medium, resulting opal film showed a deterioration of long range order, as well as a decreased film thickness due to dilution effect. From the binary liquid, the dried opal films exhibited the unprecedented topological groove patterns with varying periodic distances as a function of alcohol contents in the media. The groove patterns were consisted of the hierarchical structures of the terraced opal layers with periodic thickness variations. The origin of the groove patterns was attributed to a shear-induced periodic instability of colloidal concentration within a thin channel during the coating process which was directly converted to a groove patterns in a resulting opal film due to rapid evaporation of liquid. The groove periods of opal films were in the range of 50–500μm, and the thickness differences between peak and valley of the groove were significantly large enough to be optically distinguishable, such that the coated films can be utilized as the optical grating film to disperse infra-red light. Utilizing a lowered hydrophilicity of water/IPA dispersant, an opal film could be successfully coated on a flexible Mylar film without significant dewetting problem.

Using a 120-cm cyclotron to study the synchronous effects of ionizing radiation and hypomagnetic conditions on the simplest biological objects

The effect of α-particles on one of the simplest unicellular organisms, Synechocystis sp. PCC 6803 cyanobacteria, is studied using a 120-cm cyclotron. Suspensions of cells are irradiated in a cuvette with walls made of thin mylar films. The energy of α-particles in the solution is 24 MeV. The linear energy transfer (LET) of α-particles is close to that of relativistic nuclei of the neon-magnesium group in galactic cosmic rays, making it possible to simulate their effect on biological objects. A number of apparent changes in the Synechocystis spectral characteristics are found for samples irradiated in and outside a hypomagnetic field.

Secado de lúcuma (Pouteria obovata) empleando la técnica de Ventana RefractanteTM

Lucuma is a fruit that is experiencing a growing trend in commercial ground into flour for use in the food industry. This study aimed to obtain lucuma flour using the method of refractive window drying and evaluate the effect of the thickness of lucuma pulp and drying time on flour moisture and color. It was used a Composite Design Central Rotary (DCCR) with time between 10 and 50 min and the thickness between 1 and 3 mm. A fixed temperature of 95 °C and mylar film (metallized polyethylene terephthalate) as a refractory film of 0.1 mm was used. It was determined that the optimal conditions for lucuma flour (9.8% moisture) with this technique is when the thickness was 1.3 mm and with a time of 15 minutes; in these conditions, the effective diffusivity of water is 2.53 E-7 m2/s.

Track chambers based on precision drift tubes housed inside 30 mm mylar pipe

We describe drift chambers consisting of 3 layers of 30 mm (OD) drift tubes made of double sided aluminized mylar film with thickness 0.125 mm. A single drift tube is self-supported structure withstanding 350 g tension of 50 microns sense wire located in the tube center with 10 microns precision with respect to end-plug outer surface. Such tubes allow to create drift chambers with small amount of material, construction of such chambers doesn't require hard frames. Twenty six chambers with working area from 0.8 × 1.0 to 2.5 × 2.0 m2 including 4440 tubes have been manufactured for experiments at 70-GeV proton accelerator at IHEP(Protvino).

CPW-fed compact thin-film UWB antenna with dual band-notched characteristics

This paper presents a new compact thin-film ultrawideband (UWB) antenna with dual band-notched characteristics. The antenna contains a rectangular slot with a fork-like tuning stub. To achieve the dual band-notched characteristics, narrow and U-shaped slots are inserted on the radiator. This antenna is printed on a Mylar film substrate of 0.3 mm thickness with a dielectric constant of 3.2. The antenna has compact dimensions of 34.5 × 27.3 mm2. It operates in the frequency range 2.9–11.3 GHz with impedance matching covering the entire bandwidth and reasonable radiation properties. It also exhibits dual band-notched characteristics. One of the notched frequencies is in the range 3.3–3.7 GHz (WiMAX band) and the other in the range 5.1–5.8 GHz (WLAN band). The antenna is designed and simulated by using the commercial IE3D software, which is based on the method of moments. The antenna was fabricated and measured using Agilent E363B PNA network analyzers. The characteristics of the fabricated antenna show high correlation with those obtained from the simulation. The results confirm that the proposed antenna can achieve notch performance for WLAN and WiMAX communication systems and is also suitable for various portable UWB applications. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Percolation Properties of Triangles With Variable Aspect Ratios

Percolation is the study of random networks and their nature of connectivity. An exponential relationship between the percolation threshold and the aspect ratio of a shape is observed within this paper. Matlab simulations and a novel experimental method are utilized to determine the percolation threshold across a conductive sheet as triangles of variable aspect ratios are cut with a Universal Laser System X2-600 100 Watt CO2 laser. Resistance is measured as a voltage of 100mV is applied across the conductive sheet of aluminum coated Mylar film. This data is then analyzed to yield the percolation threshold relating to a triangle with a specified aspect ratio. We establish an equilateral triangle to have an aspect ratio of one.

Flexible, Stretchable Screens Could Put a Rolled-up Tablet in Your Pocket

The article reports that materials scientist Matthew White and his research team at the Johannes Kepler University in Linz, Austria, have developed polymer light-emitting diodes (PLED) using sheets of Mylar film as of December 2013. The features of the PLEDs are discussed including its manufacturing process and flexibility. The scientists' plans to improve the energy efficiency and display characteristics of the PLEDs are also discussed.

A new multi-strip ionization chamber used as online beam monitor for heavy ion therapy

A multi-strip ionization chamber has been built for precise and fast monitoring of the carbon beam spatial distribution at Heavy Ion Researched Facility of Lanzhou Cooling Storing Ring (HIRFL-CSR). All the detector's anode, cathode and sealed windows are made by 2μm aluminized Mylar film in order to minimize the beam lateral deflection. The sensitive area of the detector is (100×100)mm2, with the anode segmented in 100 strips, and specialized front-end electronics has been developed for simplifying the data acquisition and quick feedback of the relevant parameters to beam control system. It can complete one single beam profile in 200μs.

Carbon/Ternary Alloy/Carbon Optical Stack on Mylar as an Optical Data Storage Medium to Potentially Replace Magnetic Tape

A novel write-once-read-many (WORM) optical stack on Mylar tape is proposed as a replacement for magnetic tape for archival data storage. This optical tape contains a cosputtered bismuth-tellurium-selenium (BTS) alloy as the write layer sandwiched between thin, protective films of reactively sputtered carbon. The composition and thickness of the BTS layer were confirmed by Rutherford Backscattering (RBS) and atomic force microscopy (AFM), respectively. The C/BTS/C stack on Mylar was written to/marked by 532 nm laser pulses. Under the same conditions, control Mylar films without the optical stack were unaffected. Marks, which showed craters/movement of the write material, were characterized by optical microscopy and AFM. The threshold laser powers for making marks on C/BTS/C stacks with different thicknesses were explored. Higher quality marks were made with a 60× objective compared to a 40× objective in our marking apparatus. The laser writing process was simulated with COMSOL.

Preliminary investigation of trace element in Pterygium using Synchrotron radiation micro-beam X-ray fluorescence analysis (-XRF)

We have assessed the relative content and distribution of Iron and Zinc elements using microbeam synchrotron radiation X-ray fluorescence technique. One such technique is X-ray fluorescence (XRF), which has been used previously to map trace elements distribution in Physical samples. In this article a compromise is suggested in issue Pterygium samples. In this study, a prospective randomized clinical trial was conducted. Serial frozen sections of pterygium tissues and conjunctival tissues of 40 μm thickness were collected from 8 patients £¨10 eyes£©undergoing pterygium excision combine with limbal stem cell transplantation. A synchrotron-based XRF microprobe was used to map the distribution of Fe and Zn in whole frozen pterygium sections. The frozen sections were tested by synchrotron radiation X-ray fluorescence technique. These experiments were performed at BL15U in Shanghai, China. Then, the results have palyed that Iron and Zinc were present in both pterygium tissues and normal conjunctiva tissues (relevance ratio 100%). The contents of Iron and Zinc in normal conjunctiva tissues were significantly lower than in pterygium tissues (P < 0.05). The microelements were mostly clusteredin the pterygium tissues, while sparsely distributed in the normal conjunctiva tissue. Finally, we found that XRF imaging will be useful for mapping elemental distribution in Pterygium tissues. 40 μm frozen section on 6 μm mylar film is good for the test on BL15U. The contents of Iron and Zinc in pterygium tissue were significantly higher than in the control tissues. The results seem to be valuable in that Iron and Zinc may play a role in the development process of Pterygium.