Resin-based Composite Light-cured Properties Assessed by Laboratory Standards and Simulated Clinical Conditions

2013 ◽  
Vol 38 (2) ◽  
pp. 159-167 ◽  
Author(s):  
N Ilie ◽  
H Bauer ◽  
M Draenert ◽  
R Hickel
Keyword(s):  
Irradiation Time ◽  
Light Emitting Diode ◽  
Artificial Saliva ◽  
Flexural Modulus ◽  
Storage Conditions ◽  
Material Behavior ◽  
Indentation Modulus ◽  
Light Emitting ◽  
Clinical Conditions

SUMMARY The following parameters were varied: 1) irradiation technique: top and bottom polymerization according to the ISO standard, and polymerization from only the top, simulating clinical situations; 2) polymerization time: 5, 10, 20, and 40 seconds; 3) storage conditions: 24 hours in distilled water, thermocycling followed by storage for four weeks in artificial saliva or alcohol. Flexural strength (FS), flexural modulus (Eflexural), indentation modulus (E), Vickers hardness (HV), and degree of conversion (DC) were measured. The laboratory results were similar to those measured by mimicking clinical conditions only at high polymerization times and mild storage conditions (20 seconds and 40 seconds and storage for 24 hours in water, and 40 seconds with aging and storing in saliva). Significantly higher DC values were measured on the top than on the bottom of a 2-mm layer for all polymerization times. Overall, 5-second and 10-second irradiation times induced significantly lower DC values compared to the currently recommended polymerization times of 20 and 40 seconds at both the top and bottom of the samples. The initial DC differences as a function of irradiation time are leveled at 24 hours of storage but seem to do well in predicting long-term material behavior. A minimum irradiation time of 20 seconds is necessary clinically to achieve the best mechanical properties with modern high-intensity light emitting diode (LED) units.

scholarly journals Long-term Failure Rate of Brackets Bonded with Plasma and High-intensity Light-emitting Diode Curing Lights

2007 ◽  
Vol 77 (4) ◽  
pp. 707-710 ◽  
Author(s):  
Nikolaos Pandis ◽  
Sophia Strigou ◽  
Theodore Eliades
Keyword(s):  
Failure Rate ◽  
High Intensity ◽  
Irradiation Time ◽  
Light Emitting Diode ◽  
Posterior Teeth ◽  
Similar Treatment ◽  
Light Emitting ◽  
Curing Light ◽  
High Intensity Light

Abstract Objective: To comparatively assess the long-term failure rate of brackets bonded with a plasma or a high-intensity light-emitting diode (LED) curing light. Materials and Methods: Twenty-five patients with complete permanent dentitions with similar treatment planning and mechanotherapy were selected for the study. Brackets were bonded according to a split-mouth design with the 3M Ortholite Plasma or the high-power Satelec mini LED Ortho curing light. Irradiation with the two curing lights was performed for 9 seconds at an alternate quadrant sequence so that the bonded brackets cured with either light were equally distributed on the maxillary and mandibular right and left quadrants. First-time bracket failures were recorded for a mean period of 15 months (range 13–18 months) and the results were analyzed with the chi-square test and binary logistic regression. Results: The failure rate for brackets was 2.8% for the plasma light and 6.7% for the LED light source. Although significantly more failures were found for the mandibular arch, no difference was identified in failure rate between anterior and posterior teeth. Conclusions: High-intensity LED curing lights present a 2.5 times higher failure rate relative to plasma lamps for nominally identical irradiation time. Mandibular teeth show almost 150% higher failure incidence compared with maxillary teeth. No effect from the arch side (right vs left) and location (anterior vs posterior) was identified in this study.

scholarly journals Reflectance-Based Organic Pulse Meter Sensor for Wireless Monitoring of Photoplethysmogram Signal

Biosensors ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 87 ◽  
Author(s):  
Fahed Elsamnah ◽  
Anubha Bilgaiyan ◽  
Muhamad Affiq ◽  
Chang-Hoon Shim ◽  
Hiroshi Ishidai ◽  
...  
Keyword(s):  
Power Consumption ◽  
Structural Design ◽  
Signal To Noise Ratio ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Wireless Monitoring ◽  
Organic Light ◽  
Reduced Power Consumption

This paper compares the structural design of two organic biosensors that minimize power consumption in wireless photoplethysmogram (PPG) waveform monitoring. Both devices were fabricated on the same substrate with a red organic light-emitting diode (OLED) and an organic photodiode (OPD). Both were designed with a circular OLED at the center of the device surrounded by OPD. One device had an OLED area of 0.06 cm2, while the other device had half the area. The gap distance between the OLED and OPD was 1.65 mm for the first device and 2 mm for the second. Both devices had an OPD area of 0.16 cm2. We compared the power consumption and signal-to-noise ratio (SNR) of both devices and evaluated the PPG signal, which was successfully collected from a fingertip. The reflectance-based organic pulse meter operated successfully and at a low power consumption of 8 µW at 18 dB SNR. The device sent the PPG waveforms, via Bluetooth low energy (BLE), to a PC host at a maximum rate of 256 kbps data throughput. In the end, the proposed reflectance-based organic pulse meter reduced power consumption and improved long-term PPG wireless monitoring.

A Novel Voltage-Programmed Pixel Circuit with Poly-Si TFTs for AMOLED Displays

2018 ◽  
Vol 27 (14) ◽  
pp. 1850221
Author(s):  
Zunkai Huang ◽  
Li Tian ◽  
Hui Wang ◽  
Songlin Feng
Keyword(s):  
Threshold Voltage ◽  
Light Emitting Diode ◽  
Active Matrix ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Electrical Stress ◽  
Organic Light ◽  
Pixel Circuit ◽  
Display Performance

In this paper, we propose a novel voltage-programmed pixel circuit with polysilicon thin–flim transistors (poly-Si TFTs) for active matrix organic light-emitting diode (AMOLED) displays, which consists of one programming transistor, one driving transistor, four switching transistors and two storage capacitors, respectively. Specifically, the proposed pixel circuit is able to not only efficiently compensate for the threshold variations of TFTs, but also largely suppresses the electrical degradations of the devices caused by the long-term electrical stress. Moreover, the mobility variation of the driving transistor can be compensated as well. The simulation has been performed by HSPICE, and results indicate that the average values of nonuniformities are, respectively, 7.3% as the threshold-voltage varies by [Formula: see text][Formula: see text]V and 2.1%, as the mobility of the driving transistor varies by [Formula: see text]%, both of which are much lower than that of the conventional two-transistor and one-capacitor (2T1C) pixel. Furthermore, since the OLED is reverse-biased during the nonemission phases, the lifetime of OLED will be extended naturally. As a consequence, the proposed pixel circuit can substantially improve the display performance.

scholarly journals Long-term NO<sub>x</sub> measurements in the remote marine tropical troposphere

2020 ◽  
Author(s):  
Simone T. Andersen ◽  
Lucy J. Carpenter ◽  
Beth S. Nelson ◽  
Luis Neves ◽  
Katie A. Read ◽  
...  
Keyword(s):  
Time Series ◽  
Light Emitting Diode ◽  
Ultra Violet ◽  
Data Set ◽  
Light Emitting ◽  
Mixing Ratios ◽  
Remote Troposphere ◽  
Tropical Troposphere ◽  
Term Data

Abstract. Atmospheric nitrogen oxides (NO + NO2 = NOx) have been measured at the Cape Verde Atmospheric Observatory (CVAO) in the tropical Atlantic (16° 51' N, 24° 52' W) since October 2006. These measurements represent a unique time series of NOx in the background remote troposphere. Nitrogen dioxide (NO2) is measured via photolytic conversion to nitric oxide (NO) by ultra violet light emitting diode arrays followed by chemiluminescence detection. Since the measurements began, a blue light converter (BLC) has been used for NO2 photolysis, with a maximum spectral output of 395 nm from 2006–2015 and of 385 nm from 2015. The original BLC used was constructed with a Teflon-like material and appeared to cause an overestimation of NO2 when illuminated. To avoid such interferences, a new additional photolytic converter (PLC) with a quartz photolysis cell (maximum spectral output also 385 nm) was implemented in March 2017. Once corrections are made for the NO2 artefact from the original BLC, the two NO2 converters are shown to give comparable NO2 mixing ratios (PLC = 0.92 × BLC, R2 = 0.92), giving confidence in the quantitative measurement of NOx at very low levels. Data analysis methods for the NOx measurements made at CVAO have been developed and applied to the entire time series to produce an internally consistent and high quality long-term data set. NO has a clear diurnal pattern with a maximum mixing ratio of 2–10 pptV during the day depending on the season and ~0 pptV during the night. NO2 shows a fairly flat diurnal signal, although a small increase in daytime NOx is evident in some months. Monthly average mixing ratios of NO2 vary between 5 and 30 pptV depending on the season. Clear seasonal trends in NO and NO2 levels can be observed with a maximum in autumn/winter and a minimum in spring/summer.

scholarly journals Can exchange transfusion be replaced by double-LED phototherapy?

Open Medicine ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. 992-996
Author(s):  
Shinya Abe ◽  
Kazumichi Fujioka
Keyword(s):  
Exchange Transfusion ◽  
Light Emitting Diode ◽  
Safe Procedure ◽  
Light Emitting ◽  
Safety Issues ◽  
Led Phototherapy ◽  
Recent Developments ◽  
Good Treatment Strategy ◽  
Severe Hyperbilirubinemia

Abstract Phototherapy is a conventional treatment for neonatal jaundice and widely considered as a safe procedure. Recent developments in light-emitting diode (LED) phototherapy devices have made more effective treatments possible. Exchange transfusion (ET) is typically applied for cases of refractory severe hyperbilirubinemia despite its risk of various complications. Since the therapeutic effect of phototherapy is correlated with its irradiance, ET may be avoided by performing phototherapy with higher irradiation. Recently, we adopted double-LED phototherapy as a bridging treatment to ET to treat a case of severe hyperbilirubinemia. In this case, the continual increase of bilirubin levels was suppressed immediately after its administration, and ET was not required. Throughout the treatment, no complications or increase in oxidative stress was observed. In addition, neurodevelopment was appropriate for the patient’s age at the 1-year follow-up, and no findings of kernicterus, including physical and magnetic resonance imaging findings, were observed. We hypothesized that double-LED phototherapy may be a good treatment strategy to replace ET for infants with severe hyperbilirubinemia; however, further investigations regarding safety issues including acute and long-term complications are needed before clinical adaptation.

scholarly journals Highly Luminescent Silver-Based MOFs: Scalable Eco-Friendly Synthesis Paving the Way for Photonics Sensors and Electroluminescent Devices

2020 ◽  
Author(s):  
Mario Gutierrez ◽  
Cristina Martín ◽  
Barbara Souza ◽  
Mark Van der Auweraer ◽  
Johan Hofkens ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Metal Organic Framework ◽  
Cost Effective ◽  
One Pot ◽  
Light Emitting ◽  
Metal Organic ◽  
Potential Impact ◽  
Scalable Synthesis ◽  
Potential Use

<p><a></a>Luminescent multifunctional nanomaterials are important because of their potential impact on the development of key technologies such as smart luminescent sensors and solid-state lightings. To be technologically viable, the luminescent material needs to fulfil a number of requirements for integration into real-world devices: facile and cost-effective fabrication, a high quantum yield, structural robustness, and long-term chemical stability. To achieve these requirements, an eco-friendly and scalable synthesis of a highly photoluminescent, multistimuli responsive and electroluminescent silver-based metal-organic framework (Ag-MOF), termed “OX-2” was developed. The high synthetic yield (at least 10 g of purely crystalline OX-2 via one pot reaction), together with its exceptional photophysical and mechanically resilient properties that can be reversibly switched by temperature and pressure make this material stood out over other competing luminescent materials. The potential use of OX-2 MOF as a good electroluminescent material was tested by constructing a proof-of-concept MOF-LED (Light Emitting Diode) device, further contributing to the rare examples of electroluminescent MOFs known to date. The results reveal the huge potential for exploiting the highly luminescent Ag MOF, where OX-2 may serve as a multitasking platform to engineer innovative photonic technologies.</p>

scholarly journals Environtmentally healthy sleep light

2019 ◽  
Vol 4 (2) ◽  
pp. 274-280
Author(s):  
Tulus Ikhsan Nasution ◽  
Mahyudin K.M Nasution ◽  
Susilawati ◽  
Dara Azdena
Keyword(s):  
Community Service ◽  
Light Emitting Diode ◽  
Economic Value ◽  
Test Results ◽  
Light Emitting ◽  
Voice Control ◽  
Control Application ◽  
Led Lights ◽  
Creativity And Innovation

Healthy sleep lights that will be proposed for community service are the results of research in which the use of LED lights (Light Emitting Diode) is activated with a maximum power of 3 Watts, so that the power consumed is quite low. This healthy sleep lamp also has some uniqueness such as turning on and off with sound by utilizing applications installed on smartphones. This voice control application can also be used to vary the color of the light. This lamp can be turned on and off by touching the light nest by using a sensor system and also the color and brightness of the lamp can be adjusted using the RGB control application on the smartphone. Intensity test results for LED lights 112 - 996 (Weber / m2). The standard intensity limit for healthy bulbs based on H. Steve, H. Gaube and J. Winterhager is 3,000 (Weber / m2), so that meeting the intensity standard is an LED lamp. Our long-term goal is to develop research results into products that have economic value, facilitate students to develop creativity and innovation and create jobs by partnering with partners.

The effect of the illuminance of light emitting diode (LED) lamps on long-term memory

Displays ◽  
2017 ◽  
Vol 49 ◽  
pp. 1-5 ◽  
Author(s):  
Hee-Chang Jung ◽  
Jin-Ho Kim ◽  
Chung-Won Lee
Keyword(s):  
Light Emitting Diode ◽  
Long Term Memory ◽  
Term Memory ◽  
Light Emitting

scholarly journals Impact of severe cracked germanium (111) substrate on aluminum indium gallium phosphate light-emitting-diode’s electro-optical performance

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 253-260
Author(s):  
Luruthudass Annaniah ◽  
Mutharasu Devarajan
Keyword(s):  
Crack Formation ◽  
Light Emitting Diode ◽  
Temperature Cycle ◽  
Optical Performance ◽  
Light Emitting ◽  
Indium Gallium ◽  
Reliability Performance ◽  
Product Specification ◽  
Gallium Phosphate

AbstractCracked die is a serious failure mode in the Light Emitting Diode (LED) industry – affecting LED quality and long-term reliability performance. In this paper an investigation has been carried out to find the correlation between severe cracked germanium (Ge) substrate of an aluminum indium gallium phosphate (AlInGaP) LED and its electro-optical performance after the Temperature Cycle (TC) test. The LED dice were indented at several bond forces using a die bonder. The indented dice were analysed using a Scanning Electron Microscope (SEM). The result showed that severe cracks were observed at 180 gF onward. As the force of indentation increases, crack formation also becomes more severe thus resulting in the chipping of the substrate. The cracked dies were packaged and the TC test was performed. The results did not show any electro-optical failure or degradation, even after a 1000 cycle TC test. Several mechanically cross-sectioned cracked die LEDs, were analysed using SEM and found that no crack reached the active layer. This shows that severely cracked Ge substrate are able to withstand a −40°C/+100°C TC test up to 1000 cycles and LED optical performance is not affected. A small leakage current was observed in all of the cracked die LEDs in comparison to the reference unit. However, this value is smaller than the product specification and is of no concern.

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