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Zenita Aisah Rahmayanti,1 Dudi Aripin,1 Anna Muryani,1 Yolanda Yolanda,1 Hendra Dian Adhita Dharsono,1 Sandro Mihradi,2 Satrio Wicaksono2 1Department of Conservative Dentistry, Faculty of Dentistry, Universitas Padjadjaran, Bandung, Indonesia; 2Faculty of Mechanical and Aerospace Engineering, Bandung Institute of Technology, Bandung, IndonesiaCorrespondence: Anna Muryani, Department of Conservative Dentistry, Faculty of Dentistry, Universitas Padjadjaran, Jl. Sekeloa Selatan no. 1, Bandung, 40123, Indonesia, Tel +62 896 19972132, Email anna.muryani@unpad.ac.idPurpose: This research aimed to describe the stress distribution of an endodontically treated tooth with a mesio-occluso-distal (MOD) cavity restored with direct composite reinforced with polyethylene and e-glass ribbon fiber.Methods: This research was a descriptive study using the finite element method. A 3D model of the mandibular first molar solid after endodontic treatment with class II MOD preparation was prepared using Solidworks software. Finite element simulation was carried out using Abaqus software. In the first simulation, 180 N force was applied (vertically 90° perpendicular to the occlusal surface) at four points of loading: the tip of the mesiobuccal and distobuccal cusp, central fossa, and distal marginal ridge. For the second simulation, a 100 N force was applied at a 45° lateral angle to the occlusal surface at two loading points: the lingual slope of the mesiobuccal and distobuccal cusp.Results: This study showed that the stress concentration was located in the occlusal pit and fissure, CEJ distal area, bifurcation in dentin, and the 1/3 cervical area of root dentin. The stress value generated after vertical and lateral force did not exceed the tooth and restoration’s compressive and tensile strength value. The failure occurred at the interface of enamel and composite near the loading point area due to vertical load, both on polyethylene and e-glass fiber ribbon-reinforced composite restoration. Stress distribution of an endodontically treated tooth with a MOD cavity restored with ribbon fiber-reinforced composite using the finite element method showed that the highest stress concentration occurred on the surface close to the loading point, in narrow, concave, and sharp areas, and more apically for endodontically treated teeth.Conclusion: Neither the tooth nor restoration failed after vertical and horizontal loads. The interface between enamel and composite on the occlusal surface failed.Keywords: direct composite restoration, fiber-reinforced composite, wallpapering technique, finite element

The improvement of GaInNAs/GaAs p-i-n photodetector responsivity following the incorporation of antimony into the quaternary material and the measurements from deep level transient spectroscopy (DLTS) to support the effects leading to such improvement is reported. The results have shown that the incorporation of Sb into GaInNAs has effectively improved the performance of the p-i-n photodetector device.

The effect of the growth temperature of GaAsSbN is studied by using a combination of low temperature photoluminescence (PL), x-ray diffraction (XRD) reciprocal space maps (RSMs) and photocurrent response measurements for the application as the intrinsic layer in GaAs-based 1.3 micro m p-i-n photodetector. The RSMs have revealed traces of point defects and segregation of N and Sb, which might have a detrimental effect on the photocurrent responsivity.

The effect of annealing on the photoluminescence (PL) in GaAsSbN/GaAs quantum wells (QWs) grown by solid-source molecular-beam epitaxy is investigated by low-temperature PL measurements. The results show that the optical quality of QW can be improved in terms of PL intensity and full width at half maximum (FWHM) under the optimum condition.

Insomnia is a disorder to start, maintain, and wake up from sleep, has many sufferers in the world. For patients in remote locations who suffer from insomnia, which requires testing, the gold standard performed requires patients to take the time and travel to the health care center. By making alternatives to remote sleep insomnia testing using electrocardiography and electromyography connected to the internet of things can solve the problem of patients' access to treatment. Delivery of patient data to the server is done to make observations from the visualization of patient data in real-time. Furthermore, using artificial neural networks was used to classify EMG, ECG, and combine patient data to determine patients who have Insomnia get resulted in patient classification errors around 0.2% to 2.7%. [ABSTRACT FROM AUTHOR]

We present the reverse-bias current-voltage and deep-level transient spectroscopy (DLTS) characteristics of a Ga0.90In0.10N0.033As0.967/GaAs positive-intrinsic-negative photodiode (Eg=0.92 eV) and a trap-assisted tunneling model which considers generation-recombination and tunneling mechanisms. Using trap parameters obtained from the DLTS measurement, the model generates current-voltage characteristics of the photodiode, which were found to be in good agreement with experimental current-voltage curves at different temperature. The model also suggests that high dark current at low reverse-bias voltage is caused by the presence of traps which have low activation energy. Furthermore, it is predicted that approximately ten times reduction in the dark current can be achieved when the trap concentration of type H-1 (Ea=0.15 eV) is reduced by one order. On the other hand, a similar reduction in defect concentration of type H-2 (Ea=0.40 eV), which is nearer to midgap does not produce the same effect. [ABSTRACT FROM AUTHOR]

A GaAsSbN layer closely lattice matched to GaAs was used as an intrinsic layer (i layer) in a GaAs/GaAsSbN/GaAs p-i-n photodiode with response up to 1.3 μm. Deep level transient spectroscopy measurement on the GaAs/GaAsSbN/GaAs reveals two types of hole traps (HTs) in the GaAsSbN i layer; (i) HT1: a shallow N-related defect state (Ea∼0.10–0.12 eV) and (ii) HT2: an AsGa point defect-related midgap defect state with Ea∼0.42–0.43 eV. Reduction in growth temperature from 480 to 420 °C reduces the HT2 trap concentration from 4×1015 to 1×1015 cm-3, while increases the HT1 trap concentration from 1×1014 to 7×1014 cm-3. Reduction in the HT2 trap concentration following growth temperature reduction was attributed to the suppression of AsGa point defect formation. Evidence of possible change of the AsGa midgap state to a shallow level defect due to the formation of (AsGa–NAs) pairs was also suggested to have increased the HT1 trap concentration and reduced the HT2 trap concentration. An ∼4 dBm improvement in photoresponse under 1.3 μm laser excitation and approximately eight times reduction in dark current at -8 V reverse bias were attributed to the reduction in the overall trap concentration and mainly the reduction of the AsGa-related midgap trap concentration in the sample grown at 420 °C. [ABSTRACT FROM AUTHOR]

GaAsSbN layers closely lattice-matched to GaAs were studied for application as the intrinsic layer in GaAs-based 1.3 μm p-i-n photodetector. The GaAsSbN was grown as the intrinsic layer for the GaAs/GaAsSbN/GaAs photodetector structure using solid-source molecular beam epitaxy in conjunction with a radio frequency plasma-assisted nitrogen source and valved antimony cracker source. The lattice mismatch of the GaAsSbN layer to GaAs was kept below 4000 ppm, which is sufficient to maintain coherent growth of ∼0.45 μm thick GaAsSbN on the GaAs substrate. The growth temperature of the GaAsSbN layer was varied from 420–480 °C. All samples exhibit room temperature photocurrent response in the 1.3 μm wavelength region, with dark current density of ∼0.3–0.5 mA/cm2 and responsivity of up to 33 mA/W at 2 V reverse bias. Reciprocal space maps reveal traces of point defects and segregation (clustering) of N and Sb, which may have a detrimental effect on the photocurrent responsivity. [ABSTRACT FROM AUTHOR]

Deep level transient spectroscopy measurement on the GaAs/GaAsSbN/GaAs has shown two types of hole traps (HTs) in the GaAsSbN intrinsic layer (i layer). The improvement in photoresponse under 1.3 [mu]m laser excitation and approximately eight times reduction in dark current at -8 V reverse bias are attributed to the reduction in the overall trap concentration.

The effect of annealing on the photoluminescence (PL) in GaAsSbN/GaAs quantum wells (QWs) grown by solid-source molecular-beam epitaxy has been investigated. The annealing time and temperature are 5 min and 650–750 °C, respectively. Low-temperature (4 K) PL peaks shift to higher energies with the annealing temperatures. An As–Sb atomic interdiffusion at the heterointerface is proposed to model this effect. The compositional profile of the QW after interdiffusion is described by an error function distribution and calculated by a ten-band k·p method. The estimated interdiffusion constants D are ∼10-17–10-16 cm2/s in the above temperature range and an activation energy of 1±0.4 eV is obtained. [ABSTRACT FROM AUTHOR]