High-power broad-area InGaNAs/GaAs quantum-well lasers in the 1200 nm range

High-power broad-area InGaNAs/GaAs quantum-well (QW) edge-emitting lasers on GaAs substrates in the 1200 nm range are reported. The epitaxial layers of the InGaNAs/GaAs QW laser wafers were grown on n⁺-GaAs substrates by using metal-organic chemical vapor deposition (MOCVD). The thickness of the InGaNAs/GaAs QW layers is 70 Å/1200 Å. The indium content (x) of the In_xGa_1−xN_yAs_1−y QW layers is estimated to be 0.35-0.36, while the nitrogen content (y) is estimated to be 0.006-0.009. More indium content (In) and nitrogen content (N) in the InGaNAs QW layer enables the laser emission up to 1300 nm range. The epitaxial layer quality, however, is limited by the strain in the grown layer. The devices were made with different ridge widths from 5 to 50 μm. A very low threshold current density (J_th) of 80 A/cm² has been obtained for the 50 μm × 500 μm LD. A number of InGaNAs/GaAs epi-wafers were made into broad-area LDs. A maximum output power of 95 mW was measured for the broad-area InGaNAs/GaAs QW LDs. The variations in the output powers of the broad-area LDs are mainly due to strain-induced defects the InGaNAs QW layers.     

Refinement of Enhanced Speech Using Hybrid-Median Filter and Harmonic Regeneration Approach

This study proposes a post-processor to improve the harmonic structure of a vowel in an enhanced speech, enabling the speech quality to be improved. Initially, a speech enhancement algorithm is employed to reduce the background noise for a noisy speech. Hence the enhanced speech is post-processed by a hybrid-median filter to reduce the musical effect of residual noise. Since the harmonic spectra are impacted by background noise and a speech enhancement process, the quality of a vowel is deteriorated. A harmonic regenerated method is developed to improve the quality of post-processed speech. Experimental results show that the proposed method can improve the quality of post-processed speech by adequately regenerating harmonic spectra.     

Solder bonding with a buffer layer for MOEMS packaging using induction heating

In this paper, the selective induction heating technology is applied to glass–glass and glass–silicon solder bonding for MOEMS (optical MEMS) packaging. The Ni bumping with a buffer layer is successful to release the thermal stress for avoiding delamination. The Au wetting layer must be thick enough to prevent from being solved entirely into Sn, and it will improve bonding strength. The bonding specimens are soaked into 25°C water and placed into 85°C/85% RH oven, respectively. No moisture penetrates into the cavity after 1 day in both test conditions. In the test condition of 125°C leakage-test liquid (Galden HS260), no bubble is observed. The lowest bonding strength is 3 MPa.     

Low-Temperature Passivation of Amorphous-Silicon Thin-Film Transistors With Supercritical Fluids

In this letter, supercritical CO₂ (SCCO₂) fluids technology is employed for the first time to effectively passivate the defect states in hydrogenated amorphous-silicon thin-film transistors (a-Si:H TFTs) at low temperature (150degC ). With the high transport and diffusion properties of fluids, it is proposed to act as a transporter in delivering the molecules into the amorphous-silicon film and repairing defect states by the molecules. In addition, the propyl alcohol is used as the surfactant between nonpolar-SCCO₂ fluids and polar-H₂O molecules for mingling H₂O molecules uniformly with the SCCO₂ fluids. After the treatment of SCCO₂ fluids mixed with water and propyl alcohol, the a-Si:H TFT exhibited superior transfer characteristics and lower threshold voltage. The improvement in electrical characteristics could be verified by the significant reduction of density of states in the mobility gap of amorphous-silicon.     

Solder bonding with a buffer layer for MOEMS packaging using induction heating

In this paper, the selective induction heating technology is applied to glass–glass and glass–silicon solder bonding for MOEMS (optical MEMS) packaging. The Ni bumping with a buffer layer is successful to release the thermal stress for avoiding delamination. The Au wetting layer must be thick enough to prevent from being solved entirely into Sn, and it will improve bonding strength. The bonding specimens are soaked into 25°C water and placed into 85°C/85% RH oven, respectively. No moisture penetrates into the cavity after 1 day in both test conditions. In the test condition of 125°C leakage-test liquid (Galden HS260), no bubble is observed. The lowest bonding strength is 3 MPa.

     

Dipeptidyl Peptidase-4 Inhibitor-Related Bullous Pemphigoid: Clinical,Laboratory, and Histological Features,and Possible Pathogenesis

Dipeptidyl peptidase-4 inhibitor (DPP4i) is a widely used antidiabetic agent. Emerging cases of DPP4i-associated bullous pemphigoid (DBP), whose pathogenesis remains unclear, have been reported. Thus, a retrospective study was conducted from January 2016 to June 2021 to determine the clinical, laboratory, and histopathological features of DBP and idiopathic bullous pemphigoid (IBP). We set up in vitro experiments using vildagliptin-treated HaCaT keratinocytes to validate what we found by analyzing published RNA sequencing data about the genes related to the dermal–epidermal junction. We also observed IL-6 expression by HaCaT cells treated with vildagliptin. We enrolled 20 patients with DBP and 40 patients with IBP. The total Bullous Pemphigoid Disease Area Index (BPDAI) score was similar in both groups. However, the BPDAI score of erosions and blisters in DBP was significantly higher than that in IBP (24.6 vs. 16.68, p = 0.0189), and the score for urticaria and erythema was lower in DBP (12 vs. 19.05, p = 0.0183). The pathological features showed that the mean infiltrating eosinophil number per high-power field was significantly lower in DBP than in IBP (16.7 vs. 27.08, p = 0.023). The expression of LAMA3, LAMB3, LAMC2, DST, and COL17A1 decreased significantly in vildagliptin-treated human keratinocytes. On the other hand, IL-6, the hallmark cytokine of bullous pemphigoid (BP) severity, was found to be upregulated in HaCaT cells by vildagliptin. These experimental findings imply less of a requirement for eosinophil infiltration to drive the inflammatory cascades in DBP blistering. Both immunologic and non-immunologic pathways could be employed for the development of DBP. Our findings may help explain the higher incidence of non-inflammatory BP that was observed in DBP.     

Mechanical properties,thermal stability,and flame retardance of pultruded fiber-reinforced poly(ethylene oxide)-toughened novolak-type phenolic resin

The mechanical properties (flexural modulus, static tensile strength, notched Izod impact strength), miscibility, thermal stability, and flame retardance of a poly(ethylene oxide) (PEO)-toughened phenolic resin glass pultruded composite were investigated. The mechanical properties of a pultruded glass fiber-reinforced modified phenolic resin composite increased while the soft segment of PEO absorbs the loads in the network of brittle phenolic resin. The phenolic/PEO blend is completely miscible, from the results of differential scanning calorimetry. Its thermal degradation temperature is always higher than 370°C and decreased with increasing PEO content. The morphology of the interface between the fiber and matrix is well wetted-out with increasing PEO content from the result with a scanning electron microscope (SEM). The modified phenolic composite also shows excellent flame retardance that is UL-94, V-0, and the limited oxygen index is more than 55. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1129–1136, 1998     

Alginate-crosslinked chitosan scaffolds as pentoxifylline delivery carriers

To prevent fibrous encapsulation of implants, measures are taken to suppress inflammatory reactions around them. Sustained anti-inflammatory drug release from the scaffolds can potentially be a way to reduce inflammation around these implants. Alginate-crosslinked chitosan is often used to make biocompatible tissue engineered scaffolds. However, there is a lack of quantitative studies on the drug delivery properties of alginate-crosslinked chitosan scaffolds. For this study, chitosan, crosslinked with different concentrations of alginate, was made into porous scaffolds. Infrared and thermal gravimetric analyses showed polyelectrolyte complex formation between chitosan and alginate units. The alginate-crosslinked chitosan scaffolds were more hydrophilic, showed less swelling, had lower pentoxifylline (PTX) release efficacies, were more favorable for initial cell attachment, and were mechanically stronger and more resistant to enzymatic degradation when compared to non-crosslinked chitosan scaffolds. The differences became more significant as the concentrations of chitosan and alginate increased. Furthermore, in vitro tests showed that when PTX was slowly released from the scaffolds, it became more effective in suppressing the production of TNF-α and IL-6 by stimulated macrophage cells.     

Device characteristics of amorphous indium gallium zinc oxide thin film transistors with ammonia incorporation

The effect of ammonia gas on amorphous indium gallium zinc oxide thin film transistors is investigated. The ammonia is incorporated into the sputtered a-IGZO film during the deposition process. The results indicate that the sub-threshold swing of the NH₃ incorporated TFTs is significantly improved from 2.8 to 1.0 V/decade, and the hysteresis phenomenon is also suppressed during the forward and reverse sweeping measurement. By X-ray photoelectron spectroscopy analyses, Zn-N and O-H bonds are observed in ammonia incorporated a-IGZO film. Therefore, the improvements in the electrical performance of TFTs are attributed to the passivation of dangling bonds and/or defects by ammonia.