GaN HEMT DC I-V Device Model for Accurate RF Rectifier Simulation

Recently, various high-efficiency RF rectifiers have been proposed. In this article, to improve the simulation accuracy of RF active rectifier circuits, a new device model for GaN HEMTs is proposed that improves the reproducibility of ID-VDS characteristics in the third-quadrant region (both drain voltage and drain current are negative). Based on measured characteristic data of an actual GaN HEMT, the device parameters for this model have been decided, and the advantage of the new device model has been confirmed

4.5-/4.9-GHz-Band Selective High-Efficiency GaN HEMT Power Amplifier by Characteristic Impedance Switching

A 4.5-/4.9-GHz band-selective GaN HEMT high-efficiency power amplifier has been designed and evaluated for next-generation wireless communication systems. An optimum termination impedance for each high-efficiency operation band was changed by using PIN diodes inserted into a harmonic treatment circuit at the output side. In order to minimize the influence of the insertion loss of the PIN diodes, an additional line is arranged in parallel with the open-ended stub used for second harmonic treatment, and the line and stub are connected with the PIN diodes to change the effective characteristic impedance. The fabricated GaN HEMT amplifier achieved a maximum power-added efficiency of 57% and 66% and a maximum drain efficiency of 62% and 70% at 4.6 and 5.0GHz, respectively, with a saturated output power of 38dBm, for each switched condition

Construction of thermostable enzymes

The hyperthermophilic archaea were collected from the deep-sea in extreme environment, and the structures and functions of their hyperthermostable enzymes have been characterized. From our studies, the rules for the construction of thermostable enzymes have been discovered. Thermostable enzymes can be used for a number of industrial processes at higher temperature, taking advantage of reduced the risk of microbial contamination and solution viscosity as well as increase in the enzyme reaction rate. Using the information of sequence and structural homology among hyperthermostable enzymes, many types of thermostable enzymes have been constructed with protein engineering method. References [1] Crystal structure of beta-galactosidase from Bacillus circulans and the construction of the thermophilic mutants. FEBS Journal, vol 282,(13), pp2540-2552, 2015, K. Ishikawa, et al. [2] Construction of thermophilic xylanase and Its structural analysis, Biochemistry, vol. 55, pp4399-4409, 2016, M. Watanabe, et al. [3] Construction of thermostable cellobiohydrolase I from the fungus Talaromyces cellulolyticus by protein engineering, Protein Engineering, Design & Selection, vol. 1, pp1-8, 2019, M. Nakabayashi, et al

Microwave Characteristics of an Independently Biased 3-stack InGaP/GaAs HBT Configuration

This paper investigates various important microwave characteristics of an independently biased 3-stack InGaP/GaAs heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) chip at both small-signal and large-signal operation. By taking the advantage of the independently biased functionality, bias condition for individual transistor can be adjusted flexibly, resulting in the ability of independent control for both small-signal and large-signal performances. It was found that at small-signal operation stability and isolation characteristics of the proposed configuration can be significantly improved by controlling bias condition of the second-stage and the third-stage transistors while at large-signal operation its linearity and power gain can be improved through controlling the bias condition of the first-stage and the third-stage transistors. To demonstrate the benefits of using such an independently biased configuration, a measured optimum large-signal performance at an operation frequency of 1.6 GHz under an optimum bias condition for the high gain, low distortion were obtained as: PAE = 23.5 %, Pout = 12 dBm; Gain = 32.6 dB at IMD3 = -35 dBc. Moreover, to demonstrate the superior advantage of the proposed configuration, its small-signal and large-signal performance were also compared to that of a single stage common-emitter, a conventional 2-stack, an independently biased 2-stack and a conventional 3-stack configuration. The compared results showed that the independently biased 3-stack is the best candidate among the configurations for various wireless communications applications

Immunohistochemical Detection of Carcinogen-DNA Adducts and DNA Repair in Mouse Skin

4-Hydroxyaminoquinoline 1-oxide (4HAQO) and (±)-trans-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydroben-zo[a]pyrene (BP-DE)-DNA adducts were immunohisto-chcmically demonstrated in the nuclei of mouse skin using antibodies directed against carcinogen (4HAQO or BP) modified DNA. The specificity of the immunostaining was confirmed by several tests, including preincubation of the antibody with carcinogen modified DNA or related molecules, and digestion of the sections with DNase.Subcutaneous injection of 4HAQO dissolved in isotonic solution into an isolated portion of the mouse skin clamped off with ring-shaped forceps resulted in dose-dependent generation of DNA adducts in the nuclei of epithelial cells, fibroblasts, and panniculus carnosus cells. BP-DNA adducts could also be similarly detected dose-dependently in the nuclei of skin cells after local application of BP-DE. Nuclear staining was absent in animals injected with isotonic solution alone, and the intensity of staining correlated well with the level of unscheduled DNA synthesis (UDS) demonstrated autoradiographically after treatment with 4HAQO. Killing of mice at different time points after a single injection of 4HAQO revealed a gradual decrease in the intensity of the staining. Thus the postulated generation and repair of DNA adducts can be followed at the cellular level using the presently described method. J Invest Dermatol 92:275S–279S, 198

Atomic resolution of the crystal structure of the hyperthermophilic family 12 endocellulase and stabilizing role of the DxDxDG calcium-binding motif in Pyrococcus furiosus

AbstractHyperthermophilic glycoside hydrolase family 12 endocellulase (EGPf) from the archaeon Pyrococcus furiosus catalyzes the hydrolytic cleavage of β-1,4-glucosidic linkage in β-glucan cellulose. A truncated EGPf (EGPfΔN30) mutant lacking the proline and hydroxyl-residue rich region at the N terminus was constructed, and its crystal structure was resolved at an atomic resolution of 1.07Å. Our results indicate that the structure of EGPf, which consists of a β-jelly roll, exhibits structural similarity with the endocellulase of Thermotoga maritima. Additionally, we further determined that the thermostability of EGPf is maintained in part by the binding of Ca2+ in a DxDxDG Ca2+-binding motif, atypical of most archaeal proteins

Application of Acoustic Tomography for Gaging Discharge of Atidally Dominated River

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Crystal structure of an acetylesterase from Talaromyces cellulolyticus and the importance of a disulfide bond near the active site

AbstractCarbohydrate esterase catalyzes the de-O or de-N-acylation of substituted saccharides in plant cell walls and thus has great potential for industrial biomass saccharification. We recently identified the putative carbohydrate esterase family 3 (CE3) from Talaromyces cellulolyticus. Here, we prepared the recombinant catalytic domain of the enzyme and crystallized it. The crystal structure was determined to 1.5Å resolution. From the structural analysis, it was elucidated that a n-octyl-β-d-glucopyranoside bound to near the catalytic triad (Ser10, Asp179 and His182) and was buried in the active site cavity. Site-directed mutagenesis showed that the N-terminal disulfide bond located near the catalytic triad is involved in the activity and structural stability of the enzyme

Protein engineering of Candida rugosa lipase

Lipases (EC 3.1.1.3) catalyze the hydrolysis of emulsified long-chain triacylglycerol at the lipid–water interface. Candida rugosa lipase (CRL) is one of important industrial enzymes that are widely used in biotechnological applications such as the production of fatty acids and the synthesis of various esters. The catalytic efficiency and substrate specificity are seemed to be the key factors for industrial applications. Several approaches have been used to increase the stability of different lipases. For example, the immobilized CRL on carriers led to significant improvement in the catalyst’s activity and stability (Ref 1). In this study, we have focused on protein engineering to improve the properties of CRL. Please click Additional Files below to see the full abstract