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An 18–56-GHz gallium nitride (GaN) low-noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) is presented in this letter. This LNA is fabricated with commercial 0.1- $\mu \text{m}$ gate-length GaN-on-silicon (GaN/Si) process. The gain is 16–21.5 dB and the $\vert {S} 11\vert $ and $\vert {S} 22\vert $ are below −5 dB across the band. The noise figure (NF) is 2.2–4.4 dB and the output power at 1-dB compression point ( ${P} _{\text {1 dB}}$ ) is 10–20 dBm. This LNA has four-stage-cascade and common-source structure with $4.8\times 1$ mm2 chip area. The dc power dissipation is 1.4 W. To the best of the author’s knowledge, there has been no GaN LNA covering such a wide bandwidth at this frequency range. This LNA shows ultrawide bandwidth, low NF, high linearity, and high robustness. Moreover, it can be directly integrated with GaN power amplifiers (PAs) and switches to realize the monolithic RF front-ends, which can largely reduce the packaging loss and the module volume. This LNA has a great potential in wideband, high-speed, high-reliability, and high-integration applications.

This work studied the regulation of hole concentration and mobility in p-InGaN layers grown by metalorganic chemical vapor deposition (MOCVD) under an N-rich environment. By adjusting the growth temperature, the hole concentration can be controlled between 6 × 1017/cm3 and 3 × 1019/cm3 with adjustable hole mobility from 3 to 16 cm2/V.s. These p-InGaN layers can meet different requirements of devices for hole concentration and mobility. First-principles defect calculations indicate that the p-type doping of InGaN at the N-rich limiting condition mainly originated from Mg substituting In (MgIn). In contrast with the compensation of nitrogen vacancy in p-type InGaN grown in a Ga-rich environment, the holes in p-type InGaN grown in an N-rich environment were mainly compensated by interstitial Mg (Mgi), which has very low formation energy.

A 23–30-GHz gallium nitride (GaN) low-noise amplifier (LNA) with a noise figure (NF) of 0.87–1.51 dB is presented in this article. This LNA was fabricated with 100-nm gate-length GaN-on-silicon (GaN/Si) microwave monolithic integrated circuit (MMIC) process. The linear gain is 14–17 dB within the band. For investigating the robustness of this LNA, 1-W continuous wave (CW) at 27 GHz was stressed on the input port of the LNA. The gain decreased, and the NF increased after stress. Experimental research and first-principles calculations were carried out to investigate the physical origin of the degradation. The dehydrogenation of $\text{V}_{{\text {Ga}}}$ -H3 complexes causes the decrease of gain, and the creation of $\text{V}_{{\text {Al}}}$ -H4 in the AlN barrier is supposed to cause an increase of NF.

A series of N-(1,3-diphenylallyl)benzenamine derivatives (M) were investigated by electrospray ionization mass spectrometry in the positive-ion mode. Both the anomalous [M−H]+ and the regular [M+H]+ were observed in the ESI mass spectra. The occurrence of [M−H]+ has been supported by accurate mass spectrometry, liquid chromatography mass spectrometry, and tandem mass spectrometry analysis. Calculation results indicated that formation of [M−H]+ is attributed to the ion-molecule reaction of M with the protonated ESI solvent molecule (e.g. CH3OH2+) via hydride abstraction from a tertiary Csp3−H. The competing ionization processes leading to [M−H]+ or [M+H]+ were significantly affected by the concentration of formic acid in the electrospray ionization solvent and the proton affinity of the N atom.

A 22–30-GHz gallium nitride (GaN) low-noise amplifier (LNA) having a noise figure (NF) of 0.4–1.1 dB is presented in this letter. This LNA is fabricated with 0.1 gate-length GaN-on-silicon high-electron mobility transistor process, which is believed to have the lowest NF among GaN LNA at this frequency range reported to date. The small-signal gain is between 19.5 and 22.5 dB across the band. The output-referred 1-dB compression point (P1dB) and output-referred third-order intercept point (OIP3) are at 20.8- and 34.5-dBm level. The high robust was proven by stressing the LNA with a continuous wave input power of 30 dBm for 1 min. The three-stage LNA is $1.7\times1.3$ mm2 in area and consumes 210-mW dc power. Compared with the traditional gallium arsenide and indium phosphide LNA, the GaN monolithic microwave integrated circuit LNA in this letter exhibits a competitive NF but has much higher robust and linearity.

A 23-31 GHz Monolithic Microwave Integrated Circuit (MMIC) low-noise Amplifier (LNA) based on AlGaN/GaN on Si technology from OMMIC is presented in this paper. Common-source topology with inductive source feedback is utilized for simultaneous noise and input match. Measurement results show that the LNA has a gain of more than 22 dB while achieving an average noise Figure (NF) of 1.1 dB over the designed band and the minimum value of 0.93 dB at 27 GHz. The three stage topology achieves high linearity, providing the 1-dB compression point output power (P}$_{1dB}$) of 23 dBm and a Saturated Output Power (Psat) of $\sim28$ dBm. The robustness of this LNA was tested with 1 Watt continuous-wave input power at 27 GHz. The LNA survived after stress without obvious degradation. Compared with the traditional GaAs LNA, the GaN LNA has competitive NF and much higher linearity.

A 22-30 GHz gallium nitride (GaN) low-noise amplifier (LNA) with a noise Figure (NF) of 0.87-1.51 dB is presented in this work. This LNA was fabricated with 100 nm gate-length AlN/GaN on silicon (Si) microwave monolithic integrated circuit (MMIC) process. The linear gain is 14-17 dB with input/output return loss over 10 dB across the band. To investigate the robustness of this LNA, 1 Watt continuous wave (CW) at 27 GHz was stressed on the input port of LNA. The decrease of gain and increase of NF were found after stress. Experimental research and first-principles calculations were carried out to investigate the physical mechanism of theses degradations, which indicate that the dehydrogenation of VGaH3 complexes in GaN channel caused the decrease of gain and the creation of VAl-H4 in the aluminum nitride (AlN) barrier caused the increase of NF.

In this report, a broad band (15 GHz to 34 GHz) low noise amplifier using 100 nm GaN on silicon technology is designed and fabricated. The LNA shows an extremely low noise figure of 1.2 dB and small signal gain of 18.5±1.5 dB across the bandwidth. The LNA can work in the drain bias from 3.5 V to 8 V without increasing the noise figure. The chip size is 2 mm × 1.3 mm. The robustness of the LNA is also tested by stressing the working LNA with a continuous-wave input power, no significant degradation is observed.

Doping fluorine into the Al${}_{x}$Ga${}_{1\ensuremath{-}x}$N layer is critical to the performance of enhancement-mode Al${}_{x}$Ga${}_{1\ensuremath{-}x}$N/GaN high-mobility transistors, but the understanding of the role of F in these devices is rather limited. This study starts from the defect properties of F in Al-Ga-N alloy, investigating its interaction with native defects and impurities, as well as its effect on the alloy's Fermi energy. The insight obtained nicely explains the mechanism for the change in a device's electronic performance after doping with F. It also suggests a way to modulate electronic performance, by optimizing the F-incorporation process.

A 24.5-27 GHz gallium nitride (GaN) power amplifier (PA) is reported in this work. This PA was designed with $0.1\ \ \mu \mathrm{m}$ gate-length GaN-on-silicon (GaN/Si) microwave monolithic integrated circuit (MMIC) process. This PA has a 22-25 dB linear gain with high input/output return loss. The measured saturation output power is 35-36 dBm in pulsed work condition (10% duty cycle with 1 ms period). The total drain current is ∼827mA in saturation working condition with drain efficiency of 33%-40%. The area of this PA is $3.9\times 1.9\ \text{mm}^{2}$ with substrate thickness of $100\ \mu \mathrm{m}$ . Compared with the traditional GaN-on-silicon carbon (GaN/SiC) PA, The PA in this work shows comparable output power, high efficiency, but lower cost. This PA has a great advantage in wide commercial market, such as the next generation 5G communication and other high-speed data transmission networks.

One unique 2-substituted-8-hydroxyquinoline ligand with 2,3-dimethoxyphenyl groups was synthesized and characterized by ESI-MS, NMR spectroscopy and elemental analysis (EA). Two double cubane tetranuclear Cd(II) complexes [Cd4(L)6(CH3COO)2] (1), [Cd4(L)6(I)2] (2) and one double cubane tetranuclear Zn(II) complex [Zn4(L)6(NO3)2] (3), were prepared by solvothermal reactions of Cd(CH3COO)2, CdI2 and Zn(NO3)2. Complexes 1–3 were characterized with single crystal X-ray diffractions, powder X-ray diffractions (PXRD), thermogravimetry analyses (TGA) and EA. The building blocks exhibited unprecedented structural diversification and their self-assembly afforded tetranuclear Cd(II)/Zn(II) structures binding of different anions and solvent systems. Complexes 1–3 featured three types of supramolecular network controlled by non-covalent interactions, such as C–H⋯O, C–H···π, π···π stacking, hydrogen-bonding, and halogen-related interactions. Investigation of their photoluminescence properties exhibited disparate emission wavelengths and lifetimes in the solid state. This unique capability may provide a useful strategy to tune the optical properties of multinuclear materials, which could be exploited as important components for optoelectronic devices.

This paper reports on an in-depth research on the etching-process induced current degradation in AlGaN/GaN heterostructures by experimental research and theoretical calculations. The channel current degrades by 60% after the etching process and recovers to 90% after thermal annealing at 400 °C. It is found that fluorine is incorporated into the heterostructures of both AlGaN and GaN layers during the etching process. The degradation and recovery of the current is accompanied by the change in the concentration of fluorine in both AlGaN and GaN layers during the experiment. First-principles defect calculations of fluorine in GaN indicate that the dominant defect configuration of F is negatively charged interstitial (Fi−) with the lowest formation energy. The accompanied technology computer-aided design simulation of the energy bands reveals that Fi− raises the conduction band minimum of GaN and, thus, decreases the density of the two-dimensional electron gas, causing degradation of the channel current. This result leads to the post-etching recovery treatment without a high temperature process and ohmic contact degradation.

Gallium Nitride (GaN) high electron mobility transistors (HEMTs) have become good candidate for microwave power amplifier application. Furthermore, by combining the high power and the low noise performance, GaN HEMTs also show a great potential in high linearity low noise amplifier application. In this report, a four-stage low noise amplifier using commercial 100 nm GaN on Silicon Technology is presented. The designed LNA achieves a noise figure of 2.2-2.8 dB and a small signal gain of 25–29 dB from 23 to 31 GHz. The output 3-dB compression point (P3dB) is in the 17 dBm range. The LNA works with only one DC power supply and has a chip size of $2.3\mathbf{mm}\times 1\mathbf{mm}$ , Compared with the existing Gallium Arsenic technology, this LNA has higher gain, higher linearity while keeping the noise figure at the same level.

GaN technology has attracted main attention towards its application to high-power amplifier. Most recently, noise performance of GaN device has also won acceptance. Compared with GaAs LNA, GaN LNA has a unique superiority on power handling. In this work, we report a wideband Silicon-substrate GaN MMIC LNA operating in 18–31 GHz frequency range using a commercial 0.1 um T-Gate HEMT process. The GaN MMIC LNA has an average noise figure of 1.43 dB over the band and a minimum value of 1.27 dB at 23.2 GHz, which can compete with GaAs and InP MMIC LNA. The small-signal gain is between 22 and 25 dB across the band, the input and output return losses of the MMIC are less than −10 dB. The P1dB and OIP3 are at 17 dBm and 28 dBm level. The four-stage MMIC is 2.3×1.0 mm2 in area and consumes 280 mW DC power. Compared with GaAs and InP LNA, the GaN MMIC LNA in this work exhibits a comparative noise figure with higher linearity and power handling ability.

The origin of the threshold voltage (Vth) shift that occurs in ON-state biased AlGaN/GaN high-electron mobility transistors (HEMTs) is proposed in terms of experimental researches and first-principles calculations. Experimentally, ∼20% negative shift of the Vth is found for the 0.2 μm gate length T-gate AlGaN/GaN HEMT under the ON-state stress. 1/f noise measurements are carried out to investigate the evolution of defect distribution in the GaN channel, which indicates that the Vth shift is accompanied by the diminishing of the defect level of Ev + 0.8 eV. Combined with first-principles studies based on hybrid functionals defect calculations, we find that the defect evolution of O from negatively charged VGa-ON to neutral ON-H gives rise to the decrease in acceptors in the GaN channel and thus the negative shift of Vth. Our work indicates that the strengthening of oxygen-related defects in GaN during material growth and device fabrication would improve the reliability of AlGaN/GaN HEMTs.

Interleukin-6 (IL-6) is a pleiotropic cytokine secreted by many different cell types, and skeletal muscle is an important source of IL-6 during exercise. Here, we studied the effects of glucose deprivation in vitro on skeletal muscle-derived IL-6 expression and release in C2C12 myocytes, as well as its regulation by p38 mitogen-activated protein kinase (p38MAPK) and reactive oxygen species (ROS). C2C12 myotubes were cultured in DMEM medium containing 4.5 g · L−1 glucose (glucose control, GC) or DMEM medium containing no glucose (glucose deprivation, GD) for 0, 6, 12, 18 and 24 hours, and then incubated with 10mM NAC (a ROS scavenger) or 10 μM SB203580 (a p38MAPK inhibitor) under either GC or GD conditions for 24 hours. IL-6 expression levels were subsequently analyzed using RT–PCR, and IL-6 protein levels in the medium were measured using ELISA. Glucose deprivation significantly enhanced IL-6 expression at 18 and 24 hours compared to the glucose control, and caused IL-6 protein levels to increase significantly over the entire 24-hour measurement period. The ROS scavenger NAC inhibited the glucose deprivation-induced release of IL-6 protein almost completely, while the p38MAPK inhibitor SB203580 inhibited glucose deprivation-induced IL-6 protein release to a lesser extent. Our study suggests that glucose deprivation in C2C12 myocytes induces IL-6 expression and release, and that this IL-6 release is mainly mediated via ROS signaling. Skeletal muscle-derived IL-6 may thus play an important role in energy metabolism during exercise.

The mitochondrial respiratory complex II, or succinate:ubiquinone oxidoreductase, is an integral membrane protein complex in both the tricarboxylic acid cycle (Krebs cycle) and aerobic respiration. The gene sequences of each complex II subunit were measured by RT-PCR. N-terminal sequencing work was performed to identify the mitochondrial targeting signal peptide of each subunit. Complex II was extracted from porcine heart and purified by the ammonium sulfate precipitation method. The sample was solubilized by 0.5% (w/v) sugar detergent n-decyl-β-d-maltoside, stabilized by 200 mm sucrose, and crystallized with 5% (w/v) poly(ethylene glycol) 4000. Important factors for the extraction, purification and crystallization of mitochondrial respiratory complex II are discussed.

The synthesis of[9,10- 3 H]-3-azidosalicyl-N-(n-octadecyl)amide, which can act as the molecular probe, was consisted of three step reaction. First 3-nitrosalicylic acid reacted with oleyleamine to form 3-nitrosalicyl-N-(9'-octadecenylamide, that reduced by tritium to the [9,10- 1 H]-3-aminnsalicyl-N-(n-octadecyl)amide, It then reacted with sodium nitrite and, sodium azide to synthesize [9,10- 3 H]-3-azidosalicyl-N-(n-octadecyl)amide. Its specific activity and radiochemical purity were 46 Ci/mmol and >98% respectively.

SummaryThe mitochondrial respiratory Complex II or succinate:ubiquinone oxidoreductase (SQR) is an integral membrane protein complex in both the tricarboxylic acid cycle and aerobic respiration. Here we report the first crystal structure of Complex II from porcine heart at 2.4 Å resolution and its complex structure with inhibitors 3-nitropropionate and 2-thenoyltrifluoroacetone (TTFA) at 3.5 Å resolution. Complex II is comprised of two hydrophilic proteins, flavoprotein (Fp) and iron-sulfur protein (Ip), and two transmembrane proteins (CybL and CybS), as well as prosthetic groups required for electron transfer from succinate to ubiquinone. The structure correlates the protein environments around prosthetic groups with their unique midpoint redox potentials. Two ubiquinone binding sites are discussed and elucidated by TTFA binding. The Complex II structure provides a bona fide model for study of the mitochondrial respiratory system and human mitochondrial diseases related to mutations in this complex.