A high-linearity 100-element diode grid mixer

Grid-mixer arrays can achieve high linearity and dynamic range through quasi-optical power combining. We present a 100-element single-ended diode grid mixer operating at 2.45 GHz. Each element incorporates two diodes in series. We measure an input third-order intercept of 11 W (40.5 dBm), and output third-order intercept of 3.4 W (35.4 dBm), and an associated conversion loss of 5.1 dB. The power-handling capability of the array is 100 times larger than that of a microstrip mixer using a single element. The local oscillator (LO) drive requirement for the entire array is 1.4 W (31.6 dBm). The angular dependence of the array's IF power is also presented and is in agreement with theory     

Direct Chemical Activation of a Rationally Engineered Signaling Enzyme

Few chemical strategies for activating enzymes have been developed. Here we show that a biarsenical compound (FlAsH) can directly activate a rationally engineered protein tyrosine phosphatase (Shp2 PTP) by disrupting autoinhibitory interactions between Shp2's N‐terminal SH2 domain and its PTP domain. We found that introducing a tricysteine motif at a loop of Shp2's N‐SH2 domain confers affinity for FlAsH; binding of FlAsH to the cysteine‐enriched loop relieves Shp2's inhibitory interdomain interaction and substantially increases the enzyme's PTP activity. Activation of engineered Shp2 is substrate independent and is observed in the contexts of both purified enzyme and complex proteomes. A chemical means for activating Shp2 could be useful for investigating its roles in signaling and oncogenesis, and the loop‐targeting strategy described herein could provide a blueprint for the development of target‐specific activators of other autoinhibited enzymes.     

Lung cancer risk in relation to traffic-related nano/ultrafine particle-bound PAHs exposure: a preliminary probabilistic assessment

Exposures to carcinogenic polycyclic aromatic hydrocarbons (PAHs) have been linked to human lung cancer. The purpose of this study was to assess lung cancer risk caused by inhalation exposure to nano/ultrafine particle-bound PAHs at the population level in Taiwan appraised with recent published data. A human respiratory tract model was linked with a physiologically based pharmacokinetic model to estimate deposition fraction and internal organic-specific PAHs doses. A probabilistic risk assessment framework was developed to estimate potential lung cancer risk. We reanalyzed particle size distribution, total-PAHs, particle-bound benzo(a)pyrene (B[a]P) and PM concentrations. A dose-response profile describing the relationships between external B[a]P concentration and lung cancer risk response was constructed based on population attributable fraction (PAF). We found that 90% probability lung cancer risks ranged from 10(-5) to 10(-4) for traffic-related nano and ultrafine particle-bound PAHs, indicating a potential lung cancer risk. The particle size-specific PAF-based excess annual lung cancer incidence rate due to PAHs exposure was estimated to be less than 1 per 100,000 population, indicating a mild risk factor for lung cancer. We concluded that probabilistic risk assessment linked PAF for limiting cumulative PAHs emissions to reduce lung cancer risk plays a prominent role in future government risk assessment program.     

Niobium pentoxide as promoter in the mixed MgH<Subscript>2</Subscript>/Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> system for hydrogen storage: a multitechnique investigation of the H<Subscript>2</Subscript> uptake

Nb₂O₅ is known as good promoter for adsorption/desorption kinetics of hydrogen in magnesium hydride. In this article the interaction with hydrogen of bare Nb₂O₅, the oxidic component of the mixed MgH₂/Nb₂O₅ system, is investigated in various conditions (i.e. employing atomic, molecular and nascent hydrogen). The state of the hydrogen-Nb₂O₅ system was monitored using various techniques including: X-ray Diffraction, Electron Paramagnetic Resonance, Diffuse Reflectance UV-Vis Spectroscopy, Thermal Desorption Spectroscopy -Mass Spectrometry, Differential Scanning Calorimetry and Thermal Programmed Desorption. Niobium (V) oxide is not at all inert while interacting with hydrogen. This oxide is partially reduced by hydrogen, which is incorporated in the solid and released as both molecular hydrogen and water. This peculiar behaviour, reminiscent of some properties of the bronze family, suggests an active chemical role played by Nb₂O₅ in the mixed MgH₂/Nb₂O₅ system.     

Antiviral activities of cell-free supernatants of yogurts metabolites against some RNA viruses

The antiviral activity of the cell-free supernatants (CFS) containing the metabolites of five yogurts fermented under anaerobic conditions with Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus plantarum, Streptococcus thermophilus and Bifidobacterium bifidum, respectively, was initially evaluated against seven RNA viruses using virus-induced cytopathic effects reduction method, while comparing that of De Man, Rogosa, and Sharpe (MRS) broths containing metabolites fermented with the same bacteria. All the CFS of yogurt showed high antiviral activity against seven RNA viruses, while the CFS of MRS broth exhibited similar or lower antiviral activity. Each CFS of yogurt and MRS broth showed no cytotoxicity with normal morphology in Vero or MDCK cells. Furthermore, CFS of each yogurt was more effective than that of MRS broth against the three enteroviruses and CFS of yogurt containing metabolites fermented with L. plantarum exhibited strong anti-influenza virus activity among that of the other yogurt and MRS broth. Therefore, CFS of the yogurt containing metabolites fermented with probiotic bacteria showed high potential to be used for developing fermented milk-based foods or drugs.