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An underwater electrical discharge in a narrow dielectric capillary provides the details of the evolution of microbubbles to plasma as formed by a tungsten electrode inserted in the capillary. An increase in the applied voltage forms microbubbles after water fills the capillary. A further increase in the voltage generates a surface discharge through the boundary of the bubble, elongating the bubble shape, and eventually forming plasma by electrical breakdown. This produces atomic oxygen, atomic hydrogen, and hydroxyl radicals from dissociation of water vapor. Also, a bactericidal test in normal saline solution showed that more than 99.6% of the bacterial cells were killed within 8 s, resulting from chlorine-containing species, in particular hypochlorous acid as a major bactericidal agent.

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Theincreasedusageofwirelesscommunicationhascreatedawirelessfrequencyshortageproblem. CognitiveRadio(CR)hasattractedpublicattention,asoneofthesolutionsthatcanresolvethisissue. Inthispaper,theauthorsbuiltanactualCRsystemtestbedusingtheSDR(SoftwareDefinedRadio) platform,USRP(UniversalSoftwareRadioPeripheral)board,theSDRdevelopmenttoolkit,GNU Radio,andRaspberryPi3,whichisasingleboardcomputer.TheyconfiguredSecondaryUser(SU)s withRaspberryPi3forstraightforwardandportabletestenvironment.Theauthors'testbedperforms spectrumsensingbasedonenergydetectionanddetermineswhetherthechannelisoccupiedornot. Experimentalresultsnotonlyshowperformancebutalsoprovidetheirtestbedthatworkswellin multi-hopenvironments.

The increasing incidence of community- and hospital-acquired infections with multidrug-resistant (MDR) bacteria poses a critical threat to public health and the healthcare system. Although β-lactam antibiotics are effective against most bacterial infections, some bacteria are resistant to β-lactam antibiotics by producing β-lactamases. Among β-lactamases, metallo-β-lactamases (MBLs) are especially worrisome as only a few inhibitors have been developed against them. In MBLs, the metal ions play an important role as they coordinate a catalytic water molecule that hydrolyzes β-lactam rings. We determined the crystal structures of different variants of PNGM-1, an ancient MBL with additional tRNase Z activity. The variants were generated by site-directed mutagenesis targeting metal-coordinating residues. In PNGM-1, both zinc ions are coordinated by six coordination partners in an octahedral geometry, and the zinc-centered octahedrons share a common face. Structures of the PNGM-1 variants confirm that the substitution of a metal-coordinating residue causes the loss of metal binding and β-lactamase activity. Compared with PNGM-1, subclass B3 MBLs lack one metal-coordinating residue, leading to a shift in the metal-coordination geometry from an octahedral to tetrahedral geometry. Our results imply that a subtle change in the metal-binding site of MBLs can markedly change their metal-coordination geometry and catalytic activity.

The direct growth method is simplified manufacturing process used to avoid damages and contaminants from the graphene transfer process. In this paper, graphene nano-walls (GNWs) were direct synthesized using electron cyclotron resonance (ECR) plasma by varying the CH 4 /H 2 gas flow rate on the copper foil at low temperature (without substrate heater). Investigations were carried out of the changes in the morphology and characteristic of GNWs due to the relative intensity of hydrocarbon radical and molecule in the ECR plasma. The results of these investigations were then discussed.