Design of intelligent transformer monitoring system based on GSM

This paper proposes a method for transformer fault detection system based on GSM network, through the current transformer, voltage sensor information, the known fault information attribute conditions, and the feedback weighted coefficient through the adaptive feed forward, that can obtain high fault information attributes, thus filtering interference factors and timely get fault information properties. It solves the traditional transformer can only judge general fault and fault real-time alarm by GSM network, the system also can measure the transformer oil temperature and oil temperature alarm in super high temperature, to detect the power transformer operation parameters, and the fault running state （over-current, over-voltage, under-voltage, warning）. The actual test system show that, diagnosis ability of fault signal separation ability and small signal identification increases 17%. also meet the requirements of real-time.

Slow-light-enhanced on-chip 1D and 2D photonic crystal waveguide gas sensing in near-IR with an ultrahigh interaction factor

Nanophotonic waveguides hold great promise to achieve chip-scale gas sensors. However, their performance is limited by a short light path and small light–analyte overlap. To address this challenge, silicon-based, slow-lightenhanced gas-sensing techniques offer a promising approach. In this study, we experimentally investigated the slow light characteristics and gas-sensing performance of 1D and 2D photonic crystal waveguides(PCWs) in the near-IR(NIR) region. The proposed 2D PCW exhibited a high group index of up to 114, albeit with a high propagation loss. The limit of detection(LoD) for acetylene(C_(2)H_(2)) was 277 parts per million(ppm) for a1 mm waveguide length and an averaging time of 0.4 s. The 1D PCW shows greater application potential compared to the 2D PCW waveguide, with an interaction factor reaching up to 288%, a comparably low propagation loss of 10 dB/cm, and an LoD of 706 ppm at 0.4 s. The measured group indices of the 2D and 1D waveguides are104 and 16, respectively, which agree well with the simulation results.

Observing antimicrobial process with traceable gold nanodusters

Understanding the interaction of nanomaterials with biological systems has always been of high concern and interest.An emerging type of nanomaterials,ultrasmall metal nanoclusters(NCs,<2 nm in size),are promising in this aspect due to their well-defined molecular formulae and structures,as well as unique physical and chemical properties that are distinctly different from their larger counterparts(metal nanoparticles).For example,metal NCs possess intrinsic strong luminescence,which can be used for real-time tracking of their interactions with biological systems.Herein,luminescent gold(Au)NCs were used as traceable antimicrobial agents to study their interactions with the bacteria and tofurther understand their underlining antimicrobial mechanism.It is shown for the first time that the Au NCs would first attach on the bacterial membrane,penetrate,and subsequently accumulate inside the bacteria.Thereafter,the internalized Au NCs would induce reactive oxygen species(ROS)generation and damage the bacterial membrane,resulting in the leakage of bacterial contents,which can finally kill the bacteria.Traceable Au NCs(or other metal NCs)provide a promising platform to study the antimicrobial mechanisms as well as other fundamentals on the interfacing of functional nanomaterials with the biological systems,further increasing their acceptance in various biomedical applications.

Understanding the electrode reaction process of dechlorination of 2,4-dichlorophenol over Ni/Fe nanoparticles: Effect of pH and 2,4-dichlorophenol concentration

Herein,with the exploitation of iron and nickel electrodes,the 2,4-dichlorophenol(2,4-DCP)dechlorinating processes at the anode and cathode,respectively,were separately studied via various electrochemical techniques(e.g.,Tafel polarization,linear polarization,electrochemical impedance spectroscopy).With this in mind,Ni/Fe nanoparticles were prepared by chemical solution deposition,and utilized to test the dechlorination activities of 2,4-DCP over a bimetallic system.For the iron anode,the results showed that higher 2,4-DCP concentration and solution acidity aggravated the corrosion within the electrode.The charge transfer resistance(Rct)values of the iron electrode were 703,473,444,and 437Ω·cm2 for the initial 2,4-DCP concentrations of0,20,50,and 80 mg/L,respectively.When the bulk pH of the 2,4-DCP solution varied from 3.0,5.0to 7.0,the corresponding Rct values were 315,376,and 444Ω·cm2,respectively.For the nickel cathode,the reduction current densities on the electrode at-0.75 V(vs.saturated calomel electrode)were 80,106,and 111μA/cm2,for initial 2,4-DCP concentrations of 40,80,and125 mg/L.The dechlorination experiments demonstrated that when the initial pH of the solution was 7.0,5.0,and 3.0,the dechlorination percentage of 2,4-DCP by Ni/Fe nanoparticles was 62%,69%,and 74%,respectively,which was in line with the electrochemical experiments.10 wt.%Ni loading into Ni/Fe bimetal was affordable and gave a good dechlorination efficiency of 2,4-DCP,and fortunately the Ni/Fe nanoparticles remained comparatively stable in the dechlorination processes at pH 3.0.

Cluster Materials as Traceable Antibacterial Agents

CONSPECTUS:The precise design of nanomaterials is essential for both basic and applied materials research.However,it is difficult to precisely synthesize and manipulate nanomaterials with adjustable physicochemical properties and functions at the molecular and atomic levels.For example,the emerging precision nanomedicine requires not only the precise design of nanomaterials(or atomically precise nanochemistry)but also real-time observations of the theranostic process.Metal nanoclusters(NCs)are molecule-like metal nanomaterials with well-defined molecular formulas,structures,and properties,which can meet the above requirements.Metal NCs can be easily synthesized and manipulated,and they have strong luminescence properties,which can be used to monitor biomedical processes under working conditions and environments.Moreover,unlike metal nanoparticles and other molecules,the core(i.e.,size(number of metal atoms in each NC)and composition)and surface of metal NCs can be individually adjusted at the atomic level.The atomic-level tailoring of metal NCs has a significant impact on their physicochemical properties and further applications.In addition,the atomic-level control of metal NCs can also help us to understand the respective functions of metal NCs in biomedical applications at the molecular and atomic levels.This knowledge will facilitate the accurate screening and design of metal NCs,with the desired functions and required efficacy to realize precision nanomedicine.

Mid-infrared all-optical modulators based on an acetylene-filled hollow-core fiber

We report all-optical mid-infrared phase and intensity modulators based on the photo-thermal effect in an acetylene-filled anti-resonant hollow-core fiber.Optical absorption of the control beam promotes the gas molecules to a higher energy level,which induces localized heating through non-radiative relaxation and modulates the refractive index of the gas material and hence the accumulated phase of the signal beam propagating through the hollow-core fiber.By modulating the intensity of the control beam,the phase of the signal beam is modulated accordingly.By use of a 1.53μm near-infrared control beam,all-optical phase modulation up to 2.2πrad is experimentally demonstrated at the signal wavelength of 3.35μm.With the phase modulator placed in one arm of a Mach-Zehnder interferometer,intensity modulation with on-off ratio of 25 dB is achieved.The gas-filled hollow-core-fiber modulators could operate over an ultra-broad wavelength band from near-to mid-infrared and have promising application in mid-infrared photonic systems.

Overcoming bacterial physical defenses with molecule-like ultrasmall antimicrobial gold nanoclusters

The size of metal nanoparticles(NPs)is crucial in their biomedical applications.Although abundant studies on the size effects of metal NPs in the range of 2-100 nm have been conducted,the exploration of the ultrasmall metal nanoclusters(NCs)of~1 nm in size with unique features is quite limited.We synthesize three different sized gold(Au)NCs of different Au atom numbers and two bigger sized Au NPs protected by the same ligand to study the size influence on antimicrobial efficacy.The ultrasmall Au NCs can easily traverse the cell wall pores to be internalized inside bacteria,inducing reactive oxygen species generation to oxidize bacterial membrane and disturb bacterial metabolism.This explains why the Au NCs are antimicrobial while the Au NPs are non-antimicrobial,suggesting the key role of size in antimicrobial ability.Moreover,in contrast to the widely known size-dependent antimicrobial properties,the Au NCs of different atom numbers demonstrate molecule-like instead of size-dependent antimicrobial behavior with comparable effectiveness,indicating the unique molecule-like feature of ultrasmall Au NCs.Overcoming the bacterial defenses at the wall with ultrasmall Au NCs changes what was previously believed to harmless to the bacteria instead to a highly potent agent against the bacteria.