A new development of dyestuffs degradation system using ultrasound

Dyestuffs are often present in industrial wastewaters and can consist of hazardous substances which have a serious impact on the environment and personal health. This report describes a system developed to degrade these substances using sonochemical reactions. Ultrasonic frequencies of 118, 224, 404 and 651 kHz and power input values of 11.4, 29.0 and 41.5 W were tested on Rhodamine B and Orange II dyestuff solutions in order to find the best degradation conditions. The ultrasonic irradiation of air-saturated solutions produces free radicals that combine and generates hydrogen peroxide, and compared to the production of hydrogen peroxide when irradiating water, a decrease was found during the irradiation to dyestuff solutions, indicating that some of the free radicals were consumed in the dyestuffs degradation process. The effects of the ultrasonic irradiation conditions on the pH, nitric and nitrous acid formations as well as the total organic carbon value (TOC) were also investigated. For the ultrasonic frequencies of 224, 404 and 651 kHz, the degradation rates were very similar, however, the 118 kHz system presented a degradation rate of about one-third that of the higher frequencies for both dyestuffs. The Rhodamine B solutions were decolorized within 2 h of ultrasonic irradiation for all systems with the exception of the 118 kHz one. For Orange II, except for the 118 kHz system, all solutions were decolorized within 4 h of ultrasonic irradiation. All reactions were carried out at 25 degrees C and the total ultrasonic irradiation time was 10 h.     

Streamers in the JIPP T-llU tokamak plasmas

It is shown that the low-density Ohmically heated tokamak plasmas have streamerlike eddies at the outer region at normalized minor radius of about 0.7 and high-frequency zonal flows of large amplitudes in the core. The amplitudes of the eddies ePhi/kT(e) and n(e)/n(e) are of order of 0.5, similar to that of blobs in the tokamak plasma boundary. The waveforms are featured by pulses of complex shape with sharp fronts, similar to the results of streamer simulations by Garbet et al.. The time constant of the fronts is also in agreement with the simulation. The radial span of the eddies is estimated to be much larger than the poloidal span.     

Laser and electrical current induced phase transformation of In<Subscript>2</Subscript>Se<Subscript>3</Subscript> semiconductor thin film on Si(111)

Phase transformation of thin film (∼30 nm)In₂Se₃/Si(111) (amorphous→crystalline) was performed by resistive annealing and the reverse transformation (crystalline→amorphous) was performed by nanosecond laser annealing. As an intrinsic-vacancy, binary chalcogenide semiconductor, In₂Se₃ is of interest for non-volatile phase-change memory. Amorphous In _x Se _y was deposited at room temperature on Si(111) after pre-deposition of a crystalline In₂Se₃ buffer layer (0.64 nm). Upon resistive annealing to 380°C, the film was transformed into a γ-In₂Se₃ single crystal with its {0001} planes parallel to the Si(111) substrate and parallel to Si , as evidenced by scanning tunneling microscopy, low energy electron diffraction, and X-ray diffraction. Laser annealing with 20-ns pulses (0.1 millijoules/pulse, fluence≤50 mJ/cm²) re-amorphized the region exposed to the laser beam, as observed with photoemission electron microscopy (PEEM). The amorphous phase in PEEM appears dark, likely due to abundant defect levels inhibiting electron emission from the amorphous In _x Se _y film.     

Effect of current sweep reversal on the magnetic field stability for a Bi-2223 superconducting solenoid

The effect of current sweep reversal on the temporal drift in magnetic field intensity for a Bi-2223 solenoid was investigated by experiment and using numerical simulation. Current sweep reversal, by as small as 1% of the peak current, was found to stabilize the drift in magnetic field intensity for a Bi-2223 tape solenoid. The field drift was due to flux creep in the Bi-2223 tape and the current sweep reversal formed a barrier for flux entrance at the upper and lower surface of the conductor, preventing flux creep. With a current reversal of several% of the peak current, the barrier formation extended over half of the solenoid and the magnetic field intensity became constant with time. The current sweep reversal technique should prove useful to stabilize an ultra-high field low/high-temperature superconducting nuclear magnetic resonance magnet operated at frequencies (field intensities) beyond 1 GHz (23.5 T).     

Vacancies ordered in screw form (VOSF) and layered indium selenide thin film deposition by laser back ablation

Indium selenide thin films are important due to their applications in non-volatile memory and solar cells. In this work, we present an initial study of a new application of deposition-site selective laser back ablation (LBA) for making thin films of In₂Se₃. Invacuo annealing and subsequent characterization of the films by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicate that control of substrate temperature during deposition and post-deposition annealing temperature is critical in determining the phase and composition of the films. The initial laser fluence and target film thickness determine the amount of material deposited onto the substrate.     

Nonlinear ultrasonic imaging of imperfectly bonded interfaces

A nonlinear ultrasonic imaging system is developed for detecting and imaging damages and defects with nm order gaps in industrial materials, which were undetectable by conventional ultrasonic imaging systems. A high power pulser generating large amplitude incident waves and high gain receiver with high-pass or band-pass filters extracting the second harmonic signals are combined with a conventional C-scan imaging system. The system is applied to visualize fiber/matrix debondings or matrix crackings in CFRP plates. It also visualizes anomalous substructures in amorphous diffusion-bonded interfaces, spot-welded nuggets, and projection-welded interfaces. This system would be also useful to detect semi-closed cracks whose opening is in nm order.     

Critical events leading to cellular mortality of yeast cells following hydrostatic pressure treatment

ABSTRACT

Hydrostatic pressures of 40–150?MPa are sub-lethal conditions for yeast cells. On exposure to this pressure range, damaged yeast cells will attempt to recover, but a critical cellular event may ultimately lead to cell mortality. We employed yeast strains whose cellular organelles were labeled with green fluorescent protein to investigate this critical event. We were able to visualize the nuclear membrane, nucleus, endoplasmic reticulum, Golgi body, and plasma membranes. Of the cellular organelles tested, the nuclear membrane was the weakest, displaying damage following only 50?MPa of pressure. This nuclear membrane rupture correlated with cellular viability. Thus, we hypothesize that nuclear membrane damage is the critical event leading to cellular mortality of yeast cells following hydrostatic pressure treatment.     

Towards beyond-1 GHz solution NMR: internal 2H lock operation in an external current mode

We have commenced a project to develop a beyond-1 GHz solution NMR spectrometer using a HTS coil. Due to a small residual resistance present in the HTS conductor and joint resistance between conductors, a stable persistent current sufficient for NMR measurements is unlikely. Therefore, a current has to be supplied to the HTS coil from an external power supply. The ripple of an external power supply causes a field fluctuation which must be stabilized. In this study we show results of NMR measurements using a 500-600 MHz NMR in such an external current mode: the field fluctuations are stabilized by an internal 2H lock. The field fluctuation from the external power supply comprises a major field fluctuation component at low frequencies, 0.003-0.005 Hz, and superimposed minor field ripples at 2 Hz and 50 Hz. The former limits the time interval of the internal 2H lock, while the latter generates sidebands in the NMR spectrum. Sideband and baseline noise are controlled by appropriate selection of the feedback loop parameters of the lock. The quality of the 1D-solution NMR spectra observed in external current mode is equivalent to that obtained in persistent current mode. However, if the feedback loop time is as short as the gradient pulse width, refocusing of the NMR signal is lost and NMR peaks disappear. The 2D-NOESY and the 2D-HSQC spectra of ubiquitin in an external current mode have been acquired. The quality of the 2D spectra is equivalent to those obtained in persistent current mode; i.e. the internal 2H lock operates stably over an experimental time interval of 40-50 min. To realize a beyond-1 GHz NMR spectrometer, further investigations must be made of (i) the long term stability of a DC power supply, (ii) the enhancement of the compensation field limit for the internal 2H lock, (iii) the extension of the helium refill time interval, and (iv) a method to correct the field homogeneity in the external current mode.     

Roper–Suffridge extension operator and the lower bound for the distortion

Liczberski–Starkov gave a sharp lower bound for DΦ_n(f)(z) near the origin, where Φ_n is the Roper–Suffridge extension operator and f is a normalized convex mapping on the unit disk in C. They gave a conjecture that the sharp lower bound holds on the Euclidean unit ball Bⁿ in Cⁿ. In this paper, we will give a sharp lower bound on Bⁿ for a more general extension operator and for normalized univalent mappings f or normalized convex mappings f. We will give a lower bound for mappings f in a linear invariant family. We will also give a similar sharp lower bound on bounded convex complete Reinhardt domains in Cⁿ.