Discharge of a shock wave from an open end of a tube

IntroductionWhen a Pressure wave such as the shock waveprOPagates along a constant area straight tube andreaches at the open end, an impulsive wave is emittedOutward from the tube exit toward the surrounding areaand causes an impulsive noise laal a sonic boomproduced by a supersonic aircraft. Therefore, someauthors have investigated the discharge of a weakcompression wave from an open end in order to reducethe impulsive noise in relation to'the high speed railWaytUImel in the previous paped'…     

Experimental Investigation on Noise Suppression in Supersonic Jets from Convergent-Divergent Nozzles with Baffles

The acoustic properties of supersonic jet noise from a convergent-divergent nozzle with a baffle have been studied experimentally over the range of nozzle pressure ratios from 2.0 to 8.0. Acoustic measurements were conducted in a carefully designed anechoic room providing a free-field environment. A new approach for screech noise suppression by a cross-wire is proposed. Schlieren photographs were taken to visualize the shock wave patterns in the supersonic jet with and without the cross-wire. The effects of the baffle and the cross-wire on acoustic properties are discussed. It is shown that the baffle has little effect on the screech frequency for the underexpanded supersonic jet without the cross-wire. Also, the cross-wire introduced in supersonic jets is found to lead to a significant reduction in overall sound pressure level.     

Effect of Nonequilibrium Homogenous Condensation on Flow Fields in a Supersonic Nozzle

INTRODUCTIONManystudies[1-131onthecondensationshockwaveoccurringinthecaseoftheraPidexPansionofmoistairorsteaminasupersonicnozzlehavebeenper-formed,andthecharacteristicsofcondensationshock'wavehavenearlybeenclarilied.Acondensationshockwavealsooccursinthebladepassageinasteamturbinel14,15]andsuchacondensationshockwavinteractswiththeboundarylayeronthesurfaceoftheblade.Thus,thefiowinthebladepassageofthesteamturbinewiththecondensationshockwavehasnotyetbeenclariliedl16'17].InthepreseDtstudythee…     

Effect of Friction and Wear on Formation of Polysiloxane Films at Iron Oxide Surface in Viscous Couplings

Friction tests were conducted with silicone fluids containing iron oxide particles to investigate the effects of friction and wear on the formation of a micro-gel in viscous couplings. Polysiloxane films were formed on the surface of iron oxide particles as sliding distance increased. The relative viscosity of the particle dispersion increased as well. Frictional heat had a significant effect on the formation of polysiloxane films which had an abundance of cross-linking and terminal trimethyl structures of polydimethyl siloxane. The iron oxide surface was indicated to participate in the tribo-chemical formation of polysiloxane films. A model anti-wear agent suppressed the increase in relative viscosity with less polysiloxane films formed on the surface of the iron oxide. The metal-to-metal contact between adjacent VC plates most likely generates chemically active iron oxide surfaces with frictional heat and wear, which promotes the formation of the polysiloxane film on the surface, leading to the micro-gel.     

A Dual-Beam Irradiation Facility for a Novel Hybrid Cancer Therapy

In this paper we present the main ideas and discuss both the feasibility and the conceptual design of a novel hybrid technique and equipment for an experimental cancer therapy based on the simultaneous and/or sequential application of two beams, namely a beam of neutrons and a CW (continuous wave) or intermittent sub-terahertz wave beam produced by a gyrotron for treatment of cancerous tumors. The main simulation tools for the development of the computer aided design (CAD) of the prospective experimental facility for clinical trials and study of such new medical technology are briefly reviewed. Some tasks for a further continuation of this feasibility analysis are formulated as well.     

Removal of pesticide residue in cherry tomato by hydrostatic pressure

The reduction of Chlorpyrifos (CP) in cherry tomatoes by High hydrostatic pressure (HHP) treatment was demonstrated and compared with other washing methods. CP is commonly used as a broad-spectrum insecticide in pest control, and high residual levels have been detected in vegetables. Samples were treated at several pressures (0.1–400 MPa) and at two temperatures (5 or 25 °C) for 30 min. The optimum HHP conditions for reducing CP were around 75 MPa at 5 °C, and the removal rate was about 75%. This removal rate is slightly higher than other treatments such as soaking in ethanol solution and ultrasonic, accompanied by no visual changes (color, size and shape) in appearance. Also, no toxic intermediates were identified in the extracts of the high-pressure treated cherry tomatoes under these experimental conditions. The present results indicate that HHP can be a useful choice for removing residual pesticides.     

Antimutagenic and α-glucosidase inhibitory effects of constituents from Kaempferia parviflora

The dichloromethane extract and ethyl acetate soluble fraction of Kaempferia parviflora showed antimutagenicity and α-glucosidase inhibitory activity. 7-Methoxyflavones were the major constituents of both extracts and demonstrated antimutagenic activity. In particular, 5,7-dimethoxyflavone (IC₅₀ = 0.40 nmol/plate), 5,3′-dihydroxy-3,7,4′-trimethoxyflavone (0.40 nmol/plate), 3,5,7-trimethoxyflavone (0.42 nmol/plate) and 5-hydroxy-7-methoxyflavone (0.47 nmol/plate) showed potent antimutagenic activity. The results of structure–activity relationship studies suggest that methylation of the 5-hydroxy group enhanced activity. On the other hand, increasing the number of methoxy groups on the B ring caused a reduction in activity. In the case of an α-glucosidase inhibitory effect, 5,7,3′,4′-tetramethoxyflavone exhibited the highest activity (IC₅₀ = 20.4 μM), followed by 5,7,4′-trimethoxyflavone (54.3 μM) and 3,5,7,3′,4′-pentamethoxyflavone (64.3 μM). The results suggest that the α-glucosidase inhibitory activity was enhanced by the methoxy groups at the 5-, 3′- and 4′-position and was reduced by the methoxy group at the 3-position.     

Biochemical intervention of ergothioneine-rich edible mushroom (Flammulina velutipes) extract inhibits melanosis in crab (Chionoecetes japonicus)

We investigated the effects of decreasing phenoloxidase (PO) activity and prophenoloxidase (proPO) gene expression on the inhibition of postharvest melanosis formation in the red queen crab, Chionoecetes japonicus. The cDNA of proPO from hemocytes of C. japonicus was partially cloned and sequenced. Immersion of live crabs in a 1.0% ergothioneine (ESH)-rich mushroom extract (Flammulina velutipes; ME) solution resulted in significant inhibition of haemolymph PO activity and a reduction of the proPO gene expression in hemocytes that consequently controlled melanosis in the crabs during ice storage. Treatments with a 0.05% w/v sodium sulphite solution or a 0.05% w/v 4-hexyl-1,3-benzenediol solution had similar positive effects as the treatment with a 1.0% ME solution in vivo. In vitro experiments showed that authentic l-(+)-ESH inhibited PO activity and decreased proPO gene expression in crab hemocytes. Thus, the application of ESH-rich ME can be a novel alternative to synthetic melanosis-inhibiting agents to control postharvest melanosis in crabs.     

Protoplast Transformation of Alkalophilic Bacillus sp. by Plasmid DNA

A method for transformation of alkalophilic Bacillus sp. A-59 (ATCC21591, alkaline amylase producing bacterium) with plasmid DNA was developed. Plasmid pHWl containing a chloramphenicol acetyltransferase gene was used as a vector, because chloramphenicol was the only antibiotic found to be stable at alkaline pH condition. Transformation was carried out by a protoplast method and addition of polyethylene glycol (PEG; final concentration 22.5%) was essential for transformation. Optimum pH values of the media and buffers were slightly higher than those used in transformation of Bacillus subtilis protoplasts. Through optimization of transformation conditions for alkalophilic Bacillus sp., the transformation efficiency was increased to approximately 10⁶ transformants per μg plasmid DNA.