A PCR-based RFLP analysis of Sarcocystis cruzi (Protozoa : Sarcocystidae) in Yunnan province, PR china, reveals the water buffalo (Bubalus bubalis) as a natural intermediate host

A polymerase chain reaction-based restriction fragment length polymorphism (RFLP) approach is used to examine Sarcocystis cruzi-like taxa from the atypical intermediate host, water buffalo, in Yunnan, People's Republic of China. The loci examined lie with

A DNA-sequence based phylogeny for triculine snails (Gastropoda : Pomatiopsidae : Triculinae), intermediate hosts for Schistosoma (Trematoda : Digenea): phylogeography and the origin of Neotricula

Partial (DNA) sequences were examined for one nuclear (28S rRNA gene) and one mitochondrial (16S rRNA) locus for nine species of pomatiopsid snail (Gastropoda: Rissooidea: Pomatiopsidae) from south-east Asia and south-west China. Fresh field samples were

Influence of muscle fats on the quality of intermediate moisture fish

Chrysicthys nigrodigitatus with 12.95% fat having an iodine value of 74.8 and a saponification number of 198.48 and Citharinus citherus containing only 3.25% fat with iodine value of 67.8 and a saponification number of 145.86 were studied as examples of fatty and lean fishes respectively. The intermediate moisture (IM) products of both fish types compared with normal cooked samples, were evaluated as of acceptable colour, odour, texure and juiciness but of inferior taste due to the glycerol impact. However, during storage at 30°C the IM products became increasingly less acceptable with the deterioration being greater in the fatty fish than in the lean fish, although the fatty IM fish was superior to the IM lean fish with regard to water retention and juiciness. Overall quality differences were most apparent in colour and odour with the fatty IM fish being worse. The fatty fish had also greater evolution of TEA-reactive carbonyl breakdown products of lipid oxidation which were subsequently used up in non-enzymic browning producing the correspondingly darker fish colour and greater off odour.

Use of simple fat analysis for evaluating quality changes in intermediate moisture fish stored at tropical temperature

Changes in the quality of intermediate moisture (IM) fish during storage at 38°C were monitored by assessing the moisture content, pH, acid value, peroxide value and thiobarbituric acid (TBA) value periodically. Results adequately portrayed the hydrolysis and peroxidation of fats and the concomitant protein degradation and crosslinking reactions that have been shown by more sophisticated methods to occur in intermediate moisture fish. Since these changes markedly affect the organoleptic quality, acceptability/shelf-life and nutritive value of IM flesh-foods their predictability by simple fat analytical techniques is of practical value where/when the more sophisticated monitoring techniques are not feasible.

The local and global stability of confined planar wakes at intermediate Reynolds number

At high Reynolds numbers, wake flows become more globally unstable when they are confined within a duct or between two flat plates. At Reynolds numbers around 100, however, global analyses suggest that such flows become more stable when confined, while local analyses suggest that they become more unstable. The aim of this paper is to resolve this apparent contradiction by examining a set of obstacle-free wakes. In this theoretical and numerical study, we combine global and local stability analyses of planar wake flows at $\mathit{Re}= 100$ to determine the effect of confinement. We find that confinement acts in three ways: it modifies the length of the recirculation zone if one exists, it brings the boundary layers closer to the shear layers, and it can make the flow more locally absolutely unstable. Depending on the flow parameters, these effects work with or against each other to destabilize or stabilize the flow. In wake flows at $\mathit{Re}= 100$ with free-slip boundaries, flows are most globally unstable when the outer flows are 50 % wider than the half-width of the inner flow because the first and third effects work together. In wake flows at $\mathit{Re}= 100$ with no-slip boundaries, confinement has little overall effect when the flows are weakly confined because the first two effects work against the third. Confinement has a strong stabilizing effect, however, when the flows are strongly confined because all three effects work together. By combining local and global analyses, we have been able to isolate these three effects and resolve the apparent contradictions in previous work.

Complex chemistry DNS of n-heptane spray autoignition at high pressure and intermediate temperature conditions

Direct Numerical Simulations (DNS) of turbulent n-heptane sprays autoigniting at high pressure (P=24bar) and intermediate air temperature (Tair=1000K) have been performed to investigate the physical mechanisms present under conditions where low-temperature chemistry is expected to be important. The initial turbulence in the carrier gas, the global equivalence ratio in the spray region, and the initial droplet size distribution of the spray were varied. Results show that spray ignition exhibits a spotty nature, with several kernels developing independently in those regions where the mixture fraction is close to its most reactive value ξMR (as determined from homogeneous reactor calculations) and the scalar dissipation rate is low. Turbulence reduces the ignition delay time as it promotes mixing between air and the fuel vapor, eventually resulting in lower values of scalar dissipation. High values of the global equivalence ratio are responsible for a larger number of ignition kernels, due to the higher probability of finding regions where ξ=ξMR. Spray polydispersity results in the occurrence of ignition over a wider range of mixture fraction values. This is a consequence of the inhomogeneities in the mixing field that characterize these sprays, where poorly mixed rich spots are seen to alternate with leaner ones which are well-mixed. The DNS simulations presented in this work have also been used to assess the applicability of the Conditional Moment Closure (CMC) method to the simulation of spray combustion. CMC is found to be a valid method for capturing spray autoignition, although care should be taken in the modelling of the unclosed terms appearing in the CMC equations. © 2013 The Combustion Institute.

Improving intermediate pressure turbine performance by using a nonorthogonal stator

Intermediate pressure (IP) turbines in high bypass ratio civil aeroengines are characterized by a significant increase in radius and a low aspect ratio stator. Conventional aerodynamic designs for the IP turbine stator have had leading and trailing edges orthogonal to the hub and casing end walls. The IP turbine rotor, however, is stacked radially due to stress limits. These choices inevitably lead to a substantial gap between the IP stator and rotor at the outer diameter in a duct that is generally diffusing the flow due to the increasing radius. In this low Mach number study, the IP stator is redesigned, incorporating compound sweep so that the leading and trailing edges are no longer orthogonal to the end walls. Computational investigations showed that the nonorthogonal stator reduces the flow diffusion between the stator and rotor, which yields two benefits: The stator trailing edge velocity was reduced, as was the boundary layer growth on the casing end wall within the gap. Experimental measurements confirm that the turbine with the nonorthogonal stator has an increased efficiency by 0.49%, while also increasing the work output by 4.6%, at the design point. © 2014 by ASME.

Development of low-pH cements for immobilisation of intermediate level radioactive waste: Achievements and challenges

Although cementation is a widely recognized solidification/ stabilization process for immobilisation of Intermediate Level Radioactive Waste (ILRW), the low resistance to hyperalkaline pore waters compromises the effectiveness of the process when Portland Cement (PC) is employed. Moreover the manufacture of PC is responsible for significant CO2 emissions. In this context, low pH cements are environmentally more suitable and have emerged as a potential alternative for obtaining secure waste forms. This paper summarises the achievements on development of low-pH cements and the challenges of using these new materials for the ILRW immobilisation. The performance of waste forms is also discussed in terms of radionuclides release. Reactive magnesium oxide and magnesium phosphate cements are emphasised as they feature important advantages such as consumption of available constituents for controlling acid-base reactions, reduced permeability and higher density. Additionally, in order to identify new opportunities for study, the long-term modelling approach is also briefly discussed. Copyright © 2013 by ASME.

Low-frequency noise properties of GaN Schottky barriers deposited on intermediate temperature buffer layers

Metal-semiconductor-metal (MSM) structures were fabricated by RF-plasma-assisted MBE using different buffer layer structures. One type of buffer structure consists of an AlN high-temperature buffer layer (HTBL) and a GaN intermediate temperature buffer layer (ITBL), another buffer structure consists of just a single A IN HTBL. Systematic measurements in the flicker noise and deep level transient Fourier spectroscopy (DLTFS) measurements were used to characterize the defect properties in the films. Both the noise and DLTFS measurements indicate improved properties for devices fabricated with the use of ITBL and is attributed to the relaxation of residue strain in the epitaxial layer during growth process. (C) 2003 Elsevier Ltd. All rights reserved.

The influence of AlN/GaN superlattice intermediate layer on the properties of GaN grown on Si(111) substrates

AlN/GaN superlattice buffer is inserted between GaN epitaxial layer and Si substrate before epitaxial growth of GaN layer. High-quality and crack-free GaN epitaxial layers can be obtained by inserting AlN/GaN superlattice buffer layer. The influence of AlN/GaN superlattice buffer layer on the properties of GaN films are investigated in this paper. One of the important roles of the superlattice is to release tensile strain between Si substrate and epilayer. Raman spectra show a substantial decrease of in-plane tensile strain in GaN layers by using AlN/GaN superlattice buffer layer. Moreover, TEM cross-sectional images show that the densities of both screw and edge dislocations are significantly reduced. The GaN films grown on Si with the superlattice buffer also have better surface morphology and optical properties.

Effect of different type intermediate layers on band structure and gain of Ga1-xInxNyAs1-y-GaAs quantum well lasers

Based on the band-anticrossing model, the effect of the strain-compensated layer and the strain-mediated layer on the band structure, the gain, and the differential gain of GaInNAs-GaAs quantum well lasers have been investigated. Different band-filling mechanisms have been illustrated. Compared to the GaInNAs-GaAs single quantum well with the same wavelength,, the introduction. (if the strain-compensated layer and the strain-mediated layer increases the transparency carrier density. However, these multilayer structures help to suppress the degradation of the differential gain.

Theoretical analysis of characteristics of GaxIn1-xNyAs1-y/GaAs quantum well lasers with different intermediate layers

Based on the band anticrossing model, the effects of the strain-compensated layer and the strain-mediated layer on the band structure, gain and differential gain of GaInNAs/GaAs quantum well lasers have been investigated. The results show that the GaNAs barrier has a disadvantage in increasing the density of states in the conduction band. Meanwhile, the multilayer quantum wells need higher transparency carrier density than the GaInNAs/GaAs single quantum well with the same wavelength. However, they help to suppress the degradation of the differential gain. The calculation also shows that from the viewpoint of band structure, the strain-compensated structure and the strain-mediated structure have similar features.

Characterization of deep levels in Pt-GaN Schottky diodes deposited on intermediate-temperature buffer layers

Gallium nitride (GaN)-based Schottky junctions were fabricated by RF-plasma-assisted molecular beam epitaxy (MBE). The GaN epitaxial layers were deposited on novel double buffer layers that consist of a conventional low-temperature buffer layer (LTBL) grown at 500 degreesC and an intermediate-temperature buffer layer (ITBL) deposited at 690 degreesC. Low-frequency excess noise and deep level transient Fourier spectroscopy (DLTFS) were measured from the devices. The results demonstrate a significant reduction in the density of deep levels in the devices fabricated with the GaN films grown with an ITBL. Compared to the control sample, which was grown with just a conventional LTBL, a three-order-of-magnitude reduction in the deep levels 0.4 eV below the conduction band minimum (Ec) is observed in the bulk of the thin films using DLTFS measurements.