Experimental investigation of evolving anisotropy in unsaturated soils

This paper investigates the ‘initial’ and ‘evolving’ mechanical anisotropy of a compacted unsaturated soil. Awide campaign of triaxial compression and extension tests, involving different stress and suction paths, has been performed on both isotropically and anisotropically compacted samples of unsaturated Speswhite kaolin. The first objective is the definition of the initial yield surface of the compacted soil after suction equalisation and before any plastic loading/wetting path takes place. This is followed by the investigation of the evolution of the yield surface induced by plastic straining along different loading/wetting paths. Experimental results are interpreted by using two alternative stress variables, namely net stresses σij and Bishop’s stress σ� ij ¼ σij þ δijSrs (where δij is Kronecker delta, Sr is the degree of saturation and s is suction). Constant suction cross-sections of the yield surface are represented as distorted ellipses not passing through the origin in the q:p plane of deviator stress plotted against mean net stress, and by distorted ellipses passing through the origin in the q:p* plane of deviator stress plotted against mean Bishop’s stress. The inclination of these distorted elliptical yield curves evolves with plastic straining but remains the same at all suction levels for a given level of plastic deformation. The critical state lines in the planes q:p and q:p*, or in the semi-logarithmic v:lnp and v:lnp* planes (v is the specific volume), are generally independent of initial anisotropy or stress history, suggesting that fabric memory tends to be erased at critical state

Study of Some Epidemiological Aspects of Giardiasis in North of Baghdad

Different factors have been examined to be related with the prevalence of Girdiasis in the north of Baghdad in human beings which were (gender, age , occupation ,family size,faecal status and presence of domestic animals) during the period from the beginning of April 2009 till the end of March 2010. This study revealed that the total rate of infection in human being was 11.66% , and no significant differences (p?0.05) were noticed between male and female as their rates of infection were 52.32% and 47.68% respectively , as well as no significant relation was observed between faecal status and the rate of infection, the percentage of positive cases in diarrheal patients was higher than the non diarrheal patients who were 74.41 and 25.59 respectively ,while there was significant relation between the presence of domestic animals and prevalence of giardiasis (p?0.05) ,the infectivity rate reached to 23.25% in persons who had domestic animals in their household .Also high infection rate have been recorded among children less than 10 years old which was 51.16 % when it compared with other age groups, as well as preschool children and person belong to family composed of (5-9) individual were observed to be the majority groups that infected with Giardia which were 44.18% and 50% respectively, although there were no significant relation (p?0.05) between each of age, occupation and family size with infectivity rate of Gairdia

Maastrichtian - upper Eocene ostracoda of the subfamily Trachyleberidinae from Iraq, Jordan and Syria

Abstract available: p 16

The Formation of Galaxy Disks

We present a new set of multi-million particle SPH simulations of the formation of disk dominated galaxies in a cosmological context. Some of these galaxies are higher resolution versions of the models already described in Governato et al (2007). To correctly compare simulations with observations we create artificial images of our simulations and from them measure photometric Bulge to Disk (B/D) ratios and disk scale lengths. We show how feedback and high force and mass resolution are necessary ingredients to form galaxies that have flatter rotation curves, larger I band disk scale lengths and smaller B/D ratios. A new simulated disk galaxy has an I-band disk scale length of 9.2 kpc and a B/D flux ratio of 0.64 (face on, dust reddened).Comment: To appear in proceedings of "Formation and Evolution of Galaxy Disks", Rome, October 2007, Eds. J.G. Funes, S.J. and E.M. Corsini. Bigger figures than in printed versio

Strain rate behaviour of thermoplastic polymers

Polymers are increasingly used in structures that have to withstand impact conditions. This thesis describes an investigation of strain rate properties at room temperature of four engineering polymers; polyethylene (high density, HDPE and ultra high molecular weight, UHMWPE), nylatron and polyetheretherketone (PEEK 150g). A split Hopkinson pressure bar (SHPB) system was used to study the response of these polymers in compression tests at high strain rates up to 10' S-1. Stress equilibrium in SHPB samples was studied theoretically by examining multiple reflection effects during the initial elastic loading of the polymers; this study proved very useful in the analysis of SHPB tests. To cover a wide range of strain rate, compression studies were also made at low strain rates (10-3 _10-2 S-1) using a Hounsfield screw machine. Viscoelastic models have been applied to these results. These models fit quite well with the experimental results of HDPE, UHMWPE, and nylatron, but not to the PEEK due to the yield drop in the stress - strain curves, especially at high strain rates. An exploding wire technique was used as an axial impulsive loading system for hollow cylindrical samples. An image converter camera at framing intervals of 21ls or 10 Ils recorded the radial expansion of the cylinder. The expanding cylinder was used as a driving system for a new technique called the freely expanding ring method, which was used to obtain the stress - strain behaviour of polymeric thin rings placed as a sliding fit on the cylinder. This method produced very high tensile strain rates up to fracture (> 10' S-1). Comparisons have been made between results obtained from the quasi-static, SHPB, and expanding ring tests. The freely expanding ring and SHPB results were in good agreement indicating similar tensile and compressive high strain rate behaviour. The mechanical properties of the above polymers are strongly dependent on strain rate. The Young's modulus and the flow stress increase with increasing strain rate. Nylatron showed high strain rate strain softening at high strain, this was due to the high temperature rise during loading, when the transition temperature (Tg) of the material (50 QC) was exceeded. However, the other materials showed continuous hardening behaviour. Plots of the flow stress at 5% and 10% strain vs log strain rate showed a linear increase up to a strain rate of about 103 S-1. Above 103 s-1, the stress rose more rapidly, but then showed significant drops for nylatron and PEEK. These drops in stress are probably due to both micro crack initiation in the sample and also high temperatures around the crack tips

High-speed photographic studies of blast wave impact phenomena

An exploding wire technique (EWT) is described, which provides high rates of loading by producing cylindrical blast waves of high reflection pressure with short duration. These waves have been used for internal impact of hollow polymeric cylindrical specimens. The EWT overcomes the small size restrictions of other high strain rate testing methods like the Split-Hopkinson pressure bar technique and drop weight. [Continues.

Number 24 (November 1991)

(November 1991) - Fishes of the Sucarnoochee River System Alabama and Mississippi. By W.D. Hubbard, et al., 11 pp. Provenance and Disposition of Fish Specimens Appearing in Color Plates of Kuehne and A. Barbour\u27s Book, The American Darters. By C.R. Gilbert and S.J. Walsh, 8 pp. Museum Notes by E.G. Maurakis, 1 pp

Influence Of Ch4/h2 Reactive Ion Etching On The Deep Levels Of Si-doped Alxga1-xas (x=0.25)

We study the passivation and recovery of shallow and deep levels in Si-doped AlGaAs exposed to CH4/H2 and H2 reactive ion etching (RIE). The carrier concentration depth profile is determined by capacitance-voltage measurements. The activation energy to recover the silicon donors is found to be 1.1 eV for samples exposed to CH4/H2 RIE and 1.3 eV for samples exposed to H2 RIE. We study the behavior of DX centers in Si-doped AlGaAs layers after RIE exposure and subsequent thermal annealing by using deep level transient spectroscopy. For CH4TH2 RIE a new emission is detected at the high temperature side. We identify this emission as the DX3 center, which is assigned to a DX center with three aluminum atoms surrounding the Si donor. This DX center is only detected on the samples exposed to CH4/H2 RIE. We explain the formation of this deep level to the highly selective removal of Ga atoms in favor of Al atoms. Consequently Al-rich regions are created near the surface. © 1996 American Vacuum Society.14317731779Chevallier, J., Clerjaud, B., Pajot, B., (1991) Semiconductors and Semimetals, 34, p. 449. , Chap. 13Dautremont-Smith, W.C., (1988) Mater. Res. Soc. Symp. Proc., 104, p. 313Pearton, S.J., Dautremont-Smith, W.C., Chevallier, J., Tu, C.W., Cummings, K.D., (1986) J. Appl. Phys., 59, p. 2821Jalil, A., Chevallier, J., Pesant, J.C., Mostefaoui, R., Pajot, B., Murawala, P., Azoulay, R., (1987) Appl. Phys. Lett., 50, p. 439Chevallier, J., Pajot, B., Jalil, A., Mostefaoui, R., Rahbi, R., Boissy, M.C., (1988) Mater. Res. Soc. Symp. Proc., 104, p. 337Pavesi, L., Giannozzi, P., Reinhart, F.K., (1990) Phys. Rev. B, 42, p. 1864Pavesi, L., Giannozzi, P., (1991) Phys. Rev. B, 43, p. 2446Tavendale, A.J., Pearton, S.J., Williams, A.A., Alexiev, D., (1990) Appl. Phys. Lett., 56, p. 1457Yuan, M.H., Wang, L.P., Jin, S.X., Chen, J.J., Qin, G.G., (1991) Appl. Phys. Lett., 58, p. 925Srivastava, P.C., Chandra, S., Singh, U.P., (1991) Semicond. Sci. Technol., 6, p. 1126Cho, H.Y., Kim, E.K., Min, S., Chang, K.J., Lee, C., (1990) J. Appl. Phys., 68, p. 5077Zundel, T., Weber, J., (1989) Phys. Rev. B, 39, p. 13549Roos, G., Johnson, N.M., Herring, C., Harris, J.S., (1991) Appl. Phys. Lett., 56, p. 461Pearton, S.J., Abernathy, C.R., Lopata, J., (1991) Appl. Phys. Lett., 59, p. 3571Morrow, R.A., (1989) J. Appl. Phys., 66, p. 2973Cameron, N.I., Beaumont, S.P., Wilkinson, C.D.W., Johnson, N.P., Kean, A.H., Stanley, C.R., (1990) J. Vac. Sci. Technol. B, 8, p. 1966Cameron, N.I., Beaumont, S.P., Wilkinson, C.D.W., Johnson, N.P., Kean, A.H., Stanley, C.R., (1990) Microelectron. Eng., 11, p. 607Cheung, R., Thorns, S., McIntyre, I., Wilkinson, C.D.W., Beaumont, S.P., (1988) J. Vac. Sci. Technol. B, 6, p. 1911Jackson, G.S., Beberman, J., Feng, M.S., Hsieh, K.C., Holonyak Jr., N., Verdeyen, J., (1988) J. Appl. Phys., 64, p. 5175Dautremont-Smith, W.C., Nabity, J.C., Swaminathan, V., Stavola, M., Chevallier, J., Tu, C.W., Pearton, S.J., (1986) Appl. Phys. Lett., 49, p. 1098Jalil, A., Heurtel, A., Marfaing, Y., Chevallier, J., (1989) J. Appl. Phys., 66, p. 5854Nabity, J.C., Stavola, M., Lopata, J., Dautremont-Smith, W.C., Tu, C.W., Pearton, S.J., (1987) Appl. Phys. Lett., 50, p. 921Morrow, R.A., (1991) J. Appl. Phys., 69, p. 4306Chadi, D.J., Chang, K.J., (1988) Phys. Rev. Lett., 61, p. 873Chadi, D.J., Chang, K.J., (1988) Phys. Rev. B, 39, p. 10063Mooney, P.M., (1990) J. Appl. Phys., 67, pp. R1Chang, K.J., (1990) Proc. 20th Conference on Physics Semiconductor, 1, p. 787. , edited by E. M. Anastassakis and J. D. JoannopoulosCollot, P., Gaonach, C., (1990) Semicond. Sci. Technol., 5, p. 237Constantine, C., Johnson, D., Pearton, S.J., Chakrabarti, U.K., Emerson, A.B., Hobson, W.S., Kinsella, A.P., (1990) J. Vac. Sci. Technol. B, 8, p. 596Pearton, S.J., Chakrabarti, U.K., Hobson, W.S., (1989) J. Appl. Phys., 66, p. 2061Pearton, S.J., Abernathy, C.R., (1989) Appl. Phys. Lett., 55, p. 678Pearton, S.J., Hobson, W.S., Jones, K.S., (1989) J. Appl. Phys., 66, p. 5009Pereira, R., Van Hove, M., De Potter, M., Van Rossum, M., (1990) Electron. Lett., 26, p. 462Pereira, R., Van Hove, M., De Raedt, W., Jansen, Ph., Borghs, G., Jonckheere, R., Van Rossum, M., (1991) J. Vac. Sci. Technol. B, 9, p. 1978Chevallier, J., Dautremont-Smith, W.C., Tu, C.W., Pearton, S.J., (1985) Appl. Phys. Lett., 47, p. 108Hansen, W.L., Haler, E.E., Luke, P.N., (1982) IEEE Trans. Nucl. Sci., NS-29, p. 738Hall, R.N., (1984) IEEE Trans. Nucl. Sci., NS-31, p. 320Mooney, P.M., Theis, T.N., Wright, S.L., (1988) Appl. Phys. Lett., 53, p. 2546Mooney, P.M., Theis, T.N., Calleja, E., (1991) J. Electron. Mater., 20, p. 23Baba, T., Mizuta, M., Fujizawa, T., Yoshino, J., Kukimoto, H., (1989) Jpn. J. Appl. Phys., 28, pp. L891Morgan, T.N., (1991) J. Electron. Mater., 20, p. 6

Laboratory preparation of simulated sludge for anaerobic digestion experimentation

Health and environmental factors as well as operational difficulties are major challenges facing the development of an anaerobic digestion process. Some of these problems relate to the use of sludge collected from primary and secondary clarifier units in wastewater treatment plants for laboratory purposes. The present study addresses the preparation of sludge for laboratory purposes by using a mixture that consists of the digested sludge, which is less pathogenic, compared to the collected sludge from the primary or secondary clarifier, and food wastes. The sludge has been tested experimentally for 19 and 32 days under mesophilic conditions. The results show a steady methane production rate from the anaerobic digester which used sludge with a rate of 1.5 l/day and concentration around 60%, with comparatively low H2S gas content (10 ppm). The methane produced from the digester that used only digested sludge decreases during the experimental period

Myelin contrast across lamina at 7T, ex-vivo and in-vivo dataset

In this article we report the complete data obtained in-vivo for the paper: “Lines of Baillarger in vivo and ex-vivo: myelin contrast across lamina at 7T MRI and histology” (Fracasso et al., 2015) 1. Single participant data (4 participants) from the occipital lobe acquisition are reported for axial, coronal and sagittal slices; early visual area functional localization and laminar profiles are reported. Data from whole brain images are reported and described (5 participants), for axial, coronal and sagittal slices. Laminar profiles from occipital, parietal and frontal lobes are reported. The data reported in this manuscript complements the paper (Fracasso et al., 2015) 1 by providing the full set of results from the complete pool of participants, on a single-participant basis. Moreover, we provide histological images from the ex-vivo sample reported in Fracasso et al. (2015) 1