Salt-tolerant forages for irrigated saline land in central Iraq

Salinity is a major problem in the irrigated zones of central and southern Iraq. We investigated biomass production from five salt-tolerant forage species, represented by 15 introduced accessions and 3 local accessions, during two successive summer growing seasons. Species included pearl millet (Pennisetum glaucum), sorghum (Sorghum bicolour), guar (Cluster bean; Cyamopsis tetragonoloba), cowpea (Vigna unguiculata) and sesbania (Sesbania aculeata and S. sesban). The research site was located in the Al-Dujaila irrigation project area in Wasit. The soil had a silty clay texture with moderate salinity (ECe 10-20 dS/m). The site was irrigated with water (ECw 1.1 dS/m) from the Tigris River on a 3 to 8-day basis. We hypothesised that there would be variation in biomass production, salt accumulation and crude protein both between and within species. In addition, we thought that the legumes would be less productive than grasses as they tend to be more sensitive to salinity. Over 2 experimental seasons, the plants produced an average shoot dry mass of 12.1 t/ha with a range for accessions of 3 to 35 t/ha. There was significant variation both within and between species, supporting the first hypothesis. None of the plants accumulated excessive salt (ash < 12% DM); crude protein was variable (6 to 12%), but higher in two legumes – cowpea and sesbania. Furthermore, there was no evidence that grasses were more productive than legumes, with sesbania and cowpea achieving the highest mean biomass production across the years. We conclude that moderately saline irrigated areas of Iraq can sustain high levels of biomass production for livestock although protein may be limited

Risk of climate-induced damage in historical textiles

Eleven wool and silk historic textiles and two modern artist's canvases were examined to determine their water vapour adsorption, moisture dimensional response and tensile behaviour. All the textiles showed a similar general pattern of moisture response. A rise in ambient relative humidity (RH) from dry conditions produced expansion of a textile until a certain critical RH level after which a contraction occurred to a greater or lesser degree depending on the yarn crimp and the weave geometry. The largest expansion recorded between the dry state and 80% RH was 1.2 and 0.9% for wool and silk textiles, respectively. The largest shrinkage of 0.8% at high RH range was experienced by a modern linen canvas. Two potential damage mechanisms related to the moisture response of the textiles—stress building as a result of shrinkage of the textile restrained in its dimensional response and the fretting fatigue when yarns move with friction one against another—were found insignificant in typical textile display environments unless the textiles are severely degraded or excessively strained in their mounting

Liquid State Anomalies for the Stell-Hemmer Core-Softened Potential

We study the Stell-Hemmer potential using both analytic (exact $1d$ and approximate $2d$) solutions and numerical $2d$ simulations. We observe in the liquid phase an anomalous decrease in specific volume and isothermal compressibility upon heating, and an anomalous increase in the diffusion coefficient with pressure. We relate the anomalies to the existence of two different local structures in the liquid phase. Our results are consistent with the possibility of a low temperature/high pressure liquid-liquid phase transition.Comment: 4 pages in one gzipped ps file including 11 figures; One RevTex and 11 gzipped eps figure

Parametrization of the Hybrid Potential for Pairs of Neutral Atoms

The hybrid form is a combination of the Rydberg potential and the London inverse-sixth-power energy. It is accurate at all relevant distance scales and simple enough for use in all-atom simulations of biomolecules. One may compute the parameters of the hybrid potential for the ground state of a pair of neutral atoms from their internuclear separation, the depth and curvature of their potential at its minimum, and from their van der Waals coefficient of dispersion.Comment: 7 pages, 11 figures, includes lithium, sodium, & potassium dimers, minor correction

Driven Morse Oscillator: Model for Multi-photon Dissociation of Nitrogen Oxide

Within a one-dimensional semi-classical model with a Morse potential the possibility of infrared multi-photon dissociation of vibrationally excited nitrogen oxide was studied. The dissociation thresholds of typical driving forces and couplings were found to be similar, which indicates that the results were robust to variations of the potential and of the definition of dissociation rate. PACS: 42.50.Hz, 33.80.WzComment: old paper, 8 pages 6 eps file