Different Levels Of Water Content Research Articles

Fluoroquinolone salts with carboxylic acids

The crystallization of fluoroquinolone antibiotics norfloxacin and ciprofloxacin with carboxylic acids gave six new salts that were characterized by infrared spectroscopy, differential scanning calorimetry, X‐ray powder diffraction, and single crystal X‐ray diffraction. Five of these salts are hydrates with different levels of water content. The molecular composition, stoichiometry, and proton transfer state in these salts are confirmed from the crystal structure. The effect of carboxylate counterion, such as oxalate, tartarate, benzoate, malonate, and citrate, and hydration state on the solubility and dissolution profile of drug salts are reported in pure water (pH 6.4), 0.1 N HCl (pH 1.2), and phosphate buffer solution (pH 6.8). These salts are more soluble and exhibit faster dissolution in pure water and phosphate buffer medium than the reference drugs, but the order is reversed in acidic medium. These salts are chemically stable to the dissolution measurement conditions, whereas the reference drug norfloxacin undergoes phase transformation to norfloxacin hydrate at the end of the experiment. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:3160–3176, 2011

Blast Pressure Distribution on a Buried Obstacle in a Porous Wet Soil

The paper presents a comprehensive approach to simulate the blast pressure distribution on a rigid or flexible planar or curved obstacle buried in a porous soil medium. The Lyakhov three-phase model is adopted to take into account the volumetric components of the soil medium (air, water, and solid matrix) and their properties, in the formulation of all the branches of the equation of state that simulates the soil. The present approach considers both the bulk and the shear elastic-plastic behavior, including the effect of soil pressure on the yield strength for the stress tensor deviator. Both Godunov and the variational-difference methods are applied to solve the problem of blast wave propagation within the soil medium. An example problem of an explosion in a porous medium is presented, and the analysis of the soil-obstacle interaction under the blast action using the proposed method shows good correspondence with available experimental results. The pressure distribution along the envelope of a rigid obstacle has been investigated for different standoff distances of the explosive from the obstacle as well as for different levels of soil water contents up to saturation. In addition, the plane problems of blast response of a thin-walled lining that is buried in this medium has been studied for different levels of water content and the lining's extreme deformation including its dynamic buckling under the blast high pressures was investigated.

Reducing the Complexity of Inverse Analysis of Time Domain Reflectometry Waveforms

Inverse analysis of time domain reflectometry (TDR) waveform in the frequency domain is important in measuring complex dielectric permittivity of soils. However, for widely used probes designed as impedance mismatching and nonseparable connection between probe head and coaxial cable, none of the available models can be used for the inverse analysis. The objective of this study was to derive a model which is applicable for this specific type of probes. A two‐section (probe head and probe rods) model was derived from the full model of Feng et al. (1999) by reducing its complexity on the basis of the matching design of cable tester and coaxial cable. The model was validated by comparison of the measured spectra of properly terminated coaxial cable with the theoretical values, and the accuracy of the model was studied by the comparison of the estimated complex dielectric permittivity of ethanol by the model with those measured by the network analyzer method. This model was applied to a silt loam soil under different levels of water content and electrical conductivity (EC). The results showed that the two‐section model was applicable for this specific type of probes to measure complex dielectric permittivity at low frequency range. The lowest frequency of 30 MHz was used to estimate soil complex dielectric permittivity. The real parts of the estimated soil dielectric permittivity were close to the apparent dielectric permittivity determined by travel time analysis (TTA). The soil bulk EC calculated from the imaginary parts of the estimated soil dielectric permittivity was close to the measured values.

Fall Cone Test to Characterize Shear Strength of Organic Sediments

In this paper, the results of the standard percussion cup test, the penetration cone test, and the laboratory vane test performed on organic sediments and kaolin are discussed. First, the relationship between the water content and the cone penetration depth is explored. Second, the relationship between the shear strength, using the laboratory vane apparatus, and the water content is investigated. Finally, the relationship between the shear strength and the penetration depth of the cone, at different levels of water content, is explored.

Capillary cohesion and mechanical strength of polydisperse granular materials

We investigate the macroscopic mechanical behaviour of wet polydisperse granular media. Capillary bonding between two grains of unequal diameters is described by a realistic force law implemented in a molecular-dynamics algorithm together with a protocol for the distribution of water in the bulk. Axial-compression tests are simulated for granular samples at different levels of water content, and compared to experiments performed in similar conditions. We find good agreement between numerical and experimental data in terms of the rupture strength as a function of water content. Our results show the importance of the distribution of water for the mechanical behaviour.

Effect of pH 24, NaCl content and proteolysis index on the relationship between water content and texture parameters in biceps femoris and semimembranosus muscles in dry-cured ham

The aim of the present study was to determine the effect of pH level and NaCl content on the relationship between water content and texture parameters in semimembranosus and biceps femoris muscles in dry-cured ham. The experiment was undertaken using 18 hams, selected in a commercial slaughterhouse. Half of the hams had a pH < 5.7 and the rest a pH > 6.2, measured in the semimembranosus muscle at 24-h post mortem (pH SM24). The hams were treated with 20, 50 or 80 g of NaCl per kg of ham. At the end of the aging process nine samples from semimembranosus and biceps femoris muscles were dried to different levels of water content covering the range from 22.4% to 58.5%. At the end of the drying period, a Texture Profile Analysis was used to determine textural parameters. Samples from biceps femoris muscle and samples from hams with low pH SM24 showed a higher proteolysis index (100 × non-protein nitrogen/total nitrogen) than samples from semimembranosus muscle and samples from hams with high pH SM24, respectively. The proteolysis index decreased when the added NaCl amount increased. The proteolysis index was the parameter that best explained the modifications in the relationship between water content and the texture parameters (hardness, cohesiveness and springiness) of dry-cured ham muscles and it would be considered in order to predict the texture in dry-cured ham at different drying levels. Dry-cured hams with a lower proteolysis index were more prone to present harder texture at low water contents, which is typical of hams with crustiness problems.

ADN PROPELLANT TECHNOLOGY

This paper discusses a number of issues critical to ammonium dinitramide (ADN) propellant technology. It also includes a survey of the chemical purity levels of ADN produced by different sources, the safely properties of ADN with different levels of water content, and the prilling of neat ADN to produce spherical particles. In addition, it discusses the aging stability and processing properties of propellants containing ADN and ADN prills. To qualify ADN as a propellant ingredient, these properties must be thoroughly characterized and understood, so that the properties of ADN propellants can be predicted when this compound is incorporated in the binder.

The effect of soil moisture content on the cellulolytic mycoflora of soil amended with cellulosic remains

The fungal population of soil amended with four types of cellulosic remains under different levels of water content was recorded. 40–80% soil water content was the best level for fungal multiplication. There was no specific fungal flora isolated from any of the three cellulosic remains but some fungi grew noticeably better on some cellulose types than on others. The gross total count of fungi was the highest in soil amended with sugar cane straw at 60% water content but the least was in soil mixed with broad bean straw at 100% water content. Aspergillus, Penicillium, Chaetomium, Cladosporium, Emerciella nidulans, Fusarium and Stachybotrys were the most dominant fungi. Sugar cane straw was the most hospitable cellulosic material for soil funig. 60% water content was more suitable for the cellulolytic activity of test fungi but protein content was the highest in between 60–80% of soil water content.

Effect of Water Potnetial of Culture Medium on Geotropic Response of Primary Seminal Root in Japanese Wheat Cultivars.

It has been observed that wheat has a shallow root system in wet soil and a deep root system in dry soil. However, the control mechanisms of root growth depending on soil water status remain unclear. Since root geotropic response seems to play an important role in the formation of the root system, the effect of water potential of culture medium on the geotropic response of the primary seminal root in Japanese wheat cultivars was examined. Agar medium with different concentrations of polyethylene glycol (PEG-6000) and vermiculite medium with different levels of water content were used. Growth angle of the primary seminal root in Minaminokomugi, which usually shows small root growth angle, became larger in low water potential media (-0.05 MPa) than in the control (O MPa). Effects of low water potential on root geotropic responses in the agar medium were also examined in 133 Japanese wheat cultivars. Minaminokomugi and 50 other cultivars showed large responses in the low water potential medium. It is considered that low water potential of the culture medium stimulates positive root geotropic responses in certain Japanese wheat cultivars.

Molecular dynamics of agarose gels investigated by NMR and rayleigh scattering of Mössbauer radiation

NMR, X-ray and Rayleigh scattering of Mossbauer radiation (RSMR) measurements have been performed on agarose-water systems for different levels of water content. The NMR data provided information on the relaxation rates of protons in both polysaccharide and solvent. The RSMR measurement allowed us to determine the mean square atomic displacements as a function of the scattering vector. The values of carbon and oxygen atoms are larger when measured at distances corresponding to the helix diameter than along the chain bonds. At low hydration levels, the water molecules closely associated to the polysaccharide chains follow the dynamics of the polymer. A marked change in the dynamics of both polymer and water has been evidenced when the water weight exceeds 20% of the total weight of the sample.

Application of an N-Methylol Crosslinking Agent to Cotton from an Emulsion System

Application of DMDHEU from a kerosene-water emulsion system at different levels of water content in the system has been examined with respect to the extent of crosslinking and mechanical properties of the finished fabrics. As the water content of the treating bath is decreased, both wet and dry wrinkle-recovery angles, bound nitrogen, and bound HCHO in the crosslinked fabric increase, but there is no improvement noticed in the wrinkle-recovery/mechanical properties relationship. The increase in the extent of cross linking during application from the emulsion system appears to be due to preferential uptake of the aqueous solution containing the crosslinking agent from the emulsion system.