Thermodynamics of polymer solutions and blends

To describe the thermodynamic behavior of binary and larger polymer blends, the Hoch-Arpshofen model is used to describe highly asymmetric phase diagrams, and asymmetric enthalpies of mixing, where the miscibility gap and the extremum of the enthalpy of mixing leans toward one of the components. The Gibbs energy of mixing of polymer blends is described as where z can be mole fraction, volume fraction, or weight fraction. The Hoch-Arpshofen model contains an interaction parameter W = A + B*T independent of composition and an integer number n (2, 3, 4, …), which defines the asymmetricity of the binary phase diagram and of the Gibbs energy of mixing curve. In a binary system n defines the composition where the Gibbs energy of mixing is maximum or minimum or the composition is where the temperature of a miscibility gap is maximum or minimum. In a binary system A-B the maximum effect occurs at A_n–1B. The disorder reaction in polymers is treated as a transformation temperature, and defines T₀, the temperature where the ordered and disordered material is equal.     

Guest editorial–special issue on ground control in mining in 2020

正Ground control is the science of studying and controlling the behavior of rock strata in response to mining operations.Ground-control-related research has seen significant advancements over the last 40 years, and these accomplishments are well documented in the proceedings of the annual International Conference on Ground Control in Mining (ICGCM)[1].     

Intermittent Hypoxic Therapy Inhibits Allogenic Bone-Graft Resorption by Inhibition of Osteoclastogenesis in a Mouse Model

Systemic Intermittent Hypoxic Therapy (IHT) relies on the adaptive response to hypoxic stress. We investigated allogenic bone-graft resorption in the lumbar spine in 48 mice. The mice were exposed to IHT for 1 week before surgery or 1 week after surgery and compared with controls after 1 and 4 weeks. Complete graft resorption was observed in 33–36% of the animals in the control group, but none in the preoperative IHT group. Increased bone-graft volume was demonstrated by micro-computed tomography in the preoperative IHT group after 1 week (p = 0.03) while a non-significant difference was observed after 4 weeks (p = 0.12). There were no significant differences in the postoperative IHT group. Increased concentration of immune cells was localized in the graft area, and more positive tartrate-resistant acid phosphatase (TRAP) staining was found in controls compared with IHT allogenic bone grafts. Systemic IHT resulted in a significant increase of the major osteoclast inhibitor osteoprotegerin as well as osteogenic and angiogenic regulators Tgfbr3, Fst3l, Wisp1, and Vegfd. Inflammatory cytokines and receptor activator of nuclear factor kappa-B ligand (RANKL) stimulators IL-6, IL-17a, IL-17f, and IL-23r increased after 1 and 4 weeks, and serum RANKL expression remained constant while Ccl3 and Ccl5 decreased. We conclude that the adaptive response to IHT activates numerous pathways leading to inhibition of osteoclastic activity and inhibition of allogenic bone-graft resorption.     

Engineering a data dependence test

Many papers have been written dealing with the science of data dependence tests, particularly for dependence of arrays in loops; the techniques typically reduce the dependence problem to an algebraic problem, then solve the algebraic problem by an algorithm which has some desired blend of efficiency, generality or precision. While a sound theoretical basis is necessary for dependence-based tools, these papers often leave out many implementation details. This paper addresses the engineering aspects of data dependence testing, particularly focusing on details that are necessary in any competent implementation of a data dependence test.     

Radikalreaktionen an N-Heterocyclen. XI [1] Reaktionen von 3-Methyl-pyrazolin-5-onen mit Phenoxyl-Radikalen

Free Radical Reactions of N-Heterocyclic Compounds. XI. Reaction of 3-Methyl-pyrazolin-5-ones with Phenoxy Radicals Pyrazolin-5-ones ( 3a–i ) were oxidized with 2,4,6-trisubstituted phenoxy radicals ( 2a–d ) to the corresponding radicals ( 4a–i ), which dimerised or combined with phenoxy radical ( 2a ) depending on the R¹- and R⁴-substituents in ( 3 ). In the case of 3-methyl-1-phenyl-pyrazolin-5-one ( 3f ) the primary radical combination products were not found, but the corresponding quinone methide ( 17 ) and the o-phenol derivative ( 18 ) were isolated. Products and yields have been investigated as a function of mol ratio substrate: oxidant and solvent. The radical combination products ( 7–10 ) could de-tertbutylated in the presence of aluminium chloride or in the presence of trifluoroarcetic acid, forming heterocyclic substituted phenols ( 21 ) and ( 22 ).     

Normal vector generation for sampled data using fourier filtering

A three-dimensional surface is a useful graphic representation of a two-dimensional function which has been sampled on a regular grid. Shading the surface to simulate the effects of direct lighting makes visible small changes in the surface orientation, and enhances realism when the data represents a physical surface such as terrain. Shading interpolation calculations and surface patch generation techniques require the specification of a surface normal vector (or related slope information) at each sample point. These normal vectors are usually generated by averaging local data such as the normal vectors of the surfaces of a triangular mesh connecting the points. This paper describes a technique which uses Fourier filtering to generate normal vectors for two-dimensional sampled data. Images and analysis of frequency spectra are included to show how this technique preserves detail which is lost using the averaging method. Performance figures show that this enhancement of detail in the final image can be achieved for only a small increase in computation time.     

Turbidity control and fisheries enhancement in a bottomland hardwood backwater system in Louisiana (U.S.A.)

In response to a noticeable decline in recreational fishing in the formerly productive Larto—Saline backwater complex of east central Louisiana, a study was begun to identify causative factors for the decline and to determine effective methods to remedy the problem. To this end, water quality and fisheries surveys were conducted in the system for the study period 1 July, 1981 to 30 June, 1989. Data collected during the early years of the study indicated chronically high turbidity (> 100 FTU) to be the major factor limiting game fish production. The high turbidity can be related to man-made alterations of natural flood patterns that had changed the major source of backwater flooding from Black River to the highly turbid Red River. In September, 1986, a construction project was undertaken to restore flood patterns to approximate natural conditions. Sampling subsequent to this construction has shown a significant decrease in turbidity and an increase in game fish production.