Physical Chemistry

In this paper, a study on the batch processing and characterization of microcellular foamed high-density polyethylene (HDPE/iPP) blends is reported. A microcellular plastic is a foamed polymer with a cell density greater than 109 cells/cm3 and fully grown cells smaller than 10 µm. Recent studies have shown that the morphology and crystallinity of semicrystalline polymers have a great influence on the solubility and diffusivity of the blowing agent and on the cellular structure of the resulting foam in microcellular batch processing. In this research, blends of HDPE and iPP were used to produce materials with variety of crystalline and phase morphologies to enhance the subsequent microcellular foaming. It was possible to produce much finer and more uniform foams with the blends than with neat HDPE and iPP. Moreover, the mechanical properties and in particular the impact strength of the blends were significantly improved by foaming.
(citation # 293)

Laboratory Information System (LIS) streamlines workflow in the laboratory and eliminates time-consuming paperwork. The business today is getting increasingly pressured to be more productive and efficient with less traditional resources. If we look at a typical production process, for instance, the level of automation and optimization that has permeated into the production floor is quite astounding. Many industries have had a tremendous impact in bringing to the market the automation and optimization solutions to streamline -the production floor. The other ends of the spectrum are the back-office transaction oriented processes like Inventory Management, Materials Management, Financials and so on, Therefore a lab’s ability to process data quickly and its ability to disseminate that information efficiently throughout the plant is vital for the success of the production process. Laboratory Information Management System (LIMS) can help in managing the information flow within the lab and can be the modus operandi of connecting the lab with the rest of the organization. For instance, imagine all the information that is generated in a lab.

1. Uniform (general) corrosion
2. Galvanic (two–metal) corrosion
3. Thermogalvanic corrosion
4. Crevice corrosion (including deposit corrosion)
5. Pitting, pitting corrosion
6. Selective attack, selective leaching (de–alloying)
7. Intergranular corrosion (including exfoliation)
8. Erosion corrosion
9. Cavitation corrosion
10. Fretting corrosion
11. Stress corrosion cracking
12. Corrosion fatigue

In this contribution the vapor-liquid equilibrium of the binary mixtures formed by methyl lactate and the first four lineal alkanols has been determined at constant pressure (p = 101.325 kPa) and at constant temperature (T = 323.15 K). The results have been adequately correlated with the Wilson equation. The obtained data have been satisfactorily checked for thermodynamic consistency using the van Ness method. Furthermore, we have applied the UNIFAC method to predict the vapor-liquid equilibrium and compared these predictions with the experimental results.

The results of Hg1-xCdxTe layer growth by liquid phase epitaxy (LPE) from the Te-rich solution (Hg1-zCdz)1-yTey with z=0.0545 and y=0.806 obtained by the tipping method in a closed system are presented. The epitaxial layers with different compositions, x=0.20-0.22, and thicknesses ranging from 10 to 20 µm, which are suitable for manufacturing IR photodiode structures, were grown on (111) B-oriented Cd0.96Zn0,04Te substrates at 501-470 °C in a sealed quartz ampoule. A novel LPE apparatus for obtaining of a residual-melt-drop-free surface is described. The effect of the preliminary synthesis of the source on the reproducibility of both the liquidus temperature (ΔΘ±1.8 °C) and epilayer composition (Δx±0.003) was evaluated using the expression for the Hg-Cd-Te phase diagram. As-grown layers exhibit p-type conductivity with a carrier concentration in the range from 4×1016 to 1.4×1017 cm-3 and mobility of 240-270 cm2 V-1 s-1. The concentration and mobility of charge carriers in the layers annealed at 280 °C for 10 h under Hg overpressure were found to be 5×1015 cm-3 and 1×104 cm2 V-1 s-1, respectively.

Self-assembled monolayers (SAMs) of functionalized oligo(cyclohexylidene) molecules on gold(111) surfaces have been studied by measurement of the interfacial capacitance in concentrated electrolyte solutions and by cyclic voltammetry with Fe(CN)6 3 −/4− as the redox system. The morphology of the layers has been studied by scanning tunneling microscope (STM) and AFM. We found that sulfide-terminated oligo(cyclohexylidenes) form a well-ordered SAM on gold(111) and that the oxime end-functionality inhibits the formation of ordered SAMs. Charge-stabilized gold nanocrystals attach to sulfide-terminated SAMs on gold(111) to form robust gold(111) _ oligo(cyclohexylidene) _ gold nanocrystal molecular junctions. We show that the nanocrystal _ water interface can be charged by electron transport through the molecular layer.

The equations of motion in a system consisting of three or more bodies at a lower scale (microscale) are compared to the equations of motion in an equivalent system at a higher scale (macroscale), where only two bodies are observed, and at least one of them is a composite body comprising two or more individual bodies. The behavior of the system is the same in both cases, because only the scale of observation has changed. However, the energy observed is apparently different at both scales, and anisotropy in the potential energy observed at the macroscale emerges. These effects are due, on one hand, to an unobserved kinetic energy inside the composite body, which is associated to its internal energy (relative internal motion). The internal energy also considers the interaction potential energies between the individual bodies in the composite (internal interaction). On the other hand, in the presence of an external body there is also an unobserved, residual interaction potential energy, which cannot be considered part of the internal energy of the composite bodies. Such residual potential energy is also responsible for the anisotropy of the macroscale potential energy. Mathematical expressions for determining such residual potential energy are obtained for different situations, including the interaction between a composite body and a single body, and the interaction between two composite bodies of arbitrary sizes.

The physicochemical properties, cationic composition and rheological behaviour of exudates from Ficus glumosa were investigated. The gum was found to be mild acidic, ionic and soluble in water, sparingly soluble in ethanoland insoluble in acetone and chloroform. The trend for the decreasing concentration of elements determined in the gum sample is Mg > Ca > Mn > Zn > Fe > Ni > Zn > Cu > Cd > Pb. Rheological properties of the gums have been adequately modeled using Huggins, Kraemer, Arrhenius, Tanglertpaibul and Rao theories. The results indicated that the viscosity of the gum increases with increasing pH and concentration but decreases with increase in temperature. Values of intrinsic viscosity obtained from Huggins and Kraemer plots were similar (11.197). The value of activation energy (E vis) of the gum studied was found to be 1.915 kJ/mol. The low E vis values obtained suggests the existence of few inter and intra-interactions between the molecules of the gums within the investigated temperature. F. glumosa gum exudate hence, possesses the potentials to be used as an additive in food and other industries.

We present a study on whether and to what extent subcellular localization may compete favorably with photosensitization efficiency with respect to the overall efficiency of photoinduced cell death. We have compared the efficiency with which two cationic photosensitizers, namely methylene blue (MB) and crystal violet (CV), induce the photoinduced death of human cervical adenocarcinoma (HeLa) cells. Whereas MB is well known to generate singlet oxygen and related triplet excited species with high quantum yields in a variety of biological and chemical environments (i.e., acting as a typical type II photosensitizer), the highly mitochondria-specific CV produces triplet species and singlet oxygen with low yields, acting mostly via the classical type I mechanism (e.g., via free radicals). The findings described here indicate that the presumably more phototoxic type II photosensitizer (MB) does not lead to higher degrees of cell death compared to the type I (CV) photosensitizer. In fact, CV kills cells with the same efficiency as MB, generating at least 10 times fewer photoinduced reactive species. Therefore, subcellular localization is indeed more important than photochemical reactivity in terms of overall cell killing, with mitochondrial localization representing a highly desirable property for the development of more specific/efficient photosensitizers for photodynamic therapy applications.