Monodisperse poly(p-chloromethylstyrene) microbeads by dispersion polymerization

In this study, an alternative dispersion polymerization method for the para isomer of chloromethylstyrene was proposed. Highly monodisperse poly(p-chloro-methylstyrene) (PCMS) particles in the size range of 1.67–3.75 μm were obtained. The monodispersity and the isolation yield of PCMS particles were significantly improved relative to the methods available in the literature. Azobisisobutyronitrile and polyacrylic acid were selected as the initiator and the steric stabilizer, respectively, in the dispersion medium composed of ethanol and methoxyethanol. The results indicated that the particle size increased with increasing initiator concentration. An increase in the stabilizer concentration led to a decrease in the particle size. The methoxyethanol/ethanol ratio was found as one of the most important parameters controlling the average size and the size distribution. Contrary to the tendencies noted in the literature, the particle size decreased with increasing polymerization temperature.     

The first graphite intercalation compounds containing tris(pentafluoroethyl)trifluorophosphate

Graphite intercalation compounds (GICs) containing the tris(pentafluoroethyl)trifluorophosphate anion, [(C₂F₅)₃PF₃]⁻ are prepared for the first time by electrochemical oxidation of graphite in a nitromethane electrolyte. Powder X-ray diffraction (PXRD) data indicate that products are of stages 2-4 with gallery heights of 0.82-0.86 nm. Intercalate orientation is determined by using a structure model containing an energy minimized anion. GIC compositional parameters are obtained by microwave digestion followed by F elemental analysis, in combination with thermogravimetric analyses.     

Influence of pH on recombinant human growth hormone production by Pichia pastoris

BACKGROUND: Effect of pH on recombinant human growth hormone (rhGH) production by Pichia pastoris hGH‐Mut⁺ was investigated at pH = 4.2, 5.0, 5.5, and 6.0. RESULTS: The highest cell concentration was obtained at pH = 6.0 with 53 g L^?1, while the highest rhGH concentration was attained at pH = 5.0 as 0.27 g L^?1. Total protease secretion increased with increase in pH and with the cultivation time. Oxygen uptake rate increased with increasing pH up to pH = 6.0, having the maximum value, 37 mmol m^?3 s^?1, at pH = 5.5. K_La values were similar at all the conditions, having a maximum value of 0.14 s^?1 at pH = 5.0. Taking the final rhGH concentration into account, the most favourable pH was 5.0; where AOX1 expression level showed a similar trend to AOX activity profiles, having the highest value of 9.4 × 10¹⁰ copy mg^?1 CDW at t = 15 h; in parallel to AOX1 expression profile, hGH expression level increased until t = 15 h, with the highest value of 4.0 × 10¹⁰ copy mg^?1 CDW, where a sharp increase in rhGH concentration was obtained. The expression levels of pep4, prb1 and prc1 genes, responsible from the production of proteinase A, proteinase B and, carboxypeptidase Y, were parallel to each other. CONCLUSION: Since it was shown that pH is a crucial operating parameter in fermentation processes using P. pastoris, keeping pH constant at its determined optimum value, pH = 5.0, during the bioprocess is vital in terms of recombinant protein production. Copyright © 2010 Society of Chemical Industry     

Determination of potential methane production capacity of a granular sludge from a pilot‐scale upflow anaerobic sludge blanket reactor using a specific methanogenic activity test

A 450 dm³ pilot‐scale upflow anaerobic sludge blanket (UASB) reactor was used for the treatment of a fermentation‐based pharmaceutical wastewater. The UASB reactor performed well up to an organic loading rate (OLR) of 10.7 kg COD m^?3 d^?1 at which point 94% COD removal efficiency was achieved. This high treatment efficiency did not continue, however and the UASB reactor was then operated at lower OLRs for the remainder of the study. Specific methanogenic activity (SMA) tests were, therefore, carried out to determine the potential loading capacity of the UASB reactor. For this purpose, the SMA tests were carried out at four different initial acetate concentrations, namely 500 mg dm^?3, 1000 mg dm^?3, 1500 mg dm^?3 and 2000 mg dm^?3 so that substrate limitation could not occur. The results showed that the sludge sample taken from the UASB reactor (OLR of 6.1 kg COD m^?3 d^?1) had a potential acetoclastic methane production (PMP) rate of 72 cm³ CH₄ g^?1 VSS d^?1. When the PMP rate was compared with the actual methane production rate (AMP) of 67 cm³ CH₄ g^?1 VSS d^?1 obtained from the UASB reactor, the AMP/PMP ratio was found to be 0.94 which ensured that the UASB reactor was operated using its maximum potential acetoclastic methanogenic capacity. In order to achieve higher OLRs with desired COD removal efficiencies it was recommended that the UASB reactor should be loaded with suitable OLRs pre‐determined by SMA tests. © 2001 Society of Chemical Industry     

Extraction of phenolic compounds from Vitex agnus-castus L.

The primary objective of this study was to valorized Vitex agnus-castus residues in terms of phenolic compounds. The effects of extraction time (30–360 min), solid to liquid ratio (0.1–0.3 g_DryBiomass/ml_Solvent), type of solvent and different tissue types (leave, roots and seeds) on total polyphenols, o-diphenols, total flavonoids and anthocyanins were evaluated. The highest total polyphenol (31.5 mg_{CaffeicAcidEquivalent}/g_DryBiomass) and o-diphenol (12.4 mg_{CaffeicAcidEquivalent}/g_DryBiomass) contents were obtained from methanolic extract of leaves after 180 min using a solid/liquid ratio of 0.1 g_DryBiomass/ml_Solvent, while total flavonoids, reached a maximum value of 19.4 mg_{CatechinEquivalent}/g_DryBiomass after 360 min under the same conditions. Roots of V. agnus-castus were found to be a good source of anthocyanins with the highest yield of 0.62 mg_{MalvidinEquivalent}/g_DryBiomass using ethanol as a solvent (180 min and 0.2 g_DryBiomass/ml_Solvent). The maximum antiradical power (178.5 μl_extract/μg_DPPH) was exhibited by the methanolic leave extract obtained after 360 min at solid/liquid ratio of 0.3 g_DryBiomass/ml_Solvent.     

Experimental analysis of the effect of some compaction methods on mechanical properties and durability of cement stabilized soil

Cement stabilized soil is usually compacted by different mechanical methods to increase its strength and durability. This paper summarizes the results of an experimental study on the effect of different compaction methods on the performance of stabilized soil. The compaction methods investigated were either static compaction by applying a static pressure using an universal compression testing machine, dynamic compaction by a drop weight method, or static compaction coupled with vibration. All methods were applied on unstabilized soil or cement stabilized soil. The effect of each method of stabilization on compressive strength, shrinkage and water resistance are reported. Dynamic compaction with about 8% of cement content seems to give the best performance for the soil investigated.     

A 100-MHz macropipelined VAX microprocessor

A macropipelined CISC microprocessor was implemented in a 0.75-μm CMOS 3.3-V technology. The 1.3-million-transistor custom chip measures 1.62×1.46 cm² and dissipates 16.3 W. The 100-MHz parts were benchmarked at 50 SPEC marks. The on-chip clocking system and several high-performance logic and circuit techniques are described. Macroinstruction handling, micropipeline management, and control store structures highlight the design architecture. The hierarchical array organization and fast tag comparison technique of the primary cache are discussed. Power estimation procedures are outlined, and the results are compared to measurements. Physical design and verification methods, and CAD tools are also described. After extensive functional verification efforts are described, chip and system test results are presented