Numerical Simulation of Air Flow in Model Room

Efficient, and appropriate indoor air environment is important issue in building design. Air flow patterns which are formed in the room are mainly depended on its geometrical parameters. Investigation of flow patterns are performed on a relatively simple geometry of model room, with a small obstacle (partition) in it. There are several interesting flow phenomena which are present in the model room: flow through sudden geometry expansion, stagnation flow with lateral boundaries, flow over the obstacle, etc. Since the air velocities are low, it is assumed that flow is incompressible. Numerical calculations of these patterns have been done using RANS modeling approach. For all calculations an extended version of open-source CFD software OpenFOAM was used. Several turbulence models have been used for RANS approach, with special attention on their performance in capturing unsteady flow phenomena. Comparison of obtained numerical results and available experimental results for mean velocities shown good agreement. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of support on activity of palladium catalysts in nitrobenzene hydrogenation

The effect of two types of catalysts on the activity of the catalytic hydrogenation of nitrobenzene was studied. Catalysts were prepared by the surface deposition of palladium hydroxide with a simultaneous reduction with formaldehyde in a basic environment and were characterised by X-ray powder diffraction, transmission electron microscopy, adsorption-desorption, and catalytic tests — hydrogenation of nitrobenzene in methanol. The influence of the supports’ (activated carbon and a mixture of activated carbon and multi-walled carbon nanotubes) surface area is discussed. Despite having a size comparable (4–5 nm) to crystallites of metallic palladium, the catalyst prepared on a mixture of activated carbon and nanotubes (Pd/C/CNT) was significantly less active than the catalyst prepared on pure activated carbon (Pd/C); the rate of this reaction was approximately 30 % lower than the initial reaction rate. This feature could be attributed to the lower specific surface area of the Pd/C/CNT (531 m² g^?1) in comparison with the Pd/C (692 m² g^?1).     

Production of fructosyltransferase in mechanically stirred and air-lift bioreactors

Aureobasidium pullulans cells were cultivated in a 3 dm³ stirred bioreactor to optimize the production of fructosyltransferase (FTase). Batch experiments were focused on the influence of the initial sucrose concentration (150–350 g dm^?3), sodium nitrate concentration (10–25 g dm^?3), and stirring rate (180–540 min^?1) on the process. It was found that the FTase specific activity per cell mass was positively influenced by the conditions that impeded the cell growth such as higher sucrose concentrations or lower oxygen transfer rates. Higher content of inorganic nitrogen substrate slightly increased the overall FTase production. The presence of fructose moiety-containing saccharides in the cultivation medium was observed to be indispensable for FTase production. An addition of a concentrated sucrose solution in the 40th cultivation hour therefore essentially resumed the FTase production. Finally, scale-up experiments were performed in 12 dm³ and 100 dm³ mechanically stirred bioreactors and in 20 dm³ and 60 dm³ air-lift bioreactors.     

Pharmaceutical grade sodium [99mTc] pertechnetate from low specific activity 99Mo using an automated 99Mo/99mTc-TCM-autosolex generator

Performance study of a computer controlled automated closed cyclic module for the separation and recovery of ^99mTc from low specific activity (n, γ) ⁹⁹Mo using methyl ethyl ketone (MEK) solvent extraction technique named ⁹⁹Mo/^99mTc-TCM-AUTOSOLEX (Technetium automated solvent extraction) Generator is described. The entire system is automated and controlled by a user-friendly PC based graphical user interface that actually supervises process via an embedded system based electronic controller. The average yield of separation of ^99mTc was above 85 % and ⁹⁹Mo breakthrough in ^99mTc pertechnetate was <0.002 %. The sodium pertechnetate obtained was a clear solution having pH 6–7, Radiochemical (RC). Purity >99 %, MEK content <0.1 % (v/v), Al and Mo content <10 µg/ml. R. C. Purity of ^99mTc-radiopharmaceuticals studied was not less than 96 %. Bio-Quality control studies confirm that sodium pertechnetate obtained was sterile and pyrogen free. Imaging studies in animals and humans with limited radiopharmaceuticals show that the quality of ^99mTc-pertechenate obtained in the present module was good enough to do clinical study.     

Determination of Copper in Human Urine by RP-LC After Pre-column Derivatization with Neocuproine and Use of Monolithic Column

A selective sensitive RP-LC–UV/VIS method with pre-column derivatization was developed for the determination of copper in human urine at a trace level. This method is based on the selective reaction of 2,9-dimethyl-1,10-phenanthroline (neocuproine) with copper(I) to produce a yellow-orange hydrophobic complex in a neutral or slightly acidic buffer solution (adjusted to pH 5.9). Copper(II) was reduced to copper(I) ions by ascorbic acid as a weak reducer, which was added both to urine sample and mobile phase, respectively. A hydrophobic copper(I)–neocuproine chelate was determined by RP-LC–UV/VIS using a monolithic column Chromolith Performance RP-8e (100 × 4 mm I.D.) at 30.0 ± 0.1 °C with a methanol: aqueous buffer (pH 5.9, ammonium acetate and ascorbic acid 2.8 mmol L^?1) mobile phase at flow rate of 2.00 mL min^?1. Sample injection volume was 20 μL and detection was done at 453 nm. The method was validated over a concentration range of 0.09–11.50 μmol L^?1. The LOD of copper in human urine was found to be 0.07 μmol L^?1 concentration level, suitable for clinical analysis. The precision of the results, reported as the RSD, was below 4.6 % for copper concentration within range 0.5–5.0 μmol L^?1 in the spiked human urine samples.     

Determination of Herbicide Difenzoquat Methyl Sulfate in Citruses and Baby Juices by Kinetic‐Spectrophotometric Method and HPLC Method

The purpose of this paper is to present a new kinetic‐spectrophotometric method which involve inexpensive equipment and which can be applied by all analyst who have to determine difenzoquate methyl sulfate (DFQ) residues in citruses and baby juices. The method is based on the inhibited effect of DFQ on the oxidation of sulfanile acid (SA) by hydrogen peroxide in phosphate buffer in presence Cu(II) ion. The reaction was monitored spectrophotometrically by measuring the increase in absorbance of the reaction product at 370 nm. The proposed inhibited method permits determination of DFQ over the range 0.36 to 1.80 μg/mL and 1.80 to 7.20 μg/mL, with quantification limit of 0.184 μg/mL. The relative standard deviations are 0.73‐2.90% for the concentration interval of DFQ 1.80‐0.36 μg/mL. The method was successfully applied to determination of DFQ residues in citruses and baby juices. The HPLC method is used to verify the results. The results obtained for the same samples by the two methods are quite comparable.     

Reflectance and Cyclic Electron Flow as an Indicator of Drought Stress in Cotton (Gossypium hirsutum)

The response and the functioning of the photosynthetic machinery of cotton, Gossypium hirsutum during water stress was studied by leaf optical properties, linear (ETRII) and cyclic electron flow (CEF) and chlorophyll a fluorescence. We observed that in G. hirsutum, during water limitation, Chlorophyll b showed the best correlation with reflectance at 731 nm and is a better indicator of drought. F_v/F_m was observed to be very insensitive to mild water stress. However, during severe water stress the leaves exhibit considerable inhibition in F_v/F_m and an increase in anthocyanin levels by about 20‐fold. CEF was very responsive to mild water stress. The mild drought stress caused large decrease in the ability of the leaves to utilize the light energy. Photosystem I and photosystem II is protected from photoinhibition by high CEF and nonphotochemical quenching under mild water stress. While during severe drought stress, linear electron flow showed a sharp decrease in comparison to CEF. CEF play a major role in G. hirsutum leaves during mild as well as under severe water stress condition and is thus a good indicator of water stress.     

Peptidomimetics with tunable tertiary amide bond containing substituted β-proline and β-homoproline

Tunable cis/trans prolyl amide bond configuration in substituted β-proline (β-Pro) and β-homoproline (β-Hpro) homodimers was explored, based on position and nature of the substituent. Tertiary amide bond in β-proline (β^2,3-substituted) dimers show distinct trans configuration and β-homoproline (β³-substituted) dimers preferably exhibited cis configuration.     

Crystallographic and structural characterization of heterometallic platinum complexes Part VI. Heterohexanuclear complexes

This review classifies and analyzes heterohexanuclear platinum clusters into seven types of metal combinations:Pt₅M, Pt₄M₂, Pt₃M₃, Pt₂M₄, PtM₅, Pt₂M₃M′, and Pt₂M₂M₂′. The crystals of these clusters generally belong to six crystal classes: monoclinic, triclinic, orthorhombic, tetragonal, trigonal and cubic. Among the wide range of stereochemistry adopted by these clusters, octahedral and capped square-pyramidal are the most common. Although platinum is classified as a soft metal atom, it bonds to a variety of soft, borderline and hard metals. Nineteen different heterometal ions are involved in hexanuclear platinum clusters. The shortest Pt-M bond distance in the case of M being a non-transition element is 2.395(4) Å for germanium and for M being a transition metal ion it is 2.402(2) Å for Cobalt. The shortest Pt-Pt bond distance observed in these clusters is 2.532 Å. Several relationships between the structural parameters are identified and discussed. Some clusters exist in two isomeric forms and some show crystallographically independent molecules within the same crystal. Such isomers and independent molecules are examples of distortion isomerism.