pH-Sensitive dyes are increasingly applied on polymer substrates for the creation of novel sensor materials. Recently, these dye molecules were modified to form a covalent bond with the polymer host. This had a large influence on the pH-sensitive properties, in particular on the acidity constant (pKa ). Obtaining molecular control over the factors that influence the pKa value is mandatory for t...

A flow injection method for the determination of readily assimilable nitrogen (r.a.n.), i.e. ammonium and aminated nitrogen, is reported. The difference in pH of the sample in the presence and absence of formaldehyde, which blocks the amino function, provides the value of r.a.n. by monitoring the changes in absorbance of bromothymol blue at 616 nm. The detection and quantification limits are 10...

A flow system with a multi-channel peristaltic pump placed before the solenoid valves is proposed to overcome some limitations attributed to multi-commuted flow injection systems: the negative pressure can lead to the formation of unwanted air bubbles and limits the use of devices for separation processes (gas diffusion, dialysis or ion-exchange). The proposed approach was applied to the colori...

Cryptococcosis is one of the most common opportunistic fungal infections in patients with acquired immunodeficiency syndrome (AIDS). We report 13 cases of cryptococcal infection based on histopathology, serology and cultures. Epidemiological analysis, histochemical techniques of hematoxilin and eosin (HE) and Grocot's silver (GMS), as well special histochemical techniques such as Mayer's mucica...

A theoretical and experimental study was performed on convective micro mixing in T-shaped micro mixers. In these devices symmetric laminar vortices are developing at low Reynolds numbers Re. The symmetry breaks up with increasing Re numbers. This leads to an enormous enhancement of the mass transfer in the mixing channel. Numerical simulations of the flow characteristics and mixing behaviour ar...

Sugar Fermentation Tests The media are prepared from Coignet's gold medal gelatin in a manner similar to that described for the liquefaction test. Instead of sheet gelatin, Difco nutrient gelatin in about double strength poured out to form sheets can also be used with equally satisfactory results. After formolization the gelatin sheets are cut or punched into shapes, about 15 mm. diameter, conv...

Liwa Botanical Gardens is an ex-situ conservation area for various types of plants. Each plant produces organic matter that will provide nutrients the growth nitrogen-fixing bacteria. This indicates existence environment supports Nitrogen one needed by plants their growth. However, abundance nitrogen in atmosphere cannot be utilized directly but needs to transform into ammonium and nitrate firs...