Liquid media conditions

Static Tests Ideally, a static test would consist of immersing a test sample in the liquid medium held in an inert container under isothermal conditions. 

Penicillins, like most antibiotics, are secondary products whose synthesis is not directly linked to growth. The enzymes that produce secondary products are normally repressed or inhibited under conditions which favour rapid growth. In the early work on penicillin, Penicillium rwtatum was grown as a floating mycelium on about 2 cm depth of liquid medium. The mycelium absorbed nutrients from the medium and penicillin was excreted into the medium. The mycelium and spent medium are readily separated. 

Water reaches supercritical conditions at 373.9 °C (Table 6.13) but it becomes a suitable solvent at 200-350 °C and at pressures generated solely by the expansion of the liquid medium, about 20-100 bar (subcritical or superheated water). 

Among the five different species of Azospirillurn, only A. irakeme shows clearly pectinolytic activity on solid and in liquid medium. Moreover, this species can grow under non-diazotrophic as well as diazotrophic conditions when pectin is the sole carbon source (Khammas and Kaiser, 1991). Khammas and Kaiser (1991) analysed the pectinolytic activity of seven A. irakense isolates, and gave evidence for the presence of two types of pectinolytic enzymes. All strains tested have inducible Ca dependent pectate lyase activity. Six strains, showed also pectin methylesterase activity. So far, none of the corresponding enzymes have been purified. 

The isolates were cultured in 100 ml Erlenmeyer flasks containing 20 ml liquid medium (12) with different carbon sources. The cultures were inoculated with mycelial disks cut from the margins of 7 day-old-colonies and incubated at 25 ( under static conditions. 

Polymer gels and ionomers. Another class of polymer electrolytes are those in which the ion transport is conditioned by the presence of a low-molecular-weight solvent in the polymer. The most simple case is the so-called gel polymer electrolyte, in which the intrinsically insulating polymer (agar, poly(vinylchloride), poly(vinylidene fluoride), etc.) is swollen with an aqueous or aprotic liquid electrolyte solution. The polymer host acts here only as a passive support of the liquid electrolyte solution, i.e. ions are transported essentially in a liquid medium. Swelling of the polymer by the solvent is described by the volume fraction of the pure polymer in the gel (Fp). The diffusion coefficient of ions in the gel (Dp) is related to that in the pure solvent (D0) according to the equation ... 

Apart from the classification based on the mode of generation of cavities, cavitation can also be classified as transient cavitation and stable cavitation [3]. The classification is based on the maximum radius reached (resonant size), life time of cavity (which decides the extent of collapse) in the bulk of liquid and the pattern of cavity collapse. Generation of transient or stable cavitation usually depends on the set of operating parameters and constitution of the liquid medium. Depending on the specific application under question, it is very important to select particular set of operating conditions such that maximum effects are obtained with minimum possible energy consumption. 

The nature of the dissolved gas i.e. its polytropic constant (y), solubility in the cavitating medium etc. severely affects the cavitational activity due to its direct effect on the final collapse conditions. The magnitude of temperature reached at the collapse is affected by the amount of gas dissolved in the liquid medium. Final temperature reached by the adiabatically collapsing bubble (mainly depends on polytropic coefficient of the gas (y)) can be given by following mathematical relationship ... 

A bioslurry phase system consists of the suspension of a solid phase in water or other liquid medium to a concentration typically between 5% and 40% (w/v) and kept under agitation conditions to allow the microbial growth of the indigenous microbiota or a particular inoculated microorganism [114], Bioslurry systems for bioremediation purposes have been mostly conducted with bacterial cultures [146, 147], although in the last few years WRF were also successfully applied to soil bioremediation of PAHs, hexachlorocyclohexane and pentachlorophenol [110, 113, 114],... 

The direct treatment of the scrubbing liquid from a flue gas desulfurization step could be carried out by using the sulfur-reducing bacterium denoted as KT7 [290], This low-GC Gram-positive bacterium is related to the genus Desulfotomaculum, which is capable of reducing sulfite and sulfate to sulfide. Its optimum growth is observed at a temperature between 48°C and 70°C, at a pH of between 5 and 9 and at a conductivity of the liquid medium between 0 and 40 mS/cm. The treatment was claimed to be favored under anaerobic conditions. 

The alkene 1-decene (24) was poorly reactive in the carbonyl-ene reaction with ethyl mesoxalate and required a temperature up to 170 °C for a very long time (5 h) [42]. When performed in a homogeneous liquid medium at the same temperature but under the action of MW irradiation the reaction gave a similar result. Reaction time was appreciably shortened by use of GS/MW coupling [30]. Thus, irradiation at 60 W for only 10 min led to the ene adduct 25 in 50% yield (Scheme 7.2). Under these conditions a maximum temperature of 230 °C was measured. To obtain the same yield with conventional heating at 170 °C reaction for 1 h is required. The stereoselectivity of the reaction was not related to the mode of heating. A higher con-... 

Tests were carried out at 25°C and at initial pH 6.9. Cultures in the liquid medium were incubated in 50 mL Falcon tubes, continuously shaked at 220 rpm. Each culture contained a fresh Pseudomonas sp. 0X1 colony in 10 mL of medium. The airlift with 10 g of pumice was sterilized at 121°C for 30 min and then housed in a sterile room. One-day culture was transferred to the reactor and, after a batch phase, liquid medium with phenol as the only carbon source was continuously fed. The reactor volume V was fixed at 0.13 L. Aerobic conditions were established sparging technical air. Under these conditions microorganism started to grow immobilized on the solid s support. When immobilized biomass approached steady state, cyclic operation of the airlift was started by alternating aerobic/anaerobic conditions. 

Aerobic phase. Technical air and liquid medium were continuously fed to the airlift during the aerobic phase. Gas flow rate was set at 5 nL/h corresponding to 0.64 vvm. The feeding rate of the phenol-bearing (200 mg/L) stream was set at 20 mL/h, that is D 0.15 h The dilution rate was set at a value larger than the maximum grow rate (wash-out conditions with respect to free cells), 0.14 h"1 [60]. 

Fig. 6 Acid orange 7 and phenol concentration in the internal loop airlift reactor operated with Pseudomonas sp. 0X1 biofilm on natural pumice. (A) Aerobic phase. Gas air. Liquid continuous feeding of phenol supplemented synthetic medium. (AN) Anaerobic phase. Gas nitrogen. Liquid batch conditions, dye supplemented medium...

Subsequently, simulations are performed for the air Paratherm solid fluidized bed system with solid particles of 0.08 cm in diameter and 0.896 g/cm3 in density. The solid particle density is very close to the liquid density (0.868 g/ cm3). The boundary condition for the gas phase is inflow and outflow for the bottom and the top walls, respectively. Particles are initially distributed in the liquid medium in which no flows for the liquid and particles are allowed through the bottom and top walls. Free slip boundary conditions are imposed on the four side walls. Specific simulation conditions for the particles are given as follows Case (b) 2,000 particles randomly placed in a 4 x 4 x 8 cm3 column Case (c) 8,000 particles randomly placed in a 4 x 4 x 8 cm3 column and Case (d) 8,000 particles randomly placed in the lower half of the 4x4x8 cm3 column. The solids volume fractions are 0.42, 1.68, and 3.35%, respectively for Cases (b), (c), and (d). 

What happens upon equilibration with liquid water instead of water vapor According to Equation (6.13), the capillary radius would go to infinity for PVP —> 1. Thus, in terms of external conditions, swelling would be thermodynamically unlimited, corresponding to the formation of an infinitely dilute aqueous solution of ionomer. However, the self-organized polymer is an effectively cross-linked elastic medium. Under liquid-equilibrated conditions, swelling is not controlled by external vapor... 

A recent review of the metabolites of L. maculans and L biglobosa produced in diverse culture conditions [19] emphasized that both species biosynthesize host-selective and non-selective phytotoxins. Importantly, it was shown that the composition of metabolite profiles of L. maculans depended on the composition of the culture medium. In a chemically defined liquid medium, isolates virulent on canola produced mainly sirodesmin PL (1), a non-host-selective phytotoxin, minor sirodesmins with one, three, or four sulfurs bridging the dioxopiperazine ring (sirodesmin H (3) [20], sirodesmin J (4) and K (5) [21]) and phomalirazine (6) (Fig. 9.1). The various sirodesmins 1-5 and phomalirazine (6) caused necrotic lesions of different intensities on leaves of both resistant and susceptible plants. Phomalide (7), the first host-selective phytotoxin isolated from virulent isolates of L. maculans, caused disease symptoms (necrotic, chlorotic, and reddish lesions) on canola (susceptible to L maculans) but not on brown mustard or white mustard... 

SrY < CaY) as observed in the uninitiated cyclohexane auto-oxidation. These workers believe that in both the gas- and liquid-phase photo-oxidations that electrostatically promoted electron transfer to generate a cyclohexane radical cation-superoxide ion pair occurs. However, only under liquid-phase conditions is there a continuous medium in which radical reactions can propagate themselves. 

An outstanding feature of two-phase cocurrent flow is the variety of possible flow patterns, ranging all the way from a small quantity of gas dispersed as bubbles in a continuous liquid medium, to the opposite extreme of a small amount of liquid dispersed as droplets in a continuous gas stream. The importance of these flow patterns can be shown when one plots the rate of a transport process as a function of a flow rate of one phase while the flow rate of the second phase is maintained constant. The flux will be found not merely to increase or decrease in a smooth fashion, but rather to show in different flow ranges minima or maxima demonstrating the presence of fundamentally different transfer processes. A comprehensive understanding of the flow processes is necessary before the nature of the flow pattern can be predicted for any given set of flow conditions. 

This equation was derived above for the movement of a liquid through a stationary solid phase. Its application here to the movement of colloidal particles under experimental conditions that render the liquid medium immobile implies that the solid particle is large compared with the dimensions of the diffuse double layer k 1. It is customary to term this movement of the solid phase electrophoresis. The phenomenon is observed with particles suspended in a liquid (Fig. 6.139). 

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