Growth chambers

Molecular beam epitaxy (MBE) is a radically different growth process which utilizes a very high vacuum growth chamber and sources which are evaporated from controlled ovens (15,16). This technique is well suited to growing thin multilayer stmctures as a result of very low growth rates and the abihty to abmpdy switch source materials in the reactor chamber. The former has impeded the use of MBE for the growth of high volume LEDs. 

Another type of crystallizer is the Oslo-type unit shown in Figure 24. In units of this type, the object is to form a supersaturated solution in the upper chamber and then reHeve the supersaturation through growth in the lower chamber. The use of the downflow pipe in the crystallizer provides good mixing in the growth chamber. 

Fig. 4. Schematic of an ultrahigh vacuum molecular beam epitaxy (MBE) growth chamber, showing the source ovens from which the Group 111—V elements are evaporated the shutters corresponding to the required elements, such as that ia front of Source 1, which control the composition of the grown layer an electron gun which produces a beam for reflection high energy electron diffraction (rheed) and monitors the crystal stmcture of the growing layer and the substrate holder which rotates to provide more uniformity ia the deposited film. After Ref. 14, see text.

Orchard BJ, WJ Doucette, JK Chard, B Bugbee (2000) Uptake of trichloroethylene by hybrid poplar trees grown hydroponically in flow-through plant growth chambers. Environ Toxicol Chem 19 895-903. 

HREELS experiments [66] were performed in a UHV chamber. The chamber was pre-evacuated by polyphenylether-oil diffusion pump the base pressure reached 2 x 10 Torr. The HREELS spectrometer consisted of a double-pass electrostatic cylindrical-deflector-type monochromator and the same type of analyzer. The energy resolution of the spectrometer is 4-6 meV (32-48 cm ). A sample was transferred from the ICP growth chamber to the HREELS chamber in the atmosphere. It was clipped by a small tantalum plate, which was suspended by tantalum wires. The sample was radia-tively heated in vacuum by a tungsten filament placed at the rear. The sample temperature was measured by an infrared (A = 2.0 yum) optical pyrometer. All HREELS measurements were taken at room temperature. The electron incident and detection angles were each 72° to the surface normal. The primary electron energy was 15 eV. 

Maximal levels for -coumaric and ferulic acids of 30.0 and 6.5 pmol/1 0 g of soil ha e been reported (158) and concentrations of 4 x 10 M and 3 x 10 M, respectively, for these two acids in other soils (161)Other gtudies indicate a similar concentration range of 2.3 x 10 to 10 M for -hydroxybenzoic, vanillic and j>-coumaric acids (169). These levels may be too low to have direct measurable allelopathic effects on plants in greenhouse or growth chamber studies (non-rhizosphere soils, low microbial population). However, in field rhizosphere soils (high microbial population) these levels could be sufficient to influence microbial growth... 

Preparation of hydrilla explants. A stainless steel razor was used to remove the distal 4 to 5 cm ("apical explants") from either rooted hydrilla, or hydrilla freshly received from the field. Subtending sections containing two adjacent intact nodes ("2-node explants") with whole whorls of leaves were removed, but 1 to 2 intervening nodes were left above the next cut (Figure 2). No 2-node explants were taken below (proximal to) a subtending lateral branch. All explants were kept in tap water for 2 4 hours in a growth chamber before use in bioassays (25°C, 14-h day, ca. 200 pE m-2 sec-1). 

Assessment 3 days following treatment to dry lettuce seed. Four repetitions with 25 seeds per petri dish. Growth chamber at 25 C, 12 h light and 12 h dark periods. 

Soil Adsorption. Soil (2.5 g) and 10 mL of aqueous pesticide solution were combined in 30 mL screw cap (teflon-lined) centrifuge tubes which were then agitated for 3 hours, in darkness, in a growth chamber set at 10 1°C, 19 1°C, or 30 2°C. The tubes were centrifuged and the supernatants were analyzed by LSC. Control experiments included untreated solution/soil mixtures used for LSC background determnations and treated solutions without soil used to determine the extent of pesticide adsorption by the glass tubes. 

Islam M, Morgan J, Doyle M P and Jiang X (2004b), Fate of Escherichia coli 0157 H7 in manure compost-amended soil and on carrots and onions grown in an environmentally controlled growth chamber , Journal of Food Protection, 67 (3), 574—578. 

Place the bombarded leaves in a growth chamber for 12-24 h and analyze under a fluorescence microscope suitable for FRET measurements. Detached Arabidopsis leaves undergo senescence very quickly and thus analysis should be carried out no later than 24 h after bombardment. 

Basic equipment for plant culture media preparation and sterilization, controlled growth chamber, microscope, stereomicroscope and inverted microscope equipped with a photocamera, laminar flow cabinet. 

Material required Air-dried (27-30°C) aerial parts of S. deppei to prepare aqueous leachate, Seeds of tomato (Lycopersicon esculentum Mill. cv. Rio Grande), Osmometer, Growth Chamber Laminar flow hood. 

Bioassays are performed under sterile conditions in a laminar flow hood. Tomato seeds are previously washed and disinfected with 1% sodium hypochlorite. Seeds are germinated in the Petri dishes containing the S. deppei aqueous leachate. For control, seeds are germinated in 1% agar. Twelve seeds are placed on each Petri dish and kept in the dark at 27°C in a growth chamber. For enzyme activities, 40-50 Petri dishes are used per treatment. Primary roots (radicles) are excised after 72 h, frozen in liquid nitrogen and kept at -70 °C until use. For root growth response, experiments... 

A defined number of seeds of each plant was germinated in Petri dishes kept in a Phytotron growth chamber at 21 1°C in the dark. Root tips ( 2 mm) were collected after 5 or 7 days of germination on dependence on the plant species, and subjected to Feulgen staining procedure before the preparation of permanent slides for the observation at an Olympus CX40 microscope. 

---