Heat Isolators on a Vacuum Flask

The thing which makes the vacuum flask system useful is the vacuum between the two bottles. Producers of the vacuum flask try to create a perfect vacuum between the two bottles, but it is impossible. Little air goes inside, too. This situation creates my experiment and research question. There are many heat isolators so can there be any material that can be more successful in conserving the temperature of the liquid added than the vacuum flask system? To find an answer to my question, I chose 3 heat isolators (perlite, fire brick and silicone) and put them into the flasks instead of the vacuum. In order to investigate their performance and compare with the vacuum flask system, I planned four experiments. I added to the flasks different liquids, water at the different temperature and water at different amounts and measured the temperatures of the added liquids in different times. According to the results from these 4 experiments, I reach to a conclusion that these isolators couldn’t perform a better performance than vacuum in conserving the temperature of the liquid

Direct in-vial collection for liquid-scintillation assay of carbon-14 and tritium

Dissolution of biological materials combines the simplicity of oxygen-flask combustion with the reproducibility and purity of the final product, and convenience of direct in-vial collection of the sample by the sealed-tube method. It assures quantitative and reproducible recoveries

Mount makes liquid nitrogen-cooled gamma ray detector portable

Liquid nitrogen-cooled gamma ray detector system is made portable by attaching the detector to a fixture which provides a good thermal conductive path between the detector and the liquid nitrogen in a dewar flask and a low heat leak path between the detector and the external environment

Combustion method for assay of biological materials labeled with carbon-14 or tritium, or double-labeled

Dry catalytic combustion at high temperatures is used for assaying biological materials labeled carbon-14 and tritium, or double-labeled. A modified oxygen-flask technique is combined with standard vacuum-line techniques and includes convenience of direct in-vial collection of final combustion products, giving quantitative recovery of tritium and carbon-14

Superconductive thin film makes convenient liquid helium level sensor

Sensor consisting of superconductive film mounted on a dipstick measures the level of liquid helium in a Dewar flask. The sensor is made by depositing a thin film of niobium metal to a thickness of 2000 angstroms on a quartz substrate, which is then mounted on a graduated dipstick

Citric acid production by immobilized cells of the yeast Candida guilliermondii : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Biotechnology and Bioprocess Engineering at Massey University

The feasibility of using cells of Candida guilliermondii immobilized onto sawdust particles for production of citric acid was investigated. C. guilliermondii IMK1 from a stock culture (Department of Process and Environmental Technology, Massey University, Palmerston North, New Zealand) was reisolated for further study including strain improvement work by induced mutation using UV light. A mutant strain DT2 was isolated which produced a citric acid concentration of 9.2 g/l (yield 25 % (w/w)) in shake flask culture, using a defined medium containing 36 (g/l) glucose, compared with 4.9 (g/l) citric acid produced (yield 14 % (w/w)) by the parent strain. Experiments in a laboratory scale batch fermenter, in which a higher concentration of citric acid (11.7 g/1) was achieved, proved that citric acid production using the mutant strain C. guilliermondii DT2, could be scaled up successfully from shake flask to a 2 1 fermenter. This mutant was used throughout subsequent experiments. Sawdust was selected, as the most appropriate support material to immobilize the mutant strain C. guilliermondii DT2 via the adsorption method. Experiments using different concentrations of nitrogen nutrient in defined medium using cells of C. guilliermondii DT2 immobilized onto sawdust particles, in repeated batch shake flask culture, demonstrated a marked effect of the nitrogen concentration on citric acid production. Thus, an overall productivity of 0.11 (g/l.h) was obtained using a defined medium containing 0.53 (g/l) ammonium chloride, compared to overall productivities of 0.04 (g/l.h) and 0.01 (g/l.h) using defined media containing 0.1 (g/l) and no ammonium chloride, respectively. No significant effect of nitrogen concentration on citric acid yield was observed in this investigation. In contrast, similar experiments, in repeated batch shake flask culture, for the effect of phosphate concentration on citric acid production showed no effect of phosphate on either the production rate or yield of citric acid. In bubble column culture experiments, using cells of C.guilliermondii DT2 immobilized onto sawdust, the importance of pH control in citric acid production was demonstrated. In addition, it was demonstrated that the activity of immobilized cells which have lost the ability to produce citric acid can be revived by supplying medium containing sufficient concentrations of nitrogen and phosphate. Reduction of the nitrogen concentration in the medium from 0.53 (g/l) to 0.05 (g/l), provided that the reactor was well established, showed no significant influence on citric acid productivity, but significantly improved the citric acid yield. The highest productivity of around 0.21 - 0.24 (g/l.h) at a dilution rate of 0.21 h-1, accompanied by a citric acid yield of about 10 - 11% (w/w), was reached and maintained for more than 140 hours of stable operation. Overall, it was concludcd that cells of C. guilliermondii were succesfully immobilized onto sawdust particles, and the immobilized cell reactor produced citric acid at a higher rate compared to a free cell system. In particular, a high rate of citric acid production in a bubble column reactor, operated in continuous mode, was achieved

Electrical conductivity cell and method for fabricating the same

A flask having a threaded neck and a cap adapted for threaded engagement on the neck are used. A laminated disc between the cap and the neck forms a gas tight seal and the cap has a central opening that exposes a medial region of the disc. Piercing the disc through the opening are two electrodes, the inner ends of which contact the sample within the flask and the outer ends of which can be connected to test equipment. Cylindric glass tubes are fitted over the external portion of the electrodes to provide physical support and silicone rubber or a similar material serves to retain the glass cylinders in place and form a gas tight seal between the cylinders and the electrodes. Shrinkable tubing is shrunk over the glass tubes to afford further mechanical support and sealing. A final relatively large diameter shrinkable tube is shrunk over both electrodes and their associated glass cylinders. The support and sealing means for the electrodes is confined to a limited portion of the medial region of the disc so that the remainder of such region can be punctured by a hollow needle to introduce a test sample within the flask

Inverse modeling of European CH4 emissions: sensitivity to the observational network

Inverse modeling is widely employed to provide “top-down” emission estimates using atmospheric measurements. Here, we analyze the dependence of derived CH4 emissions on the sampling frequency and density of the observational surface network, using the TM5-4DVAR inverse modeling system and synthetic observations. This sensitivity study focuses on Europe. The synthetic observations are created by TM5 forward model simulations. The inversions of these synthetic observations are performed using virtually no knowledge on the a priori spatial and temporal distribution of emissions, i.e. the emissions are derived mainly from the atmospheric signal detected by the measurement network. Using the European network of stations for which continuous or weekly flask measurements are available for 2001, the synthetic experiments can retrieve the “true” annual total emissions for single countries such as France within 20%, and for all North West European countries together within ~5%. However, larger deviations are obtained for South and East European countries due to the scarcity of stations in the measurement network. Upgrading flask sites to stations with continuous measurements leads to an improvement for central Europe in emission estimates. For realistic emission estimates over the whole European domain, however, a major extension of the number of stations in the existing network is required. We demonstrate the potential of an extended network of a total of ~60 European stations to provide realistic emission estimates over the whole European domain

In situ recovery of secondary metabolites using adsorption resins : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy at Massey University, Palmerston North, New Zealand

Almost without exception a two to three fold increase in microbial secondary metabolite concentration was measured when adsorption resins were added in-situ during a submerged liquid fermentation. Anguidine was produced at a final concentration of 440 mg/L after five days in a shake flask that contained adsorption resin, compared to 300 mg/L without resin. Rapamcyin was produced at a final concentration of 87 mg/L after six days in a shake flask that had resin present, compared to 28 mg/L without resin. Ansamitocin P3 was produced at a final concentration of 24 mg/L after six days in a shake flask with resin, compared to 9.75 mg/L without resin. The increase in secondary metabolite concentration confirmed that the resins used provided a positive influence on secondary metabolite production. Adsorption resins for shake flask studies were selected based on their ability to achieve maximum adsorption of specific secondary metabolites in various fermentation systems. A library of adsorbed concentrations was collected for the three secondary metabolites studied. The lipophilicty of the metabolite, calculated by several software packages, was compared to the polarity of the adsorption resin to generate a relationship. By using the preceding set of data it is possible to select adsorption resins that improved the produced concentrations of the target organic secondary metabolites. The fermentation media compositions tested appeared to have no effect on the final product concentration when adsorption resins were added in situ during the fermentations. Based on the lipohilictiy of the secondary metabolite and the polarity of the resins, it is possible to select a resin that achieves a high adsorption concentration of the target organic secondary metabolite