Novel broken symmetry phase from N(2)O at high pressures and high temperatures

Simple molecular solids become unstable at high pressures, typically transforming to dense framework and/or metallic structures. We report formation of an unusual ionic solid NO(+)NO(3)(-) (nitrosonium nitrate) from N(2)O at pressures above 20 GPa and temperatures above 1000 K. Synchrotron x-ray diffraction indicates that the compound crystallizes with a structure related to the aragonite form of CaCO(3) and NaNO(3). Raman and infrared spectroscopic data indicate that the structure is noncentrosymmetric and exhibits a strong pressure dependent charge transfer and orientational order.     

Improvements in titer,productivity, and yield using solka-floc for cellulase production

Researchers studying cellulase enzymes for the economical production of fuel ethanol envision cellulose as the carbon source. However, submerged Trichoderma reesei cultures grown on cellulose exhibit high run-to-run variability. Thus, an investigation of 30 batch cellulase production experiments was instrumental in determining fermentation conditions that improved enzyme titers, yields, and productivities. Eighteen of the 30 batch experiments experienced minimal process upsets and were classified into eight groups based on agitation rate, gas sparge rate, and the use of oxygen supplementation. Comparing corn steep liquor with yeast extract/peptone also tested the effect of different sources of nitrogen in the media. Average 7-d enzyme titers were doubled from 4 to 8 FPU/mL primarily by increasing aeration.     

XAS/EXAFS studies of Ge nanoparticles produced by reaction between Mg2Ge and GeCl4

We present results of an XAS and EXAFS study of the synthesis of Ge nanoparticles formed by a metathesis reaction between Mg₂Ge and GeCl₄ in diglyme (diethylene glycol dimethyl ether). The progress of the formation reaction and the products formed at various stages in the processing was characterised by TEM and optical spectroscopy as well as in situ XAS/EXAFS studies using specially designed reaction cells.     

High-pressure and -temperature ion exchange of aluminosilicate and gallosilicate natrolite

The simultaneous application of high pressure and high temperature has been used to achieve direct ion exchange of large cesium cations for the small sodium cations found in the zeolite natrolite by putting it into a superhydrated state with increased pore size. The larger cations remain trapped upon pressure release, and thus, this method is a means of producing new cationic forms of zeolites.     

A horizontal atmospheric temperature sounder: Applications to remote sensing of atmospheric hazards

Several atmospheric hazards, including wind shear, clear-air turbulence, and wake vortices cause special problems for aircraft. These phenomena are usually characterized by a change in temperature relative to ambient, which may be detected by a millimeter wave radiometer operating on an absorption line in the atmosphere. Because of available componentry with excellent performance and relative freedom from interference by water vapor, the family of oxygen absorptions centered near 60 GHz is considered the best atmospheric feature on which the design of such an instrument could be based. This paper describes a multi-channel radiometer operating near 60 GHz which should be capable of detecting the hazards mentioned above as well as other potential dangers such as the passage of strong fronts and other severe weather. It is shown that a carefully designed instrument will be capable of measuring range to a hazard to an accuracy of about 5 percent and temperature difference to an accuracy of approximately half the actual measured difference, depending on range and temperature. An actual design is proposed, and graphs of expected performance are included.     

Use of measurement uncertainty analysis to assess accuracy of carbon mass balance closure for a cellulase production process

Closing carbon mass balances is a critical and necessary step for verifying the performance of any conversion process. We developed a methodology for calculating carbon mass balance closures for a cellulase production process and then applied measurement uncertainty analysis to calculate 95% confidence limits to assess the accuracy of the results. Cellulase production experiments were conducted in 7-L fermentors using Trichoderma reesei grown on pure cellulose (Solka-floc), glucose, or lactose. All input and output carbon-containing streams were measured and carbon dioxide in the exhaust gas was quantified using a mass spectrometer. On Solka-floc, carbon mass balances ranged from 90 to 100% closure for the first 48 h but increased to 101 to 135% closure from 72 h to the end of the cultivation at 168 h. Carbon mass balance closures for soluble sugar substrates ranged from 92 to 127% over the entire course of the cultivations. The 95% confidence intervals (CIs) for carbon mass balance closure were typically ±11 to 12 percentage points after 48 h of cultivation. Many of the carbon mass balance results did not bracket 100% closure within the 95% CIs. These results suggest that measurement problems with the experimental or analytical methods may exist. This work shows that uncertainty analysis can be a useful diagnostic tool for identifying measurement problems in complex biochemical systems.