Die-spacing technique by diffusion precipitation.

K D Jørgensen; W Finger

doi:10.1111/j.1600-0722.1979.tb01942.x

Home/Archive/PubMed

PubMed · 370966

Die-spacing technique by diffusion precipitation.

K D Jørgensen·W Finger

View original source ↗Export metadata ↓

Abstract

The present study has shown that it is possible by utilizing the principle of diffusion to precipitate on stone dies an adequate resin spacer of uniform and desirable thickness. Details and variables of the technique are described. The precipitation technique is simple and requires a minimum of time and equipment. This spacer technique opens up gateways for a new and improved casting technique cleared of most of the variables affecting the precision of the methods employed up till now. A new gypsum bonded investment for the new casting technique is being developed.

Explore related subjects

Acetone Benzoyl Peroxide Chemical Precipitation Composite Resins Dental Casting Technique Diffusion Models, Dental Solutions Surface Properties Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

K D Jørgensen, W Finger. 1979. Die-spacing technique by diffusion precipitation.. https://doi.org/10.1111/j.1600-0722.1979.tb01942.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1992

Purification and properties of 6-methylsalicylic acid synthase from Penicillium patulum.

6-Methylsalicylic acid synthase has been isolated in homogeneous form from Penicillium patulum grown in liquid culture from a spore inoculum. The enzyme is highly susceptible to proteolytic degradation in vivo and in vitro, but may be stabilized during purification by incorporating proteinase inhibitors in the buffers. The enzyme exists as a homotetramer of M(r) 750,000, with a subunit M(r) of 180,000. 6-Methylsalicyclic acid synthase also accepts acetoacetyl-CoA as an alternative starter molecule to acetyl-CoA. The enzyme also catalyses the formation of small amounts of triacetic acid lactone as an oligatory by-product of the reaction. In the absence of NADPH, triacetic acid lactone is the exclusive enzymic product, being formed at 10% of the rate of 6-methylsalicylic acid. The enzyme is inactivated by 1,3-dibromopropan-2-one, leading to the formation of cross-linked dimers similar to that observed with type I fatty acid synthases. Acetyl-CoA protects the enzyme against the inactivation and inhibits dimer formation. An adaptation of the purification method for 6-methylsalicylic acid synthase may be used for the isolation of fatty acid sythase from Penicillium patulum.

Acetone↗

PubMed1992

Possible function of tRNA(Thr)ACG in regulation of solvent formation in Clostridium acetobutylicum.

The mutation of Clostridium acetobutylicum mutant AA2, defective in the formation of acetone and butanol, was shown to be caused by a single insertion of Tn916 close to the structural gene thrA, encoding the tRNA(Thr)ACG. The DNA region containing the thrA gene was cloned and sequenced. Start and end points of the transcript were determined by primer extension and S1-mapping analysis. The results obtained were identical to predictions derived from the DNA sequence by various RNA-analysing computer programs. The rarely used ACG codon seems to be confined to genes expressed at the end of the exponential growth phase or involved in uptake or turnover of minor C or N substrates. Evolutionary aspects of this codon selection and a possible translational regulation mechanism are discussed.

Acetone↗

PubMed1992

Purification and characterization of an acetone-inducible cytochrome P-450 from hamster liver microsomes.

A form of cytochrome P-450 has been purified to electrophoretic homogeneity from the hepatic microsomes of Syrian golden hamsters treated with acetone. This P-450 form, designated ha P-450j, had an M(r) of approximately 55,000, bound dimethyl sulphoxide and exhibited a CO-reduced absorbance maximum at 451 nm. The absolute spectra of its oxidized form indicated that ha P-450j was predominantly in the low-spin state. In a reconstituted system, ha P-450j showed relatively low catalytic activities towards 7-ethoxycoumarin, 7-ethoxyresorufin, aminopyrine, ethylmorphine and benzphetamine, whereas it catalysed the oxidation of aniline, acetone and thiobenzamide with a high catalytic-centre activity. In addition, ha P-450j catalysed at a high rate the high-affinity component of dimethylnitrosamine N-demethylase; in contrast, only the low-affinity component of diethylnitrosamine N-de-ethylase was efficiently catalysed. The addition of cytochrome b5 to the reconstitution system decreased the Km value for dimethylnitrosamine N-demethylase by a factor of 5 and increased the Vmax. value, and slightly enhanced the other activities. Thiobenzamide and diethyldithiocarbamate were found to be the most effective inhibitors of the ha-P-450j-dependent aniline hydroxylation. Polyclonal antibodies against rat P-450j recognized ha P-450j in immunoblots of control and treated hamster liver microsomes. Treatment of hamsters with acetone increased the apparent abundance of ha P-450j in microsomes, whereas phenobarbital and beta-naphthoflavone did not induce it. Analysis of N-terminal amino acid sequences demonstrated that ha P-450j has a high degree of sequence identity with rat P-450j. All the evidence presented in this study indicates that ha P-450j could represent the hamster orthologue of the previously described CYP2E1(s) of other species.

Acetone↗