Instabile CO<sub>2</sub>-Fixierung und Photosynthese

Metzner, Helmut; Simon, Helmut; Metzner, B.

doi:10.1515/znb-1958-0607

Cited by 9 publications

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“…Metzner et al (356,357) have reported that new labile fixation products are obtained when illuminated algae suspensions are fixed with cold acetone. Kandler (358) has communicated experiments according to which the kill ing of algae, usually performed with hot alcohol, probably simulates a too high fixation of 14C02 in phosphoglyceric acid.…”

Section: Photosynthesismentioning

confidence: 99%

Carbohydrate Metabolism

Holzer¹

1959

Annu. Rev. Biochem.

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The following abbreviations are used: A CTH for adrenocorticotropic hormone; ADP for adenosine diphosphate; AMP for adenosine diphosphate; ATP for adenosine triphosphate; DPN for oxidized diphosphopyridine nucleotide; DPNH for reduced diphosphopyridine nucleotide; TPN for oxidized triphosphopyridine nucleotide; TPNH for reduced triphosphopyridine nucleotide; UDP for uridine diphosphate; UMP for uridine monophosphate; UTP for uridine triphosphate. • The author is grateful to Dr. H.-J. Boltze for the translation. 171Annu. Rev. Biochem. 1959.28:171-222. Downloaded from www.annualreviews.org Access provided by University of California -San Francisco UCSF on 02/04/15. For personal use only. Quick links to online content Further ANNUAL REVIEWSIn pancreatic j uice of the rat, the concentration of a-amylase is often so high that the enzyme crystallizes spontaneously (14).Cellulose metabolism has been investigated in a variety of molds and bacteria [(15 to 23); for a summary see (24)]. According to Hash & King (19,20), various �-glucosidases are present in the fungus Myrothecium verrucaria, the specificity of which is dependent on the chain length of the substrate. Cellobiose was not found to be an obligatory precursor of glucose in cellulose breakdown. "Cellulose dextrins" (hexasaccharides, etc.) may be formed from cellobiose by transglucosidation. High-speed-centrifuged par ticles from Acetobacter xylinum were shown by Glaser (21) to contain an enzyme which produces cellulose from UDP-glucose. Similar to glycogen synthesis from UDP-gl�cose a primer is required, such as cellodextrins.In various grasses, structure, synthesis, and breakdown of polyfructosans have been investigated in their dependence upon various, particularly sea sonal conditions by Schlubach (25). Avigad & Feingold (26) investigated the fructosides produced ' from sucrose by a corynebacterium. For the synthesis of hyaluronic acid in streptococci, it has been reported by Markovitz et al. (27) that glucose is a precursor of the glucuronic acid and glucosamine moieties. Tritiated UDP-glucuronic acid together with UDP-N-acetyl glucosamine, ATP, and N-acetyl glucosamine-l-phosphate were incubated with strain A streptococci and found to produce appreciable Annu. Rev. Biochem. 1959.28:171-222. Downloaded from www.annualreviews.org Access provided by University of California -San Francisco UCSF on 02/04/15. For personal use only. CARBOHYDRATE METABOLISM 173 amounts of hyaluronic acid. This indicates that the synthesis of hyaluronic acid is very likely to occur via the UDP compounds. The occurrence in group A streptococci of the UDP compounds mentioned has been ascertained chromatographically (28).Glaser & Brown (29) reported that the formation of chitin in a cell-free preparation from Neurospora crassa utilizes UDP-N-acetyl glucosamine, and requires an acetyl glucosamine polymer as a primer:UDP-acetyl glucosamine + (acetyl glucosamine),,� UDP + (acetyl g!ucosamine)n-t1 (2) The decomposition of chitin has been investigated by Berger & Reynolds (30) with a chiti...

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Section: Photosynthesismentioning

confidence: 99%

Carbohydrate Metabolism

Holzer¹

1959

Annu. Rev. Biochem.

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“…25 There have since been many attempts to extend the relation to more concentrated suspensions, generally by adding terms of higher powers of +. 26 It is significant that these relations all show the relative viscosity to depend only on 4 and not in any way on the particle size.…”

Section: Relation Of Gel-containing Materials To Master Batchmentioning

confidence: 95%

Flow properties of a linear–gel polymer system

Rosen

Rodriguez

1965

J. Appl. Polym. Sci.

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SynopsisFlow curves (shear stress versus shear rate) were obtained for poly-(ethyl acrylate) containing up to 40% of gel particles over a range of shear rates from 3 X lo-* to 7 X 108 set.-' with a specially designed bimnical rheometer and a standard Instron capillary viscometer. Crosslink density of the gels was varied by emulsion-polymerizing ethyl acrylate 7Rith 3, 10, and 30% triethyleneglycol dimethcrylate. Particle sizes were varied by adjusting the concentration of emulsifying agent and by d i g techniques. Samples for study were prepared by blending and co-precipitating the linear and gel latices. The addition of gel always increases the shear stress at a given shear rate. However, this effect is greatest a t the lowest shear rates. The flow properties of the gelcontaining materials are related quantitatively to those of the linear material through a new parameter, the rate of viscous energy dissipation, and by two material constants. These are a yield stress and a pseudo zero-shear viscosity, both of these being functions of the amount, crosslink density, and particle size of the gel phase.This investigation is concerned with the changes that the addition of gel to a substantially linear, amorphous polymer bring about in the fundamental rheological properties of the bulk material, and how these changes are related to the improved processing properties of the material. Probably the most important factor in understanding the behavior of these systems is the steady-state viscosity, i.e., the actual relation between shear stress and shear rate over as wide a range as possible.It has been known that the processing properties of raw rubber could be markedly improved by operations which increased the amount of gel, or crosslinked material, in the polymer. The observed improvements in such properties as reduced swelling on emergence from an extruder die or calender nip, smoother surface finish, better shape retention, and higher extrusion rates are in many ways similar to those produced by the addition of carbon black or other fillers to the rubber. At first thought, this may seem completely contrary to what would be expected from the addition of an essentially nonviscous material to a viscous polymer melt.

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“…However, the latter difference should not void qualitative conclusions, and sufficient normal stress measurements are available to assess the general magnitude of the Weissenberg number; for highly viscoelastic polymer solutions possessing low values of the parameters n and s it is likely to be in the range of 10 to 100 under conditions of interest (7,17,18,23,28,52, 5 4 ) . For such fluids, reference to Table 1 shows that appreciable increases in length of the entry region are predicted.…”

Section: +Sbs" ( 2 + N -S S N -S ) ] ( 3 0 )mentioning

confidence: 99%

“…From the kinematic analysis of White and Metzner (59) and Equation (18), one may, however, show that…”

Section: Constitutive Relationships For Evaluation Of Stressesmentioning

confidence: 99%

Flow behavior of viscoelastic fluids in the inlet region of a channel

Metzner

White

1965

AIChE Journal

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The behavior of viscoelastic fluids in the inlet region of a channel formed by two parallel flat plates has been analyzed with a Rivlin-Ericksen approximation to describe the fluid properties. I t was found that viscoelasticity changed the entry length; both the magnitude and direction of this change were predicted to depend upon the detailed fluid properties. These predictions of the change in the entry length were seen to find some qualitative support in available experimental evidence.The directions for further analysis, based primarily on the important observation that these materials may exhibit solidlike behavior in the immediate vicinity of the entrance, are indicated. This solidlike behavior is seen to be closely related to "melt fracture" and similar instability phenomena common to these materials; i t serves to explain directly the otherwise perplexing observations concerning the similarity of such fluid fracture phenomena in materials as divergent in their properties as viscoelastic polymeric systems and inelastic dilatant slurries.A currently important engineering problem is that of the analysis of the flow behavior of viscoelastic fluids in complex geometries. While a number of problems of interest in the polymer processing industry may be analyzed a t least approximately in terms of laminar shearing motions (12, 16, 42, 5 8 ) , most problems of engineering interest are far more complex. Examples of such complex motions are found in the turbulent flow of dilute polymer solutions in a pipe (28, 4 6 ) ; the behavior of bulk polymers in extruders, mills, and mixers ( 2 4 ) ; and in fiber spinning operations (56). I n this paper, we shall investigate one such fluid dynamic problem: the flow of a viscoelastic material in the entrance region of a conduit. PREVIOUS WORKThe entrance length problem for the flow of Newtonian fluids into conduits has attracted the efforts of a number of researchers during the past half century, many of whom have made use of the Prandtl-von Karman boundary-layer theory ( 4 8 ) and have applied it in computing the velocity and pressure fields. Schiller (47) used the von Karman-Pohlhausen integral momentum procedure, while Schlichting (49) and Atkinson and Goldstein (19) matched a Blasius type of solution with a reverseward perturbation of the fully developed velocity profile. Tomita ( 5 3 ) introduced a variational principle to solve the entrance region boundary-layer equation, while Bodoia and Osterle ( 5 ) used finite difference methods. On the other hand, some authors have avoided boundary-layer methods. Langhaar ( 2 1 ) obtained a solution to the capillary tube problem by linearizing the Navier-Stokes equation and by presuming a Bessel function solution. Wang and Longwell ( 5 5 ) carried out a full numerical solution of the complete two-dimensional Navier-Stokes equation for several special cases chosen to ascertain the limitations introduced by boundary-layer approximations.A boundary-layer theory for purely viscous power law fluids was developed by a number of researchers...

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Instabile CO₂-Fixierung und Photosynthese

Abstract: Das Ergebnis war in allen Versuchen identisch: i2P aus biologisch markiertem, isoliertem /?-32P-Lipoproteid war auch im vorher unmarkierten ax-Instabile CCVFixierung und Photosynthese V on H e l m u t M e t z n e r * , H e l m u t S im

Cited by 9 publications

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Carbohydrate Metabolism

Carbohydrate Metabolism

Flow properties of a linear–gel polymer system

Flow behavior of viscoelastic fluids in the inlet region of a channel

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Instabile CO2-Fixierung und Photosynthese

Abstract: Das Ergebnis war in allen Versuchen identisch: i2P aus biologisch markiertem, isoliertem /?-32P-Lipoproteid war auch im vorher unmarkierten ax-Instabile CCVFixierung und Photosynthese V on H e l m u t M e t z n e r * , H e l m u t S im

Cited by 9 publications

References 0 publications

Carbohydrate Metabolism

Carbohydrate Metabolism

Flow properties of a linear–gel polymer system

Flow behavior of viscoelastic fluids in the inlet region of a channel

Contact Info

Product

Resources

About

Instabile CO₂-Fixierung und Photosynthese