Showing papers by "Iowa State University published in 1970"
TL;DR: By kinetic analysis and specific labeling experiments, it has been shown that, at low concentrations of G3 the formation of products is due to hydrolysis, and at high concentrations, the products are due to a condensation reaction in which 2 molecules of G2 condense to give G6 with subsequent hydroleysis and change in product distribution.
277 citations
245 citations
TL;DR: A mathematical model for a mild stenosis is established and an approximate solution for flow through a converging-diverging tube obtained, Velocity profiles, pressures, and wall shearing stresses along the tube are determined.
213 citations
TL;DR: In this article, an exact solution to the heat flow equation for the growth of dendritic needles from a supercooled melt was obtained by taking into account the interface curvature and the interface kinetics effects under the assumption that the shape of the advancing interface corresponds to a paraboloid of revolution.
184 citations
TL;DR: In this paper, it was shown that organic soil constituents are responsible for the reduction of nitrite to N 2 and N 2 O and for the fixation of Nitrite N observed on treatment of soils with nitrite and that inorganic soil constituents were not involved in these reactions.
Abstract: Studies of the gaseous products formed by chemical decomposition of nitrite in soils showed that substantial amounts of N 2 and NO 2 and small amounts of N 2 O were evolved on treatment of neutral and acidic soils with nitrite, the largest amount of N 2 being formed in an acidic soil having a high organic matter content. The amount of NO 2 produced was inversely related to soil pH, but significant amounts of NO 2 were evolved from soils having pH values above 7. The failure of some investigators to detect NO 2 as a product of nitrite decomposition in acidic soils can be attributed to use of closed experimental systems that promoted sorption of this gas by moist soil and conversion of NO 2 to nitrate. A study of the selfdecomposition reaction of nitrous acid showed that this reaction does not proceed according to the classical equation 3HNO 2 = HNO 3 + 2NO + H 2 O and is better represented by the equation 2HNO 2 = NO + NO 2 + H 2 O. Evidence was obtained that organic soil constituents are responsible for the reduction of nitrite to N 2 and N 2 O and for the fixation of nitrite N observed on treatment of soils with nitrite and that inorganic soil constituents are not involved in these reactions. Several experiments indicated that most of the NO 2 evolved on treatment of soils with nitrite is formed by self-decomposition of nitrous acid and by atmospheric oxidation of NO produced by this reaction.
133 citations
TL;DR: In this article, a cinematographic study of filament formation between two point contact probes on the surface of bulk samples of AsTe-Ge was made and electron microprobe analysis and X-ray diffraction were also employed.
Abstract: The Ovshinsky memory effect (electrically reversible bistable resistivity) has been observed in AsTeGe glass (55%-35%-10% respectively by atomic percent). It is generally thought that an electrically induced conducting filament is responsible for the low resistance state. A cinematographic study of filament formation between two point contact probes on the surface of bulk samples of AsTeGe was made. To further characterize these filaments, electron microprobe analysis and X-ray diffraction were also employed. The cinematography results showed that the filament always grew out of the positive voltage terminal and that the formation of a continuous filament coincided with the establishment of a stable low resistance state. The electron microprobe analysis indicated that inside the filament there was a 37.6% (weight percent) increase in Te, a 40.8% decrease in As and a 47% decrease in Ge compared to the composition some distance away from the filament. X-ray diffraction patterns showed that the electric field-induced formation of filaments on the surface of amorphous AsTeGe introduced a definite crystallinity. It was not possible, however, to positively identify the crystalline structure.
121 citations
TL;DR: The fine structure of some sixty different collections of blue-green algae representing at least thirty different species was studied, and it is suggested that some of these inclusions are intracellular symbionts.
Abstract: The fine structure of some sixty different collections of blue-green algae representing at least thirty different species was studied. In addition to the usual components of blue-green algal cells, a number of different, unique, intracellular structures were observed. Membranous “stacks”, and “spheres”, and “scrolls” in which the membranes are not typical unit membranes are described. “Spheroids”, 25 to 30mμ in diameter, were found in intrathylakoidal spaces of several collections. Other inclusions, including a variety of filamentous and crystalline arrays, are described. It is suggested that some of these inclusions are intracellular symbionts.
119 citations
TL;DR: The results indicate that, after initial enzymic attack, the right- hand fragment of the substrate dissociates from the enzyme surface, however, the left-hand fragment remains at the enzyme active site long enough to permit it to become repositioned and undergo further attack.
116 citations
115 citations
TL;DR: Analysis of peripheral plasma during normal parturition in 10 cows indicated a rise in plasma corticoids on days 4-1 prepartum that was significantly different from levels obtained on days 7-5 prepartu or days 3-7 postpartum, which may result from increased synthesis by the fetal adrenals and provide the signal for termination of the pregnancy.
Abstract: Labor was initiated within 72 hr in 46 of 54 cattle treated with 20 mg dexamethasone intramuscularly. Parturition was induced in animals injected as early as 246 days postconception although the procedure was more effective later than 255 days of pregnancy. Similarly, 10 or 20mg dexamethasone intramuscularly was effective in initiating labor within 72 hr resulting in parturition in 11 of 23 ewes. Only two of eight ewes injected on days 133-139 lambed within 72 hr postinjection compared to 9 of 15 ewes injected on days 140-142 of pregnancy. Normal gestation length is 148 days for the ewes and 278-288 days for the cattle used in this study. Analysis of peripheral plasma during normal parturition in 10 cows indicated a rise in plasma corticoids on days 4-1 prepartum that was significantly different (� < .001) from levels obtained on days 7-5 prepartum or days 3-7 postpartum. This abrupt elevation in maternal plasma corticoids may result from increased synthesis by the fetal adrenals and provide the signal for termination of the pregnancy.
114 citations
TL;DR: Two kinds of structural changes occur in muscle during the first 24 hours post-mortem: a variable amount of shortening and degradation of the Z line, and at higher storage temperatures, of the M line; bovine muscle Z lines are clearly more resistant to post- autopsy degradation than porcine or rabbit Muscle Z lines.
Abstract: Ultrastructural changes in bovine, porcine, and rabbit muscle have been studied during the first 24 hours post-mortem. Samples were taken for phase and electron microscopy immediately after death, after 4, 8, and 24 hours of post-mortem storage at 2° and 37°C, and after 24 hours post-mortem at 16° and 25°C. The results show that two kinds of structural changes occur in muscle during the first 24 hours post-mortem: (a) a variable amount of shortening, this shortening occurring via a sliding of filaments in all species and at all post-mortem storage temperatures examined, and (b) degradation of the Z line, and at higher storage temperatures, of the M line also. Shortening of unrestrained muscle occurs soonest post-mortem at 37°C in all three species and is completed within four hours post-mortem in porcine and rabbit muscle and within eight hours post-mortem in bovine muscle. Post-mortem short-ening of unrestrained rabbit and porcine muscle is greatest at 37°C (sarcomere lengths of 1.5 μ); shortening of rabbit muscle is minimal at 2°C (sarcomere lenght of 1.7 μ), but shortening of porcine muscle is minimal at 25°C (sarcomere length of 1.8 μ) and is slightly greater at 2°C (sarcomere length of 1.6 μ) than at 16°C. Post-mortem shortening of bovine muscle is greatest at 2°C (sarcomere length of 1.3 μ), is minimal at 16–25°C (sarcomere length of 1.8 μ), and increases between 25–37°C (sarcomere length of 1.5 μ at 37°C). Sarcomere length measurements show that some variation occurs in the extent of post-mortem shortening within the same muscle.
Z line degradation occurs sooner post-mortem and to a greater extent at storage temperatures of 25°C or above than at temperatures of 16°C or below. Also, bovine muscle Z lines are clearly more resistant to post-mortem degradation than porcine or rabbit muscle Z lines. Loss of fibrillar structure in porcine or rabbit muscle Z lines occurs during the first four hours post-mortem at 37°C, but eight hours of post-mortem storage at 37°C are required to cause loss of fibrillar structure of bovine muscle Z lines. After 24 hours at 25 or 37°C, Z lines of rabbit and porcine muscle are usually completely absent; M lines are also frequently absent in this muscle.
TL;DR: An experimental program to study the flow characteristics of an incompressible fluid through an axisymmetric converging-diverging tube is described, the theoretical and experimental results are compared, and some speculations are made on their implications in occlusive vascular disease.
TL;DR: Screening of the fungi present in the corn revealed aflatoxin production only by A. flavus, and the toxigenic strains produced only aflatoxins B(1) and B(2).
Abstract: Samples of freshly harvested and remoistened corn, of various moisture contents, were stored at different temperatures; analyses for aflatoxin content were made periodically. At moisture levels above 17.5% and at temperatures of 24 C or warmer, aflatoxins were formed by Aspergillus flavus present in the original epiphytic mycoflora. Remoistened dried corn was subject to more rapid fungal deterioration and aflatoxin formation than freshly harvested corn. Screening of the fungi present in the corn revealed aflatoxin production only by A. flavus. The toxigenic strains produced only aflatoxins B(1) and B(2).
TL;DR: In this paper, the authors deal with the development and current status of the College Student Satisfaction Questionnaire, part of a project directed at the systematic study of college student satisfaction as an...
Abstract: This paper deals with the development and current status of the College Student Satisfaction Questionnaire, part of a project directed at the systematic study of college student satisfaction as an ...
TL;DR: The 6-S α-actinin species can be purified from a P 15-25 α actinin fraction by DEAE-cellulose chromatography.
TL;DR: In this paper, a physical picture is regarded as a set of conceptual constructs and analogies with the help of which one can qualitatively but correctly anticipate results, which one would obtain quantitatively by executing the quantum mechanical calculation.
Abstract: Publisher Summary This chapter discusses the phenomenon binding and anti-binding in the hydrogen molecule-ion. In the chapter, a physical picture is regarded as a set of conceptual constructs and analogies with the help of which one can qualitatively but correctly anticipate results, which one would obtain quantitatively by executing the quantum mechanical calculation. The variation principle is chosen as the basis for understanding wave functions. The operation of the variation principle is visualized as the process that selects the solution of the Schrodinger equation by seeking that wave function, which has the lowest energy expectation value. Thus, the characteristics of this solution can be understood by analyzing the terms, which contribute to the energy integral, and hence, are responsible for singling out the actual solution from all virtual wave functions germane to the problem.
01 Jan 1970
TL;DR: In this paper, the X-ray parametric method was used to determine the solubilities of all the rare earth metals in silver, including RAg5(La, Ce, Pr, Eu, and Yb), RAg4(Lu and Sc), R14Ag5l(La to Sm, Gd to Er, Yb and Y) and TmAg3.
Abstract: The solid solubilities of all of the naturally occurring rare-earth metals in silver have been determined by using the X-ray parametric method. The solubilities range from 0.01 to 0.02 at. pct for Eu to 10.5 at. pct for Sc. The stoichiometries of the silver-rich compounds and some of their crystal structures were determined. The silver-rich compounds found in this study are: RAg5(La, Ce, Pr, Eu, and Yb), RAg4(Lu and Sc), R14Ag5l(La to Sm, Gd to Er, Yb, and Y) and TmAg3. The silver/silver-rich compound eutectic temperatures were also determined. Analysis of these data indicates that several factors in addition to the Hume-Rothery criteria influence the formation and extent of solid solutions. These include the mutual adjustment of size and electronegativity of the solvent and solute if the pure metal size differences are less than a critical value of 22 to 25 pct, the composition of the first solvent-rich compound, and the lattice rigidity of the solvent.
TL;DR: Action of pullulanase from Aerobacter aerogenes has been tested on a number of starch oligosaccharides and dextrins, and a single α-1 α 6-linked glucose “stub” does not interfere with pullulAnase action, and oligosACcharides containing such stubs are found in the products of pullULanase action.
TL;DR: In this article, the authors measured the optical absorption over a photon energy range of 0.08-5 eV at 4.2 K by a calorimetric technique.
Abstract: The antiferromagnetic energy gap and optical properties of single crystals of Cr and of Cr alloyed with 0.45, 0.94, 2.5, and 4.5% Mn and with 1.05 and 2.0% Re have been investigated by measuring the optical absorption over a photon energy range of 0.08-5 eV. The data were taken at 4.2 K by a calorimetric technique. It is found that at 4.2 K, approximately 1% Mn or Re will cause commensurate antiferromagnetic ordering, and the energy gap shifts abruptly from 0.13 to 0.36 eV near this concentration of diluent. Evidence is given for indirect transitions occurring across a double energy gap in the noncommensurate samples, and the results are explained in terms of a band model. The widths of the absorption peak and the peak in ${\ensuremath{\epsilon}}_{2}$ in the commensurate samples are discussed in terms of a gap anisotropy and impurity broadening. Optical absorption peaks near 1, 2, and 3.4 eV are associated with direct interband transitions originating from the $N_{1}^{\ensuremath{'}}$, $\ensuremath{\Gamma}_{25}^{\ensuremath{'}}$, and ${P}_{4}$ symmetry points, with a contribution to the 1-eV absorption from transitions from the Fermi surface to the flat unoccupied band extending through ${N}_{4}$, ${\ensuremath{\Gamma}}_{12}$, ${P}_{3}$, and $H_{25}^{\ensuremath{'}}$.
TL;DR: In this article, the authors define a trait as any potentially measureable attribute of the subject whose responses are observed, e.g., anxiety, neuroticism, morale, etc.
Abstract: IN order to delineate the problem considered in this paper, and the rationale upon which the solution is based, the following definitions mill be adhered to. A trait is defined as any potentially measureable attribute of the subject whose responses are observed, e.g., anxiety, neuroticism, morale, etc. A method refers to the means used to ob: -ewe or assess the trait, e.g. peer ratings, psychologist’s ratings, questionnaires, etc. The measure refers to the particular trait-method combination administered to a subject to obtain an observation. The multitrait-multimethod matrix is comprised of correlations between measures which use a number of methods to assess each member of the same set of traits. The procedure described in this paper is based on explicit models for multitrait-multimethod data. The formal models are related to models implicit in the classical Campbell and Fiske (1959) presentation. The procedure is based also on previous research conducted by Wolins (1964) and by Stanley (1961). Another
TL;DR: Halobacterium halobium amylase had optimal activity at pH 6.4 to 6.6 in sodium beta-glycerophosphate buffer containing 0.05% NaCl at 55 C; Ca(2+) was not required.
Abstract: Halobacterium halobium amylase had optimal activity at pH 6.4 to 6.6 in sodium β-glycerophosphate buffer containing 0.05% NaCl at 55 C; Ca2+ was not required. End products from amylose were maltose, maltotriose, and glucose. The amylase, which was devoid of transglucosylase activity, had a multichain attack mechanism.
TL;DR: The mutable allele, a1m(pa−pu) of the En system at the a1 locus in maize mutates somatically and germinally to pale, colorless, and purple.
Abstract: 1.
The mutable allele, a1m(pa−pu) of the En system at the a1 locus in maize mutates somatically and germinally to pale, colorless, and purple.
2.
Colorless and pale germinal deviants arise at a high frequency. The colorless is more frequent than the pale, and each is more frequent than purple. Frequency is correlated with timing of the somatic mutation event — the earlier colorless sectoring is correlated with the higher frequency of colorless deviants.
3.
The regulatory element, En, has been identified at the a1 locus. The origin of colorless and pale deviants is accompanied by the transposition of an En element away from the a1 site.
4.
The transposing event may lead to implantation of En on the same chromosome, on another chromosome, or no implantation occurs. Transposition to a linked site occurs approximately 25% of the time. There is a preference for transposition to sites 6–20 units from a1.
5.
Secondary transpositions of En occur, and in one test, approximately 12% of the time, to an independent position. Secondary transpositions take place to new linked sites.
6.
Preliminary data indicate that transpositions can occur to both distal and proximal positions on chromosome 3.
7.
Since differences exist in the behaviour of elements in transposition, it is likely that the transposition event probably is dependent on the elements of specific mutable systems and differing elements within a system.
8.
Theoretical aspects of diverse types of impairment of normal gene function by inserted elements is discussed.
TL;DR: Spectral properties of enzyme-bound pyridoxal phosphate in native phosphorylase were compared to NaBH4-reduced enzyme, and it was suggested that pyrinium nitrogen is unprotonated and 3-hydroxyl group undissociated or strongly hydrogen bonded in these two forms at pH 7.0 in the same microscopic environment.
TL;DR: In this paper, the authors examined a constant area of second-year xylem of 2-year-old twigs and found a correlation exists between increasing disease susceptibility and increasing vessel group size (the product of average vessel diameter and average number of contiguous vessels).
Abstract: The localizing of pathogen (Ceratocystis ulmi) establishment in Dutch elm disease-resistant hosts is hypothesized as the major mechanism of resistance to this disease. Four factors are proposed that, singly or in all possible combinations, could regulate this general mechanism. We tested one of these factors, vessel size and number of contiguous vessels in the functional xylem at the point of natural inoculation. Using 23 selections from the Ulmaceae, we examined a constant area of second-year xylem of 2-year-old twigs. These anatomical data indicate that a correlation exists between increasing disease susceptibility and increasing vessel group size (the product of average vessel diameter and average number of contiguous vessels). Other evidence suggests that lateral pathogen movement is at first confined to the vessel group or groups of initial inoculation. Therefore, in a given limited time period, tylosis production could more effectively block vertical pathogen movement in vessel groups of small size. Relationships between vessel group size and the extent of sapwood discoloration are discussed. Vessel size and arrangement also is discussed in relationship to the resistance reported for young, greenhouse-grown trees. The use of vessel group size is suggested in screening programs for disease resistance. Recent research on oak suggests chemical modification of xylem tissue to lessen elm susceptibility.
TL;DR: In contrast to the existing descriptions of α-actinin activity, the P15–25 fraction causes the largest percent increase in ATPase activity and turbidity response at 100–125 mM KCl, which is very close to the KCl concentration existing in vivo.
TL;DR: In this paper, the authors define a trait as any potentially observable attribute of the subj ect. A method refers to the means used to observe or assess the trait, and a measure is the trait-method combination used to obtain an observation on the subject, and the observations yielded by a measure are treated as if they vary on an interval scale.
Abstract: THE following definitions, taken from Thurstone (1947) and from Campbell and Fiske (1959), will be employed to characterize the measurement system considered in this paper. A subject is generally the person whose responses are observed. A trait is defined as any potentially observable attribute of the subj ect. A method refers to the means used to observe or assess the trait. A measure refers to the trait-method combination used to obtain an observation on the subject. The observations yielded by a measure are treated as if they vary on an interval scale. Consider, for example, the traits called manager human relations
TL;DR: In this paper, it was shown that soil minerals and metallic cations do not promote chemical decomposition of nitrite in soils and do not play a significant role in the processes leading to gaseous loss of nitrogen from soils through chemodenitrification.
Abstract: Work reported indicates that soil minerals and metallic cations do not promote chemical decomposition of nitrite in soils and do not play a significant role in the processes leading to gaseous loss of nitrogen from soils through chemodenitrification. No reactions promoting nitrite decomposition were observed in studies of the effects of soil minerals on the decomposition of nitrite in pH 5 buffer solution, and investigations of the reactions of nitrite with metallic cations provided no indications that chemodenitrification in soils is promoted by metallic cations. Of various metallic cations tested, only ferrous, cuprous and stannous ions promoted nitrite decomposition, and soils normally do not contain sufficient amounts of these cations to promote nitrite decomposition under the conditions known to be suitable for chemodenitrification.
TL;DR: The feasibility of using soil mositure tension as a practical method of determining consistency limit values is investigated in this paper, where a definite relationship between the consistency limits and moisture tension curves is proved using generally accepted theoretical relationships.
Abstract: The feasibility of using soil mositure tension as a practical method of determining consistency limit values is investigated. Samples with known limits determined by standard methods were obtained from the Iowa State Highway Commission. The samples were mostly clays, silty clays, and silty clay loams. A total of 687 liquid limits and 273 plastic limits are determined using varying moisture tensions on pressure plate and pressure membrane apparatus respectively. The effect of textural groups on liquid limit determination is not especially critical; moisture tensions vary between 40 in. and 70 in. of water pressure. A definite relationship between the consistency limits and moisture tension curves is proved using generally accepted theoretical relationships. The moisture tension method is capable of producing a liquid limit value essentially the same as would be obtained by the standard ASTM method, but with better reproducibility. In general, the plastic limit results are not acceptable; however, the method could be used for determining the plastic limits of clays. There is essentially no operator variability with the moisture tension method.