Studies on cocurrent gas-liquid flow in helically coiled tubes. II. Theory and experiments on turbulent mass transfer with and without chemical reaction

Pure carbon dioxide was absorbed into distilled water and sodium hydroxide solution, in cocurrent two phase annular flow in helically coiled tubes in order to measure physical and chemical mass transfer coefficients and interfacial areas. (k*_La) was correlated by the pressure drop in the test sections and interfacial areas were found to vary with the liquid phase energy dissipation. According to a new theory, (k*_L) has been shown to be a function of the root mean square vorticity near the interface. The root mean square vorticity has been related to the pressure drop, gas density, liquid flow rate and liquid velocity. The physical mass transfer coefficients theoretically predicted are in good agreement with experimental results.     

Apparatus and procedure for measuring release rates from formulations of lepidopteran semiochemicals

An apparatus was developed wherein a vacuum source was used to pull air across a controlled-release-formulation dispenser or a planchet containing a known quantity of a semiochemical and into a collector filled with a polymeric adsorbent. After a set time, the semiochemical was eluted with solvent and was quantified by gas-liquid chromatography (GLC). High percentages of known quantities of the lepidopteran semiochemicals (Z)-7-dodecen-l -ol acetate (Z7DDA), boiling point (bp) 275 ° C/1 atm, (Z)-9-tetradecen-1-ol formate (Z9TDF), bp 289 °C/1 atm, and (Z,Z)-3,13-octadecadien-1-ol acetate (ZZODDA), bp 490 °C/1 atm, were recovered. The semiochemicals did not oxidize and were recovered quantitatively from the adsorbent. The release rates of Z9TDF from a controlled-release dispenser were found to be directly proportional to the airflow rates. Release rate measurements on the Z9TDF dispensers were made for the purpose of estimating the method's precision. The method was shown to give internally consistent results by measurements on another Z9TDF formulation. The accuracy of the method is discussed.Mention of a commercial or proprietary product in this paper does not constitute an endorsement by the USDA.     

The relationship between resources and capabilities of new ventures in emerging economies

Despite the fact that the resource-based view has drawn a great deal of attention in studying new ventures, our understanding on resource management in the emerging economies is limited and there are many unsolved issues. In this paper, theoretical reasoning approach is applied to analyze the relationship between the entrepreneurial resources and the organizational capabilities (including operating and dynamic capabilities) for new ventures. An empirical study in the context of emerging economy in China is conducted to verify the theoretical reasoning. As information technology becomes a key element for new ventures, the enterprise resources relevant to the network technology and e-commerce are especially focused, as well as the impact of information acquisition on the resource combination. The results from the theoretical and empirical study have shown that resource combination mediates the relationship of entrepreneurial resources and organizational capability. It is also found that the information acquisition affects the organizational capabilities significantly; however, there is an inverted U-shape relationship between the information acquisition and the resource combination in emerging economies .     

Processing of Silicon Carbide-Mullite-Alumina Nanocomposites

Nanocomposite materials in the form of nanometer-sized second-phase particles dispersed in a ceramic matrix have been shown to display enhanced mechanical properties. In spite of this potential, processing methodologies to produce these nanocomposites are not well established. In this paper, we describe a new method for processing SiC-mullite-Al₂O₃ nanocomposites by the reaction sintering of green compacts prepared by colloidal consolidation of a mixture of SiC and Al₂O₃ powders. In this method, the surface of the SiC particles was first oxidized to produce silicon oxide and to reduce the core of the SiC particles to nanometer size. Next, the surface silicon oxide was reacted with alumina to produce mullite. This process results in particles with two kinds of morphologies: nanometer-sized SiC particles that are distributed in the mullite phase and mullite whiskers in the SiC phase. Both particle types are immersed in an Al₂O₃ matrix.     

Cholesterol transport and uptake in miniature swine fed vegetable and animal fats and proteis. 1. Plasma lipoproteins and LDL clearance

In a 2×2 factorial arrangement, miniature pigs were fed four diets containing vegetable protein/fat (soybean) and animal protein (egg white)/fat (beef tallow) to demonstrate the effects of protein and fat source on total plasma cholesterol, lipoprotein distribution, low density lipoprotein (LDL) composition, and plasma clearance of LDL-cholesterol and protein. Beef tallow consumption resulted in greater plasma cholesterol concentration, decreased LDL-cholesterol concentration, and a lower LDL-cholesterol to LDL-protein ratio than did consumption of soybean oil. High density lipoprotein (HDL)-cholesterol concentration was increased by beef tallow consumption. Cholesterol percentage by weight in LDL was significantly greater in pigs consuming soybean oil than those consuming beef tallow. Percentages by weight of protein, triglyceride and phospholipid in LDL were not significantly different in any group. Dietary protein source had no significant effect on total plasma cholesterol concentration, lipoprotein concentration or LDL composition. Egg white consumption decreased fractional catabolic rate and irreversible loss of LDL-cholesterol and LDL-protein when compared with consumption of soy protein. Dietary fat source had no consistent effect on LDL clearance from plasma. Dietary fat and protein seemed to influence lipoprotein metabolism by different mechanisms. Fat source altered lipoprotein concentration and LDL composition, whereas protein source affected the removal rate of LDL from plasma. Data taken from a dissertation submitted to Iowa State University by L. S. Walsh Hentges as partial fulfillment of the requirements for the Ph.D. degree. A preliminary paper, was presented at the meeting of the American Oil Chemists' Society in Dallas, Texas, May, 1984.     

冠带层新平台技术

子午线轮胎出现不久，就采用钢丝带束层代替了纤维带束层，这对于实现子午线轮胎提高使用寿命和改善操纵性能的潜能是必要的。     

Effects of mite resistance mechanism of geraniums on mortality and behavior of foxglove aphid (Acyrthosiphon solani Kaltenbach)

Geraniums (Pelargonium xhortorum Bailey) possess a pest-resistance mechanism, based on glandular trichomes and the exudate they produce, that has been shown to be effective against the two-spotted spider mite (Tetranychus urticae Koch). Using an intact plant bioassay, the effectiveness of the resistance mechanism was determined for another potential pest, the foxglove aphid (Acyrthosiphon solani Kaltenbach). Comparisons were made between plant lines previously analyzed for their degree of resistance to mites, as well as their glandular trichome density and trichome exudate production. Over 100 aphid adults were bioassayed on each of the five plant lines used in the experiment. In addition to adult aphid survival, the production and survival of nymphs was determined in this bioassay. The results indicate that plant lines that are resistant to the two-spotted spider mite are also resistant to the foxglove aphid, while lines susceptible to mites are susceptible to the aphids. To evaluate the physical impediment features of the trichome exudate, the behavior of foxglove aphid nymphs was compared on two geranium lines, one a resistant line with high trichome densities and large quantities of exudate and the second a susceptible line with few trichomes and reduced exudate. A third leaf surface type was produced by washing the exudate from resistant leaves using a mildly basic buffer solution prior to the bioassay. Aphid behavior was divided into five categories: feeding or probing, resting, wandering, struggling, and immobilized. On both susceptible leaves and resistant leaves from which the exudate had been removed by washing, the aphids settled quickly and were observed with inserted stylets during most of the observation intervals. In contrast, aphids on the unwashed resistant leaf surfaces often became ensnared in the sticky trichome exudate and had difficulty in settling to probe the leaf. Physical entrapment by glandular trichome exudate appears to be an important aspect of aphid resistance in geraniums.     

Effects of dietary oils and methyl ethyl ketone peroxide onin vivo lipid peroxidation and antioxidants in rat heart and liver

Weanling male Sprague-Dawley rats were fed diets for four weeks which differed in their content of n−6 (corn oil; CO) and n−3 fatty acids (fish oil; FO), but were similar in their content of saturated and monounsaturated fatty acids and vitamin E. At the end of the four-week feeding period, each dietary group was subdivided into two groups. One group received a single placebo injection of α-tocopherol-stripped corn oil (TSCO); the other group received a single injection of the free radical generator, methyl ethyl ketone peroxide (MEKP), in TSCO. Twenty-four hours after injection, the effect of dietary oil and MEKP treatment on endogenous lipid peroxide (LPO) production (measured as methylene blue formed by the “Determiner LPO” assay), glutathione (GSH) and vitamin E content, and fatty acid composition of phosphatidylcholine and phosphatidylethanolamine in heart and liver from unfasted animals were measured. FO-fed rats had significantly heavier hearts and livers, increased levels of n−3 fatty acids in membrane phospholipids, and higher liver LPO levels than CO-fed rats. MEKP treatment resulted in significantly lower body weights and liver GSH levels. The data indicate that dietary n−3 fatty acids increase lipid peroxidation in liver somewhat more than in heart. The study also demonstrates that the effect of induced oxidative stress due to a single dose of MEKP on lipid peroxide formation and antioxidant status in tissues from unfasted animals was independent of the dietary oils.     

The crystal state binding of dithionite to deoxy-hemoglobin

The crystal state binding of sodium ditbionite to deoxyhemoglobinis reported. Dithionite has been used extensively to deoxygenatehemoglobin and myoglobin and there has been considerable interestamong users of dithionite about its effect on protein structureand binding site(s). We have determined that dithionite bindsto deoxygenated hemoglobin crystals at the interface of twomolecules in the crystal lattice. Specific residues involvedin hydrogen bonds or salt interactions with dithionite includeHisll6 and Hisll7 of the ft subunit and Lysl6 of the ß₂subunit of the adjacent hemoglobin molecule. No binding wasobserved at the symmetry related Hisll6 and 117 ß1 residues.We have shown that dithionite does not affect the native hemoglobinstructure or the binding of several allosteric inhibitors tohemoglobin and can be used to mount T state crystals in theair