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  • 1
    Electronic Resource
    Electronic Resource
    Circumferential tube skin temperature profiles in thermal cracking coils (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1905-1912 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Uniform temperature distributions in cracking furnaces favor the run length of the production cycle of the furnace and the tube metal life. The coupled simulation of the furnace and the reactor tubes by means of the zone method is extended to permit the calculation of circumferential nonuniformities under reaction conditions. Circumferential tube skin temperatures were found to vary over 50°C and more, due to “shadow effects.” As a result, nonuniform coking rates and coke layers are obtained. The model and computational scheme presented here can be used as a guide for plant operators and as a tool for designing.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690381206
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  • 2
    Electronic Resource
    Electronic Resource
    The development of molecular orientation and morphological texture in thermotropic copolyesters (1985)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 888-895 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Liquid crystalline polymers can be processed to form high strength/modulus materials. In processing these materials, it is apparent that molecular orientation is an important factor in determining the physical strength of the processed materials. In this study a systematic investigation was carried out to determine how a thermotropic copolyester of parahydroxybenzoic acid (PHB) and polyethylene terephthalate (PET) responds to two basic types of flows: shear and extensional flow. This was accomplished by preparing sheared and extended samples under controlled conditions of temperature and flow history. Sheared disks were prepared using a disk and plate geometry of a Rheometrics Mechanical Spectrometer (RMS model 605), while extended ribbons were prepared using a slit die attached to an Instron capillary rheometer. Two copolymerer compositions of 60 mole percent and 80 mol percent PHB were investigated. The sheared disks and extended ribbons were investigated for molecular orientation and morphological textures using wide angle x-ray scattering (WAXS) and scanning electron microscopy (SEM) analysis, respectively. It was found that extensional flow has a greater capacity for orienting such materials than shear flow. Samples annealed at their softening points for 1 minute (240°C for the 60 mole percent PHB/PET copolymer and 300°C for the 80 mole percent PHB/PET copolymer) showed no significant loss of orientation, indicating that once orientation is produced it may remain in the melt for a long period of time. Sheared samples prepared by shearing the sample while cooling showed significantly higher degrees of orientation than those not cooled while being sheared. This may indicate that a minimum stress level exists for the production of orientation in shear flow.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760251405
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  • 3
    Electronic Resource
    Electronic Resource
    Reaction injection pultrusion of thermoplastic and thermoset composites (1995)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 16 (1995), S. 378-385 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Coventional pultrusion of thermoset composites is under increasing examination for emissions of harmful volatiles from the resin wetout tank. Even though the pultrusion of thermoplastic matrix composites produces no emissions, it is difficult to wet individual fibers due to their high melt viscosities. This paper addresses both the issues of volatiles and wetting with a process called Reaction Injection Pultrusion (RIP). A prototype RIP machine was used to make both thermoplastic polyurethane and thermoset polyisocyanurate matrix composites. The RIP process produces pultruded parts with low void content, good surface finish, and acceptable mechanical properties. The low viscosity constituents used in RIP help improve fiber impregnation, while the small volume of the impregnation bath reduces emissions. Processing parameters such as line speeds, catalyst levels, and die temperaures were varied to establish processing guidelines for sustained production.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750160506
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of fireproofing design on thermal performance of horizontal members with top flange exposed (1987)
    New York, NY : Wiley-Blackwell
    Plant/Operations Progress 6 (1987), S. 193-198 
    Details
    ISSN: 0278-4513
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is common practice in the industrial sector to leave the top flanges of fireproofed beams bare. The main reason for this is to permit placement of pipes and grating on the beams without interference from fireproofing materials. To the authors' knowledge, tests of such configurations have not been conducted to determine actual resistance to fire. However, structures fireproofed in this manner have survived actual fire exposures. The purpose of this paper is to examine theoretically the effect of various fireproofing designs on the performance of these members and point out which practices can lead to premature failure of fireproofed beams where top surfaces are left bare. An approximate but practical analytical model is used to evaluate bare steel, encased (concrete/contour) and box (hollow) constructions. The need for reinforcements is demonstrated by examining the effect of bond loss in decomposable systems. Thermal performance is related to load carrying capability of the member.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prsb.720060410
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  • 5
    Electronic Resource
    Electronic Resource
    Small angle X-ray scattering from block polymers. II. The bulk state (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 598-605 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The basic theory of X-ray scattering is applied to various hypothetical models for the bulk state of block polymers in order to explain the angular dependent scattering. The intensity of scattering is calculated for a rnicellar model, a zone model, and a molecular dumbbell model. The molecular dumbbell model, in contrast to the micellar and zone models, assumes that a block copolymer containing domains may be treated as one giant molecule and that, therefore, the locations of the domains are not random but are governed by the statistics of the segments which interconnect them. Experimental and calculated scattering curves are compared for several different types of block polymers.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170817
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  • 6
    Electronic Resource
    Electronic Resource
    Physical properties of perfluoropolyethers: Dependence on composition and molecular weight (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 829-834 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Three copolymeric perfluoroethers with the structure CF3[(OCF2CF2)p(OCF2)q] OCF3, having different p/q ratios, have been fractionated. The fractions obtained have been characterized by Gel Permeation Chromatography and 19F-NMR. The viscosity η the specific volume v and the glass transition temperature, Tg have been measured by standard techniques for all the above samples as well as for some other perfluorinated polyethers.The temperature dependence of viscosity of the unfractionated samples is described by the W.L.F. equation. The values of fg (fractional free-volume at Tg) and of af (free-volume expansion coefficient) are independent of composition, for p/q ratios from 0.53 to 1.15. The critical molecular weight, Mc, is of the order of 8-9,000. From the molecular weight dependence of specific volume, the contribution to the molar volume of the in-chain CF2 group and the excess molar free volume of the chain ends have been determined. The limiting value of Tg for an infinite molecular weight polymer was found to depend linearly on the compositional ratio O/C and the extrapolated values for polytetrafluoroethylene and for the homopolymer (CF2O)n were found to be respectively 200 K and 120 K.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301405
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  • 7
    Electronic Resource
    Electronic Resource
    Extrusion of polymer tubing using a rotating mandrel (1976)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 16 (1976), S. 827-830 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A rotating mandrel in a tubing die produces multiaxial orientation in the extruded melt. If the polymer melt is quenched rapidly, some multiaxial orientation is retained in the resultant tubing. Multiaxially oriented tubing exhibits reduced crack propagation and some enhancement of yield and fracture strengths. During the processing of multiaxially oriented tubing, relaxation occurs after the melt leaves the die and gives rise to wall thickening and reduction in the lumen of the tubing; the magnitude of these effects is a function of the rate of mandrel rotation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760161210
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  • 8
    Electronic Resource
    Electronic Resource
    Impact fracture toughness tests on polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 241-248 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of impact tests are described in which the plane strain fracture toughness, Kc1, of five different polymers is measured using a three point bend specimen at striker speeds up to 5m/s. At low speeds Kc1 is determined using the maximum load and a static analysis, but at speeds greater than 1 m/s the dynamic effects render the load signal unusable. For the higher speeds the fracture is timed using contact and crack propagation gages and the analysis is performed using the striker displacement at fracture. A dynamic analysis is used to convert this measurement to the true specimen displacement and Kc1 is determined from this. The apparent downward trends in the Kc1 results obtained, especially at speeds above 3m/s, are discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300408
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  • 9
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    Biofuels. Engineering alcohol tolerance in yeast (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-10-04
    Description: Ethanol toxicity in the yeast Saccharomyces cerevisiae limits titer and productivity in the industrial production of transportation bioethanol. We show that strengthening the opposing potassium and proton electrochemical membrane gradients is a mechanism that enhances general resistance to multiple alcohols. The elevation of extracellular potassium and pH physically bolsters these gradients, increasing tolerance to higher alcohols and ethanol fermentation in commercial and laboratory strains (including a xylose-fermenting strain) under industrial-like conditions. Production per cell remains largely unchanged, with improvements deriving from heightened population viability. Likewise, up-regulation of the potassium and proton pumps in the laboratory strain enhances performance to levels exceeding those of industrial strains. Although genetically complex, alcohol tolerance can thus be dominated by a single cellular process, one controlled by a major physicochemical component but amenable to biological augmentation.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4401034/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4401034/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lam, Felix H -- Ghaderi, Adel -- Fink, Gerald R -- Stephanopoulos, Gregory -- R01 GM035010/GM/NIGMS NIH HHS/ -- R01-GM035010/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2014 Oct 3;346(6205):71-5. doi: 10.1126/science.1257859. Epub 2014 Oct 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA. Whitehead Institute for Biomedical Research, Cambridge, MA, USA. ; Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA. ; Whitehead Institute for Biomedical Research, Cambridge, MA, USA. gfink@wi.mit.edu gregstep@mit.edu. ; Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA. gfink@wi.mit.edu gregstep@mit.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25278607" target="_blank"〉PubMed〈/a〉
    Keywords: *Biofuels ; Cation Transport Proteins/genetics ; Cell Culture Techniques ; Cell Membrane/metabolism ; Chemical Engineering ; *Drug Resistance, Fungal/genetics ; Ethanol/*metabolism/pharmacology ; Fermentation ; Genetic Engineering ; Glucose/metabolism ; Hydrogen-Ion Concentration ; Phosphates/*metabolism ; Potassium Compounds/*metabolism ; Proton Pumps/genetics ; Proton-Translocating ATPases/genetics ; Saccharomyces cerevisiae/drug effects/genetics/*metabolism ; Saccharomyces cerevisiae Proteins/genetics ; Up-Regulation ; Xylose/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 10
    Electronic Resource
    Electronic Resource
    Energy balances in solar distillers (1961)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 641-649 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: There has been considerable doubt as to the manner in which the productivity of solar stills is affected by many of the designs and operating variables. To assist in designing solar stills of improved performance, theoretical equations are derived to describe the complete energy and mass transfer relationships involved in the operation of the basin type of solar still. These are supplemented with data from field operation of a 2,500-sq. ft. still. With these relationships and the aid of a digital computer, the effects of variations of design parameters on the performance of solar stills is predicted. Distiller productivity is correlated with atmospheric temperature, wind velocity, solar radiation, absorptivity and slope of transparent cover, and other variables. Curves showing the magnitude of the effects of design changes on cover temperature, brine temperature, and productivity are presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690070422
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