21 CFR 133.144 - Granular and stirred curd cheese.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Granular and stirred curd cheese. 133.144 Section... (CONTINUED) FOOD FOR HUMAN CONSUMPTION CHEESES AND RELATED CHEESE PRODUCTS Requirements for Specific Standardized Cheese and Related Products § 133.144 Granular and stirred curd cheese. (a) Description. (1...

21 CFR 133.144 - Granular and stirred curd cheese.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Granular and stirred curd cheese. 133.144 Section... (CONTINUED) FOOD FOR HUMAN CONSUMPTION CHEESES AND RELATED CHEESE PRODUCTS Requirements for Specific Standardized Cheese and Related Products § 133.144 Granular and stirred curd cheese. (a) Description. (1...

Numerical Simulations of Vortical Mode Stirring: Effects of Large Scale Shear and Strain

DTIC Science & Technology

2015-09-30

Numerical Simulations of Vortical Mode Stirring: Effects of Large-Scale Shear and Strain M.-Pascale Lelong NorthWest Research Associates...can be implemented in larger-scale ocean models. These parameterizations will incorporate the effects of local ambient conditions including latitude...talk at the 1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Nonlinear Effects in Internal Waves Conference held

Compression Buckling Behavior of Large-Scale Friction Stir Welded and Riveted 2090-T83 Al-Li Alloy Skin-Stiffener Panels

NASA Technical Reports Server (NTRS)

Hoffman, Eric K.; Hafley, Robert A.; Wagner, John A.; Jegley, Dawn C.; Pecquet, Robert W.; Blum, Celia M.; Arbegast, William J.

2002-01-01

To evaluate the potential of friction stir welding (FSW) as a replacement for traditional rivet fastening for launch vehicle dry bay construction, a large-scale friction stir welded 2090-T83 aluminum-lithium (Al-Li) alloy skin-stiffener panel was designed and fabricated by Lockheed-Martin Space Systems Company - Michoud Operations (LMSS) as part of NASA Space Act Agreement (SAA) 446. The friction stir welded panel and a conventional riveted panel were tested to failure in compression at the NASA Langley Research Center (LaRC). The present paper describes the compression test results, stress analysis, and associated failure behavior of these panels. The test results provide useful data to support future optimization of FSW processes and structural design configurations for launch vehicle dry bay structures.

Perchlorate Removal, Destruction and Field Monitoring Demonstration

DTIC Science & Technology

2007-03-01

perchlorate CSTR continuously stirred tank reactors DAB decyltrimethylammonium bromide DHS Department of Health Services DoD Department of Defense DWEL...reactors ( CSTR ) in series under anoxic conditions. A strong base anion resin was used to scavenge the concentrated spent regenerant solution as a super...evaluate perchlorate destruction in spent regenerant. The apparatus consisted of two 2.5-liter, continuously stirred tank reactors ( CSTR ) in

COED Transactions, Vol. X, No. 10, October 1978. Simulation of a Sampled-Data System on a Hybrid Computer.

ERIC Educational Resources Information Center

Mitchell, Eugene E., Ed.

The simulation of a sampled-data system is described that uses a full parallel hybrid computer. The sampled data system simulated illustrates the proportional-integral-derivative (PID) discrete control of a continuous second-order process representing a stirred-tank. The stirred-tank is simulated using continuous analog components, while PID…

Friction Stir Welding of Large Scale Cryogenic Tanks for Aerospace Applications

NASA Technical Reports Server (NTRS)

Russell, Carolyn; Ding, R. Jeffrey

1998-01-01

The Marshall Space Flight Center (MSFC) has established a facility for the joining of large-scale aluminum cryogenic propellant tanks using the friction stir welding process. Longitudinal welds, approximately five meters in length, have been made by retrofitting an existing vertical fusion weld system, designed to fabricate tank barrel sections ranging from two to ten meters in diameter. The structural design requirements of the tooling, clamping and travel system will be described in this presentation along with process controls and real-time data acquisition developed for this application. The approach to retrofitting other large welding tools at MSFC with the friction stir welding process will also be discussed.

Production of recombinant adeno-associated vectors using two bioreactor configurations at different scales

PubMed Central

Negrete, Alejandro; Kotin, Robert M.

2007-01-01

The conventional methods for producing recombinant adeno-associated virus (rAAV) rely on transient transfection of adherent mammalian cells. To gain acceptance and achieve current good manufacturing process (cGMP) compliance, clinical grade rAAV production process should have the following qualities: simplicity, consistency, cost effectiveness, and scalability. Currently, the only viable method for producing rAAV in large-scale, e.g.≥1016 particles per production run, utilizes Baculovirus Expression Vectors (BEVs) and insect cells suspension cultures. The previously described rAAV production in 40 L culture using a stirred tank bioreactor requires special conditions for implementation and operation not available in all laboratories. Alternatives to producing rAAV in stirred-tank bioreactors are single-use, disposable bioreactors, e.g. Wave™. The disposable bags are purchased pre-sterilized thereby eliminating the need for end-user sterilization and also avoiding cleaning steps between production runs thus facilitating the production process. In this study, rAAV production in stirred tank and Wave™ bioreactors was compared. The working volumes were 10 L and 40 L for the stirred tank bioreactors and 5 L and 20 L for the Wave™ bioreactors. Comparable yields of rAAV, ~2e+13 particles per liter of cell culture were obtained in all volumes and configurations. These results demonstrate that producing rAAV in large scale using BEVs is reproducible, scalable, and independent of the bioreactor configuration. Keywords: adeno-associated vectors; large-scale production; stirred tank bioreactor; wave bioreactor; gene therapy. PMID:17606302

Long-term stability of crystal-stabilized water-in-oil emulsions.

PubMed

Ghosh, Supratim; Pradhan, Mamata; Patel, Tejas; Haj-Shafiei, Samira; Rousseau, Dérick

2015-12-15

The impact of cooling rate and mixing on the long-term kinetic stability of wax-stabilized water-in-oil emulsions was investigated. Four cooling/mixing protocols were investigated: cooling from 45°C to either 25°C or 4°C with/without stirring and two cooling rates - slow (1°C/min) and fast (5°C/min). The sedimentation behaviour of the emulsions was significantly affected by cooling protocol. Stirring was critical to the stability of all emulsions, with statically-cooled (no stirring) emulsions suffering from extensive aqueous phase separation. Emulsions stirred while cooling showed sedimentation of a waxy emulsion layer leaving a clear oil layer at the top, with a smaller separation and droplet size distribution at 4°C compared to 25°C, indicating the importance of the amount of crystallized wax on emulsion stability. Light microscopy revealed that crystallized wax appeared both on the droplet surface and in the continuous phase, suggesting that stirring ensured dispersibility of the water droplets during cooling as the wax was crystallizing. Wax crystallization on the droplet surface provided stability against droplet coalescence while continuous phase wax crystals minimized inter-droplet collisions. The key novel aspect of this research is in the simplicity to tailor the spatial distribution of wax crystals, i.e., either at the droplet surface or in the continuous phase via use of a surfactant and judicious stirring and/or cooling. Knowledge gained from this research can be applied to develop strategies for long-term storage stability of crystal-stabilized W/O emulsions. Copyright © 2015 Elsevier Inc. All rights reserved.

Self-Reacting Friction Stir Welding for Aluminum Complex Curvature Applications

NASA Technical Reports Server (NTRS)

Brown, Randy J.; Martin, W.; Schneider, J.; Hartley, P. J.; Russell, Carolyn; Lawless, Kirby; Jones, Chip

2003-01-01

This viewgraph representation provides an overview of sucessful research conducted by Lockheed Martin and NASA to develop an advanced self-reacting friction stir technology for complex curvature aluminum alloys. The research included weld process development for 0.320 inch Al 2219, sucessful transfer from the 'lab' scale to the production scale tool and weld quality exceeding strenght goals. This process will enable development and implementation of large scale complex geometry hardware fabrication. Topics covered include: weld process development, weld process transfer, and intermediate hardware fabrication.

Tool For Friction Stir Tack Welding of Aluminum Alloys

NASA Technical Reports Server (NTRS)

Bjorkman, Gerald W.; Dingler, Johnny W.; Loftus, Zachary

2003-01-01

A small friction-stir-welding tool has been developed for use in tack welding of aluminum-alloy workpieces. It is necessary to tack-weld the workpieces in order to hold them together during friction stir welding because (1) in operation, a full-size friction-stir-welding tool exerts a large force that tends to separate the workpieces and (2) clamping the workpieces is not sufficient to resist this force. It is possible to tack the pieces together by gas tungsten arc welding, but the process can be awkward and time-consuming and can cause sufficient damage to necessitate rework. Friction stir tack welding does not entail these disadvantages. In addition, friction stir tack welding can be accomplished by use of the same automated equipment (except for the welding tool) used in subsequent full friction stir welding. The tool for friction stir tack welding resembles the tool for full friction stir welding, but has a narrower shoulder and a shorter pin. The shorter pin generates a smaller workpiece-separating force so that clamping suffices to keep the workpieces together. This tool produces a continuous or intermittent partial-penetration tack weld. The tack weld is subsequently consumed by action of the larger tool used in full friction stir welding tool.

MRI change metrics of facioscapulohumeral muscular dystrophy: Stir and T1.

PubMed

Ferguson, Mark R; Poliachik, Sandra L; Budech, Christopher B; Gove, Nancy E; Carter, Gregory T; Wang, Leo H; Miller, Daniel G; Shaw, Dennis W W; Friedman, Seth D

2018-06-01

MRI evaluation in facioscapulohumeral muscular dystrophy (FSHD) demonstrates fatty replacement and inflammation/edema in muscle. Our previous work demonstrated short T1 inversion recovery (STIR)-hyperintense (STIR+) signal in muscle 2 years before fatty replacement. We evaluated leg muscle STIR changes and fatty replacement within 14 months. FSHD subjects received 2 MRI scans of thigh and calf over a 6.9- to 13.8-month interval. Quality of life measures were collected. One Radiologist rated muscle changes on a semi-quantitative scale. Fifteen subjects completed longitudinal imaging. Four STIR + muscles and 3 STIR-normal (STIR-) muscles were rated as progressing to fatty tissue over the study period. STIR + muscles with confluent regions of fat at baseline increased more in fat, while STIR- muscles had increases in septal-fat over the study period. These changes may reflect two phases of FSHD, demonstrating MRI sensitivity is weighted toward gross pathological phases of the disease. Muscle Nerve 57: 905-912, 2018. © 2017 Wiley Periodicals, Inc.

Oscillations in the reduction of permanganate by hydrogen peroxide or by ninhydrin in a batch reactor and mixed-mode oscillations in a continuous-flow stirred tank reactor

NASA Astrophysics Data System (ADS)

Tóthová, Mária; Nagy, Arpád; Treindl, Ľudovít.

1999-01-01

The periodical reduction of permanganate by hydrogen peroxide or by ninhydrin with transient oscillations in a closed system has been observed and discussed in relation to the first two permanganate oscillators described earlier. The mixed-mode oscillations of the permanganate-H 2O 2 oscillating system in a continuous-flow stirred tank reactor have been described.

A new halogen-free chemical oscillator: the reaction between permanganate ion and ninhydrin in a continuously stirred tank reactor

NASA Astrophysics Data System (ADS)

Treindl, Ľudovít; Nagy, Arpád

1987-07-01

The reaction between permanganate ion and ninhydrin in the presence of phosphoric acid in aqueous solution shows sustained oscillations in a continuously stirred tank reactor (CSTR). It exhibits a kinetic bistability between an oscillatory and a stationary state. Our new oscillating system seems to be a second permanganate chemical oscillator, thus broadening the small group of non-halogen-based chemical oscillators.

Continuous formation of N-chloro-N,N-dialkylamine solutions in well-mixed meso-scale flow reactors

PubMed Central

Jolley, Katherine E

2015-01-01

Summary The continuous flow synthesis of a range of organic solutions of N,N-dialkyl-N-chloramines is described using either a bespoke meso-scale tubular reactor with static mixers or a continuous stirred tank reactor. Both reactors promote the efficient mixing of a biphasic solution of N,N-dialkylamine in organic solvent, and aqueous sodium hypochlorite to achieve near quantitative conversions, in 72–100% in situ yields, and useful productivities of around 0.05 mol/h with residence times from 3 to 20 minutes. Initial calorimetric studies have been carried out to inform on reaction exotherms, rates and safe operation. Amines which partition mainly in the organic phase require longer reaction times, provided by the CSTR, to compensate for low mass transfer rates in the biphasic system. The green metrics of the reaction have been assessed and compared to existing procedures and have shown the continuous process is improved over previous procedures. The organic solutions of N,N-dialkyl-N-chloramines produced continuously will enable their use in tandem flow reactions with a range of nucleophilic substrates. PMID:26734089

Robotic Manufacturing of 5.5 Meter Cryogenic Fuel Tank Dome Assemblies for the NASA Ares I Rocket

NASA Technical Reports Server (NTRS)

Jones, Ronald E.

2012-01-01

The Ares I rocket is the first launch vehicle scheduled for manufacture under the National Aeronautic and Space Administration's (NASA's) Constellation program. A series of full-scale Ares I development articles have been constructed on the Robotic Weld Tool at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama. The Robotic Weld Tool is a 100 ton, 7-axis, robotic manufacturing system capable of machining and friction stir welding large-scale space hardware. This presentation will focus on the friction stir welding of 5.5m diameter cryogenic fuel tank components; specifically, the liquid hydrogen forward dome (LH2 MDA), the common bulkhead manufacturing development articles (CBMDA) and the thermal protection system demonstration dome (TPS Dome). The LH2 MDA was the first full-scale, flight-like Ares I hardware produced under the Constellation Program. It is a 5.5m diameter elliptical dome assembly consisting of eight gore panels, a y-ring stiffener and a manhole fitting. All components are made from aluminumlithium alloy 2195. Conventional and self-reacting friction stir welding was used on this article. An overview of the manufacturing processes will be discussed. The LH2 MDA is the first known fully friction stir welded dome ever produced. The completion of four Common Bulkhead Manufacturing Development Articles (CBMDA) and the TPS Dome will also be highlighted. Each CBMDA and the TPS Dome consists of a 5.5m diameter spun-formed dome friction stir welded to a y-ring stiffener. The domes and y-rings are made of aluminum 2014 and 2219 respectively. The TPS Dome has an additional aluminum alloy 2195 barrel section welded to the y-ring. Manufacturing solutions will be discussed including "fixtureless" welding with self reacting friction stir welding.

Engineered catalytic biofilms for continuous large scale production of n-octanol and (S)-styrene oxide.

PubMed

Gross, Rainer; Buehler, Katja; Schmid, Andreas

2013-02-01

This study evaluates the technical feasibility of biofilm-based biotransformations at an industrial scale by theoretically designing a process employing membrane fiber modules as being used in the chemical industry and compares the respective process parameters to classical stirred-tank studies. To our knowledge, catalytic biofilm processes for fine chemicals production have so far not been reported on a technical scale. As model reactions, we applied the previously studied asymmetric styrene epoxidation employing Pseudomonas sp. strain VLB120ΔC biofilms and the here-described selective alkane hydroxylation. Using the non-heme iron containing alkane hydroxylase system (AlkBGT) from P. putida Gpo1 in the recombinant P. putida PpS81 pBT10 biofilm, we were able to continuously produce 1-octanol from octane with a maximal productivity of 1.3 g L ⁻¹(aq) day⁻¹ in a single tube micro reactor. For a possible industrial application, a cylindrical membrane fiber module packed with 84,000 polypropylene fibers is proposed. Based on the here presented calculations, 59 membrane fiber modules (of 0.9 m diameter and 2 m length) would be feasible to realize a production process of 1,000 tons/year for styrene oxide. Moreover, the product yield on carbon can at least be doubled and over 400-fold less biomass waste would be generated compared to classical stirred-tank reactor processes. For the octanol process, instead, further intensification in biological activity and/or surface membrane enlargement is required to reach production scale. By taking into consideration challenges such as biomass growth control and maintaining a constant biological activity, this study shows that a biofilm process at an industrial scale for the production of fine chemicals is a sustainable alternative in terms of product yield and biomass waste production. Copyright © 2012 Wiley Periodicals, Inc.

Functionally redundant but dissimilar microbial communities within biogas reactors treating maize silage in co-fermentation with sugar beet silage

PubMed Central

Langer, Susanne G; Ahmed, Sharif; Einfalt, Daniel; Bengelsdorf, Frank R; Kazda, Marian

2015-01-01

Numerous observations indicate a high flexibility of microbial communities in different biogas reactors during anaerobic digestion. Here, we describe the functional redundancy and structural changes of involved microbial communities in four lab-scale continuously stirred tank reactors (CSTRs, 39°C, 12 L volume) supplied with different mixtures of maize silage (MS) and sugar beet silage (SBS) over 80 days. Continuously stirred tank reactors were fed with mixtures of MS and SBS in volatile solid ratios of 1:0 (Continuous Fermenter (CF) 1), 6:1 (CF2), 3:1 (CF3), 1:3 (CF4) with equal organic loading rates (OLR 1.25 kgVS m−3 d−1) and showed similar biogas production rates in all reactors. The compositions of bacterial and archaeal communities were analysed by 454 amplicon sequencing approach based on 16S rRNA genes. Both bacterial and archaeal communities shifted with increasing amounts of SBS. Especially pronounced were changes in the archaeal composition towards Methanosarcina with increasing proportion of SBS, while Methanosaeta declined simultaneously. Compositional shifts within the microbial communities did not influence the respective biogas production rates indicating that these communities adapted to environmental conditions induced by different feedstock mixtures. The diverse microbial communities optimized their metabolism in a way that ensured efficient biogas production. PMID:26200922

Emergence of Multiscaling in a Random-Force Stirred Fluid

NASA Astrophysics Data System (ADS)

Yakhot, Victor; Donzis, Diego

2017-07-01

We consider the transition to strong turbulence in an infinite fluid stirred by a Gaussian random force. The transition is defined as a first appearance of anomalous scaling of normalized moments of velocity derivatives (dissipation rates) emerging from the low-Reynolds-number Gaussian background. It is shown that, due to multiscaling, strongly intermittent rare events can be quantitatively described in terms of an infinite number of different "Reynolds numbers" reflecting a multitude of anomalous scaling exponents. The theoretically predicted transition disappears at Rλ≤3 . The developed theory is in quantitative agreement with the outcome of large-scale numerical simulations.

Analysis of emulsion stability in acrylic dispersions

NASA Astrophysics Data System (ADS)

Ahuja, Suresh

2012-02-01

Emulsions either micro or nano permit transport or solubilization of hydrophobic substances within a water-based phase. Different methods have been introduced at laboratory and industrial scales: mechanical stirring, high-pressure homogenization, or ultrasonics. In digital imaging, toners may be formed by aggregating a colorant with a latex polymer formed by batch or semi-continuous emulsion polymerization. Latex emulsions are prepared by making a monomer emulsion with monomer like Beta-carboxy ethyl acrylate (β-CEA) and stirring at high speed with an anionic surfactant like branched sodium dodecyl benzene sulfonates , aqueous solution until an emulsion is formed. Initiator for emulsion polymerization is 2-2'- azobis isobutyramide dehydrate with chain transfer agent are used to make the latex. If the latex emulsion is unstable, the resulting latexes produce a toner with larger particle size, broader particle size distribution with relatively higher latex sedimentation, and broader molecular weight distribution. Oswald ripening and coalescence cause droplet size to increase and can result in destabilization of emulsions. Shear thinning and elasticity of emulsions are applied to determine emulsion stability.

Minimisation of costs by using disintegration at a full-scale anaerobic digestion plant.

PubMed

Winter, A

2002-01-01

Various half-scale and lab-scale investigations have already shown that the disintegration of excess sludge is a possible pre-treatment to optimise anaerobic digestion. To control these results different methods of disintegration were investigated at a full-scale plant. Two stirred ball mills and a plant for oxidation with ozone were applied. A positive influence of disintegration on the anaerobic biodegradability can be established with application of a stirred ball mill. Biogas production as well as the degree of degradation were increased by about 20%. Laboratory investigations also validate that disintegration increases the polymer demand and leads to a lower solid content after dewatering. A higher pollution level of process water after dewatering even with ammonia and COD corroborates the results of the anaerobic degradation. Capital costs for the stirred ball mill, costs for energy, manpower and maintenance can be covered if the specific costs for disposal are high. If the development of costs in future and the current discussion about sludge disposal are taken into account sewage sludge disintegration can be a suitable technique to minimise costs at waste water treatment plants.

Evaluation of an integrated continuous stirred microbial electrochemical reactor: Wastewater treatment, energy recovery and microbial community.

PubMed

Wang, Haiman; Qu, Youpeng; Li, Da; Zhou, Xiangtong; Feng, Yujie

2015-11-01

A continuous stirred microbial electrochemical reactor (CSMER) was developed by integrating anaerobic digestion (AD) and microbial electrochemical system (MES). The system was capable of treating high strength artificial wastewater and simultaneously recovering electric and methane energy. Maximum power density of 583±9, 562±7, 533±10 and 572±6 mW m(-2) were obtained by each cell in a four-independent circuit mode operation at an OLR of 12 kg COD m(-3) d(-1). COD removal and energy recovery efficiency were 87.1% and 32.1%, which were 1.6 and 2.5 times higher than that of a continuous stirred tank reactor (CSTR). Larger amount of Deltaproteobacteria (5.3%) and hydrogenotrophic methanogens (47%) can account for the better performance of CSMER, since syntrophic associations among them provided more degradation pathways compared to the CSTR. Results demonstrate the CSMER holds great promise for efficient wastewater treatment and energy recovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Two-sided friction stir riveting by extrusion: A process for joining dissimilar materials

DOE PAGES

Evans, William T.; Cox, Chase D.; Strauss, Alvin M.; ...

2016-06-25

Two-sided friction stir riveting (FSR) by extrusion is an innovative process developed to rapidly, efficiently, and securely join dissimilar materials. This process extends a previously developed one sided friction stir extrusion process to create a strong and robust joint by producing a continuous, rivet-like structure through a preformed hole in one of the materials with a simultaneous, two-sided friction stir spot weld. The two-sided FSR by extrusion process securely joins the dissimilar materials together and effectively locks them in place without the use of any separate materials or fasteners. Lastly, in this paper we demonstrate the process by joining aluminummore » to steel and illustrate its potential application to automotive and aerospace manufacturing processes.« less

High-resolution STIR for 3-T MRI of the posterior fossa: visualization of the lower cranial nerves and arteriovenous structures related to neurovascular compression.

PubMed

Hiwatashi, Akio; Yoshiura, Takashi; Yamashita, Koji; Kamano, Hironori; Honda, Hiroshi

2012-09-01

Preoperative evaluation of small vessels without contrast material is sometimes difficult in patients with neurovascular compression disease. The purpose of this retrospective study was to evaluate whether 3D STIR MRI could simultaneously depict the lower cranial nerves--fifth through twelfth--and the blood vessels in the posterior fossa. The posterior fossae of 47 adults (26 women, 21 men) without gross pathologic changes were imaged with 3D STIR and turbo spin-echo heavily T2-weighted MRI sequences and with contrast-enhanced turbo field-echo MR angiography (MRA). Visualization of the cranial nerves on STIR images was graded on a 4-point scale and compared with visualization on T2-weighted images. Visualization of the arteries on STIR images was evaluated according to the segments in each artery and compared with that on MRA images. Visualization of the veins on STIR images was also compared with that on MRA images. Statistical analysis was performed with the Mann-Whitney U test. There were no significant differences between STIR and T2-weighted images with respect to visualization of the cranial nerves (p > 0.05). Identified on STIR and MRA images were 94 superior cerebellar arteries, 81 anteroinferior cerebellar arteries, and 79 posteroinferior cerebellar arteries. All veins evaluated were seen on STIR and MRA images. There were no significant differences between STIR and MRA images with respect to visualization of arteries and veins (p > 0.05). High-resolution STIR is a feasible method for simultaneous evaluation of the lower cranial nerves and the vessels in the posterior fossa without the use of contrast material.

Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor

PubMed Central

Jitrwung, Rujira; Yargeau, Viviane

2015-01-01

Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol. PMID:25970750

Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor.

PubMed

Jitrwung, Rujira; Yargeau, Viviane

2015-05-11

Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol.

Biodegradation of Fresh vs. Oven-Dried Inedible Crop Residue in a Continuously Stirred Tank Reactor

NASA Technical Reports Server (NTRS)

Crawford, Kamau; Strayer, Richard

1998-01-01

The degradation of soluble organics and mineral recovery from fresh and oven-dried biomass were compared in an Intermediate-Scale Aerobic Bioreactor (8 L working volume) to determine if drying crop residue improves performance in a continuously stirred tank reactor (CSTR). The study was conducted in an Intermediate-Scale Aerobic Bioreactor (ISAB) CSTR with dimensions of 390 mm height x 204 mm diameter. The pH in the bioreactor was controlled at 6.0, temperature at 30 C, and aeration at 7.0 L/min. Gases monitored were CO2 evolution and dissolved oxygen. Homogeneously mixed wheat cultures, used either fresh or oven-dried biomass and were leached, then placed in the ISAB for a 4-day degradation period. Studies found that mineral recovery was greater for leached oven-dried crop residue. However, after activity by the mixed microbial communities in the ISAB CSTR, there were little notable differences in the measured mineral recovery and degradation of soluble organic compounds. Degradation of soluble organic compounds was also shown to improve for leached oven-dried crop residue, but after mixing in the CSTR the degradation of the fresh biomass seemed to be slightly greater. Time for the biomass to turn in the CSTR appeared to be one factor for the experimental differences between the fresh and oven-dried biomass. Other factors, although not as defined, were the differing physical structures in the cell walls and varying microbial components of the fresh and oven-dried treatments due to changes in chemical composition after drying of the biomass.

Development of pilot-scale fermentation and stabilization processes for the production of microsclerotia of the entomopathogenic fungus Metarhizium brunneun strain F52

USDA-ARS?s Scientific Manuscript database

Using 100L stirred-tank bioreactors, we evaluated the effect of fermentation parameters and drying protocols on the production and stabilization of microsclerotia (MS) of the entomopathogenic fungus Metarhizium brunneum (formerly M. anisopliae F52). Results showed that stirred-tank bioreactors can ...

Evaluation of parallel milliliter-scale stirred-tank bioreactors for the study of biphasic whole-cell biocatalysis with ionic liquids.

PubMed

Dennewald, Danielle; Hortsch, Ralf; Weuster-Botz, Dirk

2012-01-01

As clear structure-activity relationships are still rare for ionic liquids, preliminary experiments are necessary for the process development of biphasic whole-cell processes involving these solvents. To reduce the time investment and the material costs, the process development of such biphasic reaction systems would profit from a small-scale high-throughput platform. Exemplarily, the reduction of 2-octanone to (R)-2-octanol by a recombinant Escherichia coli in a biphasic ionic liquid/water system was studied in a miniaturized stirred-tank bioreactor system allowing the parallel operation of up to 48 reactors at the mL-scale. The results were compared to those obtained in a 20-fold larger stirred-tank reactor. The maximum local energy dissipation was evaluated at the larger scale and compared to the data available for the small-scale reactors, to verify if similar mass transfer could be obtained at both scales. Thereafter, the reaction kinetics and final conversions reached in different reactions setups were analysed. The results were in good agreement between both scales for varying ionic liquids and for ionic liquid volume fractions up to 40%. The parallel bioreactor system can thus be used for the process development of the majority of biphasic reaction systems involving ionic liquids, reducing the time and resource investment during the process development of this type of applications. Copyright © 2011. Published by Elsevier B.V.

Development of an Intermediate-Scale Aerobic Bioreactor to Regenerate Nutrients from Inedible Crop Residues

NASA Technical Reports Server (NTRS)

Finger, Barry W.; Strayer, Richard F.

1994-01-01

Three Intermediate-Scale Aerobic Bioreactors were designed, fabricated, and operated. They utilized mixed microbial communities to bio-degrade plant residues. The continuously stirred tank reactors operated at a working volume of 8 L, and the average oxygen mass transfer coefficient, k(sub L)a, was 0.01 s(exp -1). Mixing time was 35 s. An experiment using inedible wheat residues, a replenishment rate of 0.125/day, and a solids loading rate of 20 gdw/day yielded a 48% reduction in biomass. Bioreactor effluent was successfully used to regenerate a wheat hydroponic nutrient solution. Over 80% of available potassium, calcium, and other minerals were recovered and recycled in the 76-day wheat growth experiment.

Manufacturing of 5.5 Meter Diameter Cryogenic Fuel Tank Domes for the NASA Ares I Rocket

NASA Technical Reports Server (NTRS)

Jones, Ronald E.; Carter, Robert W.

2012-01-01

The Ares I rocket is the first launch vehicle scheduled for manufacture under the National Aeronautic and Space Administration s (NASA s) Constellation program. A series of full-scale Ares I development articles have been constructed on the Robotic Weld Tool at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama. The Robotic Weld Tool is a 100 ton, 7-axis, robotic manufacturing system capable of machining and friction stir welding large-scale space hardware. This presentation will focus on the friction stir welding of 5.5m diameter cryogenic fuel tank components; specifically, the liquid hydrogen forward dome (LH2 MDA) and the common bulkhead manufacturing development articles (CBMDA). The LH2 MDA was the first full-scale, flight-like Ares I hardware produced under the Constellation Program. It is a 5.5m diameter elliptical dome assembly consisting of eight gore panels, a y-ring stiffener and a manhole fitting. All components are made from aluminum-lithium alloy 2195. Conventional and self-reacting friction stir welding was used on this article. Manufacturing solutions will be discussed including the implementation of photogrammetry, an advanced metrology technique, as well as fixtureless welding. The LH2 MDA is the first known fully friction stir welded dome ever produced. The completion of four Common Bulkhead Manufacturing Development Articles (CBMDA) will also be highlighted. Each CBMDA consists of a 5.5m diameter spun-formed dome friction stir welded to a y-ring stiffener. The domes and y-rings are made of aluminum 2014 and 2219 respectively. An overview of CBMDA manufacturing processes and the effect of tooling on weld defect formation will be discussed.

Study of Low Flow Rate Ladle Bottom Gas Stirring Using Triaxial Vibration Signals

NASA Astrophysics Data System (ADS)

Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle; Li, Zushu; Goodwin, Tim

2018-02-01

Secondary steelmaking plays a great role in enhancing the quality of the final steel product. The metal quality is a function of metal bath stirring in ladles. The metal bath is often stirred by an inert gas to achieve maximum compositional and thermal uniformity throughout the melt. Ladle operators often observe the top surface phenomena, such as level of meniscus disturbance, to evaluate the status of stirring. However, this type of monitoring has significant limitations in assessing the process accurately especially at low gas flow rate bubbling. The present study investigates stirring phenomena using ladle wall triaxial vibration at a low flow rate on a steel-made laboratory model and plant scale for the case of the vacuum tank degasser. Cold model and plant data were successfully modeled by partial least-squares regression to predict the amount of stirring. In the cold model, it was found that the combined vibration signal could predict the stirring power and recirculation speed effectively in specific frequency ranges. Plant trials also revealed that there is a high structure in each data set and in the same frequency ranges at the water model. In the case of industrial data, the degree of linear relationship was strong for data taken from a single heat.

Hollow microcarriers for large-scale expansion of anchorage-dependent cells in a stirred bioreactor.

PubMed

YekrangSafakar, Ashkan; Acun, Aylin; Choi, Jin-Woo; Song, Edward; Zorlutuna, Pinar; Park, Kidong

2018-03-26

With recent advances in biotechnology, mammalian cells are used in biopharmaceutical industries to produce valuable protein therapeutics and investigated as effective therapeutic agents to permanently degenerative diseases in cell based therapy. In these exciting and actively expanding fields, a reliable, efficient, and affordable platform to culture mammalian cells on a large scale is one of the most vital necessities. To produce and maintain a very large population of anchorage-dependent cells, a microcarrier-based stirred tank bioreactor is commonly used. In this approach, the cells are exposed to harmful hydrodynamic shear stress in the bioreactor and the mass transfer rates of nutrients and gases in the bioreactor are often kept below an optimal level to prevent cellular damages from the shear stress. In this paper, a hollow microcarrier (HMC) is presented as a novel solution to protect cells from shear stress in stirred bioreactors, while ensuring sufficient and uniform mass transfer rate of gases and nutrients. HMC is a hollow microsphere and cells are cultured on its inner surface to be protected, while openings on the HMC provide sufficient exchange of media inside the HMC. As a proof of concept, we demonstrated the expansion of fibroblasts, NIH/3T3 and the expansion and cardiac differentiation of human induced pluripotent stem cells, along with detailed numerical analysis. We believe that the developed HMC can be a practical solution to enable large-scale expansion of shear-sensitive anchorage-dependent cells in an industrial scale with stirred bioreactors. © 2018 Wiley Periodicals, Inc.

Lidar for Lateral Mixing (LATMIX)

DTIC Science & Technology

2013-09-30

overflew, a strong reflection front he float could be detected in the lidar elastic backscatter channel. Initial searches have detected several liar...grid scale mixing and stirring in numerical models. Ultimately our research will also enhance modeling and understanding of upper ocean ecosystems...km. A second objective is to determine whether slow but persistent vortices enhance the stirring attributable to shear dispersion. We also share

Measurements of liquid phase residence time distributions in a pilot-scale continuous leaching reactor using radiotracer technique.

PubMed

Pant, H J; Sharma, V K; Shenoy, K T; Sreenivas, T

2015-03-01

An alkaline based continuous leaching process is commonly used for extraction of uranium from uranium ore. The reactor in which the leaching process is carried out is called a continuous leaching reactor (CLR) and is expected to behave as a continuously stirred tank reactor (CSTR) for the liquid phase. A pilot-scale CLR used in a Technology Demonstration Pilot Plant (TDPP) was designed, installed and operated; and thus needed to be tested for its hydrodynamic behavior. A radiotracer investigation was carried out in the CLR for measurement of residence time distribution (RTD) of liquid phase with specific objectives to characterize the flow behavior of the reactor and validate its design. Bromine-82 as ammonium bromide was used as a radiotracer and about 40-60MBq activity was used in each run. The measured RTD curves were treated and mean residence times were determined and simulated using a tanks-in-series model. The result of simulation indicated no flow abnormality and the reactor behaved as an ideal CSTR for the range of the operating conditions used in the investigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of the Electromagnetic Continuous Casting Technology for of Magnesium Alloys

NASA Astrophysics Data System (ADS)

Park, Joon-Pyo; Kim, Myoung-Gyun; Kim, Jong-Ho; Lee, Gyu-Chang

Currently, magnesium billets produced by ingot casting or direct chill casting process, result in low-quality surfaces and low productivity, Continuous casting technology to solve these problem has not only high-quality surface billets with fine-grained and homogeneous microstructure but also cost down. The latent heat of fusion per weight (J/g) of magnesium is similar to other metals, however, considering the heat emitted to the mold surface during continuous casting in meniscus region and converting it to the latent heat of fusion per volume, magnesium will be rapidly solidified in the mold during continuous casting, which induces subsequent surface defect formation. In this study, electromagnetic casting and stirring (EMC and EMS) techniques are proposed to control solidification process conveniently by compensating the low latent heat of solidification by volume and to fabricate magnesium billet with high-quality surface. This technique was extended to large scale billets up to 300 mm diameter and continuous casting was successfully conducted. Then magnesium billet was used for the fabrication of prototype automobile pulley.

Process intensification for the production of hydroxyapatite nanoparticles

NASA Astrophysics Data System (ADS)

Castro, Filipa Juliana Fernandes

Precipitation processes are widely used in chemical industry for the production of particulate solids. In these processes, the chemical and physical nature of synthesized particles is of key importance. The traditional stirred tank batch reactors are affected by non-uniform mixing of reactants, often resulting in broad particle size distribution. The main objective of this thesis was to apply meso and microreactors for the synthesis of hydroxyapatite (HAp) nanoparticles under near-physiological conditions of pH and temperature, in order to overcome the limitations associated with stirred tank batch reactors. Meso and microreactors offer unique features in comparison with conventional chemical reactors. Their high surface-to-volume ratio enables enhanced heat and mass transfer, as well as rapid and efficient mixing. In addition to low consumption of reagents, meso and microreactors are usually operated in continuous flow, making them attractive tools for high throughput experimentation. Precipitation of HAp was first studied in a stirred tank batch reactor, mixing being assured by a novel metal stirrer. HAp was synthetized by mixing diluted aqueous solutions of calcium hydroxide and orthophosphoric acid at 37 °C. After process optimization, a suspension of HAp nanoparticles with pH close to 7 was obtained for a mixing molar ratio Ca/P=1.33. The precipitation process was characterized by three stages: precipitation of amorphous calcium phosphate, transformation of amorphous calcium phosphate into HAp and growth of HAp crystals. The reaction system was further characterized based on equilibrium equations. The resolution of the system, which was possible with the knowledge of three process variables (temperature, pH and calcium concentration), allowed identifying and quantifying all the chemical species present in solution. The proposed model was validated by comparing the experimental and theoretical conductivity. Precipitation of HAp was then investigated in a meso oscillatory flow reactor (meso-OFR). The mesoreactor was first operated batchwise in a vertical tube and experiments were performed under the same conditions of temperature, reactants concentration and power density applied in the stirred tank batch reactor. Despite hydrodynamic conditions being not directly comparable, it was possible to assess the effectiveness of both reactors in terms of mixing and quality of the precipitated particles. The experimental results show the advantages of the meso-OFR over the stirred tank due to the production, about four times faster, of smaller and more uniform HAp nanoparticles. Afterwards, continuous-flow precipitation of HAp was carried out in one meso-OFR and in a series of eight meso-OFRs. Experiments were carried out using fixed frequency (f) and amplitude (x0), varying only the residence time. HAp nanoparticles were successfully obtained in both systems, mean particle size and aggregation degree of the prepared HAp particles decreasing with decreasing residence time. In the present work continuous-flow precipitation of HAp was also investigated in two ultrasonic microreactors. Initially, the process was carried out in a tubular microreactor immersed in an ultrasonic bath, where single-phase (laminar) and gas-liquid flow experiments were both performed. Continuous-flow precipitation of HAp in single-phase flow was then done in a Teflon microreactor with integrated piezoelectric actuator. Rod-like shape HAp nanoparticles were yielded in both reactors under near-physiological conditions of pH and temperature. Further, particles showed improved characteristics, namely in terms of size, shape, particle aggregation and crystallinity. In summary, scale-down of the HAp precipitation process has resulted in the formation of HAp nanoparticles with improved characteristics when compared with HAp particles prepared in a stirred tank batch reactor. Therefore, we believe that the work developed can be a useful contribution to the development of a platform for the continuous production of high quality HAp nanoparticles.

Friction-Stir Welding of Large Scale Cryogenic Fuel Tanks for Aerospace Applications

NASA Technical Reports Server (NTRS)

Jones, Clyde S., III; Venable, Richard A.

1998-01-01

The Marshall Space Flight Center has established a facility for the joining of large-scale aluminum-lithium alloy 2195 cryogenic fuel tanks using the friction-stir welding process. Longitudinal welds, approximately five meters in length, were made possible by retrofitting an existing vertical fusion weld system, designed to fabricate tank barrel sections ranging from two to ten meters in diameter. The structural design requirements of the tooling, clamping and the spindle travel system will be described in this paper. Process controls and real-time data acquisition will also be described, and were critical elements contributing to successful weld operation.

Process development for the mass production of Ehrlichia ruminantium.

PubMed

Marcelino, Isabel; Sousa, Marcos F Q; Veríssimo, Célia; Cunha, António E; Carrondo, Manuel J T; Alves, Paula M

2006-03-06

This work describes the optimization of a cost-effective process for the production of an inactivated bacterial vaccine against heartwater and the first attempt to produce the causative agent of this disease, the rickettsia Ehrlichia ruminantium (ER), using stirred tanks. In vitro, it is possible to produce ER using cultures of ruminant endothelial cells. Herein, mass production of these cells was optimized for stirring conditions. The effect of inoculum size, microcarrier type, concentration of serum at inoculation time and agitation rate upon maximum cell concentration were evaluated. Several strategies for the scale-up of cell inoculum were also tested. Afterwards, using the optimized parameters for cell growth, ER production in stirred tanks was validated for two ER strains (Gardel and Welgevonden). Critical parameters related with the infection strategy such as serum concentration at infection time, multiplicity and time of infection, and medium refeed strategy were analyzed. The results indicate that it is possible to produce ER in stirred tank bioreactors, under serum-free culture conditions, reaching a 6.5-fold increase in ER production yields. The suitability of this process was validated up to a 2-l scale and a preliminary cost estimation has shown that the stirred tanks are the least expensive culture method. Overall, these results are crucial to define a scaleable and fully controlled process for the production of a heartwater vaccine and open "new avenues" for the production of vaccines against other ehrlichial species, with emerging impact in human and animal health.

Production Methods in Industrial Microbiology.

ERIC Educational Resources Information Center

Gaden, Elmer L., Jr.

1981-01-01

Compares two methods (batch and continuous) in which microorganisms are used to produce industrial chemicals. Describes batch and continuous stirred-tank reactors and offers reasons why the batch method may be preferred. (JN)

Applicability of polydimethylsiloxane (PDMS) and polyethersulfone (PES) as passive samplers of more hydrophobic organic compounds in intertidal estuarine environments.

PubMed

Posada-Ureta, Oscar; Olivares, Maitane; Delgado, Alejandra; Prieto, Ailette; Vallejo, Asier; Irazola, Mireia; Paschke, Albrecht; Etxebarria, Nestor

2017-02-01

The uptake calibration of three passive samplers, stir-bars, MESCO/stir-bars and polyethersulfone tubes (PES t ), was assessed in seawater at different salinities for 17 organic compounds including organochlorine compounds, pesticides, phthalates, musk fragrances and triclosan. The calibration procedure was accomplished by exposing the samplers to a continuous flow of fortified seawater for up to 14days under laboratory conditions. Prior to the exposure, stir-bars and MESCO/stir-bars were loaded with a known amount of deuterated PAH mixture as performance reference compounds (PRC). For most of the studied compounds, the sampling rates (Rs, mL·day -1 ) were determined for each sampler at two salinities (15 and 30‰) and two nominal concentrations (25 and 50ng·L -1 ). Among the tested devices, though PES can be an outstanding cheap alternative to other passive samplers, naked or free stir-bars provided the best results in terms of uptake rates (i.e., the Rs values ranged from 30 to 350mL·day -1 ). Regarding the variation of the salinity, the Rs values obtained with naked stir-bars were statistically comparable in the full range of salinities (0-30‰) but the values obtained with MESCO/stir-bars and PES t were salinity dependent. Consequently, only stir-bars assured the required robustness to be used as passive samplers in intertidal estuarine environments. Finally, the stir-bars were applied to estimate the time-weighted average concentration of some of those contaminants in the feeding seawater of the experimental aquaria at the Plentzia Marine Station (Basque Country) and low levels of musks fragrances (0.1-0.2ng·L -1 ) were estimated. Copyright © 2016 Elsevier B.V. All rights reserved.

The microbiology of biomining: development and optimization of mineral-oxidizing microbial consortia.

PubMed

Rawlings, Douglas E; Johnson, D Barrie

2007-02-01

Biomining, the use of micro-organisms to recover precious and base metals from mineral ores and concentrates, has developed into a successful and expanding area of biotechnology. While careful considerations are made in the design and engineering of biomining operations, microbiological aspects have been subjected to far less scrutiny and control. Biomining processes employ microbial consortia that are dominated by acidophilic, autotrophic iron- or sulfur-oxidizing prokaryotes. Mineral biooxidation takes place in highly aerated, continuous-flow, stirred-tank reactors or in irrigated dump or heap reactors, both of which provide an open, non-sterile environment. Continuous-flow, stirred tanks are characterized by homogeneous and constant growth conditions where the selection is for rapid growth, and consequently tank consortia tend to be dominated by two or three species of micro-organisms. In contrast, heap reactors provide highly heterogeneous growth environments that change with the age of the heap, and these tend to be colonized by a much greater variety of micro-organisms. Heap micro-organisms grow as biofilms that are not subject to washout and the major challenge is to provide sufficient biodiversity for optimum performance throughout the life of a heap. This review discusses theoretical and pragmatic aspects of assembling microbial consortia to process different mineral ores and concentrates, and the challenges for using constructed consortia in non-sterile industrial-scale operations.

Development of a method for reliable power input measurements in conventional and single‐use stirred bioreactors at laboratory scale

PubMed Central

Werner, Sören; Jossen, Valentin; Kraume, Matthias; Eibl, Dieter

2016-01-01

Power input is an important engineering and scale‐up/down criterion in stirred bioreactors. However, reliably measuring power input in laboratory‐scale systems is still challenging. Even though torque measurements have proven to be suitable in pilot scale systems, sensor accuracy, resolution, and errors from relatively high levels of friction inside bearings can become limiting factors at smaller scales. An experimental setup for power input measurements was developed in this study by focusing on stainless steel and single‐use bioreactors in the single‐digit volume range. The friction losses inside the air bearings were effectively reduced to less than 0.5% of the measurement range of the torque meter. A comparison of dimensionless power numbers determined for a reference Rushton turbine stirrer (N P = 4.17 ± 0.14 for fully turbulent conditions) revealed good agreement with literature data. Hence, the power numbers of several reusable and single‐use bioreactors could be determined over a wide range of Reynolds numbers between 100 and >104. Power numbers of between 0.3 and 4.5 (for Re = 104) were determined for the different systems. The rigid plastic vessels showed similar power characteristics to their reusable counterparts. Thus, it was demonstrated that the torque‐based technique can be used to reliably measure power input in stirred reusable and single‐use bioreactors at the laboratory scale. PMID:28579937

Hydrocarbon fuels from brown grease: Moving from the research laboratory toward an industrial process

NASA Astrophysics Data System (ADS)

Pratt, Lawrence M.; Strothers, Joel; Pinnock, Travis; Hilaire, Dickens Saint; Bacolod, Beatrice; Cai, Zhuo Biao; Sim, Yoke-Leng

2017-04-01

Brown grease is a generic term for the oily solids and semi-solids that accumulate in the sewer system and in sewage treatment plants. It has previously been shown that brown grease undergoes pyrolysis to form a homologous series of alkanes and 1-alkenes between 7 and 17 carbon atoms, with smaller amounts of higher hydrocarbons and ketones up to about 30 carbon atoms. The initial study was performed in batch mode on a scale of up to 50 grams of starting material. However, continuous processes are usually more efficient for large scale production of fuels and commodity chemicals. This work describes the research and development of a continuous process. The first step was to determine the required reactor temperature. Brown grease consists largely of saturated and unsaturated fatty acids, and they react at different rates, and produce different products and intermediates. Intermediates include ketones, alcohols, and aldehydes, and Fe(III) ion catalyzes at least some of the reactions. By monitoring the pyrolysis of brown grease, its individual components, and intermediates, it was determined that a reactor temperature of at least 340 °C is required. A small scale (1 L) continuous stirred tank reactor was built and its performance is described.

Cultivation of E. coli in single- and ten-stage tower-loop reactors.

PubMed

Adler, I; Schügerl, K

1983-02-01

E. Coli was cultivated in batch and continuous operations in the presence of an antifoam agent in stirred-tank and in single- and ten-stage airlift tower reactors with an outer loop. The maximum specific growth rate, mu(m), the substrate yield coefficient, Y(x/s), the respiratory quotient, RQ, substrate conversion, U(s), the volumetric mass transfer coefficient, K(L)a, the specific interfacial area, a, and the specific power input, P/V(L), were measured and compared. If a medium is used with a concentration of complex substrates (extracts) 2.5 times higher than that of glucose, a spectrum of C sources is available and cell regulation influences reactor performance. Both mu(m) and Y(X/S), which were evaluated in batch reactors, cannot be used for continuous reactors or, when measured in stirred-tank reactors, cannot be employed for tower-loop reactors: mu(m) is higher in the stirred-tank batch than in the tower-loop batch reactor, mu(m) and Y(x/s) are higher in the continuous reactor than in the batch single-stage tower-loop reactor. The performance of the single-stage is better than that of the ten-stage reactor due to the inefficient trays employed. A reduction of the medium recirculation rate reduces OTR, U(s), Pr, and Y(X/S) and causes cell sedimentation and flocculation. The volumetric mass transfer coefficient is reduced with increasing cultivation time; the Sauter bubble diameter, d(s), remains constant and does not depend on operational conditions. An increase in the medium recirculation rate reduces k(L)a. The specific power input, P/V(L), for the single-stage tower loop is much lower with the same k(L)a value than for a stirred tank. The relationship k(L)a vs. P/V(L) evaluated for model media in stirred tanks, can also be used for cultivations in these reactors.

Aeration costs in stirred-tank and bubble column bioreactors

DOE PAGES

Humbird, D.; Davis, R.; McMillan, J. D.

2017-08-10

To overcome knowledge gaps in the economics of large-scale aeration for production of commodity products, Aspen Plus is used to simulate steady-state oxygen delivery in both stirred-tank and bubble column bioreactors, using published engineering correlations for oxygen mass transfer as a function of aeration rate and power input, coupled with new equipment cost estimates developed in Aspen Capital Cost Estimator and validated against vendor quotations. Here, these simulations describe the cost efficiency of oxygen delivery as a function of oxygen uptake rate and vessel size, and show that capital and operating costs for oxygen delivery drop considerably moving from standard-sizemore » (200 m 3) to world-class size (500 m 3) reactors, but only marginally in further scaling up to hypothetically large (1000 m 3) reactors. Finally, this analysis suggests bubble-column reactor systems can reduce overall costs for oxygen delivery by 10-20% relative to stirred tanks at low to moderate oxygen transfer rates up to 150 mmol/L-h.« less

Aeration costs in stirred-tank and bubble column bioreactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humbird, D.; Davis, R.; McMillan, J. D.

To overcome knowledge gaps in the economics of large-scale aeration for production of commodity products, Aspen Plus is used to simulate steady-state oxygen delivery in both stirred-tank and bubble column bioreactors, using published engineering correlations for oxygen mass transfer as a function of aeration rate and power input, coupled with new equipment cost estimates developed in Aspen Capital Cost Estimator and validated against vendor quotations. Here, these simulations describe the cost efficiency of oxygen delivery as a function of oxygen uptake rate and vessel size, and show that capital and operating costs for oxygen delivery drop considerably moving from standard-sizemore » (200 m 3) to world-class size (500 m 3) reactors, but only marginally in further scaling up to hypothetically large (1000 m 3) reactors. Finally, this analysis suggests bubble-column reactor systems can reduce overall costs for oxygen delivery by 10-20% relative to stirred tanks at low to moderate oxygen transfer rates up to 150 mmol/L-h.« less

High-Speed Friction-Stir Welding To Enable Aluminum Tailor-Welded Blanks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Upadhyay, Piyush; Carsley, John

Current joining technologies for automotive aluminum alloys are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding has been traditionally applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translatemore » to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum welded components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability utilizing a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.« less

Enabling high speed friction stir welding of aluminum tailor welded blanks

NASA Astrophysics Data System (ADS)

Hovanski, Yuri

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding (FSW) has traditionally been applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum FSW components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability using a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

Near Net Manufacturing Using Thin Gage Friction Stir Welding

NASA Technical Reports Server (NTRS)

Takeshita, Jennifer; Potter, David; Holquin, Michael

2006-01-01

Friction Stir Welding (FSW) and near net spin forming of FSW aluminumn blanks were investigated for large-scale pressure vessel applications. With a specific focus on very thin gage 2xxx and 7xxx aluminum alloys, the program concentrated on the following: the criteria used for material selection, a potential manufacturing flow, and the effectiveness and associated risks of near net spin forming. Discussion will include the mechanical properties of the friction stir welds and the parent material from before and after the spin forming process. This effort was performed under a NASA Space Exploration initiative focused on increasing the affordability, reliability and performance of pressure vessels larger than 10 ft. diameter.

High-Powered, Ultrasonically Assisted Thermal Stir Welding

NASA Technical Reports Server (NTRS)

Ding, Robert

2013-01-01

This method is a solid-state weld process capable of joining metallic alloys without melting. The weld workpieces to be joined by thermal stir welding (TSW) are drawn, by heavy forces, between containment plates past the TSW stir tool that then causes joining of the weld workpiece. TSW is similar to friction stir welding (FSW) in that material is heated into a plastic state (not melted) and stirred using a stir rod. The FSW pin tool is an integrated geometrical structure consisting of a large-diameter shoulder, and a smaller-diameter stir pin protruding from the shoulder. When the pin is plunged into a weld workpiece, the shoulder spins on the surface of the weld workpiece, thus inducing frictional heat into the part. The pin stirs the fraying surfaces of the weld joint, thus joining the weld workpiece into one structure. The shoulder and stir pin of the FSW pin tool must rotate together at a desired rotational speed. The induced frictional energy control and stir pin control of the pin tool cannot be de-coupled. The two work as one integrated unit. TSW, on the other hand, de-couples the heating and stirring of FSW, and allows for independent control of each process element. A uniquely designed induction coil heats the weld workpiece to a desired temperature, and once heated, the part moves into a stir rod whose RPM is also independently controlled. As the weld workpiece moves into the stir rod, the piece is positioned, or sandwiched, between upper and lower containment plates. The plate squeezes together, thus compressing the upper and lower surfaces of the weld workpiece. This compressive force, also called consolidation force, consolidates the plastic material within the weld nugget material as it is being stirred by the stir rod. The stir rod is positioned through the center of the top containment plate and protrudes midway through the opposite lower containment plate where it is mechanically captured. The upper and lower containment plates are separated by a distance equal to the thickness of the material being welded. The TSW process can be significantly improved by reducing the draw forces. This can be achieved by reducing the friction forces between the weld workpieces and the containment plates. High-power ultrasonic (HPU) vibrations of the containment plates achieve friction reduction in the TSW process. Furthermore, integration of the HPU energy into the TSW stir rod can increase tool life of the stir rod, and can reduce shear forces to which the stir rod is subjected during the welding process. TSW has been used to successfully join 0.500-in (˜13-mm) thick commercially pure (CP) titanium, titanium 6AL- 4V, and titanium 6AL-4V ELI in weld joint lengths up to 9 ft (˜2.75-m) long. In addition, the TSW process was used to fabricate a sub-scale hexagonally shaped gun turret component for the U.S. Navy. The turret is comprised of six 0.5000-in (˜13-mm) thick angled welds. Each angled weld joint was prepared by machining the mating surfaces to 120deg. The angled weld joint was then fixtured using an upper and lower containment plate of the same geometry of the angled weld joint. The weld joint was then stirred by the stir rod as it and the upper and lower containment plates traverse through the angled joint prep.

Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

NASA Technical Reports Server (NTRS)

Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

2003-01-01

Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading the way for future circumferential weld implementation.

Biogas by semi-continuous anaerobic digestion of food waste.

PubMed

Zhang, Cunsheng; Su, Haijia; Wang, Zhenbin; Tan, Tianwei; Qin, Peiyong

2015-04-01

The semi-continuous anaerobic digestion of food waste was investigated in 1-L and 20-L continuously stirred tank reactors (CSTRs), to identify the optimum operation condition and the methane production of the semi-continuous anaerobic process. Results from a 1-L digester indicated that the optimum organic loading rate (OLR) for semi-continuous digestion is 8 g VS/L/day. The corresponding methane yield and chemical oxygen demand (COD) reduction were 385 mL/g VS and 80.2 %, respectively. Anaerobic digestion was inhibited at high OLRs (12 and 16 g VS/L/day), due to volatile fatty acid (VFA) accumulation. Results from a 20-L digester indicated that a higher methane yield of 423 mL/g VS was obtained at this larger scale. The analysis showed that the methane production at the optimum OLR fitted well with the determined kinetics equation. An obvious decrease on the methane content was observed at the initial of digestion. The increased metabolization of microbes and the activity decrease of methanogen caused by VFA accumulation explained the lower methane content at the initial of digestion.

Molecular dynamics modeling of bonding two materials by atomic scale friction stir welding at different process parameters

NASA Astrophysics Data System (ADS)

Konovalenko S., Iv.; Psakhie, S. G.

2017-12-01

Using the molecular dynamics method, we simulated the atomic scale butt friction stir welding on two crystallites and varied the onset FSW tool plunge depth. The effects of the plunge depth value on the thermomechanical evolution of nanosized crystallites and mass transfer in the course of FSW have been studied. The increase of plunge depth values resulted in more intense heating and reducing the plasticized metal resistance to the tool movement. The mass transfer intensity was hardly dependent on the plunge depth value. The plunge depth was recommended to be used as a FSW process control parameter in addition to the commonly used ones.

Robotic Manufacturing of 18-ft (5.5m) Diameter Cryogenic Fuel Tank Dome Assemblies for the NASA Ares I Rocket

NASA Technical Reports Server (NTRS)

Jones, Ronald E.; Carter, Robert W.

2012-01-01

The Ares I rocket was the first launch vehicle scheduled for manufacture under the National Aeronautic and Space Administration's Constellation program. A series of full-scale Ares I development articles were constructed on the Robotic Weld Tool at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama. The Robotic Weld Tool is a 100 ton, 7- axis, robotic manufacturing system capable of machining and friction stir welding large-scale space hardware. This paper will focus on the friction stir welding of 18-ft (5.5m) diameter cryogenic fuel tank components; specifically, the liquid hydrogen forward dome and two common bulkhead manufacturing development articles.

Reactivation of dead sulfide species in lithium polysulfide flow battery for grid scale energy storage.

PubMed

Jin, Yang; Zhou, Guangmin; Shi, Feifei; Zhuo, Denys; Zhao, Jie; Liu, Kai; Liu, Yayuan; Zu, Chenxi; Chen, Wei; Zhang, Rufan; Huang, Xuanyi; Cui, Yi

2017-09-06

Lithium polysulfide batteries possess several favorable attributes including low cost and high energy density for grid energy storage. However, the precipitation of insoluble and irreversible sulfide species on the surface of carbon and lithium (called "dead" sulfide species) leads to continuous capacity degradation in high mass loading cells, which represents a great challenge. To address this problem, herein we propose a strategy to reactivate dead sulfide species by reacting them with sulfur powder with stirring and heating (70 °C) to recover the cell capacity, and further demonstrate a flow battery system based on the reactivation approach. As a result, ultrahigh mass loading (0.125 g cm -3 , 2 g sulfur in a single cell), high volumetric energy density (135 Wh L -1 ), good cycle life, and high single-cell capacity are achieved. The high volumetric energy density indicates its promising application for future grid energy storage.Lithium polysulfide batteries suffer from the precipitation of insoluble and irreversible sulfide species on the surface of carbon and lithium. Here the authors show a reactivation strategy by a reaction with cheap sulfur powder under stirring and heating to recover the cell capacity.

Electrokinetic instability micromixing.

PubMed

Oddy, M H; Santiago, J G; Mikkelsen, J C

2001-12-15

We have developed an electrokinetic process to rapidly stir micro- and nanoliter volume solutions for microfluidic bioanalytical applications. We rapidly stir microflow streams by initiating a flow instability, which we have observed in sinusoidally oscillating, electroosmotic channel flows. As the effect occurs within an oscillating electroosmotic flow, we refer to it here as an electrokinetic instability (EKI). The rapid stretching and folding of material lines associated with this instability can be used to stir fluid streams with Reynolds numbers of order unity, based on channel depth and rms electroosmotic velocity. This paper presents a preliminary description of the EKI and the design and fabrication of two micromixing devices capable of rapidly stirring two fluid streams using this flow phenomenon. A high-resolution CCD camera is used to record the stirring and diffusion of fluorescein from an initially unmixed configuration. Integration of fluorescence intensity over measurement volumes (voxels) provides a measure of the degree to which two streams are mixed to within the length scales of the voxels. Ensemble-averaged probability density functions and power spectra of the instantaneous spatial intensity profiles are used to quantify the mixing processes. Two-dimensional spectral bandwidths of the mixing images are initially anisotropic for the unmixed configuration, broaden as the stirring associated with the EKI rapidly stretches and folds material lines (adding high spatial frequencies to the concentration field), and then narrow to a relatively isotropic spectrum at the well-mixed conditions.

A long-lived lunar dynamo driven by continuous mechanical stirring.

PubMed

Dwyer, C A; Stevenson, D J; Nimmo, F

2011-11-09

Lunar rocks contain a record of an ancient magnetic field that seems to have persisted for more than 400 million years and which has been attributed to a lunar dynamo. Models of conventional dynamos driven by thermal or compositional convection have had difficulty reproducing the existence and apparently long duration of the lunar dynamo. Here we investigate an alternative mechanism of dynamo generation: continuous mechanical stirring arising from the differential motion, due to Earth-driven precession of the lunar spin axis, between the solid silicate mantle and the liquid core beneath. We show that the fluid motions and the power required to drive a dynamo operating continuously for more than one billion years and generating a magnetic field that had an intensity of more than one microtesla 4.2 billion years ago are readily obtained by mechanical stirring. The magnetic field is predicted to decrease with time and to shut off naturally when the Moon recedes far enough from Earth that the dissipated power is insufficient to drive a dynamo; in our nominal model, this occurred at about 48 Earth radii (2.7 billion years ago). Thus, lunar palaeomagnetic measurements may be able to constrain the poorly known early orbital evolution of the Moon. This mechanism may also be applicable to dynamos in other bodies, such as large asteroids.

Crude oil contaminated soil washing in air sparging assisted stirred tank reactor using biosurfactants.

PubMed

Urum, Kingsley; Pekdemir, Turgay; Ross, David; Grigson, Steve

2005-07-01

This study investigated the removal of crude oil from soil using air sparging assisted stirred tank reactors. Two surfactants (rhamnolipid and sodium dodecyl sulfate, SDS) were tested and the effects of different parameters (i.e. temperature, surfactant concentrations, washing time, volume/mass ratio) were investigated under varying washing modes namely, stirring only, air sparging only and the combination of stirring and air sparging. The results showed that SDS removed more than 80% crude oil from non-weathered soil samples, whilst rhamnolipid showed similar oil removal at the third and fourth levels of the parameters tested. The oil removal ability of the seawater prepared solutions were better than those of the distilled water solutions at the first and second levels of temperature and concentration of surfactant solutions. This approach of soil washing was noted to be effective in reducing the amount of oil in soil. Therefore we suggested that a field scale test be conducted to assess the efficiency of these surfactants.

A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

NASA Astrophysics Data System (ADS)

Rao, Harish Mangebettu

The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack propagation into the top sheet, into the bottom sheet, and interfacial separation. Investigation of the tested welds revealed that the voids in the weld nugget reduced the weld strength, resulting in lower fatigue life. A thin layer of IMCs formed along the faying surface which accelerated the fatigue failure.

Multi-Physics Modeling of Molten Salt Transport in Solid Oxide Membrane (SOM) Electrolysis and Recycling of Magnesium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, Adam; Pati, Soobhankar

2012-03-11

Solid Oxide Membrane (SOM) Electrolysis is a new energy-efficient zero-emissions process for producing high-purity magnesium and high-purity oxygen directly from industrial-grade MgO. SOM Recycling combines SOM electrolysis with electrorefining, continuously and efficiently producing high-purity magnesium from low-purity partially oxidized scrap. In both processes, electrolysis and/or electrorefining take place in the crucible, where raw material is continuously fed into the molten salt electrolyte, producing magnesium vapor at the cathode and oxygen at the inert anode inside the SOM. This paper describes a three-dimensional multi-physics finite-element model of ionic current, fluid flow driven by argon bubbling and thermal buoyancy, and heat andmore » mass transport in the crucible. The model predicts the effects of stirring on the anode boundary layer and its time scale of formation, and the effect of natural convection at the outer wall. MOxST has developed this model as a tool for scale-up design of these closely-related processes.« less

Field theory of the inverse cascade in two-dimensional turbulence

NASA Astrophysics Data System (ADS)

Mayo, Jackson R.

2005-11-01

A two-dimensional fluid, stirred at high wave numbers and damped by both viscosity and linear friction, is modeled by a statistical field theory. The fluid’s long-distance behavior is studied using renormalization-group (RG) methods, as begun by Forster, Nelson, and Stephen [Phys. Rev. A 16, 732 (1977)]. With friction, which dissipates energy at low wave numbers, one expects a stationary inverse energy cascade for strong enough stirring. While such developed turbulence is beyond the quantitative reach of perturbation theory, a combination of exact and perturbative results suggests a coherent picture of the inverse cascade. The zero-friction fluctuation-dissipation theorem (FDT) is derived from a generalized time-reversal symmetry and implies zero anomalous dimension for the velocity even when friction is present. Thus the Kolmogorov scaling of the inverse cascade cannot be explained by any RG fixed point. The β function for the dimensionless coupling ĝ is computed through two loops; the ĝ3 term is positive, as already known, but the ĝ5 term is negative. An ideal cascade requires a linear β function for large ĝ , consistent with a Padé approximant to the Borel transform. The conjecture that the Kolmogorov spectrum arises from an RG flow through large ĝ is compatible with other results, but the accurate k-5/3 scaling is not explained and the Kolmogorov constant is not estimated. The lack of scale invariance should produce intermittency in high-order structure functions, as observed in some but not all numerical simulations of the inverse cascade. When analogous RG methods are applied to the one-dimensional Burgers equation using an FDT-preserving dimensional continuation, equipartition is obtained instead of a cascade—in agreement with simulations.

Pilot-scale verification of maximum tolerable hydrodynamic stress for mammalian cell culture.

PubMed

Neunstoecklin, Benjamin; Villiger, Thomas K; Lucas, Eric; Stettler, Matthieu; Broly, Hervé; Morbidelli, Massimo; Soos, Miroslav

2016-04-01

Although several scaling bioreactor models of mammalian cell cultures are suggested and described in the literature, they mostly lack a significant validation at pilot or manufacturing scale. The aim of this study is to validate an oscillating hydrodynamic stress loop system developed earlier by our group for the evaluation of the maximum operating range for stirring, based on a maximum tolerable hydrodynamic stress. A 300-L pilot-scale bioreactor for cultivation of a Sp2/0 cell line was used for this purpose. Prior to cultivations, a stress-sensitive particulate system was applied to determine the stress values generated by stirring and sparging. Pilot-scale data, collected from 7- to 28-Pa maximum stress conditions, were compared with data from classical 3-L cultivations and cultivations from the oscillating stress loop system. Results for the growth behavior, analyzed metabolites, productivity, and product quality showed a dependency on the different environmental stress conditions but not on reactor size. Pilot-scale conditions were very similar to those generated in the oscillating stress loop model confirming its predictive capability, including conditions at the edge of failure.

Method for producing size selected particles

DOEpatents

Krumdick, Gregory K.; Shin, Young Ho; Takeya, Kaname

2016-09-20

The invention provides a system for preparing specific sized particles, the system comprising a continuous stir tank reactor adapted to receive reactants; a centrifugal dispenser positioned downstream from the reactor and in fluid communication with the reactor; a particle separator positioned downstream of the dispenser; and a solution stream return conduit positioned between the separator and the reactor. Also provided is a method for preparing specific sized particles, the method comprising introducing reagent into a continuous stir reaction tank and allowing the reagents to react to produce product liquor containing particles; contacting the liquor particles with a centrifugal force for a time sufficient to generate particles of a predetermined size and morphology; and returning unused reagents and particles of a non-predetermined size to the tank.

Biological production of ethanol from coal. Task 4 report, Continuous reactor studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The production of ethanol from synthesis gas by the anaerobic bacterium C. ljungdahlii has been demonstrated in continuous stirred tank reactors (CSTRs), CSTRs with cell recycle and trickle bed reactors. Various liquid media were utilized in these studies including basal medium, basal media with 1/2 B-vitamins and no yeast extract and a medium specifically designed for the growth of C. ljungdahlii in the CSTR. Ethanol production was successful in each of the three reactor types, although trickle bed operation with C. ljungdahlii was not as good as with the stirred tank reactors. Operation in the CSTR with cell recycle wasmore » particularly promising, producing 47 g/L ethanol with only minor concentrations of the by-product acetate.« less

A Micro-Electrochemical Study of Friction Stir Welded Aluminum 6061-T6

NASA Technical Reports Server (NTRS)

Hintze, Paul E.; Calle, Luz M.

2005-01-01

The corrosion behavior of friction stir welded Aluminum alloy 606 1-T6 was studied using a micro-electrochemical cell. The micro-electrochemical cell has a measurement area of about 0.25 square mm which allows for measurement of corrosion properties at a very small scale. The corrosion and breakdown potentials were measured at many points inside and outside the weld along lines perpendicular to the weld. The breakdown potential is approximately equal inside and outside the weld; however, it is lower in the narrow border between the weld and base material. The results of electrochemical measurements were correlated to micro-structural analysis. The corrosion behavior of the friction stir welded samples was compared to tungsten inert gas (TIG) welded samples of the same material.

A membrane stirrer for product recovery and substrate feeding.

PubMed

Femmer, T; Carstensen, F; Wessling, M

2015-02-01

During fermentation processes, in situ product recovery (ISPR) using submerged membranes allows a continuous operation mode with effective product removal. Continuous recovery reduces product inhibition and organisms in the reactor are not exposed to changing reaction conditions. For an effective in situ product removal, submerged membrane systems should have a sufficient large membrane area and an anti-fouling concept integrated in a compact device for the limited space in a lab-scale bioreactor. We present a new membrane stirrer with integrated filtration membranes on the impeller blades as well as an integrated gassing concept in an all-in-one device. The stirrer is fabricated by rapid prototyping and is equipped with a commercial micromesh membrane. Filtration performance is tested using a yeast cell suspension with different stirring speeds and aeration fluxes. We reduce membrane fouling by backflushing through the membrane with the product stream. © 2014 Wiley Periodicals, Inc.

Investigation of crystallization kinetics of sodium bicarbonate in a continuous stirred tank crystallizer

NASA Astrophysics Data System (ADS)

Zhu, Yi; Haut, Benoît; Halloin, Veronique; Delplancke-Ogletree, Marie-Paule

2005-08-01

In our previous work [J. Crystal Growth 263 (2004) 459], a supersaturation determination method using a high-precision densimeter was designed and developed for monitoring sodium bicarbonate supersaturation in the sodium carbonate-bicarbonate system, a two-component solution in equilibrium. In the present paper, we apply this method to the study of sodium bicarbonate continuous crystallization. It gives us access to the sodium bicarbonate supersaturation evolution. The sodium bicarbonate supersaturation evolution and their crystallization kinetics obtained in a continuous stirred tank crystallizer are investigated under different operational conditions, such as residence time, initial supersaturation and seeding. The induction time determined by density measurements is discussed. Mathematical modeling is used to interpret the supersaturation evolution. It is shown that measuring the density gives satisfying performances for studying the crystallization of a two-component solution in equilibrium, such as the sodium carbonate-bicarbonate system.

Bio-hydrogen production from molasses by anaerobic fermentation in continuous stirred tank reactor

NASA Astrophysics Data System (ADS)

Han, Wei; Li, Yong-feng; Chen, Hong; Deng, Jie-xuan; Yang, Chuan-ping

2010-11-01

A study of bio-hydrogen production was performed in a continuous flow anaerobic fermentation reactor (with an available volume of 5.4 L). The continuous stirred tank reactor (CSTR) for bio-hydrogen production was operated under the organic loading rates (OLR) of 8-32 kg COD/m3 reactor/d (COD: chemical oxygen demand) with molasses as the substrate. The maximum hydrogen production yield of 8.19 L/d was obtained in the reactor with the OLR increased from 8 kg COD/m3 reactor/d to 24 kg COD/m3 d. However, the hydrogen production and volatile fatty acids (VFAs) drastically decreased at an OLR of 32 kg COD/m3 reactor/d. Ethanoi, acetic, butyric and propionic were the main liquid fermentation products with the percentages of 31%, 24%, 20% and 18%, which formed the mixed-type fermentation.

Process Intensification of Enzymatic Fatty Acid Butyl Ester Synthesis Using a Continuous Centrifugal Contactor Separator.

PubMed

Ilmi, Miftahul; Abduh, Muhammad Y; Hommes, Arne; Winkelman, Jozef G M; Hidayat, Chusnul; Heeres, Hero J

2018-01-17

Fatty acid butyl esters were synthesized from sunflower oil with 1-butanol using a homogeneous Rhizomucor miehei lipase in a biphasic organic (triglyceride, 1-butanol, hexane)- water (with enzyme) system in a continuous setup consisting of a cascade of a stirred tank reactor and a continuous centrifugal contactor separator (CCCS), the latter being used for integrated reaction and liquid-liquid separation. A fatty acid butyl ester yield up to 93% was obtained in the cascade when operated in a once-through mode. The cascade was run for 8 h without operational issues. Enzyme recycling was studied by reintroduction of the water phase from the CCCS outlet to the stirred tank reactor. Product yield decreased over time to an average of 50% of the initial value, likely due to accumulation of 1-butanol in water phase, loss of enzyme due to agglomeration, and the formation of a separate enzyme layer.

Process Intensification of Enzymatic Fatty Acid Butyl Ester Synthesis Using a Continuous Centrifugal Contactor Separator

PubMed Central

2017-01-01

Fatty acid butyl esters were synthesized from sunflower oil with 1-butanol using a homogeneous Rhizomucor miehei lipase in a biphasic organic (triglyceride, 1-butanol, hexane)– water (with enzyme) system in a continuous setup consisting of a cascade of a stirred tank reactor and a continuous centrifugal contactor separator (CCCS), the latter being used for integrated reaction and liquid–liquid separation. A fatty acid butyl ester yield up to 93% was obtained in the cascade when operated in a once-through mode. The cascade was run for 8 h without operational issues. Enzyme recycling was studied by reintroduction of the water phase from the CCCS outlet to the stirred tank reactor. Product yield decreased over time to an average of 50% of the initial value, likely due to accumulation of 1-butanol in water phase, loss of enzyme due to agglomeration, and the formation of a separate enzyme layer. PMID:29398779

Continuous Hydrolysis of Pectate by Immobilized Endo-polygalacturonase in a Continuously Stirred Tank Reactor.

PubMed

Iwasaki, K; Inoue, M; Matsubara, Y

1998-01-01

Enzymatic hydrolysis of pectate was carried out continuously to produce pectate oligosaccharides by immobilized endo-polygalacturonase in a continuous stirred tank reactor (CSTR) with high efficiency. The enzyme was immobilized on to chitosan beads by the absorption method, and the reaction was performed with an initial pectate concentration of 10 gl(-1) at 35°C and pH 4.0 at a dilution rate of 0.87-2.8 h(-1). The hydrolysis products mainly consisted of mono-, di-, tri-, tetra-, penta-, hexa- and heptasaccharides, with the highest conversion being 0.78. A higher volumetric production rate of the total hydrolyzate, which was dependent on the dilution rate, was obtained than that by a batch reaction. The hydrolysis process was mathematically modeled from the basic material balance and rate equations, and showed agreement between the simulated and experimental results. This reactor system was found to be effective for obtaining pectate oligosaccharides with a high production rate.

Molecular dynamics modeling of bonding two materials by atomic scale friction stir welding

NASA Astrophysics Data System (ADS)

Konovalenko S., Iv.; Konovalenko, Ig. S.; Psakhie, S. G.

2017-12-01

Molecular dynamics model of atomic scale friction stir welding has been developed. Formation of a butt joint between two crystallites was modeled by means of rotating rigid conical tool traveling along the butt joint line. The formed joint had an intermixed atomic structure composed of atoms initially belonged to the opposite mated piece of metal. Heat removal was modeled by adding the extra viscous force to peripheral atomic layers. This technique provides the temperature control in the tool-affected zone during welding. Auxiliary vibration action was added to the rotating tool. The model provides the variation of the tool's angular velocity, amplitude, frequency and direction of the auxiliary vibration action to provide modeling different welding modes.

Shaken, but not stirred: how vortical flow drives small-scale aggregations of gyrotactic phytoplankton

NASA Astrophysics Data System (ADS)

Barry, Michael; Durham, William; Climent, Eric; Stocker, Roman

2011-11-01

Coastal ocean observations reveal that motile phytoplankton form aggregations at the Kolmogorov scale (mm-cm), whereas non-motile cells do not. We propose a new mechanism for the formation of this small-scale patchiness based on the interplay of turbulence and gyrotactic motility. Counterintuitively, turbulence does not stir a plankton suspension to homogeneity but drives aggregations instead. Through controlled laboratory experiments we show that the alga Heterosigma akashiwo rapidly forms aggregations in a cavity-driven vortical flow that approximates Kolmogorov eddies. Gyrotactic motility is found to be the key ingredient for aggregation, as non-motile cells remain randomly distributed. Observations are in remarkable agreement with a 3D model, and the validity of this mechanism for generating patchiness has been extended to realistic turbulent flows using Direct Numerical Simulations. Because small-scale patchiness influences rates of predation, sexual reproduction, infection, and nutrient competition, this result indicates that gyrotactic motility can profoundly affect phytoplankton ecology.

Cascade degradation of organic matters in brewery wastewater using a continuous stirred microbial electrochemical reactor and analysis of microbial communities

PubMed Central

Wang, Haiman; Qu, Youpeng; Li, Da; Ambuchi, John J.; He, Weihua; Zhou, Xiangtong; Liu, Jia; Feng, Yujie

2016-01-01

A continuous stirred microbial electrochemical reactor (CSMER), comprising of a complete mixing zone (CMZ) and microbial electrochemical zone (MEZ), was used for brewery wastewater treatment. The system realized 75.4 ± 5.7% of TCOD and 64.9 ± 4.9% of TSS when fed with brewery wastewater concomitantly achieving an average maximum power density of 304 ± 31 m W m−2. Cascade utilization of organic matters made the CSMER remove a wider range of substrates compared with a continuous stirred tank reactor (CSTR), in which process 79.1 ± 5.6% of soluble protein and 86.6 ± 2.2% of soluble carbohydrates were degraded by anaerobic digestion in the CMZ and short-chain volatile fatty acids were further decomposed and generated current in the MEZ. Co-existence of fermentative bacteria (Clostridium and Bacteroides, 19.7% and 5.0%), acetogenic bacteria (Syntrophobacter, 20.8%), methanogenic archaea (Methanosaeta and Methanobacterium, 40.3% and 38.4%) and exoelectrogens (Geobacter, 12.4%) as well as a clear spatial distribution and syntrophic interaction among them contributed to the cascade degradation process in CSMER. The CSMER shows great promise for practical wastewater treatment application due to high pre-hydrolysis and acidification rate, high energy recovery and low capital cost. PMID:27270788

Weldability of an iron meteorite by Friction Stir Spot Welding: A contribution to in-space manufacturing

NASA Astrophysics Data System (ADS)

Evans, William Todd; Neely, Kelsay E.; Strauss, Alvin M.; Cook, George E.

2017-11-01

Friction Stir Welding has been proposed as an efficient and appropriate method for in space welding. It has the potential to serve as a viable option for assembling large scale space structures. These large structures will require the use of natural in space materials such as those available from iron meteorites. Impurities present in most iron meteorites limit its ability to be welded by other space welding techniques such as electron beam laser welding. This study investigates the ability to weld pieces of in situ Campo del Cielo meteorites by Friction Stir Spot Welding. Due to the rarity of the material, low carbon steel was used as a model material to determine welding parameters. Welded samples of low carbon steel, invar, and Campo del Cielo meteorite were compared and found to behave in similar ways. This study shows that meteorites can be Friction Stir Spot Welded and that they exhibit properties analogous to that of FSSW low carbon steel welds. Thus, iron meteorites can be regarded as another viable option for in-space or Martian construction.

The Establishment of a New Friction Stir Welding Process Development Facility at NASA/MSFC

NASA Technical Reports Server (NTRS)

Vaughn, Timothy P.

2012-01-01

The primary objective of full scale development is to mitigate scale-up issues before the vehicle ever reaches production and verify assembly design models. Only at full scale can the true challenges associated with production be identified and dealt with. Also, only at full scale can the delta shift between lab and subscale hardware manufacture and assembly be assessed.

Modeling and simulation of enzymatic gluconic acid production using immobilized enzyme and CSTR-PFTR circulation reaction system.

PubMed

Li, Can; Lin, Jianqun; Gao, Ling; Lin, Huibin; Lin, Jianqiang

2018-04-01

Production of gluconic acid by using immobilized enzyme and continuous stirred tank reactor-plug flow tubular reactor (CSTR-PFTR) circulation reaction system. A production system is constructed for gluconic acid production, which consists of a continuous stirred tank reactor (CSTR) for pH control and liquid storage and a plug flow tubular reactor (PFTR) filled with immobilized glucose oxidase (GOD) for gluconic acid production. Mathematical model is developed for this production system and simulation is made for the enzymatic reaction process. The pH inhibition effect on GOD is modeled by using a bell-type curve. Gluconic acid can be efficiently produced by using the reaction system and the mathematical model developed for this system can simulate and predict the process well.

Hypoxic Three-Dimensional Scaffold-Free Aggregate Cultivation of Mesenchymal Stem Cells in a Stirred Tank Reactor.

PubMed

Egger, Dominik; Schwedhelm, Ivo; Hansmann, Jan; Kasper, Cornelia

2017-05-23

Extensive expansion of mesenchymal stem cells (MSCs) for cell-based therapies remains challenging since long-term cultivation and excessive passaging in two-dimensional conditions result in a loss of essential stem cell properties. Indeed, low survival rate of cells, alteration of surface marker profiles, and reduced differentiation capacity are observed after in vitro expansion and reduce therapeutic success in clinical studies. Remarkably, cultivation of MSCs in three-dimensional aggregates preserve stem cell properties. Hence, the large scale formation and cultivation of MSC aggregates is highly desirable. Besides other effects, MSCs cultivated under hypoxic conditions are known to display increased proliferation and genetic stability. Therefore, in this study we demonstrate cultivation of adipose derived human MSC aggregates in a stirred tank reactor under hypoxic conditions. Although aggregates were exposed to comparatively high average shear stress of 0.2 Pa as estimated by computational fluid dynamics, MSCs displayed a viability of 78-86% and maintained their surface marker profile and differentiation potential after cultivation. We postulate that cultivation of 3D MSC aggregates in stirred tank reactors is valuable for large-scale production of MSCs or their secreted compounds after further optimization of cultivation parameters.

Mitigating Abnormal Grain Growth for Friction Stir Welded Al-Li 2195 Spun Formed Domes

NASA Technical Reports Server (NTRS)

Chen, Po-Shou; Russell, Carolyn

2012-01-01

Formability and abnormal grain growth (AGG) are the two major issues that have been encountered for Al alloy spun formed dome development using friction stir welded blanks. Material properties that have significant influence on the formability include forming range and strain hardening exponent. In this study, tensile tests were performed for two 2195 friction stir weld parameter sets at 400 F to study the effects of post weld anneal on the forming range and strain hardening exponent. It was found that the formability can be enhanced by applying a newly developed post weld anneal to heat treat the friction stir welded panels. This new post weld anneal leads to a higher forming range and much improved strain hardening exponent. AGG in the weld nugget is known to cause a significant reduction of ductility and fracture toughness. This study also investigated how AGG may be influenced by the heating rate to the solution heat treatment temperature. After post-weld annealing, friction stir welds were strained to 15% and 39% by compression at 400 F before they were subjected to SHT at 950 F for 1 hour. Salt bath SHT is very effective in reducing the grain size as it helps arrest the onset of AGG and promote normal recrystallization and grain growth. However, heat treating a 18 ft dome using a salt bath is not practical. Efforts are continuing at Marshall Space Flight Center to identify the welding parameters and heat treating parameters that can help mitigate the AGG in the friction stir welds.

Growth and recombinant protein expression with Escherichia coli in different batch cultivation media.

PubMed

Hortsch, Ralf; Weuster-Botz, Dirk

2011-04-01

Parallel operated milliliter-scale stirred tank bioreactors were applied for recombinant protein expression studies in simple batch experiments without pH titration. An enzymatic glucose release system (EnBase), a complex medium, and the frequently used LB and TB media were compared with regard to growth of Escherichia coli and recombinant protein expression (alcohol dehydrogenase (ADH) from Lactobacillus brevis and formate dehydrogenase (FDH) from Candida boidinii). Dissolved oxygen and pH were recorded online, optical densities were measured at-line, and the activities of ADH and FDH were analyzed offline. Best growth was observed in a complex medium with maximum dry cell weight concentrations of 14 g L(-1). EnBase cultivations enabled final dry cell weight concentrations between 6 and 8 g L(-1). The pH remained nearly constant in EnBase cultivations due to the continuous glucose release, showing the usefulness of this glucose release system especially for pH-sensitive bioprocesses. Cell-specific enzyme activities varied considerably depending on the different media used. Maximum specific ADH activities were measured with the complex medium, 6 h after induction with IPTG, whereas the highest specific FDH activities were achieved with the EnBase medium at low glucose release profiles 24 h after induction. Hence, depending on the recombinant protein, different medium compositions, times for induction, and times for cell harvest have to be evaluated to achieve efficient expression of recombinant proteins in E. coli. A rapid experimental evaluation can easily be performed with parallel batch operated small-scale stirred tank bioreactors.

Generation of functional hepatocyte-like cells from human pluripotent stem cells in a scalable suspension culture.

PubMed

Vosough, Massoud; Omidinia, Eskandar; Kadivar, Mehdi; Shokrgozar, Mohammad-Ali; Pournasr, Behshad; Aghdami, Nasser; Baharvand, Hossein

2013-10-15

Recent advances in human embryonic and induced pluripotent stem cell-based therapies in animal models of hepatic failure have led to an increased appreciation of the need to translate the proof-of-principle concepts into more practical and feasible protocols for scale up and manufacturing of functional hepatocytes. In this study, we describe a scalable stirred-suspension bioreactor culture of functional hepatocyte-like cells (HLCs) from the human pluripotent stem cells (hPSCs). To promote the initial differentiation of hPSCs in a carrier-free suspension stirred bioreactor into definitive endoderm, we used rapamycin for "priming" phase and activin A for induction. The cells were further differentiated into HLCs in the same system. HLCs were characterized and then purified based on their physiological function, the uptake of DiI-acetylated low-density lipoprotein (LDL) by flow cytometry without genetic manipulation or antibody labeling. The sorted cells were transplanted into the spleens of mice with acute liver injury from carbon tetrachloride. The differentiated HLCs had multiple features of primary hepatocytes, for example, the expression patterns of liver-specific marker genes, albumin secretion, urea production, collagen synthesis, indocyanin green and LDL uptake, glycogen storage, and inducible cytochrome P450 activity. They increased the survival rate, engrafted successfully into the liver, and continued to present hepatic function (i.e., albumin secretion after implantation). This amenable scaling up and outlined enrichment strategy provides a new platform for generating functional HLCs. This integrated approach may facilitate biomedical applications of the hPSC-derived hepatocytes.

Electromagnetic stirring in a microbioreactor with non-conventional chamber morphology and implementation of multiplexed mixing.

PubMed

Tan, Christabel Kl; Davies, Matthew J; McCluskey, Daniel K; Munro, Ian R; Nweke, Mauryn C; Tracey, Mark C; Szita, Nicolas

2015-10-01

Microbioreactors have emerged as novel tools for early bioprocess development. Mixing lies at the heart of bioreactor operation (at all scales). The successful implementation of micro-stirring methods is thus central to the further advancement of microbioreactor technology. The aim of this study was to develop a micro-stirring method that aids robust microbioreactor operation and facilitates cost-effective parallelization. A microbioreactor was developed with a novel micro-stirring method involving the movement of a magnetic bead by sequenced activation of a ring of electromagnets. The micro-stirring method offers flexibility in chamber designs, and mixing is demonstrated in cylindrical, diamond and triangular shaped reactor chambers. Mixing was analyzed for different electromagnet on/off sequences; mixing times of 4.5 s, 2.9 s, and 2.5 s were achieved for cylindrical, diamond and triangular shaped chambers, respectively. Ease of micro-bubble free priming, a typical challenge of cylindrical shaped microbioreactor chambers, was obtained with a diamond-shaped chamber. Consistent mixing behavior was observed between the constituent reactors in a duplex system. A novel stirring method using electromagnetic actuation offering rapid mixing and easy integration with microbioreactors was characterized. The design flexibility gained enables fabrication of chambers suitable for microfluidic operation, and a duplex demonstrator highlights potential for cost-effective parallelization. Combined with a previously published cassette-like fabrication of microbioreactors, these advances will facilitate the development of robust and parallelized microbioreactors. © 2015 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Magnetic resonance measurement of muscle T2, fat-corrected T2 and fat fraction in the assessment of idiopathic inflammatory myopathies

PubMed Central

Yao, Lawrence; Yip, Adrienne L.; Shrader, Joseph A.; Mesdaghinia, Sepehr; Volochayev, Rita; Jansen, Anna V.; Miller, Frederick W.

2016-01-01

Objective. This study examines the utility of MRI, including T2 maps and T2 maps corrected for muscle fat content, in evaluating patients with idiopathic inflammatory myopathy. Methods. A total of 44 patients with idiopathic inflammatory myopathy, 18 of whom were evaluated after treatment with rituximab, underwent MRI of the thighs and detailed clinical assessment. T2, fat fraction (FF) and fat corrected T2 (fc-T2) maps were generated from standardized MRI scans, and compared with semi-quantitative scoring of short tau inversion recovery (STIR) and T1-weighted sequences, as well as various myositis disease metrics, including the Physician Global Activity, the modified Childhood Myositis Assessment Scale and the muscle domain of the Myositis Disease Activity Assessment Tool-muscle (MDAAT-muscle). Results. Mean T2 and mean fc-T2 correlated similarly with STIR scores (Spearman rs = 0.64 and 0.64, P < 0.01), while mean FF correlated with T1 damage scores (rs = 0.69, P < 0.001). Baseline T2, fc-T2 and STIR scores correlated significantly with the Physician Global Activity, modified Childhood Myositis Assessment Scale and MDAAT-muscle (rs range = 0.41–0.74, P < 0.01). The response of MRI measures to rituximab was variable, and did not significantly agree with a standardized clinical definition of improvement. Standardized response means for the MRI measures were similar. Conclusion. Muscle T2, fc-T2 and FF measurements exhibit content validity with reference to semi-quantitative scoring of STIR and T1 MRI, and also exhibit construct validity with reference to several myositis activity and damage measures. T2 was as responsive as fc-T2 and STIR scoring, although progression of muscle damage was negligible during the study. PMID:26412808

Effect of Thermal History on Microstructures and Mechanical Properties of AZ31 Magnesium Alloy Prepared by Friction Stir Processing

PubMed Central

Chai, Fang; Zhang, Datong; Li, Yuanyuan

2014-01-01

Hot-rolled AZ31 (Mg-2.57Al-0.84Zn-0.32Mn, in mass percentage) magnesium alloy is subjected to friction stir processing in air (normal friction stir processing, NFSP) and under water (submerged friction stir processing, SFSP). Thermal history of the two FSP procedures is measured, and its effect on microstructures and mechanical properties of the experimental materials is investigated. Compared with NFSP, the peak temperature during SFSP is lower and the duration time at a high temperature is shorter due to the enhanced cooling effect of water. Consequently, SFSP results in further grain refinement, and the average grain size of the NFSP and SFSP specimens in the stir zone (SZ) are 2.9 μm and 1.3 μm, respectively. Transmission electron microscopy (TEM) examinations confirm that grain refinement is attributed to continuous dynamic recrystallization both for NFSP and SFSP. The average Vickers hardness in the SZ of the NFSP and SFSP AZ31 magnesium alloy are 76 HV and 87 HV. Furthermore, the ultimate tensile strength and the elongation of the SFSP specimen increase from 191 MPa and 31.3% in the NFSP specimen to 210 MPa and 50.5%, respectively. Both the NFSP and SFSP alloys fail through ductile fracture, but the dimples are much more obvious in the SFSP alloy. PMID:28788532

Friction Stir Welding (FSW) of Aged CuCrZr Alloy Plates

NASA Astrophysics Data System (ADS)

Jha, Kaushal; Kumar, Santosh; Nachiket, K.; Bhanumurthy, K.; Dey, G. K.

2018-01-01

Friction Stir Welding (FSW) of Cu-0.80Cr-0.10Zr (in wt pct) alloy under aged condition was performed to study the effects of process parameters on microstructure and properties of the joint. FSW was performed over a wide range of process parameters, like tool-rotation speed (from 800 to 1200 rpm) and tool-travel speed (from 40 to 100 mm/min), and the resulting thermal cycles were recorded on both sides (advancing and retreating) of the joint. The joints were characterized for their microstructure and tensile properties. The welding process resulted in a sound and defect-free weld joint, over the entire range of the process parameters used in this study. Microstructure of the stir zone showed fine and equiaxed grains, the scale of which varied with FSW process parameters. Grain size in the stir zone showed direct correlation with tool rotation and inverse correlation with tool-travel speed. Tensile strength of the weld joints was ranging from 225 to 260 MPa, which is substantially lower than that of the parent metal under aged condition ( 400 MPa), but superior to that of the parent material under annealed condition ( 220 MPa). Lower strength of the FSW joint than that of the parent material under aged condition can be attributed to dissolution of the precipitates in the stir zone and TMAZ. These results are presented and discussed in this paper.

Texture Development and Material Flow Behavior During Refill Friction Stir Spot Welding of AlMgSc

NASA Astrophysics Data System (ADS)

Shen, Junjun; Lage, Sara B. M.; Suhuddin, Uceu F. H.; Bolfarini, Claudemiro; dos Santos, Jorge F.

2018-01-01

The microstructural evolution during refill friction stir spot welding of an AlMgSc alloy was studied. The primary texture that developed in all regions, with the exception of the weld center, was determined to be 〈110〉 fibers and interpreted as a simple shear texture with the 〈110〉 direction aligned with the shear direction. The material flow is mainly driven by two components: the simple shear acting on the horizontal plane causing an inward-directed spiral flow and the extrusion acting on the vertical plane causing an upward-directed or downward-directed flow. Under such a complex material flow, the weld center, which is subjected to minimal local strain, is the least recrystallized. In addition to the geometric effects of strain and grain subdivision, thermally activated high-angle grain boundary migration, particularly continuous dynamic recrystallization, drives the formation of refined grains in the stirred zone.

Altimetric lagrangian advection to reconstruct Pacific Ocean fine scale surface tracer fields

NASA Astrophysics Data System (ADS)

Rogé, Marine; Morrow, Rosemary; Dencausse, Guillaume

2015-04-01

In past studies, lagrangian stirring of surface tracer fields by altimetric surface geostrophic currents has been performed in different mid to high-latitude regions, showing good results in reconstructing finer-scale tracer patterns. Here we apply the technique to three different regions in the eastern and western tropical Pacific, and in the subtropical southwest Pacific. Initial conditions are derived from weekly gridded temperature and salinity fields, based on hydrographic data and Argo. Validation of the improved fine-scale surface tracer fields is performed using satellite AMSRE SST data, and high-resolution ship thermosalinograph data. We test two kinds of lagrangian advection. The standard one-way advection is shown to introduce an increased tracer bias as the advection time increases. Indeed, since we only use passive stirring, a bias is introduced from the missing physics, such as air-sea fluxes or mixing. A second "backward-forward" advection technique is shown to reduce the seasonal bias, but more data is lost around coasts and islands, a strong handicap in the tropical Pacific with many small islands. In the subtropical Pacific Ocean, the mesoscale temperature and salinity fronts are well represented by the one-way advection over a 10-day advection time, including westward propagating features not apparent in the initial fields. In the tropics, the results are less clear. The validation is hampered by the complex vertical stratification, and the technique is limited by the lack of accurate surface currents for the stirring - the gridded altimetric fields poorly represent the meridional currents, and are not detecting the fast tropical instability waves, nor the wind-driven circulation. We suggest that the passive lateral stirring technique is efficient in regions with moderate the high mesoscale energy and correlated mesoscale surface temperature and surface height. In other regions, more complex dynamical processes may need to be included.

Hardening Potential of an Al-Cu-Li Friction Stir Weld

NASA Astrophysics Data System (ADS)

Ivanov, Rosen; Boselli, Julien; Denzer, Diana; Larouche, Daniel; Gauvin, Raynald; Brochu, Mathieu

The evolution of the microstructure during friction stir welding of a third generation AA2199 Al-Li alloy has been described and related to the mechanical properties of welds. The coupling of electron microscopy and micro-hardness have helped generate an understanding of the relationship between grain structure, precipitate density and morphology behind the observed changes in mechanical properties during post weld artificial ageing. The ability of welds to recover hardness and strength during post weld heat treatment was linked to the limited formation of large scale precipitates which act as sinks for alloying elements. Welds obtained with high tool rotation speed (within parameters studied) showed ultimate tensile strength levels of about 93% of the base metal, an elongation of 6% at fracture, and hardness values ranging between 120-140 HV in the stir zone, thermo-mechanically affected zone, and heat affected zone upon post weld heat treatment.

Biodegradation of pulp and paper mill effluent using anaerobic followed by aerobic digestion.

PubMed

Bishnoi, Narsi R; Khumukcham, R K; Kumar, Rajender

2006-05-01

An experimental study was carried to find out the degradability of black liquor of pulp and paper mill wastewater for biomethanogenesis in continuous stirred tank reactor (CSTR) and followed by activated sludge process (ASP). Continuous stirred tank reactor was used in present study for anaerobic digestion of black liquor, while completely mixed activated sludge system was used for aerobic digestion. A maximum methane production was found up to 430 ml/day, chemical oxygen demand was reduced up to 64% and total volatile fatty acid increased up to 1500 mg/l from 975 mg/l at 7.3 pH, 37 degrees C temperature and 8 days hydraulic retention time during anaerobic digestion. In activated sludge process (aerobic digestion) chemical oxygen demand and biological oxygen demand reduction were 81% and 86% respectively at 72 hr hydraulic retention time.

Batch and continuous production of stable dense suspensions of drug nanoparticles in a wet stirred media mill

NASA Astrophysics Data System (ADS)

Afolabi, Afola we mi

One way to improve the bioavailability of poorly water-soluble drugs is to reduce particle size of drug crystals down to nanoscale via wet stirred media milling. An increase in total surface area per mass loading of the drug and specific surface area as well as reduced external mass transfer resistance allow a faster dissolution of the poorly-water soluble drug from nanocrystals. To prevent aggregation of nanoparticles, polymers and surfactants are dissolved in water acting as stabilizers via adsorption onto the drug crystals. In the last two decades, ample experimental data were generated in the area of wet stirred media milling for the production of drug nanoparticle suspensions. However, a fundamental scientific/engineering understanding of various aspects of this process is still lacking. These challenges include elucidation of the governing mechanism(s) during nanoparticle formation and physical stabilization of the nanosuspension with the use of polymers and surfactants (formulation parameters), understanding the impact of process parameters in the context of first-principle-based models, and production of truly nanosized drug particles (10-100 nm) with acceptable physical stability and minimal contamination with the media. Recirculation mode of milling operation, where the drug suspension in a holding tank continuously circulates through the stirred media mill, has been commonly used in lab, pilot, and commercial scales. Although the recirculation is continuous, the recirculation operation mode is overall a batch operation, requiring significant number of batches for a large-volume pharmaceutical product. Hence, development and investigation of a truly continuous process should offer significant advantages. To explain the impact of some of the processing parameters, stress intensity and stress number concepts were widely used in literature, which do not account for the effect of suspension viscosity explicitly. The impact of the processing parameters has not been explained in a predictive and reliable manner. In this dissertation, a comprehensive investigation of the production of Griseofulvin nanosuspensions in a wet stirred media mill operating in both the recirculation and continuous modes has been conducted to address the aforementioned fundamental challenges. Griseofulvin has been selected as a model poorly water-soluble BCS Class II drug. Impact of various formulation parameters such as stabilizer type and loading as well as processing parameters such as rotor speed, bead loading, bead size, suspension flow rate and drug loading was studied. A major novelty of the present contribution is that the impact of processing and formulation parameters has been analyzed and interpreted using a combined experimental-theoretical (microhydrodynamic model) approach. Such a comprehensive approach allowed us to intensify the process for the production of sub-100 nm drug particles, which could not be produced with top-down approaches in the literature so far. In addition, a multi-pass mode of continuous operation was developed and the so-called "Rehbinder effect", which has not been shown for the breakage of drug particles, was also elucidated. The dissertation work (1) indicated the need for a minimum polymeric stabilizer-to-drug ratio for proper stabilization of drug nanosuspensions as dictated by polymer adsorption and synergistic interactions between a polymeric stabilizer and a surfactant, (2) demonstrated the existence of an optimum polymer concentration from a breakage rate perspective in the presence of a surfactant, which results from the competing effects of viscous dampening and enhanced steric stabilization at higher polymer concentration, (3) developed fundamental understanding of the breakage dynamics-processing-formulation relationships and rationalized preparation of a single highly drug- loaded batch (20% or higher) instead of multiple dilute batches, (4) designed an intensified process for faster preparation of sub-100 nm particles with reduced specific energy consumption and media wear (i.e. minimal drug contamination), and (5) provided first evidence for the proof of Rehbinder effect during the milling of drugs. Not only do the polymers and surfactants allow proper physical stabilization of the nanoparticles in the suspensions, but they also do facilitate drug particle breakage. This dissertation also discusses applications of nanosuspensions and practical issues encountered during wet media milling.

Multivariate Analysis of Ladle Vibration

NASA Astrophysics Data System (ADS)

Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle

2016-08-01

The homogeneity of composition and uniformity of temperature of the steel melt before it is transferred to the tundish are crucial in making high-quality steel product. The homogenization process is performed by stirring the melt using inert gas in ladles. Continuous monitoring of this process is important to make sure the action of stirring is constant throughout the ladle. Currently, the stirring process is monitored by process operators who largely rely on visual and acoustic phenomena from the ladle. However, due to lack of measurable signals, the accuracy and suitability of this manual monitoring are problematic. The actual flow of argon gas to the ladle may not be same as the flow gage reading due to leakage along the gas line components. As a result, the actual degree of stirring may not be correctly known. Various researchers have used one-dimensional vibration, and sound and image signals measured from the ladle to predict the degree of stirring inside. They developed online sensors which are indeed to monitor the online stirring phenomena. In this investigation, triaxial vibration signals have been measured from a cold water model which is a model of an industrial ladle. Three flow rate ranges and varying bath heights were used to collect vibration signals. The Fast Fourier Transform was applied to the dataset before it has been analyzed using principal component analysis (PCA) and partial least squares (PLS). PCA was used to unveil the structure in the experimental data. PLS was mainly applied to predict the stirring from the vibration response. It was found that for each flow rate range considered in this study, the informative signals reside in different frequency ranges. The first latent variables in these frequency ranges explain more than 95 pct of the variation in the stirring process for the entire single layer and the double layer data collected from the cold model. PLS analysis in these identified frequency ranges demonstrated that the latent variables of the response and predictor variables are highly correlated. The predicted variable has shown linear relationship with the stirring energy and bath recirculation speed. This outcome can improve the predictability of the mixing status in ladle metallurgy and make the online control of the process easier. Industrial testing of this input will follow.

A Review of Permanent Magnet Stirring During Metal Solidification

NASA Astrophysics Data System (ADS)

Zeng, Jie; Chen, Weiqing; Yang, Yindong; Mclean, Alexander

2017-12-01

Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of sintered NdFeB material which has excellent magnetic characteristics, can be employed to generate a magnetic field for the stirring of liquid metal during solidification. Recent experience with steel casting indicates that PMS requires less than 20 pct of the total energy compared with EMS. Despite the excellent magnetic density properties and low power consumption, this relatively new technology has received comparatively little attention by the metal casting community. This paper reviews simulation modeling, experimental studies, and industrial trials of PMS conducted during recent years. With the development of magnetic simulation software, the magnetic field and associated flow patterns generated by PMS have been evaluated. Based on the results obtained from laboratory experiments, the effects of PMS on metal solidification structures and typical defects such as surface pinholes and center cavities are summarized. The significance of findings obtained from trials of PMS within the metals processing sector, including the continuous casting of steel, are discussed with the aim of providing an overview of the relevant parameters that are of importance for further development and industrial application of this innovative technology.

Gypsum crystal size distribution in four continuous flow stirred slurry boric acid reactors in series compared with the batch

NASA Astrophysics Data System (ADS)

Çakal, G. Ö.; Eroğlu, İ.; Özkar, S.

2006-04-01

Colemanite, one of the important boron minerals, is dissolved in aqueous sulfuric acid to produce boric acid. In this reaction, gypsum is obtained as a by-product. Gypsum crystals are in the shape of thin needles. These crystals should be grown to an easily filterable size in order to increase the production yield and purity of boric acid. In this paper, the particle size distributions and the volume-weighted mean diameters of the gypsum crystals obtained in batch and continuous flow systems were compared. Experiments in both batch and continuous reactors were performed at a temperature of 85 °C, a stirring rate of 400 rpm, and the inlet CaO to SO42- molar ratio of 1.0 using colemanite mineral in particle size smaller than 150 μm. The average diameter of the gypsum crystals obtained at 3.5 h from the batch reactor was found to be 37-41 μm. This value for the continuous system at steady state was observed to change between 44-163 μm. The particle size of the gypsum crystals was found to increase with the residence time of the solid in the continuous system.

Hydraulic characterization and optimization of total nitrogen removal in an aerated vertical subsurface flow treatment wetland.

PubMed

Boog, Johannes; Nivala, Jaime; Aubron, Thomas; Wallace, Scott; van Afferden, Manfred; Müller, Roland Arno

2014-06-01

In this study, a side-by-side comparison of two pilot-scale vertical subsurface flow constructed wetlands (6.2 m(2)×0.85 m, q(i)=95 L/m(2) d, τ(n)=3.5 d) handling primary treated domestic sewage was conducted. One system (VA-i) was set to intermittent aeration while the other was aerated continuously (VAp-c). Intermittent aeration was provided to VA-i in an 8 h on/4 h off pattern. The intermittently aerated wetland, VA-i, was observed to have 70% less nitrate nitrogen mass outflow than the continuously aerated wetland, VAp-c. Intermittent aeration was shown to increase treatment performance for TN while saving 33% of running energy cost for aeration. Parallel tracer experiments in the two wetlands showed hydraulic characteristics similar to one Continuously Stirred Tank Reactor (CSTR). Intermittent aeration did not significantly affect the hydraulic functioning of the system. Hydraulic efficiencies were 78% for VAp-c and 76% for VA-i. Copyright © 2014 Elsevier Ltd. All rights reserved.

Expansion of Human Mesenchymal Stem Cells in a Microcarrier Bioreactor.

PubMed

Tsai, Ang-Chen; Ma, Teng

2016-01-01

Human mesenchymal stem cells (hMSCs) are considered as a primary candidate in cell therapy owing to their self-renewability, high differentiation capabilities, and secretions of trophic factors. In clinical application, a large quantity of therapeutically competent hMSCs is required that cannot be produced in conventional petri dish culture. Bioreactors are scalable and have the capacity to meet the production demand. Microcarrier suspension culture in stirred-tank bioreactors is the most widely used method to expand anchorage dependent cells in a large scale. Stirred-tank bioreactors have the potential to scale up and microcarriers provide the high surface-volume ratio. As a result, a spinner flask bioreactor with microcarriers has been commonly used in large scale expansion of adherent cells. This chapter describes a detailed culture protocol for hMSC expansion in a 125 mL spinner flask using microcarriers, Cytodex I, and a procedure for cell seeding, expansion, metabolic sampling, and quantification and visualization using microculture tetrazolium (MTT) reagent.

THE FATE OF PLANETESIMALS IN TURBULENT DISKS WITH DEAD ZONES. I. THE TURBULENT STIRRING RECIPE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okuzumi, Satoshi; Ormel, Chris W., E-mail: okuzumi@geo.titech.ac.jp

2013-07-01

Turbulence in protoplanetary disks affects planet formation in many ways. While small dust particles are mainly affected by the aerodynamical coupling with turbulent gas velocity fields, planetesimals and larger bodies are more affected by gravitational interaction with gas density fluctuations. For the latter process, a number of numerical simulations have been performed in recent years, but a fully parameter-independent understanding has not been yet established. In this study, we present simple scaling relations for the planetesimal stirring rate in turbulence driven by magnetorotational instability (MRI), taking into account the stabilization of MRI due to ohmic resistivity. We begin with order-of-magnitudemore » estimates of the turbulence-induced gravitational force acting on solid bodies and associated diffusion coefficients for their orbital elements. We then test the predicted scaling relations using the results of recent ohmic-resistive MHD simulations by Gressel et al. We find that these relations successfully explain the simulation results if we properly fix order-of-unity uncertainties within the estimates. We also update the saturation predictor for the density fluctuation amplitude in MRI-driven turbulence originally proposed by Okuzumi and Hirose. Combination of the scaling relations and saturation predictor allows us to know how the turbulent stirring rate of planetesimals depends on disk parameters such as the gas column density, distance from the central star, vertical resistivity distribution, and net vertical magnetic flux. In Paper II, we apply our recipe to planetesimal accretion to discuss its viability in turbulent disks.« less

Assessment of Ductile-to-Brittle Transition Behavior of Localized Microstructural Regions in a Friction-Stir Welded X80 Pipeline Steel with Miniaturized Charpy V-Notch Testing

NASA Astrophysics Data System (ADS)

Avila, Julian A.; Lucon, Enrico; Sowards, Jeffrey; Mei, Paulo Roberto; Ramirez, Antonio J.

2016-06-01

Friction-stir welding (FSW) is an alternative welding process for pipelines. This technology offers sound welds, good repeatability, and excellent mechanical properties. However, it is of paramount importance to determine the toughness of the welds at low temperatures in order to establish the limits of this technology. Ductile-to-brittle transition curves were generated in the present study by using a small-scale instrumented Charpy machine and miniaturized V-notch specimens (Kleinstprobe, KLST); notches were located in base metal, heat-affected, stirred, and hard zones within a FSW joint of API-5L X80 Pipeline Steel. Specimens were tested at temperatures between 77 K (-196 °C) and 298 K (25 °C). Based on the results obtained, the transition temperatures for the base material and heat-affected zone were below 173 K (-100 °C); conversely, for the stirred and hard zones, it was located around 213 K (-60 °C). Fracture surfaces were characterized and showed a ductile fracture mechanism at high impact energies and a mixture of ductile and brittle mechanisms at low impact energies.

Influence of tool speeds on dissimilar friction stir spot welding characteristics of bulk metallic glass/Mg alloy

NASA Astrophysics Data System (ADS)

Shin, Hyung-Seop; Jung, Yoon-Chul; Lee, Jin-Kyu

2012-08-01

A small-scale joining technique of dissimilar friction stir spot welding (FSSW) between bulk metallic glass and Mg alloy sheet has been tried using an apparatus which was devised with a CNC milling machine to give a precise control of tool speeds. The influence of tool speeds on the joining characteristics during FSSW was investigated. As a result, it was found that the rotation speed and plunge speed of a tool during FSSW significantly influenced the welding performance of dissimilar FSSW between bulk metallic glasses and Mg alloy.

Convective stirring efficiency in strongly temperature-dependent, infinite Prandtl number fluids: application to planetary mantles.

NASA Astrophysics Data System (ADS)

Tosi, N.; Samuel, H.

2017-12-01

Many rocky planetary bodies currently exhibit solid-state convection, or have experienced this process during their histories.Such a style of convection is characterized by the negligible influence of inertia, and a rheology known to be strongly temperature-dependent. Convective motion within such planetary envelopes determine their ability to preserve or to homogenize compositional heterogeneities.Therefore, understanding the efficiency of convective stirring is key to the interpretation of petrological, geochemical, and cosmochemical data originating on the Earth from sampled erupted lava, or inferred from meteorite analysis (e.g., Mars). In order to study this problem we have conducted series of numerical experiments in 2D and 3D Cartesian domains heated from below and cooled from above. We varied systematically the Rayleigh number and the activation energy using a strongly temperature-dependent viscosity based on the Arrhenius law for diffusion creep. Given the large values of activation energy considered, all our experiments fall into the stagnant lid regime. Stirring efficiency is determined by computing the finite-time Lyapunov exponents, which provide a measure of the Lagrangian deformation.This systematic exploration allows the degree of heterogeneity and its spatial variability to be quantified, and yields mixing times for both 2D and 3D geometries.Our results indicate significant differences between geometries: 2D cases lead more frequently to steady solutions, for which stirring efficiency is spatially heterogeneous and mostly weak. On the other hand, 3D cases show more time dependence of the velocity field and generally yield more efficient convective stirring, even for cases with a weak time-dependence of the flow. Scaling laws for stirring efficiencies are derived, and will serve as a basis to discuss the application to planetary mantles.

A simple eccentric stirred tank mini-bioreactor: mixing characterization and mammalian cell culture experiments.

PubMed

Bulnes-Abundis, David; Carrillo-Cocom, Leydi M; Aráiz-Hernández, Diana; García-Ulloa, Alfonso; Granados-Pastor, Marisa; Sánchez-Arreola, Pamela B; Murugappan, Gayathree; Alvarez, Mario M

2013-04-01

In industrial practice, stirred tank bioreactors are the most common mammalian cell culture platform. However, research and screening protocols at the laboratory scale (i.e., 5-100 mL) rely primarily on Petri dishes, culture bottles, or Erlenmeyer flasks. There is a clear need for simple-easy to assemble, easy to use, easy to clean-cell culture mini-bioreactors for lab-scale and/or screening applications. Here, we study the mixing performance and culture adequacy of a 30 mL eccentric stirred tank mini-bioreactor. A detailed mixing characterization of the proposed bioreactor is presented. Laser induced fluorescence (LIF) experiments and computational fluid dynamics (CFD) computations are used to identify the operational conditions required for adequate mixing. Mammalian cell culture experiments were conducted with two different cell models. The specific growth rate and the maximum cell density of Chinese hamster ovary (CHO) cell cultures grown in the mini-bioreactor were comparable to those observed for 6-well culture plates, Erlenmeyer flasks, and 1 L fully instrumented bioreactors. Human hematopoietic stem cells were successfully expanded tenfold in suspension conditions using the eccentric mini-bioreactor system. Our results demonstrate good mixing performance and suggest the practicality and adequacy of the proposed mini-bioreactor. Copyright © 2012 Wiley Periodicals, Inc.

Looking for practical tools to achieve next-future applicability of dark fermentation to produce bio-hydrogen from organic materials in Continuously Stirred Tank Reactors.

PubMed

Tenca, A; Schievano, A; Lonati, S; Malagutti, L; Oberti, R; Adani, F

2011-09-01

This study aimed at finding applicable tools for favouring dark fermentation application in full-scale biogas plants in the next future. Firstly, the focus was obtaining mixed microbial cultures from natural sources (soil-inocula and anaerobically digested materials), able to efficiently produce bio-hydrogen by dark fermentation. Batch reactors with proper substrate (1 gL(glucose)(-1)) and metabolites concentrations, allowed high H(2) yields (2.8 ± 0.66 mol H(2)mol(glucose)(-1)), comparable to pure microbial cultures achievements. The application of this methodology to four organic substrates, of possible interest for full-scale plants, showed promising and repeatable bio-H(2) potential (BHP=202 ± 3 NL(H2)kg(VS)(-1)) from organic fraction of municipal source-separated waste (OFMSW). Nevertheless, the fermentation in a lab-scale CSTR (nowadays the most diffused typology of biogas-plant) of a concentrated organic mixture of OFMSW (126 g(TS)L(-1)) resulted in only 30% of its BHP, showing that further improvements are still needed for future full-scale applications of dark fermentation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Azimuthal MHD stirring of metal in vessels with cross-sections of different configuration

NASA Astrophysics Data System (ADS)

Siraev, R. R.; Khripchenko, S. Yu

2017-11-01

Continuous casting of cylindrical ingots from aluminum and preparation of aluminum-based alloys and composites require intensive mixing of liquid metal phase in the crystallization area of the melt. It is evident that the topology of the flow in the liquid phase of an ingot should influence the processes occurring during crystallization. Contemporary continuous casting machines use MHD-stirrers that generate an azimuthal motion in a crystallizer with a warm top of circular cross-section in the presence of rotating magnetic field. The flow of metal in the liquid phase of an ingot is similar to its rotation in a solid state, and transport processes are most intensively carried out in the near near-wall region and near the ingot solidification front, where shear flows are essential. In this work, we consider the possibility of amplifying transport processes in the entire volume of a stirred metal by making the cross-section shape of the warm top of the crystallizer different from a circle. It has been found numerically that the total energy of the flow in a crucible of square cross-section is twice as lower as that in a crucible with circular cross-section at the same inductor current. Turbulent pulsations in the square crucible, as well as in the circular one, are concentrated mainly in the near-wall region. The energy of pulsations in the square crucible also reduces, but the time of stirring of the passive impurity introduced into the volume of the metal is less than in the circular crucible. The effect of MHD stirring on the vertical temperature distribution on the square crucible is higher than in the “round crucible”.

Investigating the kinetics of the enzymatic depolymerization of polygalacturonic acid in continuous UF-membrane reactors.

PubMed

Gallifuoco, Alberto; Cantarella, Maria; Marucci, Mariagrazia

2007-01-01

A stirred tank membrane reactor is used to study the kinetics of polygalacturonic acid (PGA) enzymatic hydrolysis. The reactor operates in semicontinuous configuration: the native biopolymer is loaded at the initial time and the system is continuously fed with the buffer. The effect of retention time (from 101 to 142 min) and membrane molecular weight cutoff (from 1 to 30 kDa) on the rate of permeable oligomers production is investigated. Reaction products are clustered in two different classes, those sized below the membrane cutoff and those above. The reducing power measured in the permeate is used as an estimate of total product concentration. The characteristic breakdown times range from 40 to 100 min. The overall kinetics obeys a first-order law with a characteristic time estimated to 24 min. New mathematical data handling are developed and illustrated using the experimental data obtained. Finally, the body of the experimental results suggests useful indications (reactor productivity, breakdown induction period) for implementing the bioprocess at the industrial scale.

Friction-Stir Welding of Aluminum For the Space Program

NASA Technical Reports Server (NTRS)

Jones, Clyde S.; Smelser, Jerry W. (Technical Monitor)

2002-01-01

The Marshall Space Flight Center is developing and characterizing the friction stir welding process for the Space Shuttle and other space programs. This revolutionary process, invented and patented by The Weld Institute in England, offers tremendous advantages for joining aluminum for high performance applications. It is particularly suited for advanced aluminum-lithium alloys, such as 2195, the primary structural alloy used in the External Tank. The friction stir welding process joins metals with minimal heat input, resulting in high-strength joints with high ductility. It is a simple process to demonstrate using a common milling machine for sample parts, but relatively expensive to implement on large-scale hardware, due to the high cost of tooling needed to handle the high forging pressures characteristic of the process. Recent developments at the Marshall Space Flight Center have demonstrated friction stir welding on linear joints up to 5 meters (15 ft.), with material thickness ranging between 2.5 mm and 16.5 mm (0.100" to 0.650"). High efficiency weld joints have been produced in aluminum from the 2000, 5000, and 6000 series alloy systems. A "retractable pin tool" system was patented by MSFC that allows use of friction stir welding for joints with changing material thickness, and with less rigid tooling than previously considered. This presentation will describe the details of alloys welded to-date and technical advances under development at MSFC. These developments could have substantial benefit to industrial applications for welding aluminum.

Nonlinear versus Ordinary Adaptive Control of Continuous Stirred-Tank Reactor

PubMed Central

Dostal, Petr

2015-01-01

Unfortunately, the major group of the systems in industry has nonlinear behavior and control of such processes with conventional control approaches with fixed parameters causes problems and suboptimal or unstable control results. An adaptive control is one way to how we can cope with nonlinearity of the system. This contribution compares classic adaptive control and its modification with Wiener system. This configuration divides nonlinear controller into the dynamic linear part and the static nonlinear part. The dynamic linear part is constructed with the use of polynomial synthesis together with the pole-placement method and the spectral factorization. The static nonlinear part uses static analysis of the controlled plant for introducing the mathematical nonlinear description of the relation between the controlled output and the change of the control input. Proposed controller is tested by the simulations on the mathematical model of the continuous stirred-tank reactor with cooling in the jacket as a typical nonlinear system. PMID:26346878

Graft polymerization of wood sawdust and peat with ethylene carbonate. A novel method for the preparation of supports with enhanced mechanical properties to be used in biofiltration of organic vapors.

PubMed

Hernández-Meléndez, O; Peydecastaing, J; Bárzana, E; Vaca-Garcia, C; Hernández-Luna, M; Borredon, M E

2009-01-01

The graft polymerization reaction between ethylene carbonate (EC) and scots pine sawdust (SPS) or peat moss (PM) offers a solvent-free approach to the simple and inexpensive aliphatic derivatization of these lignocellulosic fibers. This reaction was studied with liquid or vapor EC phases in three different reactor configurations: batch stirred (BSR), semi-continuous stirred (SSR) and continuous tubular in the gas phase (CVTR). The use of a vapor phase allowed a satisfactory grafting yield and minimal production of non-grafted polyol by-products. The crosslinking agent 4,4'-methylenebis(phenylisocyanate) (MDI) achieved superior characteristics to form shaped tablets resistant to water disaggregation, a high water retention capacity and high compression strength, characteristics that conventional organic supports like PM or PM-polyurethane foam mixtures used in biofiltration of waste gases do not completely possess.

Performance of continuous stirred tank reactor (CSTR) on fermentative biohydrogen production from melon waste

NASA Astrophysics Data System (ADS)

Cahyari, K.; Sarto; Syamsiah, S.; Prasetya, A.

2016-11-01

This research was meant to investigate performance of continuous stirred tank reactor (CSTR) as bioreactor for producing biohydrogen from melon waste through dark fermentation method. Melon waste are commonly generated from agricultural processing stages i.e. cultivation, post-harvesting, industrial processing, and transportation. It accounted for more than 50% of total harvested fruit. Feedstock of melon waste was fed regularly to CSTR according to organic loading rate at value 1.2 - 3.6 g VS/ (l.d). Optimum condition was achieved at OLR 2.4 g VS/ (l.d) with the highest total gas volume 196 ml STP. Implication of higher OLR value is reduction of total gas volume due to accumulation of acids (pH 4.0), and lower substrate volatile solid removal. In summary, application of this method might valorize melon waste and generates renewable energy sources.

Microstructure evolution and mechanical properties of nano-SiCp/AZ91 composite processed by extrusion and equal channel angular pressing (ECAP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, X.G.; Ying, T.

Nano-SiCp/AZ91 magnesium matrix composite was fabricated by stir casting. The as-cast ingots were extruded at 350 °C, then processed by equal channel angular pressing (ECAP) at various temperatures (250 °C, 300 °C and 350 °C). Grains are significantly refined after the extrusion and the ECAP. A basal fibre texture was detected by neutron diffraction after the extrusion, which inclines about 45° to the extrusion direction (ED) after the ECAP. Nano-scaled SiC particles agglomerate in the as-cast composite. After the extrusion, the agglomeration tends to form continuous or discontinuous strips along the extrusion direction. By application of the ECAP, the agglomeratedmore » SiC particles are partly dispersed and the strips formed during the extrusion tend to be thinner and broken with the increasing pass number. The yield tensile strength (YTS) and the ultimate tensile strength (UTS) of the composite are dramatically increased after the extrusion. ECAP for one pass at various temperatures further increases the strength, however, the YTS decreases with the increasing ECAP temperature and the pass number. The Orowan equations predict the maximum YTS of the composite may be up to 400 MPa providing SiC particles are homogenously distributed in the matrix. - Highlights: •Nano-scaled SiC particles were successfully added into AZ91 by stirring casting. •Agglomeration of nano-particles were improved by extrusion and ECAP. •Yield strength of the composite is 328 MPa after one pass of ECAP. •Further ECAP process with optimized parameters may fully disperse nano-particles. •Yield strength is predicted to up to 400 MPa when particles are fully dispersed.« less

Complete genome sequence of Peptoniphilus sp. strain ING2-D1G isolated from a mesophilic lab-scale completely stirred tank reactor utilizing maize silage in co-digestion with pig and cattle manure for biomethanation.

PubMed

Tomazetto, Geizecler; Hahnke, Sarah; Maus, Irena; Wibberg, Daniel; Pühler, Alfred; Schlüter, Andreas; Klocke, Michael

2014-12-20

The bacterium Peptoniphilus sp. strain ING2-D1G (DSM 28672), a mesophilic and obligate anaerobic bacterium belonging to the order Clostridiales was isolated from a biogas-producing lab-scale completely stirred tank reactor (CSTR) optimized for anaerobic digestion of maize silage in co-fermentation with pig and cattle manure. In this study, the whole genome sequence of Peptoniphilus sp. strain ING2-D1G, a new isolate potentially involved in protein breakdown and acidogenesis during biomass degradation, is reported. The chromosome of this strain is 1.6Mb in size and encodes genes predicted to be involved in the production of acetate, lactate and butyrate specifying the acidogenic metabolism of the isolate. Copyright © 2014 Elsevier B.V. All rights reserved.

Dispersion/dilution enhances phytoplankton blooms in low-nutrient waters

NASA Astrophysics Data System (ADS)

Lehahn, Yoav; Koren, Ilan; Sharoni, Shlomit; D'Ovidio, Francesco; Vardi, Assaf; Boss, Emmanuel

2017-03-01

Spatial characteristics of phytoplankton blooms often reflect the horizontal transport properties of the oceanic turbulent flow in which they are embedded. Classically, bloom response to horizontal stirring is regarded in terms of generation of patchiness following large-scale bloom initiation. Here, using satellite observations from the North Pacific Subtropical Gyre and a simple ecosystem model, we show that the opposite scenario of turbulence dispersing and diluting fine-scale (~1-100 km) nutrient-enriched water patches has the critical effect of regulating the dynamics of nutrients-phytoplankton-zooplankton ecosystems and enhancing accumulation of photosynthetic biomass in low-nutrient oceanic environments. A key factor in determining ecological and biogeochemical consequences of turbulent stirring is the horizontal dilution rate, which depends on the effective eddy diffusivity and surface area of the enriched patches. Implementation of the notion of horizontal dilution rate explains quantitatively plankton response to turbulence and improves our ability to represent ecological and biogeochemical processes in oligotrophic oceans.

Biodegradation of phenol in synthetic and industrial wastewater by Rhodococcus erythropolis UPV-1 immobilized in an air-stirred reactor with clarifier.

PubMed

Prieto, M B; Hidalgo, A; Rodríguez-Fernández, C; Serra, J L; Llama, M J

2002-05-01

Phenol biodegradation by suspended and immobilized cells of Rhodococcus erythropolis UPV-1 was studied in discontinuous and continuous mode under optimum culture conditions. Phenol-acclimated cells were adsorbed on diatomaceous earth, where they grew actively forming a biofilm of short filaments. Immobilization protected cells against phenol and resulted in a remarkable enhancement of their respiratory activity and a shorter lag phase preceding active phenol degradation. Under optimum operation conditions in a laboratory-scale air-stirred reactor, the immobilized cells were able to completely degrade phenol in synthetic wastewater at a volumetric productivity of 11.5 kg phenol m(-3) day(-1). Phenol biodegradation was also tested in two different industrial wastewaters (WW1 and WW2) obtained from local resin manufacturing companies, which contained both phenols and formaldehyde. In this case, after wastewater conditioning (i.e., dilution, pH, nitrogen and phosphorous sources and micronutrient amendments) the immobilized cells were able to completely remove the formaldehyde present in both waters. Moreover, they biodegraded phenols completely at a rate of 0.5 kg phenol m(-3) day(-1) in the case of WW1 and partially (but at concentrations lower than 50 mg l(-1)) at 0.1 and 1.0 kg phenol m(-3) day(-1) in the cases of WW2 and WW1, respectively.

Continuous hydrogen and methane production from Agave tequilana bagasse hydrolysate by sequential process to maximize energy recovery efficiency.

PubMed

Montiel Corona, Virginia; Razo-Flores, Elías

2018-02-01

Continuous H 2 and CH 4 production in a two-stage process to increase energy recovery from agave bagasse enzymatic-hydrolysate was studied. In the first stage, the effect of organic loading rate (OLR) and stirring speed on volumetric hydrogen production rate (VHPR) was evaluated in a continuous stirred tank reactor (CSTR); by controlling the homoacetogenesis with the agitation speed and maintaining an OLR of 44 g COD/L-d, it was possible to reach a VHPR of 6 L H 2 /L-d, equivalent to 1.34 kJ/g bagasse. In the second stage, the effluent from CSTR was used as substrate to feed a UASB reactor for CH 4 production. Volumetric methane production rate (VMPR) of 6.4 L CH 4 /L-d was achieved with a high OLR (20 g COD/L-d) and short hydraulic retention time (HRT, 14 h), producing 225 mL CH 4 /g-bagasse equivalent to 7.88 kJ/g bagasse. The two-stage continuous process significantly increased energy conversion efficiency (56%) compared to one-stage hydrogen production (8.2%). Copyright © 2017 Elsevier Ltd. All rights reserved.

3D Tracking of Diatom Motion in Turbulent Flow

NASA Astrophysics Data System (ADS)

Variano, E. A.; Brandt, L.; Sardina, G.; Ardekani, M.; Pujara, N.; Ayers, S.; Du Clos, K.; Karp-Boss, L.; Jumars, P. A.

2016-02-01

We present laboratory measurements of single-celled and chain forming diatom motion in a stirred turbulence tank. The overarching goal is to explore whether diatoms track flow with fidelity (passive tracers) or whether interactions with cell density and shape result in biased trajectories that alter settling velocities. Diatom trajectories are recorded in 3D using a stereoscopic, calibrated tracking tool. Turbulence is created in a novel stirred tank, designed to create motions that match those found in the ocean surface mixed layer at scales less than 10 cm. The data are analyzed for evidence of enhanced particle clustering, an indicator of turbulently altered settling rates

Interfacial and Mechanical Behavior of AA5456 Filling Friction-Stir-Welded Lap Joints Using Similar and Dissimilar Pins

NASA Astrophysics Data System (ADS)

Behmand, Saleh Alaei; Mirsalehi, Seyyed Ehsan; Omidvar, Hamid; Safarkhanian, Mohammad Ali

2016-10-01

In this article, filling friction stir welding (FFSW) of the remaining exit holes of AA5456 alloy friction-stir-welded lap joints was studied. For this purpose, the influences of different rotating speeds, holding times, and pin materials, AA5456 and AA2024, on the metallurgical structure and joint strength were investigated. The observations showed that defect-free lap joints are successfully obtainable by this method using similar and dissimilar consumable pins. The results indicated that the higher rotating speed and holding time adversely affect the weld performance. The best result was achieved for 30 seconds holding time, 500 rpm rotating speed, and AA2024 consumable pin. In this condition, a lap shear strength of 10 pct higher than that of the nonfilled joint, equivalent to about 94 pct of the original defect-free FSW joint, was obtained, whereas the GTAW filled joint showed only approximately 87 pct of the continuous FSW joint strength.

Semiconductor nanocrystal quantum dot synthesis approaches towards large-scale industrial production for energy applications

DOE PAGES

Hu, Michael Z.; Zhu, Ting

2015-12-04

This study reviews the experimental synthesis and engineering developments that focused on various green approaches and large-scale process production routes for quantum dots. Fundamental process engineering principles were illustrated. In relation to the small-scale hot injection method, our discussions focus on the non-injection route that could be scaled up with engineering stir-tank reactors. In addition, applications that demand to utilize quantum dots as "commodity" chemicals are discussed, including solar cells and solid-state lightings.

Microstructural Characteristics and Mechanical Properties of Friction Stir Welded Thick 5083 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Imam, Murshid; Sun, Yufeng; Fujii, Hidetoshi; Ma, Ninshu; Tsutsumi, Seiichiro; Murakawa, Hidekazu

2017-01-01

Joining thick sections of aluminum alloys by friction stir welding (FSW) in a single pass needs to overcome many challenges before it comes to full-scale industrial use. Important parameters controlling the structure-properties relationships both across weld cross-section and through thickness direction were investigated through mechanical testing, electron backscatter diffraction technique, transmission electron microscopy, and occurrence of serrated plastic flow. The evolution of the properties in the weld cross-section shows that the presence of undissolved and fragmented Al_6MnFe particles cause discrepancies in establishing the Hall-Petch relationship, and derive the strengthening from the Orowan strengthening mechanism. A `stop action' friction stir weld has been prepared to understand the role of geometrical features of the tool probe in the development of the final microstructure after complete weld. Sectioning through the `stop action' weld with the probe in situ displays the individual effect of thread and flat on the grain structure formation. The material at the thread surface experiences more severe deformation than the material at flat surface. Both the high-angle boundaries and mean grain size are found to be higher at the thread surface. The strain hardening capacity, stress serration amplitude, and frequency are observed to be higher in the stir zone than other weld regions.

Friction Stir Welding of GR-Cop 84 for Combustion Chamber Liners

NASA Technical Reports Server (NTRS)

Russell, Carolyn K.; Carter, Robert; Ellis, David L.; Goudy, Richard

2004-01-01

GRCop-84 is a copper-chromium-niobium alloy developed by the Glenn Research Center for liquid rocket engine combustion chamber liners. GRCop-84 exhibits superior properties over conventional copper-base alloys in a liquid hydrogen-oxygen operating environment. The Next Generation Launch Technology program has funded a program to demonstrate scale-up production capabilities of GR-Cop 84 to levels suitable for main combustion chamber production for the prototype rocket engine. This paper describes a novel method of manufacturing the main combustion chamber liner. The process consists of several steps: extrude the GR-Cop 84 powder into billets, roll the billets into plates, bump form the plates into cylinder halves and friction stir weld the halves into a cylinder. The cylinder is then metal spun formed to near net liner dimensions followed by finish machining to the final configuration. This paper describes the friction stir weld process development including tooling and non-destructive inspection techniques, culminating in the successful production of a liner preform completed through spin forming.

Production of biohythane from food waste via an integrated system of continuously stirred tank and anaerobic fixed bed reactors.

PubMed

Yeshanew, Martha M; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

2016-11-01

The continuous production of biohythane (mixture of biohydrogen and methane) from food waste using an integrated system of a continuously stirred tank reactor (CSTR) and anaerobic fixed bed reactor (AFBR) was carried out in this study. The system performance was evaluated for an operation period of 200days, by stepwise shortening the hydraulic retention time (HRT). An increasing trend of biohydrogen in the CSTR and methane production rate in the AFBR was observed regardless of the HRT shortening. The highest biohydrogen yield in the CSTR and methane yield in the AFBR were 115.2 (±5.3)L H2/kgVSadded and 334.7 (±18.6)L CH4/kgCODadded, respectively. The AFBR presented a stable operation and excellent performance, indicated by the increased methane production rate at each shortened HRT. Besides, recirculation of the AFBR effluent to the CSTR was effective in providing alkalinity, maintaining the pH in optimal ranges (5.0-5.3) for the hydrogen producing bacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

Coproduction of hydrogen and methane via anaerobic fermentation of cornstalk waste in continuous stirred tank reactor integrated with up-flow anaerobic sludge bed.

PubMed

Cheng, Xi-Yu; Li, Qian; Liu, Chun-Zhao

2012-06-01

A 10 L continuous stirred tank reactor (CSTR) system was developed for a two-stage hydrogen fermentation process with an integrated alkaline treatment. The maximum hydrogen production rate reached 218.5 mL/L h at a cornstalk concentration of 30 g/L, and the total hydrogen yield and volumetric hydrogen production rate reached 58.0 mL/g-cornstalk and 0.55-0.57 L/L d, respectively. A 10 L up-flow anaerobic sludge bed (UASB) was used for continuous methane fermentation of the effluents obtained from the two-stage hydrogen fermentation. At the optimal organic loading rate of 15.0 g-COD/Ld, the COD removal efficiency and volumetric biogas production rate reached 83.3% and 4.6L/Ld, respectively. Total methane yield reached 200.9 mL/g-cornstalk in anaerobic fermentation with the effluents and alkaline hydrolysate. As a result, the total energy recovery by coproduction of hydrogen and methane with anaerobic fermentation of cornstalk reached 67.1%. Copyright © 2012 Elsevier Ltd. All rights reserved.

MSVAT-SPACE-STIR and SEMAC-STIR for Reduction of Metallic Artifacts in 3T Head and Neck MRI.

PubMed

Hilgenfeld, T; Prager, M; Schwindling, F S; Nittka, M; Rammelsberg, P; Bendszus, M; Heiland, S; Juerchott, A

2018-05-24

The incidence of metallic dental restorations and implants is increasing, and head and neck MR imaging is becoming challenging regarding artifacts. Our aim was to evaluate whether multiple-slab acquisition with view angle tilting gradient based on a sampling perfection with application-optimized contrasts by using different flip angle evolution (MSVAT-SPACE)-STIR and slice-encoding for metal artifact correction (SEMAC)-STIR are beneficial regarding artifact suppression compared with the SPACE-STIR and TSE-STIR in vitro and in vivo. At 3T, 3D artifacts of 2 dental implants, supporting different single crowns, were evaluated. Image quality was evaluated quantitatively (normalized signal-to-noise ratio) and qualitatively (2 reads by 2 blinded radiologists). Feasibility was tested in vivo in 5 volunteers and 5 patients, respectively. Maximum achievable resolution and the normalized signal-to-noise ratio of MSVAT-SPACE-STIR were higher compared with SEMAC-STIR. Performance in terms of artifact correction was dependent on the material composition. For highly paramagnetic materials, SEMAC-STIR was superior to MSVAT-SPACE-STIR (27.8% smaller artifact volume) and TSE-STIR (93.2% less slice distortion). However, MSVAT-SPACE-STIR reduced the artifact size compared with SPACE-STIR by 71.5%. For low-paramagnetic materials, MSVAT-SPACE-STIR performed as well as SEMAC-STIR. Furthermore, MSVAT-SPACE-STIR decreased artifact volume by 69.5% compared with SPACE-STIR. The image quality of all sequences did not differ systematically. In vivo results were comparable with in vitro results. Regarding susceptibility artifacts and acquisition time, MSVAT-SPACE-STIR might be advantageous over SPACE-STIR for high-resolution and isotropic head and neck imaging. Only for materials with high-susceptibility differences to soft tissue, the use of SEMAC-STIR might be beneficial. Within limited acquisition times, SEMAC-STIR cannot exploit its full advantage over TSE-STIR regarding artifact suppression. © 2018 by American Journal of Neuroradiology.

Cuprous Oxide Scale up: Gram Production via Bulk Synthesis using Classic Solvents at Low Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, A.; Han, T. Y.

Cuprous oxide is a p-type semiconducting material that has been highly researched for its interesting properties. Many small-scale syntheses have exhibited excellent control over size and morphology. As the demand for cuprous oxide grows, the synthesis method need to evolve to facilitate large-scale production. This paper supplies a facile bulk synthesis method for Cu₂O on average, 1-liter reaction volume can produce 1 gram of particles. In order to study the shape and size control mechanisms on such a scale, the reaction volume was diminished to 250 mL producing on average 0.3 grams of nanoparticles per batch. Well-shaped nanoparticles have beenmore » synthesized using an aqueous solution of CuCl₂, NaOH, SDS surfactant, and NH₂OH-HCl at mild temperatures. The time allotted between the addition of NaOH and NH₂OH-HCl was determined to be critical for Cu(OH)2 production, an important precursor to the final produce The effects of stirring rates on a large scale was also analyzed during reagent addition and post reagent addition. A morphological change from rhombic dodecahedra to spheres occurred as the stirring speed was increased. The effects of NH₂OH-HCl concentration were also studied to control the etching effects of the final product.« less

Theoretical and Practical Issues That Are Relevant When Scaling Up hMSC Microcarrier Production Processes

PubMed Central

Jossen, Valentin; Schirmer, Cedric; Mostafa Sindi, Dolman; Eibl, Regine; Kraume, Matthias; Pörtner, Ralf; Eibl, Dieter

2016-01-01

The potential of human mesenchymal stem cells (hMSCs) for allogeneic cell therapies has created a large amount of interest. However, this presupposes the availability of efficient scale-up procedures. Promising results have been reported for stirred bioreactors that operate with microcarriers. Recent publications focusing on microcarrier-based stirred bioreactors have demonstrated the successful use of Computational Fluid Dynamics (CFD) and suspension criteria (N S1u, N S1) for rapidly scaling up hMSC expansions from mL- to pilot scale. Nevertheless, one obstacle may be the formation of large microcarrier-cell-aggregates, which may result in mass transfer limitations and inhomogeneous distributions of stem cells in the culture broth. The dependence of microcarrier-cell-aggregate formation on impeller speed and shear stress levels was investigated for human adipose derived stromal/stem cells (hASCs) at the spinner scale by recording the Sauter mean diameter (d 32) versus time. Cultivation at the suspension criteria provided d 32 values between 0.2 and 0.7 mm, the highest cell densities (1.25 × 106 cells mL−1 hASCs), and the highest expansion factors (117.0 ± 4.7 on day 7), while maintaining the expression of specific surface markers. Furthermore, suitability of the suspension criterion N S1u was investigated for scaling up microcarrier-based processes in wave-mixed bioreactors for the first time. PMID:26981131

Chondral lesions in the patellofemoral joint in MRI: Intra-individual comparison of short-tau inversion recovery sequence (STIR) with 2D multiple-echo data image combination sequence (MEDIC).

PubMed

Bodelle, Boris; Luboldt, Wolfgang; Wichmann, Julian L; Fischer, Sebastian; Vogl, Thomas J; Beeres, Martin

2016-01-01

To determine the value of the 2D multiple-echo data image combination (MEDIC) sequence relative to the short-tau inversion recovery (STIR) sequence regarding the depiction of chondral lesions in the patellofemoral joint. During a period of 6 month patients with acute pain at the anterior aspect of the knee, joint effusion and suspected chondral lesion defect in the patellofemoral joint underwent MRI including axial MEDIC and STIR imaging. Patients with chondral lesions in the patellofemoral joint on at least one sequence were included. The MEDIC and STIR sequence were quantitatively compared regarding the patella cartilage-to-effusion contrast-to-noise ratio (CNR) and qualitatively regarding the depiction of chondral lesions independently scored by two radiologists on a 3-point scale (1 = not depicted; 2 = blurred depicted; 3 = clearly depicted) using the Wilcoxon-Mann-Whitney-Test. For the analysis of inter-observer agreement the Cohen's Weighted Kappa test was used. 30 of 58 patients (male: female, 21:9; age: 44 ± 12 yrs) revealed cartilage lesions (fissures, n = 5 including fibrillation; gaps, n = 15; delamination, n = 7; osteoarthritis, n = 3) and were included in this study. The STIR-sequence was significantly (p < 0.001) superior to the MEDIC-sequence regarding both, the patella cartilage-to-effusion CNR (mean CNR: 232 ± 61 vs. 40 ± 16) as well as the depiction of chondral lesion (mean score: 2.83 ± 0.4 vs. 1.75 ± 0.7) with substantial inter-observer agreement in the rating of both sequences (κ = 0.76-0.89). For the depiction of chondral lesions in the patellofemoral joint, the axial STIR-sequence should be chosen in preference to the axial MEDIC-sequence.

Method for multi-axis, non-contact mixing of magnetic particle suspensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, James E.; Solis, Kyle J.

Continuous, three-dimensional control of the vorticity vector is possible by progressively transitioning the field symmetry by applying or removing a dc bias along one of the principal axes of mutually orthogonal alternating fields. By exploiting this transition, the vorticity vector can be oriented in a wide range of directions that comprise all three spatial dimensions. Detuning one or more field components to create phase modulation causes the vorticity vector to trace out complex orbits of a wide variety, creating very robust multiaxial stirring. This multiaxial, non-contact stirring is particularly attractive for applications where the fluid volume has complex boundaries, ormore » is congested.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azhar, A.; Hamdy, M.K.

Use of ultrafiltration membrane systems in stirred cell and in thin-channel systems for immobilizing enzyme (sweet potato intrinsic and crystalline beta-amylase) in hydrolysis of sweet potato through a continuous operation mode were studied. Both the filtration rate and reducing sugars, produced as the result of enzymic hydrolysis, decreased with the filtration time. The immobilized enzymes in the thin-channel system showed a much better performance compared to that in the stirred cell system. Addition of crystalline sweet potato beta-amylase to the sweet potato increased both the filtration rate and reducing-sugars content. Alcohol fermentation of the filtrate resulted in an alcohol contentmore » of 4.2%. This represented fermentation of 95% of the sugars with an efficiency of 88%.« less

Survival of Alternaria alternata during anaerobic digestion of biomass in stirred tank reactors.

PubMed

Schleusner, Y; Bandte, M; Gossmann, M; Heiermann, M; Plöchl, M; Büttner, C

2012-01-01

The survival of Alternaria alternate during anaerobic digestion was investigated in context of a joint research project. The aim of this project was to estimate the phytosanitary risk of dissemination of pathogens by returning treated biomass as organic fertilizer to arable land. The studies were carried out in lab-scale stirred tank reactors under mesophilic conditions. After insertion of infected plant material into the reactors the influence on the viability of the fungal pathogen was studied concerning exposure time, pretreatment and storage of the digestates for four weeks or six months. The results clearly showed that anaerobic digestion leads to a complete inactivation of A. alternate already after an exposure time of six hours.

Steel refining possibilities in LF

NASA Astrophysics Data System (ADS)

Dumitru, M. G.; Ioana, A.; Constantin, N.; Ciobanu, F.; Pollifroni, M.

2018-01-01

This article presents the main possibilities for steel refining in Ladle Furnace (LF). These, are presented: steelmaking stages, steel refining through argon bottom stirring, online control of the bottom stirring, bottom stirring diagram during LF treatment of a heat, porous plug influence over the argon stirring, bottom stirring porous plug, analysis of porous plugs disposal on ladle bottom surface, bottom stirring simulation with ANSYS, bottom stirring simulation with Autodesk CFD.

Consultancy on Large-Scale Submerged Aerobic Cultivation Process Design - Final Technical Report: February 1, 2016 -- June 30, 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crater, Jason; Galleher, Connor; Lievense, Jeff

NREL is developing an advanced aerobic bubble column model using Aspen Custom Modeler (ACM). The objective of this work is to integrate the new fermentor model with existing techno-economic models in Aspen Plus and Excel to establish a new methodology for guiding process design. To assist this effort, NREL has contracted Genomatica to critique and make recommendations for improving NREL's bioreactor model and large scale aerobic bioreactor design for biologically producing lipids at commercial scale. Genomatica has highlighted a few areas for improving the functionality and effectiveness of the model. Genomatica recommends using a compartment model approach with an integratedmore » black-box kinetic model of the production microbe. We also suggest including calculations for stirred tank reactors to extend the models functionality and adaptability for future process designs. Genomatica also suggests making several modifications to NREL's large-scale lipid production process design. The recommended process modifications are based on Genomatica's internal techno-economic assessment experience and are focused primarily on minimizing capital and operating costs. These recommendations include selecting/engineering a thermotolerant yeast strain with lipid excretion; using bubble column fermentors; increasing the size of production fermentors; reducing the number of vessels; employing semi-continuous operation; and recycling cell mass.« less

Culture scale-up and immobilisation of a mixed methanotrophic consortium for methane remediation in pilot-scale bio-filters.

PubMed

Karthikeyan, Obulisamy Parthiba; Saravanan, Nadarajan; Cirés, Samuel; Alvarez-Roa, Carlos; Razaghi, Ali; Chidambarampadmavathy, Karthigeyan; Velu, Chinnathambi; Subashchandrabose, Gobalakrishnan; Heimann, Kirsten

2017-02-01

Robust methanotrophic consortia for methane (CH 4 ) remediation and by-product development are presently not readily available for industrial use. In this study, a mixed methanotrophic consortium (MMC), sequentially enriched from a marine sediment, was assessed for CH 4 removal efficiency and potential biomass-generated by-product development. Suitable packing material for bio-filters to support MMC biofilm establishment and growth was also evaluated. The enriched MMC removed ∼7-13% CH 4 under a very high gas flow rate (2.5 L min -1 ; 20-25% CH 4 ) in continuous-stirred tank reactors (∼10 L working volume) and the biomass contained long-chain fatty acids (i.e. C 16 and C 18 ). Cultivation of the MMC on plastic bio-balls abated ∼95-97% CH 4 in pilot-scale non-sterile outdoor-operated bio-filters (0.1 L min -1 ; 1% CH 4 ). Contamination by cyanobacteria had beneficial effects on treating low-level CH 4 , by providing additional oxygen for methane oxidation by MMC, suggesting that the co-cultivation of MMC with cyanobacterial mats does not interfere with and may actually be beneficial for remediation of CH 4 and CO 2 at industrial scale.

Development of Surface Nanocomposite Based on Al-Ni-O Ternary System on Al6061 Alloy by Friction-Stir Processing and Evaluation of Its Properties

NASA Astrophysics Data System (ADS)

Adel Mehraban, F.; Karimzadeh, F.; Abbasi, M. H.

2015-05-01

In this study, an Al/Al2O3-Al3Ni hybrid nanocomposite was developed on the surface of Al6061-T6 plate with preplaced NiO powder on its surface using friction-stir processing (FSP). The x-ray diffraction results showed that NiO particles were reduced by Al during FSP and Al3Ni and Al2O3 were formed as in situ reaction products. A thermodynamic analysis indicated that the reaction is thermodynamically possible and exothermic. Thus, the reaction that is initiated by the severe plastic deformation and friction associated with FSP could continue by the heat that is generated by the exothermic reaction. During each FSP pass, the FSP products are detached quickly from the interface and the growth of the particles is limited and nanometer-sized reinforcements were produced. The presence of facet and hexagonal nanoparticles in transmission electron microscopy micrographs of the stir zone confirmed the formation of Al3Ni and Al2O3 nanoreinforcements, respectively. Mechanical test results showed that the microhardness and ultimate tensile strength in the stir zone of nanocomposite decreased due to the dissolution of precipitates in Al6061-T6 during FSP. The tribological properties of Al6061 at 350°C were significantly improved by developing surface Al/Al2O3-Al3Ni nanocomposite.

Comparison of start-up strategies and process performance during semi-continuous anaerobic digestion of sugarcane filter cake co-digested with bagasse.

PubMed

Janke, Leandro; Leite, Athaydes F; Nikolausz, Marcell; Radetski, Claudemir M; Nelles, Michael; Stinner, Walter

2016-02-01

The anaerobic digestion of sugarcane filter cake and the option of co-digestion with bagasse were investigated in a semi-continuous feeding regime to assess the main parameters used for large-scale process designing. Moreover, fresh cattle manure was considered as alternative inoculum for the start-up of biogas reactors in cases where digestate from a biogas plant would not be available in remote rural areas. Experiments were carried out in 6 lab-scale semi-continuous stirred-tank reactors at mesophilic conditions (38±1°C) while the main anaerobic digestion process parameters monitored. Fresh cattle manure demonstrated to be appropriate for the start-up process. However, an acclimation period was required due to the high initial volatile fatty acids concentration (8.5gL(-1)). Regardless the mono-digestion of filter cake presented 50% higher biogas yield (480mLgVS(-1)) than co-digestion with bagasse (320mLgVS(-1)) during steady state conditions. A large-scale co-digestion system would produce 58% more biogas (1008m(3)h(-1)) than mono-digestion of filter cake (634m(3)h(-1)) due to its higher biomass availability for biogas conversion. Considering that the biogas production rate was the technical parameter that displayed the most relevant differences between the analyzed substrate options (0.99-1.45m(3)biogasm(3)d(-1)). The decision of which substrate option should be implemented in practice would be mainly driven by the available construction techniques, since economically efficient tanks could compensate the lower biogas production rate of co-digestion option. Copyright © 2015 Elsevier Ltd. All rights reserved.

Teaching Simulation and Modelling at Royal Military College.

ERIC Educational Resources Information Center

Bonin, Hugues W.; Weir, Ronald D.

1984-01-01

Describes a course designed to assist students in writing differential equations to represent chemical processes and to solve these problems on digital computers. Course outline and discussion of computer projects and the simulation and optimization of a continuously stirred tank reactor process are included. (JN)

METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: II. MODEL DEVELOPMENT AND VERIFICATION

EPA Science Inventory

A comprehensive dynamic model is presented that simulates methanogenesis and sulfate reduction in a continuously stirred tank reactor (CSTR). This model incorporates the complex chemistry of anaerobic systems. A salient feature of the model is its ability to predict the effluent ...

AEROBIC BIODEGRADATION OF GASOLINE OXYGENATES MTBE AND TBA

EPA Science Inventory

MTBE degradation was investigated using a continuously stirred tank reactor (CSTR) with biomass retention (porous pot reactor) operated under aerobic conditions. MTBE was fed to the reactor at an influent concentration of 150 mg/l (1.70 mmol/l). A second identifical rector was op...

Two-Compartment Pharmacokinetic Models for Chemical Engineers

ERIC Educational Resources Information Center

Kanneganti, Kumud; Simon, Laurent

2011-01-01

The transport of potassium permanganate between two continuous-stirred vessels was investigated to help chemical and biomedical engineering students understand two-compartment pharmacokinetic models. Concepts of modeling, mass balance, parameter estimation and Laplace transform were applied to the two-unit process. A good agreement was achieved…

Fluid dynamic analysis of a continuous stirred tank reactor for technical optimization of wastewater digestion.

PubMed

Hurtado, F J; Kaiser, A S; Zamora, B

2015-03-15

Continuous stirred tank reactors (CSTR) are widely used in wastewater treatment plants to reduce the organic matter and microorganism present in sludge by anaerobic digestion. The present study carries out a numerical analysis of the fluid dynamic behaviour of a CSTR in order to optimize the process energetically. The characterization of the sludge flow inside the digester tank, the residence time distribution and the active volume of the reactor under different criteria are determined. The effects of design and power of the mixing system on the active volume of the CSTR are analyzed. The numerical model is solved under non-steady conditions by examining the evolution of the flow during the stop and restart of the mixing system. An intermittent regime of the mixing system, which kept the active volume between 94% and 99%, is achieved. The results obtained can lead to the eventual energy optimization of the mixing system of the CSTR. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biohydrogen production from waste bread in a continuous stirred tank reactor: A techno-economic analysis.

PubMed

Han, Wei; Hu, Yun Yi; Li, Shi Yi; Li, Fei Fei; Tang, Jun Hong

2016-12-01

Biohydrogen production from waste bread in a continuous stirred tank reactor (CSTR) was techno-economically assessed. The treating capacity of the H 2 -producing plant was assumed to be 2 ton waste bread per day with lifetime of 10years. Aspen Plus was used to simulate the mass and energy balance of the plant. The total capital investment (TCI), total annual production cost (TAPC) and annual revenue of the plant were USD931020, USD299746/year and USD639920/year, respectively. The unit hydrogen production cost was USD1.34/m 3 H 2 (or USD14.89/kg H 2 ). The payback period and net present value (NPV) of the plant were 4.8years and USD1266654, respectively. Hydrogen price and operators cost were the most important variables on the NPV. It was concluded that biohydrogen production from waste bread in the CSTR was feasible for practical application. Copyright © 2016 Elsevier Ltd. All rights reserved.

Continuous-flow stirred-tank reactor 20-L demonstration test: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, D.D.; Collins, J.L.

One of the proposed methods of removing the cesium, strontium, and transuranics from the radioactive waste storage tanks at Savannah River is the small-tank tetraphenylborate (TPB) precipitation process. A two-reactor-in-series (15-L working volume each) continuous-flow stirred-tank reactor (CSTR) system was designed, constructed, and installed in a hot cell to test the Savannah River process. The system also includes two cross-flow filtration systems to concentrate and wash the slurry produced in the process, which contains the bulk of radioactivity from the supernatant processed through the system. Installation, operational readiness reviews, and system preparation and testing were completed. The first test usingmore » the filtration systems, two CSTRs, and the slurry concentration system was conducted over a 61-h period with design removal of Cs, Sr, and U achieved. With the successful completion of Test 1a, the following tests, 1b and 1c, were not required.« less

Globally linearized control on diabatic continuous stirred tank reactor: a case study.

PubMed

Jana, Amiya Kumar; Samanta, Amar Nath; Ganguly, Saibal

2005-07-01

This paper focuses on the promise of globally linearized control (GLC) structure in the realm of strongly nonlinear reactor system control. The proposed nonlinear control strategy is comprised of: (i) an input-output linearizing state feedback law (transformer), (ii) a state observer, and (iii) an external linear controller. The synthesis of discrete-time GLC controller for single-input single-output diabatic continuous stirred tank reactor (DCSTR) has been studied first, followed by the synthesis of feedforward/feedback controller for the same reactor having dead time in process as well as in disturbance. Subsequently, the multivariable GLC structure has been designed and then applied on multi-input multi-output DCSTR system. The simulation study shows high quality performance of the derived nonlinear controllers. The better-performed GLC in conjunction with reduced-order observer has been compared with the conventional proportional integral controller on the example reactor and superior performance has been achieved by the proposed GLC control scheme.

Effect of organic loading rate on dark fermentative hydrogen production in the continuous stirred tank reactor and continuous mixed immobilized sludge reactor from waste pastry hydrolysate.

PubMed

Han, Wei; Hu, Yunyi; Li, Shiyi; Nie, Qiulin; Zhao, Hongting; Tang, Junhong

2016-12-01

Waste pastry (6%, w/v) was hydrolyzed by the produced glucoamylase and protease to obtain the glucose (19.8g/L) and free amino nitrogen (179mg/L) solution. Then, the effect of organic loading rate (OLR) (8-40kgCOD/(m 3 d)) on dark fermentative hydrogen production in the continuous stirred tank reactor (CSTR) and continuous mixed immobilized sludge reactor (CMISR) from waste pastry hydrolysate was investigated and compared. The maximum hydrogen production rate of CSTR (277.76mL/(hL)) and CMISR (320.2mL/(hL)) were achieved at OLR of 24kgCOD/(m 3 d) and 32kgCOD/(m 3 d), respectively. Carbon recovery ranged from 75.2-84.1% in the CSTR and CMISR with the balance assumed to be converted to biomass. One gram waste pastry could produce 0.33g (1.83mmol) glucose which could be further converted to 79.24mL (3.54mmol) hydrogen in the CMISR or 91.66mL (4.09mmol) hydrogen in the CSTR. This is the first study which reports dark fermentative hydrogen production from waste pastry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Genesis of Microstructures in Friction Stir Welding of Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Tchein, Gnofam Jacques; Jacquin, Dimitri; Coupard, Dominique; Lacoste, Eric; Girot Mata, Franck

2018-06-01

This paper is focused on the genesis of microstructures in friction stir welding (FSW) of the Ti-6Al-4V alloy. Several titanium joints, initially prepared with four different preheat treatments, were processed by FSW. Detailed microstructural analyses were performed in order to investigate change in the microstructure during the process. In this work, the FSW processing allows a controlled and stable microstructure to be produced in the stirring zone, regardless of the initial heat treatment or the welding conditions. The welded material undergoes a severe thermomechanical treatment which can be divided into two steps. First, the friction in the shoulder and the plastic strain give rise to the necessary conditions to allow a continuous dynamic recrystallization of the β phase. This operation produces a fine and equiaxed β grain structure. Second, once the pin has moved away, the temperature decreases, and the material undergoes a heat treatment equivalent to air quenching. The material thus exhibits a β → β + α transformation with germination of a fine intergranular Widmanstätten phase within the ex-fully-recrystallized- β grains.

Mesophilic and thermophilic anaerobic co-digestion of rendering plant and slaughterhouse wastes.

PubMed

Bayr, Suvi; Rantanen, Marianne; Kaparaju, Prasad; Rintala, Jukka

2012-01-01

Co-digestion of rendering and slaughterhouse wastes was studied in laboratory scale semi-continuously fed continuously stirred tank reactors (CSTRs) at 35 and 55 °C. All in all, 10 different rendering plant and slaughterhouse waste fractions were characterised showing high contents of lipids and proteins, and methane potentials of 262-572 dm(3)CH(4)/kg volatile solids(VS)(added). In mesophilic CSTR methane yields of ca 720 dm(3) CH(4)/kg VS(fed) were obtained with organic loading rates (OLR) of 1.0 and 1.5 kg VS/m(3) d, and hydraulic retention time (HRT) of 50 d. For thermophilic process, the lowest studied OLR of 1.5 kg VS/m(3) d, turned to be unstable after operation of 1.5 HRT, due to accumulating ammonia, volatile fatty acids (VFAs) and probably also long chain fatty acids (LCFAs). In conclusion, mesophilic process was found to be more feasible for co-digestion than thermophilic process, methane yields being higher and process more stable in mesophilic conditions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Scale-up synthesis of zinc borate from the reaction of zinc oxide and boric acid in aqueous medium

NASA Astrophysics Data System (ADS)

Kılınç, Mert; Çakal, Gaye Ö.; Yeşil, Sertan; Bayram, Göknur; Eroğlu, İnci; Özkar, Saim

2010-11-01

Synthesis of zinc borate was conducted in a laboratory and a pilot scale batch reactor to see the influence of process variables on the reaction parameters and the final product, 2ZnO·3B 2O 3·3.5H 2O. Effects of stirring speed, presence of baffles, amount of seed, particle size and purity of zinc oxide, and mole ratio of H 3BO 3:ZnO on the zinc borate formation reaction were examined at a constant temperature of 85 °C in a laboratory (4 L) and a pilot scale (85 L) reactor. Products obtained from the reaction in both reactors were characterized by chemical analysis, X-ray diffraction, particle size distribution analysis, thermal gravimetric analysis and scanning electron microscopy. The kinetic data for the zinc borate production reaction was fit by using the logistic model. The results revealed that the specific reaction rate, a model parameter, decreases with increase in particle size of zinc oxide and the presence of baffles, but increases with increase in stirring speed and purity of zinc oxide; however, it is unaffected with the changes in the amount of seed and reactants ratio. The reaction completion time is unaffected by scaling-up.

Potential development of compressed bio-methane gas production from pig farms and elephant grass silage for transportation in Thailand.

PubMed

Dussadee, Natthawud; Reansuwan, Kamoldara; Ramaraj, Rameshprabu

2014-03-01

This research project evaluated biogas production using anaerobic co-digestion of pig manure and elephant grass silage in large scale to delivered transportation directly for cars. Anaerobic co-digestion was estimated in three full-scale continuously stirred tank reactors (CSTRs) at 40°C. In the form of compressed bio-methane gas (CBG) production was 14,400m(3)/day (CH4 60-70%) amount of CBG was 9600m(3)/day. The procedure was enhanced by using molecular sieve, activated carbon for removal of moisture and CO2 membrane H2S and CO2 respectively. The results were demonstrated the amount of CO2, H2S gas was reduced along with CH4 was improved up to 90% by volume and compressed to 250bar tank pressure gauge to the fuel for cars. The CBG production, methane gas improvement and performance were evaluated before entering the delivered systems according to the energy standards. The production of CBG is advantageous to strengthen the Thailand biogas market. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stable operation during pilot-scale anaerobic digestion of nutrient-supplemented maize/sugar beet silage.

PubMed

Nges, Ivo Achu; Björn, Annika; Björnsson, Lovisa

2012-08-01

Biogas production from maize/sugar beet silage was studied under mesophilic conditions in a continuous stirred tank reactor pilot-scale process. While energy crop mono-digestion is often performed with very long hydraulic retention times (HRTs), the present study demonstrated an efficient process operating with a 50-day HRT and a corrected total solids (TS(corr)) based organic loading rate of 3.4 kg/m(3)d. The good performance was attributed to supplementation with both macro- and micronutrients and was evidenced by good methane yields (318 m(3)/ton TS(corr)), which were comparable to laboratory maximum expected yields, plus low total volatile fatty acid concentrations (<0.8 g/L). A viscoplastic and thixotropic digester fluid behaviour was observed, and the viscosity problems common in crop mono-digestion were not seen in this study. The effluent also complied with Swedish certification standards for bio-fertilizer for farmland application. Nutrient addition thus rendered a stable biogas process, while the effluent was a good quality bio-fertilizer. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mass flow and energy balance plus economic analysis of a full-scale biogas plant in the rice-wine-pig system.

PubMed

Li, Jiang; Kong, Chuixue; Duan, Qiwu; Luo, Tao; Mei, Zili; Lei, Yunhui

2015-10-01

This paper presents mass flow and energy balance as well as an economic analysis for a biogas plant in a rice-wine-pig system at a practical rather than laboratory scale. Results showed feeding amount was 65.30 t d(-1) (total solid matter (TSM) 1.3%) for the normal temperature continuous stirred tank reactor (CSTR), and 16.20 t d(-1) (TSM 8.4%) for the mesophilic CSTR. The digestion produced 80.50 t d(-1) of mass, with 76.41 t d(-1) flowing into rice fields and 4.49 t d(-1) into composting. Energy consumption of this plant fluctuated with seasons, and surplus energy was 823, 221 kWh/year. Thus, biogas plant was critical for material recycling and energy transformation of this agro-ecosystem. The economic analysis showed that the payback time of the plant was 10.9 years. It also revealed application of biogas as a conventional energy replacement would be attractive for a crop-wine-livestock ecosystem with anaerobic digestion of manure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of Microcrystals of Piroxicam Monohydrate by Antisolvent Precipitation via Microfabricated Metallic Membranes with Ordered Pore Arrays.

PubMed

Othman, Rahimah; Vladisavljević, Goran T; Simone, Elena; Nagy, Zoltan K; Holdich, Richard G

2017-12-06

Microcrystals of piroxicam (PRX) monohydrate with a narrow size distribution were prepared from acetone/PRX solutions by antisolvent crystallization via metallic membranes with ordered pore arrays. Crystallization was achieved by controlled addition of the feed solution through the membrane pores into a well-stirred antisolvent. A complete transformation of an anhydrous form I into a monohydrate form of PRX was confirmed by Raman spectroscopy and differential scanning calorimetry. The size of the crystals was 7-34 μm and was controlled by the PRX concentration in the feed solution (15-25 g L -1 ), antisolvent/solvent volume ratio (5-30), and type of antisolvent (Milli-Q water or 0.1-0.5 wt % aqueous solutions of hydroxypropyl methyl cellulose (HPMC), poly(vinyl alcohol) or Pluronic P-123). The smallest crystals were obtained by injecting 25 g L -1 PRX solution through a stainless-steel membrane with a pore size of 10 μm into a 0.06 wt % HPMC solution stirred at 1500 rpm using an antisolvent/solvent ratio of 20. HPMC provided better steric stabilization of microcrystals against agglomeration than poly(vinyl alcohol) and Pluronic P-123, due to hydrogen bonding interactions with PRX and water. A continuous production of large PRX monohydrate microcrystals with a volume-weighted mean diameter above 75 μm was achieved in a continuous stirred membrane crystallizer. Rapid pouring of Milli-Q water into the feed solution resulted in a mixture of highly polydispersed prism-shaped and needle-shaped crystals.

Development and performance of an alternative biofilter system.

PubMed

Lee, D H; Lau, A K; Pinder, K L

2001-01-01

Step tracer tests were carried out on lab-scale biofilters to determine the residence time distributions (RTDs) of gases passing through two types of biofilters: a standard biofilter with vertical gas flow and a modified biofilter with horizontal gas flow. Results were used to define the flow patterns in the reactors. "Non-ideal flow" indicates that the flow reactors did not behave like either type of ideal reactor: the perfectly stirred reactor [often called a "continuously stirred tank reactor" (CSTR)] or the plug-flow reactor. The horizontal biofilter with back-mixing was able to accommodate a shorter residence time without the usual requirement of greater biofilter surface area for increased biofiltration efficiency. Experimental results indicated that the first bed of the modified biofilter behaved like two CSTRs in series, while the second bed may be represented by two or three CSTRs in series. Because of the flow baffles used in the horizontal biofilter system, its performance was more similar to completely mixed systems, and hence, it could not be modeled as a plug-flow reactor. For the standard biofilter, the number of CSTRs was found to be between 2 and 9 depending on the airflow rate. In terms of NH3 removal efficiency and elimination capacity, the standard biofilter was not as good as the modified system; moreover, the second bed of the modified biofilter exhibited greater removal efficiency than the first bed. The elimination rate increased as biofilter load increased. An opposite trend was exhibited with respect to removal efficiency.

Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Formed Domes

NASA Technical Reports Server (NTRS)

Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

2010-01-01

Simulated service testing (SST) development was required to help qualify a new 2195 aluminum lithium (Al-Li) alloy spin forming dome fabrication process for the National Aeronautics and Space Administration (NASA) Exploration Development Technology Program. The application for the technology is to produce high strength low weight tank components for NASA s next generation launch vehicles. Since plate material is not currently manufactured large enough to fabricate these domes, two plates are joined by means of friction stir welding. The plates are then pre-contour machined to near final thicknesses allowing for a thicker weld land and anticipating the level of stretch induced by the spin forming process. The welded plates are then placed in a spin forming tool and hot stretched using a trace method producing incremental contours. Finally the dome receives a room temperature contour stretch to final dimensions, heat treatment, quenching, and artificial aging to emulate a T-8 condition of temper. Stress corrosion cracking (SCC) tests were also performed by alternate immersion in a sodium chloride (NaCl) solution using the typical double beam assembly and with 4-point loaded specimens and use of bent-beam stress-corrosion test specimens under alternate immersion conditions. In addition, experiments were conducted to determine the threshold stress intensity factor for SCC (K(sub ISCC)) which to our knowledge has not been determined previously for Al-Li 2195 alloy. The successful simulated service and stress corrosion testing helped to provide confidence to continue to Ares 1 scale dome fabrication

Biosurfactant production by Aureobasidium pullulans in stirred tank bioreactor: New approach to understand the influence of important variables in the process.

PubMed

Brumano, Larissa Pereira; Antunes, Felipe Antonio Fernandes; Souto, Sara Galeno; Dos Santos, Júlio Cesar; Venus, Joachim; Schneider, Roland; da Silva, Silvio Silvério

2017-11-01

Surfactants are amphiphilic molecules with large industrial applications produced currently by chemical routes mainly derived from oil industry. However, biotechnological process, aimed to develop new sustainable process configurations by using favorable microorganisms, already requires investigations in more details. Thus, we present a novel approach for biosurfactant production using the promising yeast Aureobasidium pullulans LB 83, in stirred tank reactor. A central composite face-centered design was carried out to evaluate the effect of the aeration rate (0.1-1.1min -1 ) and sucrose concentration (20-80g.L -1 ) in the biosurfactant maximum tensoactivity and productivity. Statistical analysis showed that the use of variables at high levels enhanced tensoactivity, showing 8.05cm in the oil spread test and productivity of 0.0838cm.h -1 . Also, unprecedented investigation of aeration rate and sucrose concentration relevance in biosurfactant production by A. pullulans in stirred tank reactor was detailed, demonstrating the importance to establish adequate conditions in bioreactors, aimed to scale-up process. Copyright © 2017 Elsevier Ltd. All rights reserved.

7 CFR 58.735 - Quality specifications for raw materials.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 3 2011-01-01 2011-01-01 false Quality specifications for raw materials. 58.735 Section 58.735 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING... specifications for raw materials. (a) Cheddar colby, washed or soaked curd, granular or stirred curd cheese...

Drug Transport and Pharmacokinetics for Chemical Engineers

ERIC Educational Resources Information Center

Simon, Laurent; Kanneganti, Kumud; Kim, Kwang Seok

2010-01-01

Experiments in continuous-stirred vessels were proposed to introduce methods in pharmacokinetics and drug transport to chemical engineering students. The activities can be incorporated into the curriculum to illustrate fundamentals learned in the classroom. An appreciation for the role of pharmacokinetics in drug discovery will also be gained…

Solidification structures grown under induced flow and continuous casting of steel

NASA Technical Reports Server (NTRS)

Tsavaras, A. A.

1984-01-01

The use of induced flow as a means to control solidification structures in strand cast steel is investigated. The quality problems in strand cast steel stemming from columnar growth can be partially controlled, by Electro Magnetic Stirring (EMS). Induced flow changes the normal morphology of dendrites. Solids grown under intense stirring conditions show both negative and positive segregation which is considered unacceptable by some steel producers. The inclusion size and population is strongly affected by induced flow (EMS). Laboratory and industrial data show substantial reduction in inclusion size and content, but the overall effect of flow on inclusions is affected by the particular type of flow patterns utilized in each case. Productivity and quality are raised substantially in steel strand casting by utilizing EMS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azhar, A.; Hamdy, M.K.

Use of ultrafiltration membrane systems in stirred cell and in thin-channel systems for immobilizing enzyme (sweet potato intrinsic and crystalline /beta/-amylase) in hydrolysis of sweet potato through a continuous operation mode were studied. Both the filtration rate and reducing sugars, produced as the result of enzymatic hydrolysis, decreased with the filtration time. THe immobilized enzymes in the thin-channel system showed a much better performance compared to that in the stirred cell system. Addition of crystalline sweet potato /beta/-amylase to the sweet potato increased both the filtration rate and reducing-sugars content. Alcoholic fermentation of the filtrate resulted in an alcohol contentmore » of 4.2%. This represented fermentation of 95% of the sugars with an efficiency of 88%. 17 refs.« less

High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

NASA Astrophysics Data System (ADS)

Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

2015-05-01

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high volumes. While friction-stir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of high-volume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

Nano-Sized Grain Refinement Using Friction Stir Processing

DTIC Science & Technology

2013-03-01

friction stir weld is a very fine grain microstructure produced as a result of dynamic recrystallization. The friction stir ... Friction Stir Processing, Magnesium, Nano-size grains Abstract A key characteristic of a friction stir weld is a very fine grain microstructure...state process developed on the basis of the friction stir welding (FSW) technique invented by The Welding Institute (TWI) in 1991 [2]. During

Influence of tool shape on lattice rearrangement under loading conditions reproducing friction stir welding

NASA Astrophysics Data System (ADS)

Konovalenko, Ivan S.; Konovalenko, Igor S.

2015-10-01

Metal behavior under loading conditions that reproduce friction stir welding was studied on the atomic scale. Calculations were conducted based on molecular dynamics simulation with potentials calculated within the embedded atom method. The loading of the interface between two crystallites, whose structure corresponded to aluminum alloy 2024, was simulated by the motion of a cone-shaped tool along the interface with constant angular and translational velocities. The motion of the rotating tool causes fracture of the workpiece crystal structure with subsequent mixing of surface atoms of the interfacing crystallites. It is shown that the resistance force acting on the moving tool from the workpiece and the process of structural defect formation in the workpiece depend on the tool shape.

Solid State Welding Development at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Ding, Robert J.; Walker, Bryant

2012-01-01

What is TSW and USW? TSW is a solid state weld process consisting of an induction coil heating source, a stir rod, and non-rotating containment plates Independent heating, stirring and forging controls Decouples the heating, stirring and forging process elements of FSW. USW is a solid state weld process consisting of an induction coil heating source, a stir rod, and a non-rotating containment plate; Ultrasonic energy integrated into non-rotating containment plate and stir rod; Independent heating, stirring and forging controls; Decouples the heating, stirring and forging process elements of FSW.

Thermal Stir Welding: A New Solid State Welding Process

NASA Technical Reports Server (NTRS)

Ding, R. Jeffery; Munafo, Paul M. (Technical Monitor)

2002-01-01

Thermal Stir Shielding is a revolutionary new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating and stirring functions are independent allowing more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

Long-term performance of anaerobic digestion for crop residues containing heavy metals and response of microbial communities.

PubMed

Lee, Jongkeun; Kim, Joonrae Roger; Jeong, Seulki; Cho, Jinwoo; Kim, Jae Young

2017-01-01

In order to investigate the long-term stability on the performance of the anaerobic digestion process, a laboratory-scale continuous stirred-tank reactor (CSTR) was operated for 1100 days with sunflower harvested in a heavy metal contaminated site. Changes of microbial communities during digestion were identified using pyrosequencing. According to the results, soluble heavy metal concentrations were lower than the reported inhibitory level and the reactor performance remained stable up to OLR of 2.0g-VS/L/day at HRT of 20days. Microbial communities commonly found in anaerobic digestion for cellulosic biomass were observed and stably established with respect to the substrate. Thus, the balance of microbial metabolism was maintained appropriately and anaerobic digestion seems to be feasible for disposal of heavy metal-containing crop residues from phytoremediation sites. Copyright © 2016 Elsevier Ltd. All rights reserved.

GE pilot plant gasifies all coal types and grades without pretreatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1978-03-01

A pilot-scale coal gasification plant at General Electric Company's Research and Development Center, Schenectady, New York, is converting more than three-quarters of a ton of low-grade coal per hour into 100,000 cubic feet of fuel gas suitable for running electric power plants. GE is also going to test new ideas for coal feeding and stirring the reacting mixture to prevent caking. One unique approach will be the use of an extruder to feed coal continuously into the pressurized gasifier through a gas-tight seal, much as toothpaste is squeezed from a tube. The 6-inch-diameter rod of fuel that leaves the extrudermore » is comprised of a mixture of fine coal particles and tar (the latter is a by-product of the gasification process). Once inside, the rod is broken into chunks to form the bed being gasified.« less

Experimental and modeling study of a two-stage pilot scale high solid anaerobic digester system.

PubMed

Yu, Liang; Zhao, Quanbao; Ma, Jingwei; Frear, Craig; Chen, Shulin

2012-11-01

This study established a comprehensive model to configure a new two-stage high solid anaerobic digester (HSAD) system designed for highly degradable organic fraction of municipal solid wastes (OFMSW). The HSAD reactor as the first stage was naturally separated into two zones due to biogas floatation and low specific gravity of solid waste. The solid waste was retained in the upper zone while only the liquid leachate resided in the lower zone of the HSAD reactor. Continuous stirred-tank reactor (CSTR) and advective-diffusive reactor (ADR) models were constructed in series to describe the whole system. Anaerobic digestion model No. 1 (ADM1) was used as reaction kinetics and incorporated into each reactor module. Compared with the experimental data, the simulation results indicated that the model was able to well predict the pH, volatile fatty acid (VFA) and biogas production. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bioreactor concepts for cell culture-based viral vaccine production.

PubMed

Gallo-Ramírez, Lilí Esmeralda; Nikolay, Alexander; Genzel, Yvonne; Reichl, Udo

2015-01-01

Vaccine manufacturing processes are designed to meet present and upcoming challenges associated with a growing vaccine market and to include multi-use facilities offering a broad portfolio and faster reaction times in case of pandemics and emerging diseases. The final products, from whole viruses to recombinant viral proteins, are very diverse, making standard process strategies hardly universally applicable. Numerous factors such as cell substrate, virus strain or expression system, medium, cultivation system, cultivation method, and scale need consideration. Reviewing options for efficient and economical production of human vaccines, this paper discusses basic factors relevant for viral antigen production in mammalian cells, avian cells and insect cells. In addition, bioreactor concepts, including static systems, single-use systems, stirred tanks and packed-beds are addressed. On this basis, methods towards process intensification, in particular operational strategies, the use of perfusion systems for high product yields, and steps to establish continuous processes are introduced.

Design Tool for Planning Permanganate Injection Systems

DTIC Science & Technology

2010-08-01

Chemical Spill 10 CSTR continuously stirred tank reactors CT contact time EDB ethylene dibromide ESTCP Environmental Security Technology...63 6.2 Simulating Oxidant Distribution Using a Series of CSTRs ...ER- 0625. 6.2 SIMULATING OXIDANT DISTRIBUTION USING A SERIES OF CSTRS 6.2.1 MODEL DEVELOPMENT The transport and consumption of permanganate

Integrating the ChE Curriculum via a Recurring Laboratory

ERIC Educational Resources Information Center

Kubilius, Matthew B.; Tu, Raymond S.; Anderson, Ryan

2014-01-01

A recurring framework has been integrated throughout the curriculum via a Continuously Stirred Tank Reactor (CSTR) platform. This laboratory is introduced during the material and energy balance course, and subsequent courses can use these results when explaining more advanced concepts. Further, this laboratory gives students practical experience…

Rewriting of States' Standards on Social Studies Stirs Debate

ERIC Educational Resources Information Center

Robelen, Erik W.

2010-01-01

As debate continues around the development and adoption of common standards in English and mathematics, several states are independently wrestling with rewrites of standards in a content area largely absent from that national discussion--social studies--and encountering their own shares of controversy. Flash points in the social studies debates…

Friction Stir Back Extrusion of Aluminium Alloys for Automotive Applications

NASA Astrophysics Data System (ADS)

Xu, Zeren

Since the invention of Friction Stir Welding in 1991 as a solid state joining technique, extensive scientific investigations have been carried out to understand fundamental aspects of material behaviors when processed by this technique, in order to optimize processing conditions as well as mechanical properties of the welds. Based on the basic principles of Friction Stir Welding, several derivatives have also been developed such as Friction Stir Processing, Friction Extrusion and Friction Stir Back Extrusion. Friction Stir Back Extrusion is a novel technique that is proposed recently and designed for fabricating tubes from lightweight alloys. Some preliminary results have been reported regarding microstructure and mechanical properties of Friction Stir Back Extrusion processed AZ31 magnesium alloy, however, systematic study and in-depth investigations are still needed to understand the materials behaviors and underlying mechanisms when subjected to Friction Stir Back Extrusion, especially for age-hardenable Al alloys. In the present study, Friction Stir Back Extrusion processed AA6063-T5 and AA7075-T6 alloys are analyzed with respect to grain structure evolution, micro-texture change, recrystallization mechanisms, precipitation sequence as well as mechanical properties. Optical Microscopy, Electron Backscatter Diffraction, Transmission Electron Microscopy, Vickers Hardness measurements and uniaxial tensile tests are carried out to characterize the microstructural change as well as micro and macro mechanical properties of the processed tubes. Special attention is paid to the micro-texture evolution across the entire tube and dynamic recrystallization mechanisms that are responsible for grain refinement. Significant grain refinement has been observed near the processing zone while the tube wall is characterized by inhomogeneous grain structure across the thickness for both alloys. Dissolution of existing precipitates is noticed under the thermal hysterias imposed by Friction Stir Back Extrusion process, resulting in decreased strength but improved elongation of the processed tubes; a post-process aging step can effectively restore the mechanical properties of the processed tubes by allowing for the reprecipitation of solute elements in the form of fine, dispersed precipitates. Texture analysis performed for AA6063 alloy suggests the dominance of simple shear type textures with clear transition from initial texture to stable B/ ?B components via intermediate types that are stable under moderate strain levels. In order to identify the texture components properly, rigid body rotations are applied to the existing coordinate system to align it to local shear reference frame. Surprisingly, for AA7075 tubes, and fibers are observed to be the dominant texture components in the transition region as well as thermomechanically affected zone while the processing zone is characterized by random texture. The underlying mechanisms responsible for the formation of random texture are discussed in Chapter 5 based on Electron Backscatter Diffraction analysis. Comparative discussions are also carried out for the recrystallization mechanisms that are responsible for grain structure evolution of both alloys. Continuous grain subdivision and reorientation is cited as the dominant mechanism for the recrystallization of AA6063 alloys, while dynamic recrystallization occurs mainly in the form of Geometric Dynamic Recrystallization and progressive subgrain rotations near grain boundaries in AA7075 alloys.

Bioaugmentation as a solution to increase methane production from an ammonia-rich substrate.

PubMed

Fotidis, Ioannis A; Wang, Han; Fiedel, Nicolai R; Luo, Gang; Karakashev, Dimitar B; Angelidaki, Irini

2014-07-01

Ammonia-rich substrates inhibit the anaerobic digestion (AD) process and constitute the main reason for low energy recovery in full-scale reactors. It is estimated that many full-scale AD reactors are operating in ammonia induced "inhibited steady-state" with significant losses of the potential biogas production yield. To date there are not any reliable methods to alleviate the ammonia toxicity effect or to efficiently digest ammonia-rich waste. In the current study, bioaugmentation as a possible method to alleviate ammonia toxicity effect in a mesophilic continuously stirred-tank reactor (CSTR) operating under "inhibited steady state" was tested. A fast growing hydrogenotrophic methanogen (i.e., Methanoculleus bourgensis MS2(T)) was bioaugmented in the CSTR reactor at high ammonia levels (5 g NH4(+)-N L(-1)). A second CSTR reactor was used as control with no bioaugmentation. The results derived from this study clearly demonstrated a 31.3% increase in methane production yield in the CSTR reactor, at steady-state, after bioaugmentation. Additionally, high-throughput 16S rRNA gene sequencing analysis showed a 5-fold increase in relative abundance of Methanoculleus spp. after bioaugmentation. On the contrary to all methods used today to alleviate ammonia toxicity effect, the tested bioaugmentation process performed without interrupting the continuous operation of the reactor and without replacing the ammonia-rich feedstock.

Modified Light Duty AM2 Capability Assessment

DTIC Science & Technology

The Modified Light -Duty AM2 matting was designed specifically for lightweight, remote-piloted aircraft (RPA) applications. An in- depth study was... Ratio (CBR) of 6. To understand the full potential of the Modified Light -Duty AM2, a full- scale evaluation was performed with contingency C-17 and...stir welding for use in fabrication of the lightweight RPA matting in conjunction with a full- scale test on the Modified Light -Duty AM2 matting system

Small Schools' Ripple Effects Debated

ERIC Educational Resources Information Center

Robelen, Erik W.

2006-01-01

Major initiatives in New York City and Chicago to close unsuccessful schools and create small schools in their wake are stirring criticism from some community activists, local politicians, and others. Critics charge that the growing scale of the efforts is producing negative ripple effects on other schools in these cities. In Chicago, the chief…

[Optimization of stir-baking with vinegar technology for Curcumae Radix by orthogonal test].

PubMed

Shi, Dianhua; Su, Benzheng; Sun, Lili; Zhang, Jun; Qu, Yongsheng

2011-05-01

To optimize the stir-baking with vinegar technology for Curcumae Radix. The intrinsic quality (the content of Curcumin) and traditional outward appearance were chosen as indexes. The best technology was determined by orthogonal test L9 (3(4)). The factors of the moistening time, stir-baking temperature and stir-baking time were investigated. The optimal technology was as follows: the quantity of vinegar was 10%, the moistening time was 10 min, the stir-baking temperature was 130 degrees C and the stir-baking time was 10 min. The optimal stir-baking with vinegar technology for Curcumae Radix is reasonable, which can be used to guide the standardized production of Curcumae Radix stir-baked with vinegar.

Friction-Stir-Welded and Spin-Formed End Domes for Cryogenic Tanks

NASA Technical Reports Server (NTRS)

Hales, S. J.; Tayon, W. A.; Domack, M. S.

2012-01-01

Manufacturing of single-piece end domes for cryogenic tanks employing spin forming of tailored, friction-stir-welded blanks of Al-Li alloy 2195 plate offers cost and reliability benefits. The introduction of plastic deformation into a friction stir weld is a unique feature of the proposed manufacturing route. This investigation addressed abnormal grain growth [AGG] within the friction stir weldments during postfabrication processing of a prototype dome. The phenomenon of AGG was observed during the solution heat treatment [SHT] phase of T8 tempering and is a major concern for meeting specifications. Such abrupt microstructural transitions can be detrimental to notch-sensitive mechanical properties, such as ductility and/or fracture toughness. If the issue of AGG cannot be resolved, then the acceptance of this approach as a viable manufacturing route may be in jeopardy. The innovative approach adopted in this investigation was the insertion of a stand-alone, Intermediate Annealing Treatment [IAT] between the spin forming and T8 processing operations. A simple, recovery annealing step was deemed to be the most readily-scalable solution when fabricating thin-walled, ellipsoidal domes. The research effort culminated in the development of an effective IAT, which resulted in a significant decrease in AGG following SHT. The processing philosophy adopted in designing the IAT is outlined and the microstructural reasons for success are discussed. The analytical results presented are consistent with promoting continuous grain growth during the IAT, thereby suppressing AGG during the SHT.

Ultrasonic Low-Friction Containment Plate for Thermal and Ultrasonic Stir Weld Processes

NASA Technical Reports Server (NTRS)

Graff, Karl; Short, Matt

2013-01-01

The thermal stir welding (TSW) process is finding applications in fabrication of space vehicles. In this process, workpieces to be joined by TSW are drawn, by heavy forces, between "containment plates," past the TSW tool that then causes joining of the separate plates. It is believed that the TSW process would be significantly improved by reducing the draw force, and that this could be achieved by reducing the friction forces between the workpieces and containment plates. Based on use of high-power ultrasonics in metal forming processes, where friction reduction in drawing dies has been achieved, it is believed that ultrasonic vibrations of the containment plates could achieve similar friction reduction in the TSW process. By applying ultrasonic vibrations to the containment plates in a longitudinal vibration mode, as well as by mounting and holding the containment plates in a specific manner such as to permit the plates to acoustically float, friction between the metal parts and the containment plates is greatly reduced, and so is the drawing force. The concept was to bring in the ultrasonics from the sides of the plates, permitting the ultrasonic hardware to be placed to the side, away from the equipment that contains the thermal stir tooling and that applies clamping forces to the plates. Tests demonstrated that one of the major objectives of applying ultrasonics to the thermal stir system, that of reducing draw force friction, should be achievable on a scaled-up system.

Fate of LCFA in the co-digestion of cow manure, food waste and discontinuous addition of oil.

PubMed

Neves, L; Oliveira, R; Alves, M M

2009-12-01

Different concentrations of oily waste were added in a discontinuous mode and recurrently to anaerobic continuous stirred tank reactors fed with cow manure and food waste. Four continuous stirred tank reactors were run in parallel. A control reactor (R1) received no additional oil and R2, R3 and R4 received increasing concentrations of oil in two different experimental approaches. First, the lipids composition was forced to change suddenly, in three moments, without changing the total chemical oxygen demand (COD) fed to the reactors. The only long chain fatty acid (LCFA) detected onto the R1 solid matrix was palmitic acid (C16:0). Nevertheless in the solid matrix of R2, R3 and R4C16:0 and stearic acid were detected. For occasional increase in the oil concentration up to 7.7gCOD(oil)/L(reactor) (55% Oil(COD)/Total(COD)) no statistical differences were detected between the reactors, in terms of methane production, effluent soluble COD, effluent volatile fatty acids and total and volatile solids removal. Therefore this experiment allowed to conclude that cow manure-food waste co-digestion presents sufficient buffer capacity to endure solid-associated LCFA concentration up to 20-25gCOD-LCFA/kgTS. In a second experiment higher concentrations of oil were added, raising occasionally the concentration in the reactors to 9, 12, 15 and 18gCOD(oil)/L(reactor). All pulses had a positive effect in methane production, with the exception of the highest oil pulse concentration, that persistently impaired the reactor performance. This experiment demonstrates that threshold values for LCFA and C16:0 accumulation onto the solid matrix, of about 180-220gCOD-LCFA/kgTS and 120-150gCOD-C16:0/kgTS, should not be surpassed in order to prevent persistent reactor failure, as occurs in some full scale co-digestion plants.

Preparation of Microcrystals of Piroxicam Monohydrate by Antisolvent Precipitation via Microfabricated Metallic Membranes with Ordered Pore Arrays

PubMed Central

2017-01-01

Microcrystals of piroxicam (PRX) monohydrate with a narrow size distribution were prepared from acetone/PRX solutions by antisolvent crystallization via metallic membranes with ordered pore arrays. Crystallization was achieved by controlled addition of the feed solution through the membrane pores into a well-stirred antisolvent. A complete transformation of an anhydrous form I into a monohydrate form of PRX was confirmed by Raman spectroscopy and differential scanning calorimetry. The size of the crystals was 7–34 μm and was controlled by the PRX concentration in the feed solution (15–25 g L–1), antisolvent/solvent volume ratio (5–30), and type of antisolvent (Milli-Q water or 0.1–0.5 wt % aqueous solutions of hydroxypropyl methyl cellulose (HPMC), poly(vinyl alcohol) or Pluronic P-123). The smallest crystals were obtained by injecting 25 g L–1 PRX solution through a stainless-steel membrane with a pore size of 10 μm into a 0.06 wt % HPMC solution stirred at 1500 rpm using an antisolvent/solvent ratio of 20. HPMC provided better steric stabilization of microcrystals against agglomeration than poly(vinyl alcohol) and Pluronic P-123, due to hydrogen bonding interactions with PRX and water. A continuous production of large PRX monohydrate microcrystals with a volume-weighted mean diameter above 75 μm was achieved in a continuous stirred membrane crystallizer. Rapid pouring of Milli-Q water into the feed solution resulted in a mixture of highly polydispersed prism-shaped and needle-shaped crystals. PMID:29234241

Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production.

PubMed

Nges, Ivo Achu; Escobar, Federico; Fu, Xinmei; Björnsson, Lovisa

2012-01-01

Currently, there is increasing competition for waste as feedstock for the growing number of biogas plants. This has led to fluctuation in feedstock supply and biogas plants being operated below maximum capacity. The feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) was therefore studied in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process. Co-digesting industrial waste and crops led to significant improvement in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also avoids the need for micronutrients normally required in crop digestion. The batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. This was done based on the ratio of methane yields observed for laboratory batch and CSTR experiments compared to full scale CSTR digestion of industrial waste. The economy of crop-based biogas production is limited under Swedish conditions; therefore, adding crops to existing industrial waste digestion could be a viable alternative to ensure a constant/reliable supply of feedstock to the anaerobic digester. Copyright © 2011 Elsevier Ltd. All rights reserved.

Production of nitrous oxide from anaerobic digester centrate and its use as a co-oxidant of biogas to enhance energy recovery.

PubMed

Scherson, Yaniv D; Woo, Sung-Geun; Criddle, Craig S

2014-05-20

Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) is a new process for wastewater treatment that removes nitrogen from wastewater and recovers energy from the nitrogen in three steps: (1) NH4(+) oxidation to NO2(-); (2) NO2(-) reduction to N2O gas; and (3) N2O conversion to N2 with energy production. In this work, we optimize Steps 1 and 2 for anaerobic digester centrate, and we evaluate Step 3 for a full-scale biogas-fed internal combustion engine. Using a continuous stirred reactor coupled to a bench-scale sequencing batch reactor, we observed sustained partial oxidation of NH4(+) to NO2(-) and sustained (3 months) partial reduction of NO2(-) to N2O (75-80% conversion, mass basis), with >95% nitrogen removal (Step 2). Alternating pulses of acetate and NO2(-) selected for Comamonas (38%), Ciceribacter (16%), and Clostridium (11%). Some species stored polyhydroxybutyrate (PHB) and coupled oxidation of PHB to reduction of NO2(-) to N2O. Some species also stored phosphorus as polyphosphate granules. Injections of N2O into a biogas-fed engine at flow rates simulating a full-scale system increased power output by 5.7-7.3%. The results underscore the need for more detailed assessment of bioreactor community ecology and justify pilot- and full-scale testing.

Real Reform Takes More than "Stirring the Pot"

ERIC Educational Resources Information Center

Yager, Robert E.; Ali, Mohamed Moustafa; Hacieminoglu, Esme

2010-01-01

This article is the first in what will become a continuing series of articles highlighting the perspectives of renowned science educators. The first featured article is by Robert Yager, Science Education Center, University of Iowa, USA. Dr. Yager has directed over 100 NSF projects designed to improve K-16 science programs. He has served as…

We Continue to "Drag-on" the Motivation

ERIC Educational Resources Information Center

Laird, Shirley

2010-01-01

The author's fifth-graders are usually easy to motivate, especially with an assignment as exciting as dragons and mythical beasts! Since many of the author's projects are "typical" subjects such as flowers, animals, still life and so on, the idea of creating mythical creatures really caused a stir in her classroom. In this article, the author…

Hydrolysis-acidogenesis of food waste in solid-liquid-separating continuous stirred tank reactor (SLS-CSTR) for volatile organic acid production.

PubMed

Karthikeyan, Obulisamy Parthiba; Selvam, Ammaiyappan; Wong, Jonathan W C

2016-01-01

The use of conventional continuous stirred tank reactor (CSTR) can affect the methane (CH4) recovery in a two-stage anaerobic digestion of food waste (FW) due to carbon short circuiting in the hydrolysis-acidogenesis (Hy-Aci) stage. In this research, we have designed and tested a solid-liquid-separating CSTR (SLS-CSTR) for effective Hy-Aci of FW. The working conditions were pH 6 and 9 (SLS-CSTR-1 and -2, respectively); temperature-37°C; agitation-300rpm; and organic loading rate (OLR)-2gVSL(-1)day(-1). The volatile fatty acids (VFA), enzyme activities and bacterial population (by qPCR) were determined as test parameters. Results showed that the Hy-Aci of FW at pH 9 produced ∼35% excess VFA as compared to that at pH 6, with acetic and butyric acids as major precursors, which correlated with the high enzyme activities and low lactic acid bacteria. The design provided efficient solid-liquid separation there by improved the organic acid yields from FW. Copyright © 2015 Elsevier Ltd. All rights reserved.

Efficient azo dye decolorization in a continuous stirred tank reactor (CSTR) with built-in bioelectrochemical system.

PubMed

Cui, Min-Hua; Cui, Dan; Gao, Lei; Cheng, Hao-Yi; Wang, Ai-Jie

2016-10-01

A continuous stirred tank reactor with built-in bioelectrochemical system (CSTR-BES) was developed for azo dye Alizarin Yellow R (AYR) containing wastewater treatment. The decolorization efficiency (DE) of the CSTR-BES was 97.04±0.06% for 7h with sludge concentration of 3000mg/L and initial AYR concentration of 100mg/L, which was superior to that of the sole CSTR mode (open circuit: 54.87±4.34%) and the sole BES mode (without sludge addition: 91.37±0.44%). The effects of sludge concentration and sodium acetate (NaAc) concentration on azo dye decolorization were investigated. The highest DE of CSTR-BES for 4h was 87.66±2.93% with sludge concentration of 12,000mg/L, NaAc concentration of 2000mg/L and initial AYR concentration of 100mg/L. The results in this study indicated that CSTR-BES could be a practical strategy for upgrading conventional anaerobic facilities against refractory wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cassava Stillage Treatment by Thermophilic Anaerobic Continuously Stirred Tank Reactor (CSTR)

NASA Astrophysics Data System (ADS)

Luo, Gang; Xie, Li; Zou, Zhonghai; Zhou, Qi

2010-11-01

This paper assesses the performance of a thermophilic anaerobic Continuously Stirred Tank Reactor (CSTR) in the treatment of cassava stillage under various organic loading rates (OLRs) without suspended solids (SS) separation. The reactor was seeded with mesophilic anaerobic granular sludge, and the OLR increased by increments to 13.80 kg COD/m3/d (HRT 5d) over 80 days. Total COD removal efficiency remained stable at 90%, with biogas production at 18 L/d (60% methane). Increase in the OLR to 19.30 kg COD/m3/d (HRT 3d), however, led to a decrease in TCOD removal efficiency to 79% due to accumulation of suspended solids and incomplete degradation after shortened retention time. Reactor performance subsequently increased after OLR reduction. Alkalinity, VFA and pH levels were not significantly affected by OLR variation, indicating that no additional alkaline or pH adjustment is required. More than half of the SS in the cassava stillage could be digested in the process when HRT was 5 days, which demonstrated the suitability of anaerobic treatment of cassava stillage without SS separation.

Continuous biological waste gas treatment in stirred trickle-bed reactor with discontinuous removal of biomass.

PubMed

Laurenzis, A; Heits, H; Wübker, S; Heinze, U; Friedrich, C; Werner, U

1998-02-20

A new reactor for biological waste gas treatment was developed to eliminate continuous solvents from waste gases. A trickle-bed reactor was chosen with discontinuous movement of the packed bed and intermittent percolation. The reactor was operated with toluene as the solvent and an optimum average biomass concentration of between 5 and 30 kg dry cell weight per cubic meter packed bed (m3pb). This biomass concentration resulted in a high volumetric degradation rate. Reduction of surplus biomass by stirring and trickling caused a prolonged service life and prevented clogging of the trickle bed and a pressure drop increase. The pressure drop after biomass reduction was almost identical to the theoretical pressure drop as calculated for the irregular packed bed without biomass. The reduction in biomass and intermittent percolation of mineral medium resulted in high volumetric degradation rates of about 100 g of toluene m-3pb h-1 at a load of 150 g of toluene m-3pb h-1. Such a removal rate with a trickle-bed reactor was not reported before. Copyright 1998 John Wiley & Sons, Inc.

Anaerobic co-digestion of cheese whey and the screened liquid fraction of dairy manure in a single continuously stirred tank reactor process: Limits in co-substrate ratios and organic loading rate.

PubMed

Rico, Carlos; Muñoz, Noelia; Rico, José Luis

2015-01-01

Mesophilic anaerobic co-digestion of cheese whey and the screened liquid fraction of dairy manure was investigated with the aim of determining the treatment limits in terms of the cheese whey fraction in feed and the organic loading rate. The results of a continuous stirred tank reactor that was operated with a hydraulic retention time of 15.6 days showed that the co-digestion process was possible with a cheese whey fraction as high as 85% in the feed. The efficiency of the process was similar within the range of the 15-85% cheese whey fraction. To study the effect of the increasing loading rate, the HRT was progressively shortened with the 65% cheese whey fraction in the feed. The reactor efficiency dropped as the HRT decreased but enabled a stable operation over 8.7 days of HRT. At these operating conditions, a volumetric methane production rate of 1.37 m(3) CH4 m(-3) d(-1) was achieved. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Hydraulic Retention Time on Anaerobic Digestion of Wheat Straw in the Semicontinuous Continuous Stirred-Tank Reactors

PubMed Central

Shi, Xiao-Shuang; Yu, Jun-Hong; Yin, Hua; Hu, Shu-Min; Huang, Shu-Xia

2017-01-01

Three semicontinuous continuous stirred-tank reactors (CSTR) operating at mesophilic conditions (35°C) were used to investigate the effect of hydraulic retention time (HRT) on anaerobic digestion of wheat straw. The results showed that the average biogas production with HRT of 20, 40, and 60 days was 46.8, 79.9, and 89.1 mL/g total solid as well as 55.2, 94.3, and 105.2 mL/g volatile solids, respectively. The methane content with HRT of 20 days, from 14.2% to 28.5%, was the lowest among the three reactors. The pH values with HRT of 40 and 60 days were in the acceptable range compared to that with HRT of 20 days. The propionate was dominant in the reactor with HRT of 20 days, inhibiting the activities of methanogens and causing the lower methane content in biogas. The degradation of cellulose, hemicellulose, and crystalline cellulose based on XRD was also strongly influenced by HRTs. PMID:28589134

Reuse of drinking water treatment residuals in a continuous stirred tank reactor for phosphate removal from urban wastewater.

PubMed

Bai, Leilei; Wang, Changhui; Pei, Yuansheng; Zhao, Jinbo

2014-01-01

This work proposed a new approach of reusing drinking water treatment residuals (WTR) in a continuous stirred tank reactor (CSTR) to remove phosphate (P) from urban wastewater. The results revealed that the P removal efficiency of the WTR was more than 94% for urban wastewater, in the condition of initial P concentration (P0) of 10 mg L⁻¹, hydraulic retention time (HRT) of 2 h and WTR dosage (M0) of 10 g L⁻¹. The P mass transfer from the bulk to the solid-liquid interface in the CSTR system increased at lower P0, higher M0 and longer HRT. The P adsorption capacity of WTR from urban wastewater was comparable to that of the 201 × 4 resin and unaffected by ions competition. Moreover, WTR had a limited effect on the metals' (Fe, Al, Zn, Cu, Mn and Ni) concentrations of the urban wastewater. Based on the principle of waste recycling, the reuse of WTR in CSTR is a promising alternative technology for P removal from urban wastewater.

Dynamics of the microbial community during continuous methane fermentation in continuously stirred tank reactors.

PubMed

Tang, Yue-Qin; Shigematsu, Toru; Morimura, Shigeru; Kida, Kenji

2015-04-01

Methane fermentation is an attractive technology for the treatment of organic wastes and wastewaters. However, the process is difficult to control, and treatment rates and digestion efficiency require further optimization. Understanding the microbiology mechanisms of methane fermentation is of fundamental importance to improving this process. In this review, we summarize the dynamics of microbial communities in methane fermentation chemostats that are operated using completely stirred tank reactors (CSTRs). Each chemostat was supplied with one substrate as the sole carbon source. The substrates include acetate, propionate, butyrate, long-chain fatty acids, glycerol, protein, glucose, and starch. These carbon sources are general substrates and intermediates of methane fermentation. The factors that affect the structure of the microbial community are discussed. The carbon source, the final product, and the operation conditions appear to be the main factors that affect methane fermentation and determine the structure of the microbial community. Understanding the structure of the microbial community during methane fermentation will guide the design and operation of practical wastewater treatments. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Improvement of rheological properties of firm acid gels by skim milk heating is conserved after stirring.

PubMed

Cayot, P; Fairise, J F; Colas, B; Lorient, D; Brulé, G

2003-11-01

The enhancement of the strength of set acid gels by heating milk was related to rheological parameters (water retention capacity, storage modulus) of corresponding stirred gels. To obtain accurate rheological data from stirred gel it was necessary to maintain a constant granulometry of gel particles and to recognize time after stirring as a contributing factor. Two hours after stirring, the gel exhibited a higher storage modulus when milk was heated above 80 degrees C. A measurement of viscosity of just-stirred yoghurt was sufficient to predict correctly the quality of a stirred gel analysed by viscoelastic measurements. Increased resistance to syneresis of just-stirred gels was related to higher viscosity. The quantity of beta-lactoglobulin (beta-Ig) bound to casein micelles explains the improvement of these gel qualities. We have considered that the structure of the initial firm gel (mesostructure level) was conserved in fragments within the stirred gel. Consequently, the explanation given by various authors for the effect of heating milk on the properties of set gels can also be applied to stirred gels. The same mechanism, described in literature for structure formation of set gels from acidified milk is purposed to explain the role of heating milk on the recovery of gel structure after stirring. The beta-Ig association with casein micelles during heating favoured micelle connections during the acidification. It also favoured the association of gel fragments after stirring during the recovery in gel structure.

StirMark Benchmark: audio watermarking attacks based on lossy compression

NASA Astrophysics Data System (ADS)

Steinebach, Martin; Lang, Andreas; Dittmann, Jana

2002-04-01

StirMark Benchmark is a well-known evaluation tool for watermarking robustness. Additional attacks are added to it continuously. To enable application based evaluation, in our paper we address attacks against audio watermarks based on lossy audio compression algorithms to be included in the test environment. We discuss the effect of different lossy compression algorithms like MPEG-2 audio Layer 3, Ogg or VQF on a selection of audio test data. Our focus is on changes regarding the basic characteristics of the audio data like spectrum or average power and on removal of embedded watermarks. Furthermore we compare results of different watermarking algorithms and show that lossy compression is still a challenge for most of them. There are two strategies for adding evaluation of robustness against lossy compression to StirMark Benchmark: (a) use of existing free compression algorithms (b) implementation of a generic lossy compression simulation. We discuss how such a model can be implemented based on the results of our tests. This method is less complex, as no real psycho acoustic model has to be applied. Our model can be used for audio watermarking evaluation of numerous application fields. As an example, we describe its importance for e-commerce applications with watermarking security.

New Tool Creates a Big Stir

NASA Technical Reports Server (NTRS)

2001-01-01

A new self-adjusting, retractable pin tool for friction stir welding is now used in the manufacturing of components for NASA Space Shuttles. Friction stir welding is a process that makes straight-line welds without bringing the parent material to a liquid state. This is accomplished through high-speed rotation, which generates frictional heat between the welding tool and the piece being welded. This heat causes the material to soften to the point of plasticity without allowing it to melt. The plasticized material is then transferred from the front edge of the welding tool to the trail edge, where it joins the pieces being welded. However, a major flaw of this method is its reliance on a single-piece pin tool. The weld is left unfinished and a hole remains where the pin was inserted. The hole must be covered with a rivet in order to preserve the integrity of the weld. The NASA-developed pin tool, however, eliminates the need for this finishing step, as its retraction allows continuous rewelding at lesser depths, until the hole is completely closed. With this NASA technology, welding of higher strength alloys, as well as non-planer and variable thickness structures can be achieved.

Quantification of chaotic strength and mixing in a micro fluidic system

NASA Astrophysics Data System (ADS)

Kim, Ho Jun; Beskok, Ali

2007-11-01

Comparative studies of five different techniques commonly employed to identify the chaotic strength and mixing efficiency in micro fluidic systems are presented to demonstrate the competitive advantages and shortcomings of each method. The 'chaotic electroosmotic stirrer' of Qian and Bau (2002 Anal. Chem. 74 3616-25) is utilized as the benchmark case due to its well-defined flow kinematics. Lagrangian particle tracking methods are utilized to study particle dispersion in the conceptual device using spectral element and fourth-order Runge-Kutta discretizations in space and time, respectively. Stirring efficiency is predicted using the stirring index based on the box counting method, and Poincaré sections are utilized to identify the chaotic and regular regions under various actuation conditions. Finite time Lyapunov exponents are calculated to quantify the chaotic strength, while the probability density function of the stretching field is utilized as an alternative method to demonstrate the statistical analysis of chaotic and partially chaotic cases. Mixing index inverse, based on the standard deviation of scalar species distribution, is utilized as a metric to quantify the mixing efficiency. Series of numerical simulations are performed by varying the Peclet number (Pe) at fixed kinematic conditions. The mixing time (tm) is characterized as a function of the Pe number, and tm ~ ln(Pe) scaling is demonstrated for fully chaotic cases, while tm ~ Peα scaling with α ≈ 0.33 and α = 0.5 are observed for partially chaotic and regular cases, respectively. Employing the aforementioned techniques, optimum kinematic conditions and the actuation frequency of the stirrer that result in the highest mixing/stirring efficiency are identified.

Influence of tool shape on lattice rearrangement under loading conditions reproducing friction stir welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konovalenko, Ivan S., E-mail: ivkon@ispms.tsc.ru; Konovalenko, Igor S., E-mail: igkon@ispms.tsc.ru; National Research Tomsk Polytechnic University, Tomsk, 634050

2015-10-27

Metal behavior under loading conditions that reproduce friction stir welding was studied on the atomic scale. Calculations were conducted based on molecular dynamics simulation with potentials calculated within the embedded atom method. The loading of the interface between two crystallites, whose structure corresponded to aluminum alloy 2024, was simulated by the motion of a cone-shaped tool along the interface with constant angular and translational velocities. The motion of the rotating tool causes fracture of the workpiece crystal structure with subsequent mixing of surface atoms of the interfacing crystallites. It is shown that the resistance force acting on the moving toolmore » from the workpiece and the process of structural defect formation in the workpiece depend on the tool shape.« less

Tidal stirring and phytoplankton bloom dynamics in an estuary

USGS Publications Warehouse

Cloern, J.E.

1991-01-01

In South San Francisco Bay, estuarine phytoplankton biomass fluctuates at the time scale of days to weeks; much of this variability is associated with fluctuations in tidal energy. During the spring seasons of every year from 1980-1990, episodic blooms occurred in which phytoplankton biomass rose from a baseline of 2-4mg chlorophyll a m-3, peaked at 20-40 chlorophyll a m-3, then returned to baseline values, all within several weeks. Each episode of biomass increase occurred during neap tides, and each bloom decline coincided with spring tides. This suggests that daily variations in the rate of vertical mixing by tidal stirring might control phytoplankton bloom dynamics in some estuaries. Simulation experiments with a numerical model of phytoplankton population dynamics support this hypothesis. -from Author

Macrostructure of Friction Stir Welds

NASA Technical Reports Server (NTRS)

Aloor, S.; Nowak, B.; Vargas, R.; McClure, J. C.; Murr, L. E.; Nunes, A. C.; Munafo, Paul M. (Technical Monitor)

2002-01-01

This paper will discuss two of the well know large scale features of friction stir welds: the "onion rings" seen in transverse sections, and the striations on the surface of the work piece. It will be shown that the surface features (sometimes called "tool marks") are the result of irregularities on the rotating shoulder of the pin tool and disappear when the shoulder is polished. The "onion ring" structure seen in transverse cross sections is formed by parts of the "carousel", the zone of material adjacent to and rotating with the pin tool, that are shed off in each rotation. The relation between the carousel and the "ring vortex", a rotational flow extending both in and out of the carousel and resembling a smoke-ring with the hole centered on the pin tool, will be discussed.

Evaluation of Municipal Wastewater Treatment Plant Activated Sludge for Biodegradation of Propylene Glycol as an Aircraft Deicing Fluid

DTIC Science & Technology

2012-03-01

Propylene Glycol Deicer Biodegredation Kinetics: Complete-Mix Stirred Tank Reactors , Filter, and Fluidized Bed . Journal of Environmental...scale sequencing batch reactor containing municipal waste water treatment facility activated sludge (AS) performing simultaneous organic carbon...Sequencing Batch Reactor Operation ..................................................................... 13 PG extraction from AS

Heat Exchanger Lab for Chemical Engineering Undergraduates

ERIC Educational Resources Information Center

Rajala, Jonathan W.; Evans, Edward A.; Chase, George G.

2015-01-01

Third year chemical engineering undergraduate students at The University of Akron designed and fabricated a heat exchanger for a stirred tank as part of a Chemical Engineering Laboratory course. The heat exchanger portion of this course was three weeks of the fifteen week long semester. Students applied concepts of scale-up and dimensional…

Muscle MRI of classic infantile pompe patients: Fatty substitution and edema-like changes.

PubMed

Pichiecchio, Anna; Rossi, Marta; Cinnante, Claudia; Colafati, Giovanna Stefania; De Icco, Roberto; Parini, Rossella; Menni, Francesca; Furlan, Francesca; Burlina, Alberto; Sacchini, Michele; Donati, Maria Alice; Fecarotta, Simona; Casa, Roberto Della; Deodato, Federica; Taurisano, Roberta; Di Rocco, Maja

2017-06-01

The aim of this study was to evaluate the muscle MRI pattern of 9 patients (median age: 6.5 ± 2.74 years) affected by classic infantile-onset Pompe disease who were treated with enzyme replacement therapy. We performed and qualitatively scored T1-weighted (T1-w) sequences of the facial, shoulder girdle, paravertebral, and lower limb muscles and short-tau inversion recovery (STIR) sequences of the lower limbs using the Mercuri and Morrow scales, respectively. On T1-w images, mild (grade 1) or moderate (grade 2) involvement was found in the tongue in 6 of 6 patients and in the adductor magnus muscle in 6 of 9. STIR hyperintensity was detected in all areas examined and was categorized as limited to mild in 5 of 8 patients. On T1-w sequences, mild/moderate adipose substitution in the adductor magnus and tongue muscles was documented. STIR edema-like alterations of thigh and calf muscles are novel findings. Correlations with biopsy findings and clinical parameters are needed to fully understand these findings. Muscle Nerve 55: 841-848, 2017. © 2016 Wiley Periodicals, Inc.

Comparison of high pressure homogenization and stirred bead milling for the production of nano-crystalline suspensions.

PubMed

Nakach, Mostafa; Authelin, Jean-René; Perrin, Marc-Antoine; Lakkireddy, Harivardhan Reddy

2018-05-19

Currently, the two technologies primarily used for the manufacturing of nano-crystalline suspensions using top down process (i.e. wet milling) are high pressure homogenization (HPH) and stirred bead milling (SBM). These two technologies are based upon different mechanisms, i.e., cavitation forces for HPH and shear forces for stirred bead milling. In this article, the HPH and SBM technologies are compared in terms of the impact of the suspension composition the process parameters and the technological configuration on milling performances and physical quality of the suspensions produced. The data suggested that both HPH and SBM are suitable for producing nano-crystalline suspensions, although SBM appeared more efficient than HPH, since the limit of milling (d 50 ) for SBM was found to be lower than that obtained with HPH (100 nm vs 200 nm). For both these technologies, regardless of the process parameters used for milling and the scale of manufacturing, the relationship of d 90 versus d 50 could be described by a unique master curve (technology signature of milling pathway) outlining that the HPH leads to more uniform particle size distribution as compared to SBM. Copyright © 2018 Elsevier B.V. All rights reserved.

Auto-Adjustable Tool for Self-Reacting and Conventional Friction Stir Welding

NASA Technical Reports Server (NTRS)

Carter, Robert W. (Inventor)

2002-01-01

A friction stir welding dcvice that is configured to perform convention friction stir welding as well as self-reacting friction stir welding is described. A pin passes hrough an upper shoulder and can selectively attach 10 and detach from a lower shoulder in a preferred embodiment. A controller maintains thc discrete position of, and/or force applied by, the upper and lower shoulders during self-reacting friction stir welding, or maintains the pin at a desired depth and/or applied force during conventional friction stir welding.

Microstructural characterisation of friction stir welding joints of mild steel to Ni-based alloy 625

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, J.; University of Campinas; Ramirez, A.J., E-mail: ramirezlondono.1@osu.edu

2015-12-15

In this study, 6-mm-thick mild steel and Ni-based alloy 625 plates were friction stir welded using a tool rotational speed of 300 rpm and a travel speed of 100 mm·min{sup −1}. A microstructural characterisation of the dissimilar butt joint was performed using optical microscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy (XEDS). Six different weld zones were found. In the steel, the heat-affected zone (HAZ) was divided into three zones and was composed of ferrite, pearlite colonies with different morphologies, degenerated regions of pearlite and allotriomorphic and Widmanstätten ferrite. The stir zone (SZ) of the steel showedmore » a coarse microstructure consisting of allotriomorphic and Widmanstätten ferrite, degenerate pearlite and MA constituents. In the Ni-based alloy 625, the thermo-mechanically affected zone (TMAZ) showed deformed grains and redistribution of precipitates. In the SZ, the high deformation and temperature produced a recrystallised microstructure, as well as fracture and redistribution of MC precipitates. The M{sub 23}C{sub 6} precipitates, present in the base material, were also redistributed in the stir zone of the Ni-based alloy. TMAZ in the steel and HAZ in the Ni-based alloy could not be identified. The main restorative mechanisms were discontinuous dynamic recrystallisation in the steel, and discontinuous and continuous dynamic recrystallisation in the Ni-based alloy. The interface region between the steel and the Ni-based alloy showed a fcc microstructure with NbC carbides and an average length of 2.0 μm. - Highlights: • Comprehensive microstructural characterisation of dissimilar joints of mild steel to Ni-based alloy • Friction stir welding of joints of mild steel to Ni-based alloy 625 produces sound welds. • The interface region showed deformed and recrystallised fcc grains with NbC carbides and a length of 2.0 μm.« less

Thermal Stir Welding: A New Solid State Welding Process

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey

2003-01-01

Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

Thermal Stir Welding: A New Solid State Welding Process

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

2002-01-01

Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

On the advective Cahn-Hilliard Equation

NASA Astrophysics Data System (ADS)

O'Naraigh, Lennon; Thiffeault, Jean-Luc

2006-11-01

The advective Cahn-Hilliard equation describes the chef's problem of stirring olive oil and soy sauce. An efficient way of doing this is to choose a chaotic mixing protocol. Intuition suggests that bubbles of oil and soy will form on a certain scale, and previous studies of Cahn-Hilliard dynamics indicate the presence of one dominant length scale. See, for example, Berthier et al., 2001. The Cahn-Hilliard demixing mechanism however, contains a hyperdiffusion term and in this study we show how, by stirring the mixture at sufficiently large amplitude, we may excite the diffusion and overwhelm the demixing to create a homogeneous liquid. At intermediate amplitudes we see regions with oil and soy bubbles, and regions with hyperdiffusive filaments, implying that the problem in fact possesses two length scales. In this state, the system is in dynamical equilibrium and this is surprising, given that the homogenous state is unstable in the unstirred case. We compare our results with the case for a variable mobility, in which coarsening (growth of bubble size) is dominated by interfacial, rather than bulk, effects. The no-flow equivalent of this situation was considered by Zhu et al. (1999). We discuss the possibility that these results point in fact to the real-world limitations of the binary fluid model.

Evaluation of power density on the bioethanol production using mesoscale oscillatory baffled reactor and stirred tank reactor

NASA Astrophysics Data System (ADS)

Yussof, H. W.; Bahri, S. S.; Mazlan, N. A.

2018-03-01

A recent development in oscillatory baffled reactor technology is down-scaling the reactor, so that it can be used for production of small-scale bioproduct. In the present study, a mesoscale oscillatory baffled reactor (MOBR) with central baffle system was developed. The reactor performance of the MOBR was compared with conventional stirred tank reactor (STR) to evaluate the performance of bioethanol fermentation using Saccharomyces cerevisiae. Evaluation was made at similar power density of 24.21, 57.38, 112.35 and 193.67 Wm-3 by varying frequency (f), amplitude (xo) and agitation speed (rpm). It was found that the MOBR improved the mixing intensity resulted in lower glucose concentration (0.988 gL-1) and higher bioethanol concentration (38.98 gL-1) after 12 hours fermentation at power density of 193.67 Wm-3. Based on the results, the bioethanol yield obtained using MOBR was 39% higher than the maximum achieved in STR. Bioethanol production using MOBR proved to be feasible as it is not only able to compete with conventional STR but also offers advantages of straight-forward scale-up, whereas it is complicated and difficult in STR. Overall, MOBR offers great prospective over the conventional STR.

Ultrasound assisted synthesis of stable oil in milk emulsion: Study of operating parameters and scale-up aspects.

PubMed

Patil, Leena; Gogate, Parag R

2018-01-01

In the present work, application of ultrasound and stirring individually or in combination for improved emulsification of turmeric oil in skimmed milk has been investigated. The effect of different operating parameters/strategies such as addition of surfactant, sodium dodecyl sulfate (SDS), at different concentrations, quantity of oil phase, applied power, sonication time and duty cycle on the droplet size have been investigated. The stability of emulsion was analyzed in terms of the fraction of the emulsion that remains stable for a period of 28days. Optimized set of major emulsification process variables has been used at higher emulsion volumes. The effectiveness of treatment approach was analyzed based on oil droplet size, energy density and the time required for the formation of stable emulsion. It was observed that the stable emulsion at 50mL capacity with mean droplet diameter of about 235.4nm was obtained with the surfactant concentration of 5mg/mL, 11% of rated power (power density: 0.31W/mL) and irradiation time of 5min. The emulsion stability was higher in the case of ultrasound assisted approach as compared to the stirring. For the preparation of stable emulsion at 300mL capacity, it was observed that the sequential approach, i.e., stirring followed by ultrasound, gave lower mean droplet diameter (232.6nm) than the simultaneous approach, i.e., ultrasound and stirring together (257.9nm). However, the study also revealed that the simultaneous approach required very less time (15min) to synthesize stable emulsion as compared to the sequential approach (30min stirring and 60min ultrasound). It was successfully demonstrated that the ultrasound-assisted emulsification in the presence of SDS could be used for the preparation of stable turmeric oil-dairy emulsions, also providing insights into the role of SDS in increasing the stability of emulsions and of ultrasound in giving lower droplet sizes. Copyright © 2017 Elsevier B.V. All rights reserved.

Stirring effect on kaolinite dissolution rate

NASA Astrophysics Data System (ADS)

Metz, Volker; Ganor, Jiwchar

2001-10-01

Experiments were carried out measuring kaolinite dissolution rates using stirred and nonstirred flow-through reactors at pHs 2 to 4 and temperatures of 25°C, 50°C, and 70°C. The results show an increase of kaolinite dissolution rate with increasing stirring speed. The stirring effect is reversible, i.e., as the stirring slows down the dissolution rate decreases. The effect of stirring speed on kaolinite dissolution rate is higher at 25°C than at 50°C and 70°C and at pH 4 than at pHs 2 and 3. It is suggested that fine kaolinite particles are formed as a result of stirring-induced spalling or abrasion of kaolinite. These very fine particles have an increased ratio of reactive surface area to specific surface area, which results in enhancement of kaolinite dissolution rate. A balance between production and dissolution of the fine particles explains both the reversibility and the temperature and pH dependence of the stirring effect. Since the stirring effect on kaolinite dissolution rate varies with temperature and pH, measurement of kinetic parameters such as activation energy may be influenced by stirring. Therefore, standard use of nonagitated reaction vessels for kinetic experiments of mineral dissolution and precipitation is recommended, at least for slow reactions that are surface controlled.

Stir-bar supported micro-solid-phase extraction for the determination of polychlorinated biphenyl congeners in serum samples.

PubMed

Sajid, Muhammad; Basheer, Chanbasha

2016-07-15

In present work, a new configuration of micro-solid phase extraction was introduced and termed as stir-bar supported micro-solid-phase extraction (SB-μ-SPE). A tiny stir-bar was packed inside the porous polypropylene membrane along with sorbent material and the edges of membrane sheet were heat sealed to secure the contents. The packing of stir-bar inside the μ-SPE device does not allow the device to stick with the wall or any corner of the sample vial during extraction, which is, however, a frequent observation in routine μ-SPE. Moreover, it enhances effective surface area of the sorbent exposed to sample solution through continuous agitation (motion and rotation). It also completely immerses the SB-μ-SPE device in the sample solution even for non-polar sorbents. Polychlorinated biphenyls (PCBs) were selected as model compounds and the method performance was evaluated in human serum samples. After extraction, samples were analyzed by gas chromatography mass spectrometry (GC-MS). The factors that affect extraction efficiency of SB-μ-SPE were optimized. Under optimum conditions, a good linearity (0.1-100ngmL(-1)) with coefficients of determinations ranging from 0.9868 to 0.9992 was obtained. Limits of detections were ranged between 0.003 and 0.047ngmL(-1). Acceptable values for inter-day (3.2-9.1%) and intra-day (3.1-7.2%) relative standard deviations were obtained. The optimized method was successfully applied to determine the concentration of PCB congeners in human serum samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Stirred tank bioreactor culture combined with serum-/xenogeneic-free culture medium enables an efficient expansion of umbilical cord-derived mesenchymal stem/stromal cells.

PubMed

Mizukami, Amanda; Fernandes-Platzgummer, Ana; Carmelo, Joana G; Swiech, Kamilla; Covas, Dimas T; Cabral, Joaquim M S; da Silva, Cláudia L

2016-08-01

Mesenchymal stem/stromal cells (MSC) are being widely explored as promising candidates for cell-based therapies. Among the different human MSC origins exploited, umbilical cord represents an attractive and readily available source of MSC that involves a non-invasive collection procedure. In order to achieve relevant cell numbers of human MSC for clinical applications, it is crucial to develop scalable culture systems that allow bioprocess control and monitoring, combined with the use of serum/xenogeneic (xeno)-free culture media. In the present study, we firstly established a spinner flask culture system combining gelatin-based Cultispher(®) S microcarriers and xeno-free culture medium for the expansion of umbilical cord matrix (UCM)-derived MSC. This system enabled the production of 2.4 (±1.1) x10(5) cells/mL (n = 4) after 5 days of culture, corresponding to a 5.3 (±1.6)-fold increase in cell number. The established protocol was then implemented in a stirred-tank bioreactor (800 mL working volume) (n = 3) yielding 115 million cells after 4 days. Upon expansion under stirred conditions, cells retained their differentiation ability and immunomodulatory potential. The development of a scalable microcarrier-based stirred culture system, using xeno-free culture medium that suits the intrinsic features of UCM-derived MSC represents an important step towards a GMP compliant large-scale production platform for these promising cell therapy candidates. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficient preparation of enantiopure D-phenylalanine through asymmetric resolution using immobilized phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1 in a recirculating packed-bed reactor.

PubMed

Zhu, Longbao; Zhou, Li; Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (eeD) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (eeD>99%) in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.

Efficient Preparation of Enantiopure D-Phenylalanine through Asymmetric Resolution Using Immobilized Phenylalanine Ammonia-Lyase from Rhodotorula glutinis JN-1 in a Recirculating Packed-Bed Reactor

PubMed Central

Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h−1 and 0.32 g L−1 h−1, respectively. The optical purity (ee D) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (ee D>99%) in the scaled-up reactor reached 7.2 g L−1 h−1. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine. PMID:25268937

Comprehensive clone screening and evaluation of fed-batch strategies in a microbioreactor and lab scale stirred tank bioreactor system: application on Pichia pastoris producing Rhizopus oryzae lipase

PubMed Central

2014-01-01

Background In Pichia pastoris bioprocess engineering, classic approaches for clone selection and bioprocess optimization at small/micro scale using the promoter of the alcohol oxidase 1 gene (PAOX1), induced by methanol, present low reproducibility leading to high time and resource consumption. Results An automated microfermentation platform (RoboLector) was successfully tested to overcome the chronic problems of clone selection and optimization of fed-batch strategies. Different clones from Mut+P. pastoris phenotype strains expressing heterologous Rhizopus oryzae lipase (ROL), including a subset also overexpressing the transcription factor HAC1, were tested to select the most promising clones. The RoboLector showed high performance for the selection and optimization of cultivation media with minimal cost and time. Syn6 medium was better than conventional YNB medium in terms of production of heterologous protein. The RoboLector microbioreactor was also tested for different fed-batch strategies with three clones producing different lipase levels. Two mixed substrates fed-batch strategies were evaluated. The first strategy was the enzymatic release of glucose from a soluble glucose polymer by a glucosidase, and methanol addition every 24 hours. The second strategy used glycerol as co-substrate jointly with methanol at two different feeding rates. The implementation of these simple fed-batch strategies increased the levels of lipolytic activity 80-fold compared to classical batch strategies used in clone selection. Thus, these strategies minimize the risk of errors in the clone selection and increase the detection level of the desired product. Finally, the performance of two fed-batch strategies was compared for lipase production between the RoboLector microbioreactor and 5 liter stirred tank bioreactor for three selected clones. In both scales, the same clone ranking was achieved. Conclusion The RoboLector showed excellent performance in clone selection of P. pastoris Mut+ phenotype. The use of fed-batch strategies using mixed substrate feeds resulted in increased biomass and lipolytic activity. The automated processing of fed-batch strategies by the RoboLector considerably facilitates the operation of fermentation processes, while reducing error-prone clone selection by increasing product titers. The scale-up from microbioreactor to lab scale stirred tank bioreactor showed an excellent correlation, validating the use of microbioreactor as a powerful tool for evaluating fed-batch operational strategies. PMID:24606982

Mechanical Properties and Microstructure of Dissimilar Friction Stir Welds of 11Cr-Ferritic/Martensitic Steel to 316 Stainless Steel

NASA Astrophysics Data System (ADS)

Sato, Yutaka S.; Kokawa, Hiroyuki; Fujii, Hiromichi T.; Yano, Yasuhide; Sekio, Yoshihiro

2015-12-01

Dissimilar joints between ferritic and austenitic steels are of interest for selected applications in next generation fast reactors. In this study, dissimilar friction-stir welding of an 11 pct Cr ferritic/martensitic steel to a 316 austenitic stainless steel was attempted and the mechanical properties and microstructure of the resulting welds were examined. Friction-stir welding produces a stir zone without macroscopic weld-defects, but the two dissimilar steels are not intermixed. The two dissimilar steels are interleaved along a sharp zigzagging interface in the stir zone. During small-sized tensile testing of the stir zone, this sharp interface did not act as a fracture site. Furthermore, the microstructure of the stir zone was refined in both the ferritic/martensitic steel and the 316 stainless steel resulting in improved mechanical properties over the adjacent base material regions. This study demonstrates that friction-stir welding can produce welds between dissimilar steels that contain no macroscopic weld-defects and display suitable mechanical properties.

Joining dissimilar materials using Friction Stir scribe technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyay, Piyush; Hovanski, Yuri; Jana, Saumyadeep

2016-10-03

The ability to effectively join materials with vastly different melting points like Aluminum-Steel, Polymer composites - metals has been one of the road blocks in realizing multi-material components for light weighting efforts. Friction stir scribe (FSS) technique is a promising method that produces continuous overlap joint between materials with vastly different melting regimes and high temperature flow characteristics. FSS uses an offset cutting tool at the tip of the FSW pin to create an insitu mechanical interlock between material interfaces. With investments from Vehicle Technology office, US DOE and several automotive manufacturers and suppliers PNNL is developing the FSS processmore » and has demonstrated viability of joining several material combinations. Details of welding trails, unique challenges and mitigation strategies in different material combinations will be discussed. Joint characterization including mechanical tests and joint performances will also be presented.« less

Microstructure evolution and texture development in a friction stir-processed AISI D2 tool steel

NASA Astrophysics Data System (ADS)

Yasavol, N.; Abdollah-zadeh, A.; Vieira, M. T.; Jafarian, H. R.

2014-02-01

Crystallographic texture developments during friction stir processing (FSP) of AISI D2 tool were studied with respect to grain sizes in different tool rotation rates. Comparison of the grain sizes in various rotation rates confirmed that grain refinement occurred progressively in higher rotation rates by severe plastic deformation. It was found that the predominant mechanism during FSP should be dynamic recovery (DRV) happened concurrently with continuous dynamic recrystallization (CDRX) caused by particle-stimulated nucleation (PSN). The developed shear texture relates to the ideal shear textures of D1 and D2 in bcc metals. The prevalence of highly dense arrangement of close-packed planes of bcc and the lowest Taylor factor showed the lowest compressive residual stress which is responsible for better mechanical properties compared with the grain-precipitate refinement.

Fanning the flames: climate change stacks odds against fire suppression.

Treesearch

Jonathan Thompson

2005-01-01

There is little question that global warming would increase the risk of wildfires by drying out vegetation and stirring the winds that spread fire. Until recently, however, land managers were unable to formulate appropriate responses because the spatial scales of predictions were far too coarse. Current research being done at the PNW Research Station in Portland,...

Shaken but not stirred: Multiscale habitat suitability modeling of sympatric marten species (Martes martes and Martes foina) in the northern Iberian Peninsula

Treesearch

Maria Vergara; Samuel A. Cushman; Fermin Urra; Aritz Ruiz-Gonzalez

2016-01-01

Multispecies and multiscale habitat suitability models (HSM) are important to identify the environmental variables and scales influencing habitat selection and facilitate the comparison of closely related species with different ecological requirements. Objectives This study explores the multiscale relationships of habitat suitability for the pine (Martes...

Effect of Initial Microstructure on the Microstructural Evolution and Joint Efficiency of a WE43 Alloy During Friction Stir Welding

DTIC Science & Technology

2013-04-01

to maximize joint efficiency. 15. SUBJECT TERMS friction stir welding, strain rate, dynamic recrystallization , joint efficiency, stir zone (SZ...stir welding, Strain rate, Dynamic recrystallization , Joint efficiency, Stir Zone (SZ) Abstract The initial microstructure plays an important role in... eutectic Mg17Al12 phase. Park et al. [7] demonstrated the importance of texture and related it to the mechanical properties of an AZ61 alloy

Biohydrogen production in a continuous stirred tank bioreactor from synthesis gas by anaerobic photosynthetic bacterium: Rhodopirillum rubrum.

PubMed

Younesi, Habibollah; Najafpour, Ghasem; Ku Ismail, Ku Syahidah; Mohamed, Abdul Rahman; Kamaruddin, Azlina Harun

2008-05-01

Hydrogen may be considered a potential fuel for the future since it is carbon-free and oxidized to water as a combustion product. Bioconversion of synthesis gas (syngas) to hydrogen was demonstrated in continuous stirred tank bioreactor (CSTBR) utilizing acetate as a carbon source. An anaerobic photosynthetic bacterium, Rhodospirillum rubrum catalyzed water-gas shift reaction which was applied for the bioconversion of syngas to hydrogen. The continuous fermentation of syngas in the bioreactor was continuously operated at various gas flow rates and agitation speeds, for the period of two months. The gas flow rates were varied from 5 to 14 ml/min. The agitation speeds were increasingly altered in the range of 150-500 rpm. The pH and temperature of the bioreactor was set at 6.5 and 30 degrees C. The liquid flow rate was kept constant at 0.65 ml/min for the duration of 60 days. The inlet acetate concentration was fed at 4 g/l into the bioreactor. The hydrogen production rate and yield were 16+/-1.1 mmol g(-1)cell h(-1) and 87+/-2.4% at fixed agitation speed of 500 rpm and syngas flow rate of 14 ml/min, respectively. The mass transfer coefficient (KLa) at this condition was approximately 72.8h(-1). This new approach, using a biocatalyst was considered as an alternative method of conventional Fischer-Tropsch synthetic reactions, which were able to convert syngas into hydrogen.

Differential Evolution algorithm applied to FSW model calibration

NASA Astrophysics Data System (ADS)

Idagawa, H. S.; Santos, T. F. A.; Ramirez, A. J.

2014-03-01

Friction Stir Welding (FSW) is a solid state welding process that can be modelled using a Computational Fluid Dynamics (CFD) approach. These models use adjustable parameters to control the heat transfer and the heat input to the weld. These parameters are used to calibrate the model and they are generally determined using the conventional trial and error approach. Since this method is not very efficient, we used the Differential Evolution (DE) algorithm to successfully determine these parameters. In order to improve the success rate and to reduce the computational cost of the method, this work studied different characteristics of the DE algorithm, such as the evolution strategy, the objective function, the mutation scaling factor and the crossover rate. The DE algorithm was tested using a friction stir weld performed on a UNS S32205 Duplex Stainless Steel.

Production and Isolation of Azaspiracid-1 and -2 from Azadinium spinosum Culture in Pilot Scale Photobioreactors

PubMed Central

Jauffrais, Thierry; Kilcoyne, Jane; Séchet, Véronique; Herrenknecht, Christine; Truquet, Philippe; Hervé, Fabienne; Bérard, Jean Baptiste; Nulty, Cíara; Taylor, Sarah; Tillmann, Urban; Miles, Christopher O.; Hess, Philipp

2012-01-01

Azaspiracid (AZA) poisoning has been reported following consumption of contaminated shellfish, and is of human health concern. Hence, it is important to have sustainable amounts of the causative toxins available for toxicological studies and for instrument calibration in monitoring programs, without having to rely on natural toxin events. Continuous pilot scale culturing was carried out to evaluate the feasibility of AZA production using Azadinium spinosum cultures. Algae were harvested using tangential flow filtration or continuous centrifugation. AZAs were extracted using solid phase extraction (SPE) procedures, and subsequently purified. When coupling two stirred photobioreactors in series, cell concentrations reached 190,000 and 210,000 cell·mL−1 at steady state in bioreactors 1 and 2, respectively. The AZA cell quota decreased as the dilution rate increased from 0.15 to 0.3 day−1, with optimum toxin production at 0.25 day−1. After optimization, SPE procedures allowed for the recovery of 79 ± 9% of AZAs. The preparative isolation procedure previously developed for shellfish was optimized for algal extracts, such that only four steps were necessary to obtain purified AZA1 and -2. A purification efficiency of more than 70% was achieved, and isolation from 1200 L of culture yielded 9.3 mg of AZA1 and 2.2 mg of AZA2 of >95% purity. This work demonstrated the feasibility of sustainably producing AZA1 and -2 from A. spinosum cultures. PMID:22822378

Calculation of energy costs of composite biomass stirring at biogas stations

NASA Astrophysics Data System (ADS)

Suslov, D. Yu; Temnikov, D. O.

2018-03-01

The paper is devoted to the study of the equipment to produce biogas fuel from organic wastes. The bioreactor equipped with a combined stirring system ensuring mechanical and bubbling stirring is designed. The method of energy cost calculation of the combined stirring system with original design is suggested. The received expressions were used in the calculation of the stirring system installed in the 10 m3 bioreactor: power consumed by the mixer during the start-up period made Nz =9.03 kW, operating power of the mixer made NE =1.406 kW, compressor power for bubbling stirring made NC =18.5 kW. Taking into account the operating mode of single elements of the stirring system, the energy cost made 4.38% of the total energy received by the biogas station.

Ultrasonic Stir Welding

NASA Technical Reports Server (NTRS)

Nabors, Sammy

2015-01-01

NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

The effect of feed rate and recycle rate variable on leaching process of Na2Zro3 with HCl in continuous stirred tank reactor (CSTR) series

NASA Astrophysics Data System (ADS)

Palupi, Bekti; Supranto, Sediawan, Wahyudi Budi; Setyadji, Moch.

2017-05-01

This time, the natural resources of zircon sand is processed into several zirconium products which is utilized for various industries, such as ceramics, glass industry, metal industry and nuclear industry. The process of zircon sand into zirconium products through several stages, one of them is leaching process of Na2ZrO3 with HCl. In this research, several variations of recycle-rate/feed-rate had been done to determine the effect on leaching process. The leaching was processed at temperature of 90°C, ratio of Na2ZrO3:HCl = 1g:30mL, and 142 rotary per minute of stirring speed for 30 minutes with variation of recycle-rate/feed-rate such as 0.478, 0.299, 0.218, 0.171 and 0.141. The diameter size of Na2ZrO3 powder that used are 0.088 to 0.149 mm. This process was carried out in Continuous Stirred Tank Reactor (CSTR) series with recycle. Based on this research, the greater of the recycle-rate/feed-rate variable, the obtained Zr recovery decreased. The correlation between recycle-rate/feed-rate and Zr recovery is shown by the equation y = -146.91x + 103.51, where y is the Zr recovery and x is the recycle-rate/feed-rate. The highest Zr recovery was 90.52% obtained at recycle-rate/feed-rate 0.141. The mathematical modeling involving the probability model P(r) = 2β2r2 exp(-βr2) can be applied to this leaching process with Sum of Squared Errors (SSE) values in the range of 6×10-7 - 7×10-6.

Diagnostic performance of dark-blood T2-weighted CMR for evaluation of acute myocardial injury.

PubMed

Srichai, Monvadi B; Lim, Ruth P; Lath, Narayan; Babb, James; Axel, Leon; Kim, Daniel

2013-01-01

We compared the image quality and diagnostic performance of 2 fat-suppression methods for black-blood T2-weighted fast spin-echo (FSE), which are as follows: (a) short T1 inversion recovery (STIR; FSE-STIR) and (b) spectral adiabatic inversion recovery (SPAIR; FSE-SPAIR), for detection of acute myocardial injury. Edema-sensitive T2-weighted FSE cardiac magnetic resonance (CMR) imaging is useful in detecting acute myocardial injury but may experience reduced myocardial signal and signal dropout. The SPAIR pulse aims to eliminate artifacts associated with the STIR pulse. A total of 65 consecutive patients referred for CMR evaluation of myocardial structure and function underwent FSE-STIR and FSE-SPAIR, in addition to cine and late gadolinium enhancement (LGE) CMR. T2-weighted FSE images were independently evaluated by 2 readers for image quality and artifacts (Likert scale of 1-5; best-worst) and presence of increased myocardial signal suggestive of edema. In addition, clinical CMR interpretation, incorporating all CMR sequences available, was recorded for comparison. Diagnostic performance of each T2-weighted sequence was measured using recent (<30 days) troponin elevation greater than 2 times the upper limit of normal as the reference standard for acute myocardial injury. Of the 65 patients, there were 21 (32%) with acute myocardial injury. Image quality and artifact scores were significantly better with FSE-SPAIR compared with FSE-STIR (2.15 vs 2.68, P < 0.01; 2.62 vs 3.05, P < 0.01, respectively). The sensitivity, specificity, positive predictive value, and negative predictive value for acute myocardial injury were as follows: 29%, 93%, 67%, and 73% for FSE-SPAIR; 38%, 91%, 67%, and 75% for FSE-STIR; 71%, 98%, 94%, and 88% for clinical interpretation including LGE, T2, and wall motion. There was a statistically significant difference in sensitivity between the clinical interpretation and each of the T2-weighted sequences but not between each T2-weighted sequence. Although FSE-SPAIR demonstrated significantly improved image quality and decreased artifacts, isolated interpretations of each T2-weighted technique demonstrated high specificity but overall low sensitivity for the detection of myocardial injury, with no difference in accuracy between the techniques. However, real-world interpretation in combination with cine and LGE CMR methods significantly improves the overall sensitivity and diagnostic performance.

Advanced bulk processing of lightweight materials for utilization in the transportation sector

NASA Astrophysics Data System (ADS)

Milner, Justin L.

The overall objective of this research is to develop the microstructure of metallic lightweight materials via multiple advanced processing techniques with potentials for industrial utilization on a large scale to meet the demands of the aerospace and automotive sectors. This work focused on (i) refining the grain structure to increase the strength, (ii) controlling the texture to increase formability and (iii) directly reducing processing/production cost of lightweight material components. Advanced processing is conducted on a bulk scale by several severe plastic deformation techniques including: accumulative roll bonding, isolated shear rolling and friction stir processing to achieve the multiple targets of this research. Development and validation of the processing techniques is achieved through wide-ranging experiments along with detailed mechanical and microstructural examination of the processed material. On a broad level, this research will make advancements in processing of bulk lightweight materials facilitating industrial-scale implementation. Where accumulative roll bonding and isolated shear rolling, currently feasible on an industrial scale, processes bulk sheet materials capable of replacing more expensive grades of alloys and enabling low-temperature and high-strain-rate formability. Furthermore, friction stir processing to manufacture lightweight tubes, made from magnesium alloys, has the potential to increase the utilization of these materials in the automotive and aerospace sectors for high strength - high formability applications. With the increased utilization of these advanced processing techniques will significantly reduce the cost associated with lightweight materials for many applications in the transportation sectors.

Protein crystallization in a 100 nl solution with new stirring equipment

PubMed Central

Maki, S.; Murai, R.; Yoshikawa, H. Y.; Kitatani, T.; Nakata, S.; Kawahara, H.; Hasenaka, H.; Kobayashi, A.; Okada, S.; Sugiyama, S.; Adachi, H.; Matsumura, H.; Takano, K.; Murakami, S.; Inoue, T.; Sasaki, T.; Mori, Y.

2008-01-01

To investigate quantitatively the effects of stirring on protein crystallization, a new stirring system which can agitate a protein solution, ∼100 nl, by providing Hagen–Poiseuille flow has been successfully developed. In addition, this new stirring system provides flow with a well defined pattern and velocity. Using this system, hen egg-white lysozyme was crystallized in 100–200 nl solutions while being stirred. The optimum stirring conditions for lysozyme crystals have been explored by evaluating the Reynolds (Re) number and the crystals obtained. Intermittent flow, as well as a low Re number, was found to contribute significantly to the growth of a smaller number of larger crystals. PMID:18421156

CFD simulation of an unbaffled stirred tank reactor driven by a magnetic rod: assessment of turbulence models.

PubMed

Li, Jiajia; Deng, Baoqing; Zhang, Bing; Shen, Xiuzhong; Kim, Chang Nyung

2015-01-01

A simulation of an unbaffled stirred tank reactor driven by a magnetic stirring rod was carried out in a moving reference frame. The free surface of unbaffled stirred tank was captured by Euler-Euler model coupled with the volume of fluid (VOF) method. The re-normalization group (RNG) k-ɛ model, large eddy simulation (LES) model and detached eddy simulation (DES) model were evaluated for simulating the flow field in the stirred tank. All turbulence models can reproduce the tangential velocity in an unbaffled stirred tank with a rotational speed of 150 rpm, 250 rpm and 400 rpm, respectively. Radial velocity is underpredicted by the three models. LES model and RNG k-ɛ model predict the better tangential velocity and axial velocity, respectively. RNG k-ɛ model is recommended for the simulation of the flow in an unbaffled stirred tank with magnetic rod due to its computational effort.

Effects of different cooking methods on health-promoting compounds of broccoli*

PubMed Central

Yuan, Gao-feng; Sun, Bo; Yuan, Jing; Wang, Qiao-mei

2009-01-01

The effects of five domestic cooking methods, including steaming, microwaving, boiling, stir-frying, and stir-frying followed by boiling (stir-frying/boiling), on the nutrients and health-promoting compounds of broccoli were investigated. The results show that all cooking treatments, except steaming, caused significant losses of chlorophyll and vitamin C and significant decreases of total soluble proteins and soluble sugars. Total aliphatic and indole glucosinolates were significantly modified by all cooking treatments but not by steaming. In general, the steaming led to the lowest loss of total glucosinolates, while stir-frying and stir-frying/boiling presented the highest loss. Stir-frying and stir-frying/boiling, the two most popular methods for most homemade dishes in China, cause great losses of chlorophyll, soluble protein, soluble sugar, vitamin C, and glucosinolates, but the steaming method appears the best in retention of the nutrients in cooking broccoli. PMID:19650196

Barbell-shaped stir bar sorptive extraction using dummy template molecularly imprinted polymer coatings for analysis of bisphenol A in water.

PubMed

Liu, Ruimei; Feng, Feng; Chen, Guolin; Liu, Zhimin; Xu, Zhigang

2016-07-01

This study reports the development of a novel dummy template molecularly imprinted polymer (MIP)-coated barbell-shaped stir bar. The MIP stir bar coatings were prepared by using 2,2-bis(4-hydroxyphenyl)butane (BPB), 4,4'-dihydroxydiphenylmethane (BPF), 4-tert-butylphenol (PTBP), and tetrabromobisphenol A (TBBA) as dummy templates using a capillary in situ polymerization method. Uniform coatings can be prepared controllably. The method is simple, easy, and reproducible. The barbell-shaped stir bar was developed by using medical silicone tubes as wheels. The wheels could be removed and reinstalled when necessary; therefore, the barbell-shaped stir bar was easy to disassemble and reassemble. The novel MIP-coated stir bar showed good selectivity for the target analyte, bisphenol A (BPA). The established method is selective and sensitive with a lower detection limit for BPA of 0.003 μg/L. The dummy template MIP-coated stir bar is suitable for trace BPA analysis in real environmental water samples without template leakage. The novel stir bar can be used at least 100 times.

Detection of biological uranium reduction using magnetic resonance.

PubMed

Vogt, Sarah J; Stewart, Brandy D; Seymour, Joseph D; Peyton, Brent M; Codd, Sarah L

2012-04-01

The conversion of soluble uranyl ions (UO₂²⁺) by bacterial reduction to sparingly soluble uraninite (UO₂(s)) is being studied as a way of immobilizing subsurface uranium contamination. Under anaerobic conditions, several known types of bacteria including iron and sulfate reducing bacteria have been shown to reduce U (VI) to U (IV). Experiments using a suspension of uraninite (UO₂(s)) particles produced by Shewanella putrefaciens CN32 bacteria show a dependence of both longitudinal (T₁) and transverse (T₂) magnetic resonance (MR) relaxation times on the oxidation state and solubility of the uranium. Gradient echo and spin echo MR images were compared to quantify the effect caused by the magnetic field fluctuations (T*₂) of the uraninite particles and soluble uranyl ions. Since the precipitate studied was suspended in liquid water, the effects of concentration and particle aggregation were explored. A suspension of uraninite particles was injected into a polysaccharide gel, which simulates the precipitation environment of uraninite in the extracellular biofilm matrix. A reduction in the T₂ of the gel surrounding the particles was observed. Tests done in situ using three bioreactors under different mixing conditions, continuously stirred, intermittently stirred, and not stirred, showed a quantifiable T₂ magnetic relaxation effect over the extent of the reaction. Copyright © 2011 Wiley Periodicals, Inc.

[GC-MS combined with AMDIS and Kováts retention index to investigate dynamic change rules of volatile components from Atractylodis Macrocephalae Rhizoma with different stir-baking degrees].

PubMed

Chen, Hong-Ping; Pan, Huan-Huan; Zhang, Xin; Liu, Fei; Chen, Mei-Jun; Luo, Guan-Hua; Liu, You-Ping

2016-07-01

To investigate the dynamic change rules of volatile components from Atractylodis Macrocephalae Rhizoma with different stir-baking degrees (from slight stir-baking, stir-baking to yellow, stir-baking to brown, to stir-baking to scorch). In the present experiment, the Atractylodis Macrocephalae Rhizoma samples with different stir-baking degrees were collected at different processing time points. The contents of volatile oil in various samples were determined by steam distillation method, and the volatile compounds were extracted by using static headspace sampling method. Gas chromatography-mass spectrography (GC-MS) and automated mass spectral deconrolution and identification system (AMDIS) were combined with Kováts retention index to analyze the chemical constituents of the volatile compounds. The results showed that with the deepening of the stir-baking degree, the content of volatile oil was decreased step by step in 4 phases, and both the compositions and contents of volatile components from Atractylodis Macrocephalae Rhizoma showed significant changes. The results showed that the dynamic change rules of volatile components from Atractylodis Macrocephalae Rhizoma in the process of stir-baking were closely related to the processing degree; in addition, Atractylodis Macrocephalae Rhizoma and honey bran had adsorption on each other. These results can provide a scientific basis for elucidating the stir-baking (with bran) mechanism of Atractylodis Macrocephalae Rhizoma. Copyright© by the Chinese Pharmaceutical Association.

Preparation of polydimethylsiloxane/beta-cyclodextrin/divinylbenzene coated "dumbbell-shaped" stir bar and its application to the analysis of polycyclic aromatic hydrocarbons and polycyclic aromatic sulfur heterocycles compounds in lake water and soil by high performance liquid chromatography.

PubMed

Yu, Chunhe; Yao, Zhimin; Hu, Bin

2009-05-08

A "dumbbell-shaped" stir bar was proposed to prevent the friction loss of coating during the stirring process, and thus prolonged the lifetime of stir bars. The effects of the coating components, including polydimethylsiloxane (PDMS), beta-cyclodextrin (beta-CD) and divinylbenzene (DVB) were investigated according to an orthogonal experimental design, using three polycyclic aromatic hydrocarbons (PAHs) and four polycyclic aromatic sulfur heterocycles (PASHs) as model analytes. Four kinds of stir bars coated with PDMS, PDMS/beta-CD, PDMS/DVB and PDMS/beta-CD/DVB were prepared and their extraction efficiencies for the target compounds were compared. It was demonstrated that PDMS/beta-CD/DVB-coated stir bar showed the best affinity to the studied compounds. The preparation reproducibility of PDMS/beta-CD/DVB-coated stir bar ranged from 3.2% to 15.2% (n = 6) in one batch, and 5.2% to 13.4% (n = 6) among batches. The "dumbbell-shaped" stir bar could be used for about 40 times, which were 10 extractions more than a normal stir bar. The prepared PDMS/beta-CD/DVB-coated "dumbbell-shaped" stir bar was used for stir bar sorptive extraction (SBSE) of PAHs and PASHs and the desorbed solution was introduced into HPLC-UV for subsequent analysis. The limits of detection of the proposed method for seven target analytes ranged from 0.007 to 0.103 microg L(-1), the relative standard deviations were in the range of 6.3-12.9% (n = 6, c = 40 microg L(-1)), and the enrichment factors were 19-86. The proposed method was successfully applied to the analysis of seven target analytes in lake water and soil samples.

Multi-stir bar sorptive extraction for analysis of odor compounds in aqueous samples.

PubMed

Ochiai, Nobuo; Sasamoto, Kikuo; Ieda, Teruyo; David, Frank; Sandra, Pat

2013-11-08

As reproducible coating of stir bars with more polar phases was found to be very difficult, a supporting grid was used in the development of an ethyleneglycol-modified Silicone (EG Silicone) coated stir bar. This new polar coating showed good performance for the extraction of polar solutes, but long term use also showed degradation of the coating due to friction while stirring. In order to address the lower robustness of the EG Silicone stir bar which has a much softer coating compared to a conventional polydimethylsiloxane (PDMS) stir bar, a novel SBSE procedure termed multi-SBSE ((m)SBSE) was developed. (m)SBSE consists of the robust PDMS stir bar stirring at the bottom of the vial and the EG Silicone stir bar attached on the inner side wall of the vial (a magnetic clip is used for the set-up). After extraction, the two stir bars are placed in a single glass desorption liner and are simultaneously thermally desorbed. The desorbed compounds were analyzed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Compared to conventional SBSE, (m)SBSE provides more uniform enrichment of a wide range of odor compounds in aqueous sample since both stir bars can complement each other, while eliminating the damage of the EG Silicone phase during the extraction. The robustness of the EG Silicone stir bar was dramatically increased and more than 30 extraction and desorption cycles were possible without loss in performance. The recoveries for polar solutes such as 2-acetyl pyrrole (logKow: 0.55), benzyl alcohol (logKow: 1.08), guaiacol (logKow: 1.34), and indole (logKow: 2.05) were increased by a factor of about 2-7. The (m)SBSE-TD-GC-MS method showed good linearity (r(2)>0.9913) and high sensitivity (limit of detection: 0.011-0.071 ng mL(-1)) for the test compounds spiked in water. The feasibility and benefit of the method was demonstrated with analysis of odor compounds in roasted green tea. The normalized areas obtained from (m)SBSE showed the best enrichment for most of the selected compounds compared to conventional SBSE using the PDMS stir bar or the EG Silicone stir bar. Fifteen compounds were determined in the range of 0.15-210 ng mL(-1) (RSD<14%, n=6). Copyright © 2013 Elsevier B.V. All rights reserved.

Tulane/Xavier Vaccine Peptide Program

DTIC Science & Technology

2014-09-01

liposomes, and hydrophobically modified chitosan (HMC) coated liposomes. The oil-in-water (O/W) microemulsions are composed of isopropyl myristate...vesicles. To prepare the hydrophobically modified chitosan (HMC) coated liposomes, chitosan is added drop by drop to the liposome dispersion with...continuous stirring for 2 hours to ensure chitosan has been evenly attached on the liposome surface. A representative electron micrograph of the

Development of a Design Tool for Planning Aqueous Amendment Injection Systems Permanganate Design Tool

DTIC Science & Technology

2010-08-01

CSTR continuously stirred tank reactors CT contact time EDB ethylene dibromide ESTCP Environmental Security Technology Certification Program...63 6.2 Simulating Oxidant Distribution Using a Series of CSTRs -------------------- 63 6.2.1 Model...SIMULATING OXIDANT DISTRIBUTION USING A SERIES OF CSTRS 6.2.1 MODEL DEVELOPMENT The transport and consumption of permanganate are simulated within the

Differences between Cheddar cheese manufactured by the milled-curd and stirred-curd methods using different commercial starters.

PubMed

Shakeel-ur-Rehman; Drake, M A; Farkye, N Y

2008-01-01

Traditionally, Cheddar cheese is made by the milled-curd method. However, because of the mechanization of cheese making and time constraints, the stirred-curd method is more commonly used by many large-scale commercial manufacturers. This study was undertaken to evaluate quality differences during ripening (at 2 and 8 degrees C) of Cheddar cheese made by the milled-curd and stirred-curd methods, using 4 different commercial starters. Twenty-four vats (4 starters x 2 methods x 3 replicates) were made, with approximately 625 kg of pasteurized (72 degrees C x 16 s) whole milk in each vat. Fat, protein, and salt contents of the cheeses were not affected by the starter. Starter cell densities in cheese were not affected by the method of manufacture. Nonstarter lactic acid bacteria counts at 90, 180, and 270 d were influenced by the manufacturing method, with a higher trend in milled-curd cheeses. Proteolysis in cheese (percentage of water-soluble N) was influenced by the starter and manufacturing method (270 d). Sensory analysis by a trained descriptive panel (n = 8) revealed differences in cooked, whey, sulfur, brothy, milk fat, umami, and bitter attributes caused by the starter, whereas only brothy flavor was influenced by storage temperature. The method of manufacture influenced diacetyl, sour, and salty flavors.

Front propagation in a regular vortex lattice: Dependence on the vortex structure.

PubMed

Beauvier, E; Bodea, S; Pocheau, A

2017-11-01

We investigate the dependence on the vortex structure of the propagation of fronts in stirred flows. For this, we consider a regular set of vortices whose structure is changed by varying both their boundary conditions and their aspect ratios. These configurations are investigated experimentally in autocatalytic solutions stirred by electroconvective flows and numerically from kinematic simulations based on the determination of the dominant Fourier mode of the vortex stream function in each of them. For free lateral boundary conditions, i.e., in an extended vortex lattice, it is found that both the flow structure and the front propagation negligibly depend on vortex aspect ratios. For rigid lateral boundary conditions, i.e., in a vortex chain, vortices involve a slight dependence on their aspect ratios which surprisingly yields a noticeable decrease of the enhancement of front velocity by flow advection. These different behaviors reveal a sensitivity of the mean front velocity on the flow subscales. It emphasizes the intrinsic multiscale nature of front propagation in stirred flows and the need to take into account not only the intensity of vortex flows but also their inner structure to determine front propagation at a large scale. Differences between experiments and simulations suggest the occurrence of secondary flows in vortex chains at large velocity and large aspect ratios.

Minimizing hydrodynamic stress in mammalian cell culture through the lobed Taylor-Couette bioreactor.

PubMed

Sorg, Robin; Tanzeglock, Timm; Soos, Miroslav; Morbidelli, Massimo; Périlleux, Arnaud; Solacroup, Thomas; Broly, Hervé

2011-12-01

The objective of the present study was to investigate the effect of hydrodynamic stress heterogeneity on metabolism and productivity of an industrial mammalian cell line. For this purpose, a novel Lobed Taylor-Couette (LTC) mixing unit combining a narrow distribution of hydrodynamic stresses and a membrane aeration system to prevent cell damage by bubble bursting was developed. A hydrodynamic analysis of the LTC was developed to reproduce, in a uniform hydrodynamic environment, the same hydrodynamic stress encountered locally by cells in a stirred tank, particularly at the large scale, e.g., close and far from the impeller. The developed LTC was used to simulate the stress values near the impeller of a laboratory stirred tank bioreactor, equal to about 0.4 Pa, which is however below the threshold value leading to cell death. It was found that the cells actively change their metabolism by increasing lactate production and decreasing titer while the consumption of the main nutrients remains substantially unchanged. When considering average stress values ranging from 1 to 10 Pa found by other researchers to cause physiological response of cells to the hydrodynamic stress in heterogeneous stirred vessels, our results are close to the lower boundary of this interval. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Research on change process of nitrosation granular sludge in continuous stirred-tank reactor].

PubMed

Yin, Fang-Fang; Liu, Wen-Ru; Wang, Jian-Fang; Wu, Peng; Shen, Yao-Liang

2014-11-01

In order to investigate the effect of different types of reactors on the nitrosation granular sludge, a continuous stirred-tank reactor (CSTR) was studied, using mature nitrosation granular sludge cultivated in sequencing batch reactor (SBR) as seed sludge. Results indicated that the change of reactor type and influent mode could induce part of granules to lose stability with gradual decrease in sludge settling ability during the initial period of operation. However, the flocs in CSTR achieved fast granulation in the following reactor operation. In spite of the changes of particle size distribution, e. g. the decreasing number of granules with diameter larger than 2.5 mm and the increasing number of granules with diameter smaller than 0.3 mm, granular sludge held the absolute predominance of sludge morphology in CSTR during the entire experimental period. Moreover, results showed that the change of reactor type and influent mode didn't affect the nitrite accumulation rate which was still kept at about 85% in effluent. Additionally, the average activity of the sludge in CSTR was stronger than that of the seed sludge, because the newly generated small particles in CSTR had higher specific reactive activity than the larger granules.

Production of Concentrated Pickering Emulsions with Narrow Size Distributions Using Stirred Cell Membrane Emulsification.

PubMed

Manga, Mohamed S; York, David W

2017-09-12

Stirred cell membrane emulsification (SCME) has been employed to prepare concentrated Pickering oil in water emulsions solely stabilized by fumed silica nanoparticles. The optimal conditions under which highly stable and low-polydispersity concentrated emulsions using the SCME approach are highlighted. Optimization of the oil flux rates and the paddle stirrer speeds are critical to achieving control over the droplet size and size distribution. Investigating the influence of oil volume fraction highlights the criticality of the initial particle loading in the continuous phase on the final droplet size and polydispersity. At a particle loading of 4 wt %, both the droplet size and polydispersity increase with increasing of the oil volume fraction above 50%. As more interfacial area is produced, the number of particles available in the continuous phase diminishes, and coincidently a reduction in the kinetics of particle adsorption to the interface resulting in larger polydisperse droplets occurs. Increasing the particle loading to 10 wt % leads to significant improvements in both size and polydispersity with oil volume fractions as high as 70% produced with coefficient of variation values as low as ∼30% compared to ∼75% using conventional homogenization techniques.

Laser-Assisted Stir Welding of 25-mm-Thick HSLA-65 Plate

NASA Astrophysics Data System (ADS)

Williamson, Keith M.

2002-12-01

Laser-assisted stir welding is a hybrid process that combines energy from a laser with functional heating and mechanical energy to join materials in the solid state. The technology is an adaptation of friction stir welding which is particularly suited for joining thick plates. Aluminum plates up to 75 mm thick have been successfully joined using friction stir welding. Since joining occurs in the solid state, stir technology offers the capability for fabricating full penetration joints in thick plates with better mechanical properties and less weld distortion than is possible by fusion processes. Currently friction stir welding is being used in several industries to improve productivity, reduce weight, and increase the strength of welded structures. Examples include: (a) the aircraft/aerospace industry where stir technology is currently being used to fabricate the space shuttle's external tank as well as components of the Delta family of rockets; (b) the shipping industry where container manufacturers are using stir technology to produce lighter containers with more payload capacity; and (c) the oil industry where offshore platform manufactures are using automated stir welding plants to fabricate large panels and structures up to 16 meters long with widths as required. In all these cases, stir technology has been restricted to aluminum alloys; however, stainless and HSLA 65 steels have been recently stir welded with friction as the primary heat source. One of the difficulties in adapting stir welding to steel is tool wear aggravated by the high tool rubbing velocities needed to provide frictional heat input into the material. Early work showed that the tool shoulder reached temperatures above 1000 C and the weld seam behind the tool stayed within this temperature range for up to 25 mm behind the tool. Cross sections of stir welded samples showed that the heat-affected zone is relatively wide and follows the profile of the tool shoulder. Besides minimizing the tool wear by increasing the energy into the material, another benefit of the proposed Laser Assisted Stir Welding (LASW is to reduce the width of the heat affected zone which typically has the lowest hardness in the weld region. Additionally, thermal modeling of the friction stir process shows that the heat input is asymmetric and suggests that the degree of asymmetry could improve the efficiency of the process. These asymmetries occur because the leading edge of the tool supplies heat to cold material while the trailing edge provides heat to material already preheated by the leading edge. As a result, flow stresses on the advancing side of the joint are lower than corresponding values on the retreating side. The proposed LASW process enhances these asymmetries by providing directional heating to increase the differential in flow stress across the joint and improve the stir tool efficiency. Theoretically the LASW process can provide the energy input to allow the flow stresses on the advancing side to approach zero and the stir efficiency to approach 100 percent. Reducing the flow stresses on the advancing side of the weld creates the greatest pressure differential across the stir weld and eliminates the possibility of voids on the advancing side of the joint. Small pressure differentials result in poor stir welds because voids on the advancing side are not filled by the plastic flow of material from the retreating side.

Development and application of kinetic model on biological anoxic/aerobic filter.

PubMed

Kim, Youngnoh; Tanaka, Kazuhiro; Lee, Yong-Woo; Chung, Jinwook

2008-01-01

An up-flow biological anoxic filter (BANF) has been developed to achieve high removal performance of suspended solids and BOD removal as well as nitrogen. With a view to understand treatment mechanisms, we developed a filtration model that incorporates filtration, deposit scoring and biological reactions simultaneously. The biological reactions consist of four types of reaction; dissolution of organic particles; utilization of dissolved organic matter; denitrification; and self-degradation of bacteria. Whereas the reactor is generally assumed to be a plug flow reactor in the filtration model, it is assumed a continuous-flow stirred tank reactor (CSTR) in the model of biological reactions. The hydrodynamics is supposed that the filter bottom (the portion sludge settled) is a CSTR and the filter bed (the portion filled with filter media) consists of number of CSTR of equal size arranged in series. The model obtained in this study was verified and simulated using experimental results taken from a pilot-scale plant and predicted the experimental data well, applying to design and operate BANF.

Reactivation of dead sulfide species in lithium polysulfide flow battery for grid scale energy storage

DOE PAGES

Jin, Yang; Zhou, Guangmin; Shi, Feifei; ...

2017-09-06

Lithium polysulfide batteries possess several favorable attributes including low cost and high energy density for grid energy storage. However, the precipitation of insoluble and irreversible sulfide species on the surface of carbon and lithium (called “dead” sulfide species) leads to continuous capacity degradation in high mass loading cells, which represents a great challenge. To address this problem, herein we propose a strategy to reactivate dead sulfide species by reacting them with sulfur powder with stirring and heating (70 °C) to recover the cell capacity, and further demonstrate a flow battery system based on the reactivation approach. As a result, ultrahighmore » mass loading (0.125 g cm –3, 2g sulfur in a single cell), high volumetric energy density (135 Wh L –1), good cycle life, and high single-cell capacity are achieved. The high volumetric energy density indicates its promising application for future grid energy storage.« less

Use of collagen hydrolysate as a complex nitrogen source for the synthesis of penicillin by Penicillium chrysogenum.

PubMed

Leonhartsberger, S; Lafferty, R M; Korneti, L

1993-09-01

Optimal conditions for both biomass formation and penicillin synthesis by a strain of Penicillium chrysogenum were determined when using a collagen-derived nitrogen source. Preliminary investigations were carried out in shaken flask cultures employing a planned experimental program termed the Graeco-Latin square technique (Auden et al., 1967). It was initially determined that up to 30% of a conventional complex nitrogen source such as cottonseed meal could be replaced by the collagen-derived nitrogen source without decreasing the productivity with respect to the penicillin yield. In the pilot scale experiments using a 30 l stirred tank type of bioreactor, higher penicillin yields were obtained when 70% of the conventional complex nitrogen source in the form of cottonseed meal was replaced by the collagen hydrolysate. Furthermore, the maximum rate of penicillin synthesis continued for over a longer period when using collagen hydrolysate as a complex nitrogen source. Penicillin synthesis rates were determined using a linear regression.

Reactivation of dead sulfide species in lithium polysulfide flow battery for grid scale energy storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Yang; Zhou, Guangmin; Shi, Feifei

Lithium polysulfide batteries possess several favorable attributes including low cost and high energy density for grid energy storage. However, the precipitation of insoluble and irreversible sulfide species on the surface of carbon and lithium (called “dead” sulfide species) leads to continuous capacity degradation in high mass loading cells, which represents a great challenge. To address this problem, herein we propose a strategy to reactivate dead sulfide species by reacting them with sulfur powder with stirring and heating (70 °C) to recover the cell capacity, and further demonstrate a flow battery system based on the reactivation approach. As a result, ultrahighmore » mass loading (0.125 g cm –3, 2g sulfur in a single cell), high volumetric energy density (135 Wh L –1), good cycle life, and high single-cell capacity are achieved. The high volumetric energy density indicates its promising application for future grid energy storage.« less

Heterotrophic Cultivation of Cyanobacteria: Study of Effect of Exogenous Sources of Organic Carbon, Absolute Amount of Nutrients, and Stirring Speed on Biomass and Lipid Productivity

PubMed Central

Meireles dos Santos, Aline; Vieira, Karem Rodrigues; Basso Sartori, Rafaela; Meireles dos Santos, Alberto; Queiroz, Maria Isabel; Queiroz Zepka, Leila; Jacob-Lopes, Eduardo

2017-01-01

The production of bioproducts from cyanobacteria with techno-economic feasibility is a challenge to these biotechnological processes. The choice of low-cost raw materials is of great importance for the overall economy of bioprocesses, as they represent a significant percentage in the final cost of the product. The objective of this work was to study the operational parameters of cultivation (exogenous sources of organic carbon and absolute amount of nutrients) to optimize productivity in bioproducts by Aphanothece microscopica Nägeli, for further evaluation of stirring speed. The experiments were performed in a bubble column bioreactor, operating at 30°C, pH of 7.6, C/N ratio of 20, 100 mg/L of inoculum, continuous aeration of 1 volume of air per volume of culture per minute (VVM), and absence of light. The results indicate that absolute amounts of 5,000/250 using cassava starch resulted in improved system performance, reaching biomass productivity of 36.66 mg/L/h in parallel with lipid productivity of 6.65 mg/L/h. Finally, experiments with variation in stirring speed indicate that 200 rpm resulted in better average rate of substrate consumption (44.01 mg/L/h), in parallel to biomass productivity of 39.27 mg/L/h. However, the increase of stirring speed had a negative effect on lipid productivity of the process. The technological route developed indicates potential to production of biomass and bulk oil, as a result of the capacity of cyanobacteria to adapt their metabolism in varying culture conditions, which provides opportunities to modify, control, and thereby maximize the formation of targeted compounds. PMID:28265559

Medial tibial pain: a dynamic contrast-enhanced MRI study.

PubMed

Mattila, K T; Komu, M E; Dahlström, S; Koskinen, S K; Heikkilä, J

1999-09-01

The purpose of this study was to compare the sensitivity of different magnetic resonance imaging (MRI) sequences to depict periosteal edema in patients with medial tibial pain. Additionally, we evaluated the ability of dynamic contrast-enhanced imaging (DCES) to depict possible temporal alterations in muscular perfusion within compartments of the leg. Fifteen patients with medial tibial pain were examined with MRI. T1-, T2-weighted, proton density axial images and dynamic and static phase post-contrast images were compared in ability to depict periosteal edema. STIR was used in seven cases to depict bone marrow edema. Images were analyzed to detect signs of compartment edema. Region-of-interest measurements in compartments were performed during DCES and compared with controls. In detecting periosteal edema, post-contrast T1-weighted images were better than spin echo T2-weighted and proton density images or STIR images, but STIR depicted the bone marrow edema best. DCES best demonstrated the gradually enhancing periostitis. Four subjects with severe periosteal edema had visually detectable pathologic enhancement during DCES in the deep posterior compartment of the leg. Percentage enhancement in the deep posterior compartment of the leg was greater in patients than in controls. The fast enhancement phase in the deep posterior compartment began slightly slower in patients than in controls, but it continued longer. We believe that periosteal edema in bone stress reaction can cause impairment of venous flow in the deep posterior compartment. MRI can depict both these conditions. In patients with medial tibial pain, MR imaging protocol should include axial STIR images (to depict bone pathology) with T1-weighted axial pre and post-contrast images, and dynamic contrast enhanced imaging to show periosteal edema and abnormal contrast enhancement within a compartment.

Development of Microstructure and Crystallographic Texture in a Double-Sided Friction Stir Welded Microalloyed Steel

NASA Astrophysics Data System (ADS)

Rahimi, S.; Wynne, B. P.; Baker, T. N.

2017-01-01

The evolution of microstructure and crystallographic texture has been investigated in double-sided friction stir welded microalloyed steel, using electron backscatter diffraction (EBSD). The microstructure analyses show that the center of stirred zone reached a temperature between Ac1 and Ac3 during FSW, resulting in a dual-phase austenitic/ ferritic microstructure. The temperatures in the thermo-mechanically affected zone and the overlapped area between the first and second weld pass did not exceed the Ac1. The shear generated by the rotation probe occurs in austenitic/ferritic phase field where the austenite portion of the microstructure is transformed to a bainitic ferrite, on cooling. Analysis of crystallographic textures with regard to shear flow lines generated by the probe tool shows the dominance of simple shear components across the whole weld. The austenite texture at Ac1 - Ac3 is dominated by the B { {1bar{1}2} }< 110rangle and bar{B} { {bar{1}1bar{2}} }< bar{1}bar{1}0rangle simple shear texture components, where the bainite phase textures formed on cooling were inherited from the shear textures of the austenite phase with relatively strong variant selection. The ferrite portion of the stirred zone and the ferrites in the thermo-mechanically affected zones and the overlapped area underwent shear deformation with textures dominated by the D1 { {bar{1}bar{1}2} }< 111rangle and D2 { {11bar{2}} }< 111rangle simple shear texture components. The formation of ultrafine equiaxed ferrite with submicron grain size has been observed in the overlapped area between the first and second weld pass. This is due to continuous dynamic strain-induced recrystallization as a result of simultaneous severe shear deformation and drastic undercooling.

Welding Development: Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Ding, Jeff

2007-01-01

This paper presents the basic understanding of the friction stir welding process. It covers process description, pin tool operation and materials, metal flow theory, mechanical properties, and materials welded using the process. It also discusses the thermal stir welding process and the differences between thermal stir and friction stir welding. MSFC weld tools used for development are also presented.

Anaerobic treatment of animal byproducts from slaughterhouses at laboratory and pilot scale.

PubMed

Edström, Mats; Nordberg, Ake; Thyselius, Lennart

2003-01-01

Different mixtures of animal byproducts, other slaughterhouse waste (i.e., rumen, stomach and intestinal content), food waste, and liquid manure were codigested at mesophilic conditions (37 degrees C) at laboratory and pilot scale. Animal byproducts, including blood, represent 70-80% of the total biogas potential from waste generated during slaughter of animals. The total biogas potential from waste generated during slaughter is about 1300 MJ/cattle and about 140 MJ/pig. Fed-batch digestion of pasteurized (70 degrees C, 1 h) animal byproducts resulted in a fourfold increase in biogas yield (1.14 L/g of volatile solids [VS]) compared with nonpasteurized animal byproducts (0.31 L/g of VS). Mixtures with animal byproducts representing 19-38% of the total dry matter were digested in continuous-flow stirred tank reactors at laboratory and pilot scale. Stable processes at organic loading rates (OLRs) exceeding 2.5 g of VS/(L.d) and hydraulic retention times (HRTs) less than 40 d could be obtained with total ammonia nitrogen concentrations (NH4-N + NH3-N) in the range of 4.0-5.0 g/L. After operating one process for more than 1.5 yr at total ammonia nitrogen concentrations >4 g/L, an increase in OLR to 5 g of VS/(L.d) and a decrease in HRT to 22 d was possible without accumulation of volatile fatty acids.

Chaotic characteristics enhanced by impeller of perturbed six-bent-bladed turbine in stirred tank

NASA Astrophysics Data System (ADS)

Luan, Deyu; Zhang, Shengfeng; Lu, Jianping; Zhang, Xiaoguang

The fundamental way of improving the mixing efficiency is to induce the chaotic flow in a stirred vessel. The impeller form plays an important role for changing the structure of flow field and realizing chaotic mixing. Based on the velocity time series acquired by the experiment of particle image velocimetry (PIV), with the software Matlab, the macro-instability (MI), largest Lyapunov exponent (LLE), and Kolmogorov entropy in the water stirred tank is investigated respectively with the impeller of perturbed six-bent-bladed turbine (6PBT). The results show that the MI characteristics are obvious and two peak values of MI frequency are observed at the speed N = 60 rpm. With the increasing speed (more than 100 rpm), the peak characteristics of MI frequency disappear and a multi-scale wavelet structure of characterizing the chaotic flow field appears. Moreover, under the speed N = 60 rpm, the LLE is less than 0 and Kolmogorov entropy is 0, which means that the flow field is in the periodic moving state. As the speed is increased to more than 100 rpm, the LLE and Kolmogorov entropy are all more than 0, which indicates that the flow field goes into the chaotic mixing. When the speed reaches up to about 210 rpm, both of the LLE and Kolmogorov entropy achieve the optimum values, which will result in an excellent chaos with the highest mixing efficient. So it is feasible that the MI frequency, the LLE and the Kolmogorov entropy can be used to analyze the flow field characteristics in a stirred tank. The research results promote the understanding of the chaotic mixing mechanism and provide a theoretical reference for the development of new type impeller.

Energy efficiency in industrial mixing and cooling of non-Newtonian fluid in a stirred tank reactor

NASA Astrophysics Data System (ADS)

Baghli, Houda; Benyettou, Mohamed; Tchouar, Noureddine; Merah, Abdelkrim; Djafri, Mohammed

2018-05-01

This paper study the energy efficiency of the mixing and cooling of a non-Newtonian fluid manufactured on an industrial scale in a stirred tank reactor equipped with jacketed cooling side. The purpose of this study is to optimize the heat transfer to degrease the cooling time and recommend a technologic innovation to realize this purpose without altering the quality of this product. First the different production processes are analyzed. The decrease of the shear stress with time indicates that this fluid is non-Newtonian and has to be characterized. The rheological behavior of this fluid is determined by a series of viscosimetric measurements, at different shear rates (30 to 400 s-1), and at different temperatures in the range (20° C to 80 °C), representing the stress and temperature conditions recorded during production, storage and packaging cycles of this product. Experimental results show that the nature of the fluid is pseudo-plastic with flow behavior index n<1 and follow the power law model, with the influence of temperature on flow consistency index K. A thermo-dependent model is given to express this rheological parameters and viscosity of this fluid as a function of temperature, valid for the fluid temperature between 20 to 80 °C. This rheological model is used to achieve the heat transfer simulation in the industrial stirred tank with an anchor impeller mixing. Simulation results shows that the cooling time by mixing can be the quarter by reducing the stirring speed to 125 rpm, and decreasing the coolant temperature to 20°C and therefore reduce energy consumption. A technologic integration of a natural cooling thermo-siphon devise outside the process is proposed to afford a cooling fluid below 20°C.

Autogeneous Friction Stir Weld Lack-of-Penetration Defect Detection and Sizing Using Directional Conductivity Measurements with MWM Eddy Current Sensor

NASA Technical Reports Server (NTRS)

Goldfine, Neil; Zilberstei, Vladimir; Lawson, Ablode; Kinchen, David; Arbegast, William

2000-01-01

Al 2195-T8 plate specimens containing Friction Stir Welds (FSW), provided by Lockheed Martin, were inspected using directional conductivity measurements with the MWM sensor. Sensitivity to lack-of-penetration (LOP) defect size has been demonstrated. The feature used to determine defect size was the normalized longitudinal component of the MWM conductivity measurements. This directional conductivity component was insensitive to the presence of a discrete crack. This permitted correlation of MWM conductivity measurements with the LOP defect size as changes in conductivity were apparently associated with metallurgical features within the first 0.020 in. of the LOP defect zone. Transverse directional conductivity measurements also provided an indication of the presence of discrete cracks. Continued efforts are focussed on inspection of a larger set of welded panels and further refinement of LOP characterization tools.

Synthesis of Commercial Products from Copper Wire-Drawing Waste

NASA Astrophysics Data System (ADS)

Ayala, J.; Fernández, B.

2014-06-01

Copper powder and copper sulfate pentahydrate were obtained from copper wire-drawing scale. The hydrometallurgical recycling process proposed in this article yields a high-purity copper powder and analytical grade copper sulfate pentahydrate. In the first stage of this process, the copper is dissolved in sulfuric acid media via dismutation of the scale. In the second stage, copper sulfate pentahydrate is precipitated using ethanol. Effects such as pH, reaction times, stirring speed, initial copper concentration, and ethanol/solution volume ratio were studied during the precipitation from solution reaction. The proposed method is technically straightforward and provides efficient recovery of Cu from wire-drawing scale.

Molecularly imprinted polymeric stir bar: Preparation and application for the determination of naftopidil in plasma and urine samples.

PubMed

Peng, Jun; Xiao, Deli; He, Hua; Zhao, Hongyan; Wang, Cuixia; Shi, Tian; Shi, Kexin

2016-01-01

In this study, molecularly imprinting technology and stir bar absorption technology were combined to develop a microextraction approach based on a molecularly imprinted polymeric stir bar. The molecularly imprinted polymer stir bar has a high performance, is specific, economical, and simple to prepare. The obtained naftopidil-imprinted polymer-coated bars could simultaneously agitate and adsorb naftopidil in the sample solution. The ratio of template/monomer/cross-linker and conditions of template removal were optimized to prepare a stir bar with highly efficient adsorption. Fourier transform infrared spectroscopy, scanning electron microscopy, selectivity, and extraction capacity experiments showed that the molecularly imprinted polymer stir bar was prepared successfully. To utilize the molecularly imprinted polymer stir bar for the determination of naftopidil in complex body fluid matrices, the extraction time, stirring speed, eluent, and elution time were optimized. The limits of detection of naftopidil in plasma and urine sample were 7.5 and 4.0 ng/mL, respectively, and the recoveries were in the range of 90-112%. The within-run precision and between-run precision were acceptable (relative standard deviation <7%). These data demonstrated that the molecularly imprinted polymeric stir bar based microextraction with high-performance liquid chromatography was a convenient, rapid, efficient, and specific method for the precise determination of trace naftopidil in clinical analysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

NASA Technical Reports Server (NTRS)

McGill, Preston; Burkholder, Jonathan

2012-01-01

Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

The Spiral Wave Instability Induced by a Giant Planet. I. Particle Stirring in the Inner Regions of Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Bae, Jaehan; Nelson, Richard P.; Hartmann, Lee

2016-12-01

We have recently shown that spiral density waves propagating in accretion disks can undergo a parametric instability by resonantly coupling with and transferring energy into pairs of inertial waves (or inertial-gravity waves when buoyancy is important). In this paper, we perform inviscid three-dimensional global hydrodynamic simulations to examine the growth and consequence of this instability operating on the spiral waves driven by a Jupiter-mass planet in a protoplanetary disk. We find that the spiral waves are destabilized via the spiral wave instability (SWI), generating hydrodynamic turbulence and sustained radially alternating vertical flows that appear to be associated with long wavelength inertial modes. In the interval 0.3 {R}{{p}}≤slant R≤slant 0.7{R}{{p}}, where R p denotes the semimajor axis of the planetary orbit (assumed to be 5 au), the estimated vertical diffusion rate associated with the turbulence is characterized by {α }{diff}∼ (0.2{--}1.2)× {10}-2. For the disk model considered here, the diffusion rate is such that particles with sizes up to several centimeters are vertically mixed within the first pressure scale height. This suggests that the instability of spiral waves launched by a giant planet can significantly disperse solid particles and trace chemical species from the midplane. In planet formation models where the continuous local production of chondrules/pebbles occurs over Myr timescales to provide a feedstock for pebble accretion onto these bodies, this stirring of solid particles may add a time constraint: planetary embryos and large asteroids have to form before a gas giant forms in the outer disk, otherwise the SWI will significantly decrease the chondrule/pebble accretion efficiency.

Friction Stir Welding of Thick Section Aluminum for Military Vehicle Applications

DTIC Science & Technology

2012-12-01

Friction Stir Welding of Thick Section Aluminum for Military Vehicle Applications by Brian Thompson, Kevin Doherty, Craig Niese, Mike Eff...International Symposium on Friction Stir Welding (9ISFSW), Huntsville, AL, 15–17 May 2012. Approved for public release...Aberdeen Proving Ground, MD 21005-5069 ARL-RP-417 December 2012 Friction Stir Welding of Thick Section Aluminum for Military

Characterization of Multilayered Multipass Friction Stir Weld on ASTM A572 G50 Steel

DOE PAGES

Lim, Yong Chae; Sanderson, Samuel; Mahoney, Murray; ...

2014-01-01

A multilayered multipass friction stir weld (MM-FSW) on ASTM A572 Grade 50 steel was characterized to understand its potential application for thick-section structures. The 15-mm-thick section was fabricated by stacking up three steel plates and then friction stir welding the plates together in a total of 5 passes. The unique butt/lap joint configuration encountered in the multilayer weld was examined to understand the effect of tool rotation direction on the joint quality especially the formation of hooking defect. Charpy V-notch impact toughness tests showed generally higher impact toughness energy for the stir zone than the base metal with a ductilemore » fracture mode. The microhardness value was measured from 195 to 220 HV in the stir zone, while the base metal showed an average value of 170 HV. The microstructure in the stir zone and the adjacent heat affected zone was quantified using Optical and Scanning Electron Microscopy (SEM) including Electron Backscatter Diffraction (EBSD). The increased toughness and hardness were correlated with the refined microstructure in stir zone, resulting from severe plastic deformation and subsequent dynamic recrystallization during friction stir welding.« less

Controlling the length scale and distribution of the ductile phase in metallic glass composites through friction stir processing

PubMed Central

Arora, Harpreet Singh; Mridha, Sanghita; Grewal, Harpreet Singh; Singh, Harpreet; Hofmann, Douglas C; Mukherjee, Sundeep

2014-01-01

We demonstrate the refinement and uniform distribution of the crystalline dendritic phase by friction stir processing (FSP) of titanium based in situ ductile-phase reinforced metallic glass composite. The average size of the dendrites was reduced by almost a factor of five (from 24 μm to 5 μm) for the highest tool rotational speed of 900 rpm. The large inter-connected dendrites become more fragmented with increased circularity after processing. The changes in thermal characteristics were measured by differential scanning calorimetry. The reduction in crystallization enthalpy after processing suggests partial devitrification due to the high strain plastic deformation. FSP resulted in increased hardness and modulus for both the amorphous matrix and the crystalline phase. This is explained by interaction of shear bands in amorphous matrix with the strain-hardened dendritic phase. Our approach offers a new strategy for microstructural design in metallic glass composites. PMID:27877687

Controlling the length scale and distribution of the ductile phase in metallic glass composites through friction stir processing.

PubMed

Arora, Harpreet Singh; Mridha, Sanghita; Grewal, Harpreet Singh; Singh, Harpreet; Hofmann, Douglas C; Mukherjee, Sundeep

2014-06-01

We demonstrate the refinement and uniform distribution of the crystalline dendritic phase by friction stir processing (FSP) of titanium based in situ ductile-phase reinforced metallic glass composite. The average size of the dendrites was reduced by almost a factor of five (from 24 μ m to 5 μ m) for the highest tool rotational speed of 900 rpm. The large inter-connected dendrites become more fragmented with increased circularity after processing. The changes in thermal characteristics were measured by differential scanning calorimetry. The reduction in crystallization enthalpy after processing suggests partial devitrification due to the high strain plastic deformation. FSP resulted in increased hardness and modulus for both the amorphous matrix and the crystalline phase. This is explained by interaction of shear bands in amorphous matrix with the strain-hardened dendritic phase. Our approach offers a new strategy for microstructural design in metallic glass composites.

Improving the Quality of Protein Crystals Using Stirring Crystallization

NASA Astrophysics Data System (ADS)

Adachi, Hiroaki; Matsumura, Hiroyoshi; Niino, Ai; Takano, Kazufumi; Kinoshita, Takayoshi; Warizaya, Masaichi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

2004-04-01

Recent reports state that a high magnetic field improves the crystal quality of bovine adenosine deaminase (ADA) with an inhibitor [Kinoshita et al.: Acta Cryst. D59 (2003) 1333]. In this paper, we examine the effect of stirring solution on ADA crystallization using a vapor-diffusion technique with rotary and figure-eight motion shakers. The probability of obtaining high-quality crystals is increased with stirring in a figure-eight pattern. Furthermore, rotary stirring greatly increased the probability of obtaining high-quality crystals, however, nucleation time was also increased. The crystal structure with the inhibitor was determined at a high resolution using a crystal obtained from a stirred solution. These results indicate that stirring with simple equipment is as useful as the high magnetic field technique for protein crystallization.

Inverse Thermal Analysis of Ti-6Al-4V Friction Stir Welds Using Numerical-Analytical Basis Functions with Pseudo-Advection

NASA Astrophysics Data System (ADS)

Lambrakos, S. G.

2018-04-01

Inverse thermal analysis of Ti-6Al-4V friction stir welds is presented that demonstrates application of a methodology using numerical-analytical basis functions and temperature-field constraint conditions. This analysis provides parametric representation of friction-stir-weld temperature histories that can be adopted as input data to computational procedures for prediction of solid-state phase transformations and mechanical response. These parameterized temperature histories can be used for inverse thermal analysis of friction stir welds having process conditions similar those considered here. Case studies are presented for inverse thermal analysis of friction stir welds that use three-dimensional constraint conditions on calculated temperature fields, which are associated with experimentally measured transformation boundaries and weld-stir-zone cross sections.

Cardiovascular magnetic resonance of myocardial edema using a short inversion time inversion recovery (STIR) black-blood technique: Diagnostic accuracy of visual and semi-quantitative assessment

PubMed Central

2012-01-01

Background The short inversion time inversion recovery (STIR) black-blood technique has been used to visualize myocardial edema, and thus to differentiate acute from chronic myocardial lesions. However, some cardiovascular magnetic resonance (CMR) groups have reported variable image quality, and hence the diagnostic value of STIR in routine clinical practice has been put into question. The aim of our study was to analyze image quality and diagnostic performance of STIR using a set of pulse sequence parameters dedicated to edema detection, and to discuss possible factors that influence image quality. We hypothesized that STIR imaging is an accurate and robust way of detecting myocardial edema in non-selected patients with acute myocardial infarction. Methods Forty-six consecutive patients with acute myocardial infarction underwent CMR (day 4.5, +/- 1.6) including STIR for the assessment of myocardial edema and late gadolinium enhancement (LGE) for quantification of myocardial necrosis. Thirty of these patients underwent a follow-up CMR at approximately six months (195 +/- 39 days). Both STIR and LGE images were evaluated separately on a segmental basis for image quality as well as for presence and extent of myocardial hyper-intensity, with both visual and semi-quantitative (threshold-based) analysis. LGE was used as a reference standard for localization and extent of myocardial necrosis (acute) or scar (chronic). Results Image quality of STIR images was rated as diagnostic in 99.5% of cases. At the acute stage, the sensitivity and specificity of STIR to detect infarcted segments on visual assessment was 95% and 78% respectively, and on semi-quantitative assessment was 99% and 83%, respectively. STIR differentiated acutely from chronically infarcted segments with a sensitivity of 95% by both methods and with a specificity of 99% by visual assessment and 97% by semi-quantitative assessment. The extent of hyper-intense areas on acute STIR images was 85% larger than those on LGE images, with a larger myocardial salvage index in reperfused than in non-reperfused infarcts (p = 0.035). Conclusions STIR with appropriate pulse sequence settings is accurate in detecting acute myocardial infarction (MI) and distinguishing acute from chronic MI with both visual and semi-quantitative analysis. Due to its unique technical characteristics, STIR should be regarded as an edema-weighted rather than a purely T2-weighted technique. PMID:22455461

Evaluation of T2-weighted versus short-tau inversion recovery sagittal sequences in the identification and localization of canine intervertebral disc extrusion with low-field magnetic resonance imaging.

PubMed

Housley, Daniel; Caine, Abby; Cherubini, Giunio; Taeymans, Olivier

2017-07-01

Sagittal T2-weighted sequences (T2-SAG) are the foundation of spinal protocols when screening for the presence of intervertebral disc extrusion. We often utilize sagittal short-tau inversion recovery sequences (STIR-SAG) as an adjunctive screening series, and experience suggests that this combined approach provides superior detection rates. We hypothesized that STIR-SAG would provide higher sensitivity than T2-SAG in the identification and localization of intervertebral disc extrusion. We further hypothesized that the parallel evaluation of paired T2-SAG and STIR-SAG series would provide a higher sensitivity than could be achieved with either independent sagittal series when viewed in isolation. This retrospective diagnostic accuracy study blindly reviewed T2-SAG and STIR-SAG sequences from dogs (n = 110) with surgically confirmed intervertebral disc extrusion. A consensus between two radiologists found no significant difference in sensitivity between T2-SAG and STIR-SAG during the identification of intervertebral disc extrusion (T2-SAG: 92.7%, STIR-SAG: 94.5%, P = 0.752). Nevertheless, STIR-SAG accurately identified intervertebral disc extrusion in 66.7% of cases where the evaluation of T2-SAG in isolation had provided a false negative diagnosis. Additionally, one radiologist found that the parallel evaluation of paired T2-SAG and STIR-SAG series provided a significantly higher sensitivity than T2-SAG in isolation, during the identification of intervertebral disc extrusion (T2-SAG: 78.2%, paired T2-SAG, and STIR-SAG: 90.9%, P = 0.017). A similar nonsignificant trend was observed when the consensus of both radiologists was taken into consideration (T2-SAG: 92.7%, paired T2-SAG, and STIR-SAG = 97.3%, P = 0.392). We therefore conclude that STIR-SAG is capable of identifying intervertebral disc extrusion that is inconspicuous in T2-SAG, and that STIR-SAG should be considered a useful adjunctive sequence during preliminary sagittal screening for intervertebral disc extrusion in low-field magnetic resonance. © 2017 American College of Veterinary Radiology.

Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction.

PubMed

Chisvert, Alberto; Benedé, Juan L; Anderson, Jared L; Pierson, Stephen A; Salvador, Amparo

2017-08-29

With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L -1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

Advanced Welding Concepts

NASA Technical Reports Server (NTRS)

Ding, Robert J.

2010-01-01

Four advanced welding techniques and their use in NASA are briefly reviewed in this poster presentation. The welding techniques reviewed are: Solid State Welding, Friction Stir Welding (FSW), Thermal Stir Welding (TSW) and Ultrasonic Stir Welding.

ManTech Implementing a Strategy to Deliver Weapon Systems Affordability

DTIC Science & Technology

2010-11-01

Tile 2007 – Translational Friction Stir Welding 2006 – Uncooled Focal Plane Array Producibility 2006 – Engine Rotor Life Extension 2005...compelling ideas will continue to help drive our Department’s innovative engine and ensure our Nation maintains its competitive edge on the...Sheets Composite Vertical Stabilizer Apache AH-64 NAVY The Challenge: Butt welding exterior ship panels produces a weld protrusion that exceeds the

JPRS Report, East Europe

DTIC Science & Technology

1989-12-12

Pressure Towards the West"] [Text] Albania is stirring. Young Albanians, especially students and academicians, are absolutely consumed with curiosity...teaching themselves and by listening to foreign radio stations—also in the hope of getting out to the West some day. The young Albanians love and...Europe—the propor- tion of young people will continue to grow. Still, the young generation no longer remembers liberation and reconstruction from

MRI assessment of bone marrow oedema in the sacroiliac joints of patients with spondyloarthritis: is the SPAIR T2w technique comparable to STIR?

PubMed

Dalto, Vitor Faeda; Assad, Rodrigo Luppino; Crema, Michel Daoud; Louzada-Junior, Paulo; Nogueira-Barbosa, Marcello Henrique

2017-09-01

To compare short tau inversion-recovery (STIR) with another fat saturation method in the assessment of sacroiliac joint inflammation. This prospective cross-sectional study comprised 76 spondyloarthritis (SpA) patients who underwent magnetic resonance imaging of the sacroiliac joints in a 1.5-T scanner, using STIR, spectral attenuated inversion recovery (SPAIR) T2w and spectral presaturation with inversion recovery (SPIR) T1w post-contrast sequences. Two independent readers (R1 and R2) assessed the images using the Spondyloarthritis Research Consortium of Canada (SPARCC) score. We assessed agreement of the SPARCC scores for SPAIR T2w and STIR with that for T1 SPIR post-contrast (reference standard) using the St. Laurent coefficient. We evaluated each sequence using the concordance correlation coefficient (CCC). We observed a strong agreement between STIR and SPAIR T2w sequences. Lin's CCC was 0.94 for R1 and 0.84 for R2 for STIR and 0.94 for R1 and 0.84 for R2 for SPAIR. The interobserver evaluation revealed a good CCC of 0.79 for SPAIR and 0.78 for STIR. STIR technique and SPAIR T2w sequence showed high agreement in the evaluation of sacroiliac joint subchondral bone marrow oedema in patients with SpA. SPAIR T2w may be an alternative to the STIR sequence for this purpose. • There are no studies evaluating which fat saturation technique should be used. • SPAIR T2w may be an alternative to STIR for sacroiliac joint evaluation. • The study will lead to changes in guidelines for spondyloarthritis.

The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Z.L., E-mail: zhilihuhit@163.com; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology

Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that themore » tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming.« less

Comparing diffusion weighted imaging with clinical and blood parameters, and with short tau inversion recovery sequence in detecting spinal and sacroiliac joint inflammation in axial spondyloarthritis.

PubMed

Chung, Ho Yin; Xu, Xiaopei; Lau, Vince Wing Hang; Ho, Grace; Lee, Ka Lai; Li, Philip Hei; Tsang, Helen Hoi Lun; Kwok, Suet Kei; Lau, Chak Sing; Wong, Chun Sing

2017-01-01

To investigate the usefulness of diffusion weighted imaging (DWI) by comparing with clinical features, blood parameters and traditional short tau inversion recovery (STIR) sequence in detecting spinal and sacroiliac (SI) joint inflammation in axial spondyloarthritis (axSpA) patients. One hundred and ten axSpA patients were recruited. Clinical, radiological and blood parameters were recorded. DWI and STIR MRI were performed simultaneously and results were scored according to the Spondyloarthritis Research Consortium of Canada (SPARCC) for comparison. Apparent diffusion coef cient (ADC) values were also calculated. DWI did not correlate with clinical parameters or blood parameters. It also had lowered sensitivity. When compared with STIR sequence, it correlated well with STIR sequence at the SI joint level (CC 0.76, p<0.001), but weakly at the spinal level (CC 0.23, p=0.02). At the SI joint level, the presence of inflammation on both STIR sequence and DWI was associated with an increase in maximum (B=0.24, p=0.02 in STIR; B=0.37, p<0.001 in DWI) and mean ADC values (B=0.17, p=0.003 in STIR; B=0.15, p=0.01 in DWI). Maximum (B=0.19, p=0.04) and mean spinal ADC values (B=0.18, p=0.01) were also positively associated with DWI detected spinal inflammation. Presence of Modic lesions showed positive correlation with STIR sequence (B=7.12, p=0.01) but not spinal ADC values. Despite DWI correlates with STIR sequence, it has lower sensitivity. However, ADC values appear to be independent of Modic lesions and may supplement STIR sequence to differentiate degeneration.

Evaluation of radiological impacts of tenorm in the Tunisian petroleum industry.

PubMed

Hrichi, Hajer; Baccouche, Souad; Belgaied, Jamel-Eddine

2013-01-01

The health impacts associated with uncontrolled release of TENORM in products and wastes released in the petroleum industry are of great concern. In this study, evaluation of TENORM in the Tunisian petroleum products and wastes is presented. Fourteen products samples, twelve waste samples and three samples from the surrounding environment were collected from the Tunisian Refinery STIR site and from two onshore production oilfields. The activity concentrations of (232)Th, (226)Ra and (40)K for all samples were determined using gamma-ray spectrometry with High Purity Germanium (HPGe) detector. The activity concentrations of (224)Ra were calculated only for scale samples. The radium equivalent activity, external and internal hazard indices, absorbed doses rates in air and annual effective dose were also estimated. It was noticed that maximum value of Ra(eq) activity was found to be 398 Bq/kg in scale (w8) collected from an onshore production oilfield which exceeds the maximum Ra(eq) value of 370 Bq/kg recommended for safe use. All hazard indices indicated that scale samples (w6, w7, w8 and w11) could be a significant waste problem especially sample (w8). In this study, the radium isotopic data were used to provide an estimate of scale samples ages by the use of the (224)Ra/(228)Ra activity ratio dating method. Ages of collected scales were found to be in the range 0.91-2.4 years. In this work, radioactivity (NORM contamination) in samples collected from the refinery STIR are showed to be insignificant if compared to those from onshore oilfield production sites. Copyright © 2012 Elsevier Ltd. All rights reserved.

Recent Developments and Research Progress on Friction Stir Welding of Titanium Alloys: An Overview

NASA Astrophysics Data System (ADS)

Karna, Sivaji; Cheepu, Muralimohan; Venkateswarulu, D.; Srikanth, V.

2018-03-01

Titanium and its alloys are joined by various welding processes. However, Fusion welding of titanium alloys resulted solidification problems like porosity, segregation and columnar grains. The problems occurred in conventional welding processes can be resolved using a solid state welding i.e. friction stir welding. Aluminium and Magnesium alloys were welded by friction stir welding. However alloys used for high temperature applications such as titanium alloys and steels are arduous to weld using friction stir welding process because of tool limitations. Present paper summarises the studies on joining of Titanium alloys using friction stir welding with different tool materials. Selection of tool material and effect of welding conditions on mechanical and microstructure properties of weldments were also reported. Major advantage with friction stir welding is, we can control the welding temperature above or below β-transus temperature by optimizing the process parameters. Stir zone in below beta transus condition consists of bi-modal microstructure and microstructure in above β-transus condition has large prior β- grains and α/β laths present in the grain. Welding experiments conducted below β- transus condition has better mechanical properties than welding at above β-transus condition. Hardness and tensile properties of weldments are correlated with the stir zone microstructure.

Melt Stirring by Horizontal Crucible Vibration

NASA Technical Reports Server (NTRS)

Wolf, M. F.; Elwell, D.; Feigelson, R. S.

1985-01-01

Horizontal vibration suggested as technique for more effective stirring of melts in crystal-growth apparatus. Vibrational technique may replace accelerated crucible rotation. Potential superiority of vibrational technique shown by preliminary experiments in which ink stirred into water.

40 CFR 761.350 - Subsampling from composite samples.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-liter sample, stir the composite using a broom handle or similar long, narrow, sturdy rod that reaches the bottom of the container. Stir the mixture for a minimum of 10 complete revolutions of the stirring...

Mechanism for Self-Reacted Friction Stir Welding

NASA Technical Reports Server (NTRS)

Venable, Richard; Bucher, Joseph

2004-01-01

A mechanism has been designed to apply the loads (the stirring and the resection forces and torques) in self-reacted friction stir welding. This mechanism differs somewhat from mechanisms used in conventional friction stir welding, as described below. The tooling needed to apply the large reaction loads in conventional friction stir welding can be complex. Self-reacted friction stir welding has become popular in the solid-state welding community as a means of reducing the complexity of tooling and to reduce costs. The main problems inherent in self-reacted friction stir welding originate in the high stresses encountered by the pin-and-shoulder assembly that produces the weld. The design of the present mechanism solves the problems. The mechanism includes a redesigned pin-and-shoulder assembly. The welding torque is transmitted into the welding pin by a square pin that fits into a square bushing with set-screws. The opposite or back shoulder is held in place by a Woodruff key and high-strength nut on a threaded shaft. The Woodruff key reacts the torque, while the nut reacts the tensile load on the shaft.

Characterization of microbial community structure during continuous anaerobic digestion of straw and cow manure

PubMed Central

Sun, Li; Pope, Phillip B; Eijsink, Vincent G H; Schnürer, Anna

2015-01-01

Responses of bacterial and archaeal communities to the addition of straw during anaerobic digestion of manure at different temperatures (37°C, 44°C and 52°C) were investigated using five laboratory-scale semi-continuous stirred tank reactors. The results revealed that including straw as co-substrate decreased the species richness for bacteria, whereas increasing the operating temperature decreased the species richness for both archaea and bacteria, and also the evenness of the bacteria. Taxonomic classifications of the archaeal community showed that Methanobrevibacter dominated in the manure samples, while Methanosarcina dominated in all digesters regardless of substrate. Increase of the operating temperature to 52°C led to increased relative abundance of Methanoculleus and Methanobacterium. Among the bacteria, the phyla Firmicutes and Bacteroidetes dominated within all samples. Compared with manure itself, digestion of manure resulted in a higher abundance of an uncultured class WWE1 and lower abundance of Bacilli. Adding straw to the digesters increased the level of Bacteroidia, while increasing the operating temperature decreased the level of this class and instead increased the relative abundance of an uncultured genus affiliated to order MBA08 (Clostridia). A considerable fraction of bacterial sequences could not be allocated to genus level, indicating that novel phylotypes are resident in these communities. PMID:26152665

Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate.

PubMed

Estevez, Maria M; Sapci, Zehra; Linjordet, Roar; Schnürer, Anna; Morken, John

2014-04-01

The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L(-1) d(-1) and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Feasibility of Underwater Friction Stir Welding of HY-80 Steel

DTIC Science & Technology

2011-03-01

UNDERWATER FRICTION STIR WELDING OF HY-80 STEEL by William C. Stewart March 2011 Thesis Advisor: Terry McNelley Second Reader: Sarath Menon...Master’s Thesis 4. TITLE AND SUBTITLE Feasibility of Underwater Friction Stir Welding of HY-80 Steel 5. FUNDING NUMBERS 6. AUTHOR(S) William...DISTRIBUTION CODE A 13. ABSTRACT (maximum 200 words) The purpose of this thesis is to determine the feasibility of underwater friction stir welding

Physical Simulation of a Duplex Stainless Steel Friction Stir Welding by the Numerical and Experimental Analysis of Hot Torsion Tests

NASA Astrophysics Data System (ADS)

da Fonseca, Eduardo Bertoni; Santos, Tiago Felipe Abreu; Button, Sergio Tonini; Ramirez, Antonio Jose

2016-09-01

Physical simulation of friction stir welding (FSW) by means of hot torsion tests was performed on UNS S32205 duplex stainless steel. A thermomechanical simulator Gleeble 3800® with a custom-built liquid nitrogen cooling system was employed to reproduce the thermal cycle measured during FSW and carry out the torsion tests. Microstructures were compared by means of light optical microscopy and electron backscatter diffraction. True strain and strain rate were calculated by numerical simulation of the torsion tests. Thermomechanically affected zone (TMAZ) was reproduced at peak temperature of 1303 K (1030 °C), rotational speeds of 52.4 rad s-1 (500 rpm) and 74.5 rad s-1 (750 rpm), and 0.5 to 0.75 revolutions, which represent strain rate between 10 and 16 s-1 and true strain between 0.5 and 0.8. Strong grain refinement, similar to the one observed in the stir zone (SZ), was attained at peak temperature of 1403 K (1130 °C), rotational speed of 74.5 rad s-1 (750 rpm), and 1.2 revolution, which represent strain rate of 19 s-1 and true strain of 1.3. Continuous dynamic recrystallization in ferrite and dynamic recrystallization in austenite were observed in the TMAZ simulation. At higher temperature, dynamic recovery of austenite was also observed.

Microstructure, texture, and mechanical properties of friction stir welded commercial brass alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heidarzadeh, A., E-mail: ak.hz62@gmail.com

Microstructural evolution during friction stir welding of single-phase brass and corresponding mechanical properties were investigated. For this purpose, 2 mm thick brass plate was friction stir welded at a rotational speed of 450 rpm and traverse speed of 100 mm/min. The microstructure of the joint was studied using optical microscopy, scanning electron microscopy equipped with electron back scattered diffraction system, and scanning transmission electron microscopy. The mechanical properties were measured using hardness and tensile tests. The formation of subgrains and their transformation into new grains in conjunction with existence of A{sub 1}{sup ⁎}, A{sub 2}{sup ⁎} and C texture componentsmore » revealed that the continuous dynamic recrystallization plays a dominant role in the microstructural evolution. However, grain boundary bulging, along with the formation of twin boundaries, and presence of the G texture component showed that the discontinues dynamic recrystallization may participate in the new grain formation. Furthermore, the different strengthening mechanisms, which caused the higher strength of the joint, were discussed. - Highlights: •Microstructural evolution during FSW of a single phase brass was investigated. •CDRX and DDRX were the main mechanisms of the grain structure formation during FSW. •GDRX and SRX were not contributed in grain structure formation. •The lamellas TBs were formed in the SZ of the joints. •Grain boundary, dislocation, and texture effects resulted in higher strength.« less

Mass Transfer Coefficientin Stirred Tank for p-Cresol Extraction Process from Coal Tar

NASA Astrophysics Data System (ADS)

Fardhyanti, D. S.; Tyaningsih, D. S.; Afifah, S. N.

2017-04-01

Indonesia is a country that has a lot of coal resources. The Indonesian coal has a low caloric value. Pyrolysis is one of the process to increase the caloric value. One of the by-product of the pyrolysis process is coal tar. It contains a lot of aliphatic or aromatic compounds such asp-cresol (11% v/v). It is widely used as a disinfectant. Extractionof p-Cresol increases the economic value of waste of coal. The aim of this research isto study about mass tranfer coefficient in the baffled stirred tank for p-Cresolextraction from coal tar. Mass transfer coefficient is useful for design and scale up of industrial equipment. Extraction is conducted inthe baffled stirred tank equipped with a four-bladed axial impeller placed vertically in the vessel. Sample for each time processing (5, 10, 15, 20, 25 and 30minutes) was poured into a separating funnel, settled for an hour and separated into two phases. Then the two phases were weighed. The extract phases and raffinate phases were analyzed by Spectronic UV-Vis. The result showed that mixing speed of p-Cresol extraction increasesthe yield of p-Cresol and the mass transfer coefficient. The highest yield of p-Cresol is 49.32% and the highest mass transfer coefficient is 4.757 x 10-6kg/m2s.

Hybrid friction stir welding for dissimilar materials through electro-plastic effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xun; Lan, Shuhuai; Ni, Jun

A hybrid Friction Stir Welding approach and device for dissimilar materials joining employing Electro-Plastic Effect. The approach and device include an introduction of high density, short period current pulses into traditional friction stir welding process, which therefore can generate a localized softened zone in the workpiece during plastic stirring without significant additional temperature increase. This material softened zone is created by high density current pulses based on Electro-Plastic Effect and will move along with the friction stir welding tool. Smaller downward force, larger processing window and better joint quality for dissimilar materials are expected to be achieved through this hybridmore » welding technique.« less

The Effect of Premixed Al-Cu Powder on the Stir Zone in Friction Stir Welding of AA3003-H18

NASA Astrophysics Data System (ADS)

Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

2015-02-01

In this research, 3-mm-thick AA3003-H18 non-heat-treatable aluminum alloy plates were joined by friction stir welding (FSW). It was performed by adding pure Cu and premixed Cu-Al powders at various rotational speeds of 800, 1000, and 1200 rpm and constant traveling speeds of 100 mm/min. At first, the powder was filled into the gap (0.2 or 0.4 mm) between two aluminum alloy plates, and then the FSW process was performed in two passes. The microstructure, mechanical properties, and formation of intermetallic compounds were investigated in both cases of using pure Cu and premixed Al-Cu powders. The results of using pure Cu and premixed Al-Cu powders were compared in the stir zone at various rotational speeds. The copper particle distribution and formation of Al-Cu intermetallic compounds (Al2Cu and AlCu) in the stir zone were desirable using premixed Al-Cu powder into the gap. The hardness values were significantly increased by formation of Al-Cu intermetallic compounds in the stir zone and it was uniform throughout the stir zone when premixed Al-Cu powder was used. Also, longitudinal tensile strength from the stir zone was higher when premixed Al-Cu powder was used instead of pure Cu powder.

Analysis of biogenic carbonyl compounds in rainwater by stir bar sorptive extraction technique with chemical derivatization and gas chromatography‐mass spectrometry

PubMed Central

Lewis, Alastair C.; Shaw, Marvin D.

2016-01-01

Stir bar sorptive extraction is a powerful technique for the extraction and analysis of organic compounds in aqueous matrices. Carbonyl compounds are ubiquitous components in rainwater, however, it is a major challenge to accurately identify and sensitively quantify carbonyls from rainwater due to the complex matrix. A stir bar sorptive extraction technique was developed to efficiently extract carbonyls from aqueous samples following chemical derivatization by O‐(2,3,4,5,6‐pentafluorobenzyl) hydroxylamine hydrochloride. Several commercial stir bars in two sizes were used to simultaneously measure 29 carbonyls in aqueous samples with detection by gas chromatography with mass spectrometry. A 100 mL aqueous sample was extracted by stir bars and the analytes on stir bars were desorbed into a 2 mL solvent solution in an ultrasonic bath. The preconcentration Coefficient for different carbonyls varied between 30 and 45 times. The limits of detection of stir bar sorptive extraction with gas chromatography mass spectrometry for carbonyls (10–30 ng/L) were improved by ten times compared with other methods such as gas chromatography with electron capture detection and stir bar sorptive extraction with high‐performance liquid chromatography and mass spectrometry. The technique was used to determine carbonyls in rainwater samples collected in York, UK, and 20 carbonyl species were quantified including glyoxal, methylglyoxal, isobutenal, 2‐hydroxy ethanal. PMID:27928898

Bio-Inspired Ceramic/Carbon Composites

DTIC Science & Technology

2013-05-01

the links between CNTs and the ceramic when the CNT is previously synthesized. Spark Plasma Sintering of SiC/CNTs composites Composites containing...5% of CVD MWCNTs and 95% of SiC nanoparticles (size  100nm) were prepared by Spark Plasma Sintering under different conditions. Table I shows the...additives when necessary (additives were added to help to improve the sintering increasing the density values), and the mixture continuously stirred until

Determination of Noncovalent Binding Using a Continuous Stirred Tank Reactor as a Flow Injection Device Coupled to Electrospray Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Santos, Inês C.; Waybright, Veronica B.; Fan, Hui; Ramirez, Sabra; Mesquita, Raquel B. R.; Rangel, António O. S. S.; Fryčák, Petr; Schug, Kevin A.

2015-07-01

Described is a new method based on the concept of controlled band dispersion, achieved by hyphenating flow injection analysis with ESI-MS for noncovalent binding determinations. A continuous stirred tank reactor (CSTR) was used as a FIA device for exponential dilution of an equimolar host-guest solution over time. The data obtained was treated for the noncovalent binding determination using an equimolar binding model. Dissociation constants between vancomycin and Ac-Lys(Ac)-Ala-Ala-OH peptide stereoisomers were determined using both the positive and negative ionization modes. The results obtained for Ac- L-Lys(Ac)- D-Ala- D-Ala (a model for a Gram-positive bacterial cell wall) binding were in reasonable agreement with literature values made by other mass spectrometry binding determination techniques. Also, the developed method allowed the determination of dissociation constants for vancomycin with Ac- L-Lys(Ac)- D-Ala- L-Ala, Ac- L-Lys(Ac)- L-Ala- D-Ala, and Ac- L-Lys(Ac)- L-Ala- L-Ala. Although some differences in measured binding affinities were noted using different ionization modes, the results of each determination were generally consistent. Differences are likely attributable to the influence of a pseudo-physiological ammonium acetate buffer solution on the formation of positively- and negatively-charged ionic complexes.

Expansion of Human Induced Pluripotent Stem Cells in Stirred Suspension Bioreactors.

PubMed

Almutawaa, Walaa; Rohani, Leili; Rancourt, Derrick E

2016-01-01

Human induced pluripotent stem cells (hiPSCs) hold great promise as a cell source for therapeutic applications and regenerative medicine. Traditionally, hiPSCs are expanded in two-dimensional static culture as colonies in the presence or absence of feeder cells. However, this expansion procedure is associated with lack of reproducibility and low cell yields. To fulfill the large cell number demand for clinical use, robust large-scale production of these cells under defined conditions is needed. Herein, we describe a scalable, low-cost protocol for expanding hiPSCs as aggregates in a lab-scale bioreactor.

Edge of polar cap patches

NASA Astrophysics Data System (ADS)

Hosokawa, K.; Taguchi, S.; Ogawa, Y.

2016-04-01

On the night of 4 December 2013, a sequence of polar cap patches was captured by an all-sky airglow imager (ASI) in Longyearbyen, Norway (78.1°N, 15.5°E). The 630.0 nm airglow images from the ASI of 4 second exposure time, oversampled the emission of natural lifetime (with quenching) of at least ˜30 sec, introduce no observational blurring effects. By using such high-quality ASI images, we succeeded in visualizing an asymmetry in the gradients between the leading/trailing edges of the patches in a 2-D fashion. The gradient in the leading edge was found to be 2-3 times steeper than that in the trailing edge. We also identified fingerlike structures, appearing only along the trailing edge of the patches, whose horizontal scale size ranged from 55 to 210 km. These fingers are considered to be manifestations of plasma structuring through the gradient-drift instability (GDI), which is known to occur only along the trailing edge of patches. That is, the current 2-D observations visualized, for the first time, how GDI stirs the patch plasma and such a mixing process makes the trailing edge more gradual. This result strongly implies a close connection between the GDI-driven plasma stirring and the asymmetry in the large-scale shape of patches and then suggests that the fingerlike structures can be used as markers to estimate the fine-scale structure in the plasma flow within patches.

Evaluation of Microstructure, Mechanical Properties and Corrosion Resistance of Friction Stir-Welded Aluminum and Magnesium Dissimilar Alloys

NASA Astrophysics Data System (ADS)

Verma, Jagesvar; Taiwade, Ravindra V.; Sapate, Sanjay G.; Patil, Awanikumar P.; Dhoble, Ashwinkumar S.

2017-10-01

Microstructure, mechanical properties and corrosion resistance of dissimilar friction stir-welded aluminum and magnesium alloys were investigated by applying three different rotational speeds at two different travel speeds. Sound joints were obtained in all the conditions. The microstructure was examined by an optical and scanning electron microscope, whereas localized chemical information was studied by energy-dispersive spectroscopy. Stir zone microstructure showed mixed bands of Al and Mg with coarse and fine equiaxed grains. Grain size of stir zone reduced compared to base metals, indicated by dynamic recrystallization. More Al patches were observed in the stir zone as rotational speed increased. X-ray diffraction showed the presence of intermetallics in the stir zone. Higher tensile strength and hardness were obtained at a high rotational speed corresponding to low travel speed. Tensile fractured surface indicated brittle nature of joints. Dissimilar friction stir weld joints showed different behaviors in different corrosive environments, and better corrosion resistance was observed at a high rotational speed corresponding to low travel speed (FW3) in a sulfuric and chloride environments. Increasing travel speed did not significantly affect on microstructure, mechanical properties and corrosion resistance as much as the rotational speed.

Locus of Control, Risk Orientation, and Decision Making Among U.S. Army Aviators

DTIC Science & Technology

2009-09-01

accident groups. These two items assessed the perceived impact of Professionalism and Crew Management Skills on the outcome of the scenario. Overall...could potentially make an impact on safety. In addition to a simple conversion of existing civil scales to a military context, an innovative...invulnerable). Although the validity of the measurement instrument was not established, the documents nevertheless served to stir interest in the impact

Production in stirred-tank bioreactor of recombinant bovine chymosin B by a high-level expression transformant clone of Pichia pastoris.

PubMed

Noseda, Diego Gabriel; Recúpero, Matías; Blasco, Martín; Bozzo, Joaquín; Galvagno, Miguel Ángel

2016-07-01

An intense screening of Pichia pastoris clones transformed with the gene of bovine chymosin under methanol-inducible AOX1 promoter was performed, obtaining a transformant clone with a higher milk-clotting activity value in comparison with our previous studies. The scaling of recombinant-chymosin production was carried out by a fed-batch strategy in a stirred-tank bioreactor using biodiesel-byproduct crude glycerol as the carbon source and pure methanol for the induction of chymosin expression, achieving a biomass concentration of 158 g DCW/L and a maximum coagulant activity of 192 IMCU/ml after 120 h of methanol induction. Recombinant bovine chymosin was purified from bioreactor-fermentation culture by a procedure including anion-exchange chromatography which allowed obtaining heterologous chymosin with high level of purity and activity; suggesting that this downstream step could be scaled up in a successful manner for chymosin purification. Thermoestability assay permitted to establish that unformulated recombinant chymosin could be stored at 5 °C without decrease of enzyme activity throughout at least 120 days. Finally, reiterative methanol-inductions of recombinant chymosin expression in bioreactor demonstrated that the reutilization of cell biomass overcame the low enzyme productivity usually reached by P. pastoris system. Copyright © 2016 Elsevier Inc. All rights reserved.

Friction-Stir Welding and Mathematical Modeling

NASA Technical Reports Server (NTRS)

Rostant, Victor D.

1999-01-01

The friction-stir welding process is a remarkable way for making butt and lap joints in aluminum alloys. This process operates by passing a rotating tool between two closely butted plates. Through this process it generates a lot of heat and heated material is stirred from both sides of the plates in which the outcome will one high quality weld. My research has been done to study the FSW through mathematical modeling, and using modeling to better understand what take place during the friction-stir weld.

Molecularly imprinted polymers based stir bar sorptive extraction for determination of cefaclor and cefalexin in environmental water.

PubMed

Peng, Jun; Liu, Donghao; Shi, Tian; Tian, Huairu; Hui, Xuanhong; He, Hua

2017-07-01

Although stir bar sportive extraction was thought to be a highly efficiency and simple pretreatment approach, its wide application was limited by low selectivity, short service life, and relatively high cost. In order to improve the performance of the stir bar, molecular imprinted polymers and magnetic carbon nanotubes were combined in the present study. In addition, two monomers were utilized to intensify the selectivity of molecularly imprinted polymers. Fourier transform infrared spectroscopy, scanning electron microscopy, and selectivity experiments showed that the molecularly imprinted polymeric stir bar was successfully prepared. Then micro-extraction based on the obtained stir bar was coupled with HPLC for determination of trace cefaclor and cefalexin in environmental water. This approach had the advantages of stir bar sportive extraction, high selectivity of molecular imprinted polymers, and high sorption efficiency of carbon nanotubes. To utilize this pretreatment approach, pH, extraction time, stirring speed, elution solvent, and elution time were optimized. The LOD and LOQ of cefaclor were found to be 3.5 ng · mL -1 and 12.0 ng · mL -1 , respectively; the LOD and LOQ of cefalexin were found to be 3.0 ng · mL -1 and 10.0 ng · mL -1 , respectively. The recoveries of cefaclor and cefalexin were 86.5 ~ 98.6%. The within-run precision and between-run precision were acceptable (relative standard deviation <7%). Even when utilized in more than 14 cycles, the performance of the stir bar did not decrease dramatically. This demonstrated that the molecularly imprinted polymeric stir bar based micro-extraction was a convenient, efficient, low-cost, and a specific method for enrichment of cefaclor and cefalexin in environmental samples.

Weld defect identification in friction stir welding using power spectral density

NASA Astrophysics Data System (ADS)

Das, Bipul; Pal, Sukhomay; Bag, Swarup

2018-04-01

Power spectral density estimates are powerful in extraction of useful information retained in signal. In the current research work classical periodogram and Welch periodogram algorithms are used for the estimation of power spectral density for vertical force signal and transverse force signal acquired during friction stir welding process. The estimated spectral densities reveal notable insight in identification of defects in friction stir welded samples. It was observed that higher spectral density against each process signals is a key indication in identifying the presence of possible internal defects in the welded samples. The developed methodology can offer preliminary information regarding presence of internal defects in friction stir welded samples can be best accepted as first level of safeguard in monitoring the friction stir welding process.

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

PubMed Central

Lau, Phei Li; Allen, Ray W K

2013-01-01

Summary The palladium metal catalysed Heck reaction of 4-iodoanisole with styrene or methyl acrylate has been studied in a continuous plug flow reactor (PFR) using supercritical carbon dioxide (scCO2) as the solvent, with THF and methanol as modifiers. The catalyst was 2% palladium on silica and the base was diisopropylethylamine due to its solubility in the reaction solvent. No phosphine co-catalysts were used so the work-up procedure was simplified and the green credentials of the reaction were enhanced. The reactions were studied as a function of temperature, pressure and flow rate and in the case of the reaction with styrene compared against a standard, stirred autoclave reaction. Conversion was determined and, in the case of the reaction with styrene, the isomeric product distribution was monitored by GC. In the case of the reaction with methyl acrylate the reactor was scaled from a 1.0 mm to 3.9 mm internal diameter and the conversion and turnover frequency determined. The results show that the Heck reaction can be effectively performed in scCO2 under continuous flow conditions with a palladium metal, phosphine-free catalyst, but care must be taken when selecting the reaction temperature in order to ensure the appropriate isomer distribution is achieved. Higher reaction temperatures were found to enhance formation of the branched terminal alkene isomer as opposed to the linear trans-isomer. PMID:24367454

Open Thermodynamic System Concept for Fluviokarst Underground Temperature and Discharge Flow Assessments

NASA Astrophysics Data System (ADS)

Machetel, P.; Yuen, D. A.

2012-12-01

In this work, we propose to use Open Thermodynamic System (OTS) frameworks to assess temperatures and discharges of underground flows in fluviokarstic systems. The theoretical formulation is built on the first and second laws of thermodynamics. However, such assumptions would require steady states in the Control Volume to cancel the heat exchanges between underground water and embedding rocks. This situation is obviously never perfectly reached in Nature where flow discharges and temperatures vary with rainfalls, recessions and seasonal or diurnal fluctuations. First, we will shortly show that the results of a pumping test campaign on the Cent-Font (Hérault, France) fluviokarst during summer 2005 are consistent with this theoretical approach. Second, we will present the theoretical formalism of the OTS framework that leads to equation systems involving the temperatures and/or the discharges of the underground and surface flows.Third, this approach will be applied to the white (2003) conceptual model of fluviokarst, and we will present the numerical model built to assess the applicability of these assumptions. The first order of the field hydrologic properties observed at the Cent-Fonts resurgence are well described by the calculations based on this OTS framework. If this agreement is necessary, it is not sufficient to validate the method. In order to test its applicability, the mixing process has been modelized as a cooling reaction in a Continuous Stirred Tank Reactor (CSTR) for which matrix and intrusive flows are introduced continuously while effluent water is recovered at the output. The enthalpy of the various flows is conserved except for the part that exchanges heat with the embedding rocks. However the numerical model shows that in the water saturated part of the CS, the matrix flow swepts heat by convective-advective processes while temporal heat fluctuations from intrusive flows cross the CV walls. The numerical model shows that the convective flow from matrix damps the diurnal fluctuations on very short space and time scales. The case of the seasonal temperature fluctuations depends on the relative global space and time scales between the global transport properties of the fluviokarst and the fluctuations. This works shows that, under these circumstances and framework, temperature can be considered as a conservative tracer because most of the heat exchanged with the embedding rocks during non-steady periods is brought back by the convergence of matrix flows toward the CV. This mechanism cancels the effects of the heat exchanges for the diurnal fluctuations and also reduces those that are due to seasonal variations of temperature. The OTS approach may therefore bring new tools for underground fluid temperatures and discharges assessment and may also probably offer potential applications for geothermal studies. The mixing process in the fluviokarst Conduit System is analogous to a chemical reaction in a Continuous Stirred Tank Reactor (CSTR).

The Effect of Friction Stir Processing on Microstructure and Tensile Behavior of Thixomolded AZ91 Magnesium Alloy

NASA Astrophysics Data System (ADS)

Mansoor, B.; Decker, R. F.; Kulkarni, S.; LeBeau, S. E.; Khraisheh, M. K.

Friction Stir Processing (FSP) to partial sheet thickness can be utilized to engineer unique microstructures in metallic alloys. These composite microstructures consist of three distinct layers associated with stirred, transition and core micro structural regions. The stirred region is of particular interest where severe plastic deformation imparted by the rotating and translating FSP tool under frictional heat leads to grain refinement down to 1 urn grain size. In this work, partial depth penetration into thixomolded AZ91 Mg plate from the top and bottom surfaces by friction stir processing is explored. Furthermore, low temperature aging treatments are applied to the processed material. The present results with AZ91 Mg show that FSP processed material exhibits higher strength (> 300 MPa), and improvement in ductility (> 7 % tensile elongation). It is found that in addition to Hall-Petch strengthening produced by 1 um grain size in the stirred region, the enhanced strength levels and ductility are strongly influenced by dispersoids of the intermetallic precipitates found in this alloy.

Design and scale-up of an oxidative scrubbing process for the selective removal of hydrogen sulfide from biogas.

PubMed

Krischan, J; Makaruk, A; Harasek, M

2012-05-15

Reliable and selective removal of hydrogen sulfide (H(2)S) is an essential part of the biogas upgrading procedure in order to obtain a marketable and competitive natural gas substitute for flexible utilization. A promising biogas desulfurization technology has to ensure high separation efficiency regardless of process conditions or H(2)S load without the use or production of toxic or ecologically harmful substances. Alkaline oxidative scrubbing is an interesting alternative to existing desulfurization technologies and is investigated in this work. In experiments on a stirred tank reactor and a continuous scrubbing column in laboratory-scale, H(2)S was absorbed from a gas stream containing large amounts of carbon dioxide (CO(2)) into an aqueous solution prepared from sodium hydroxide (NaOH), sodium bicarbonate (NaHCO(3)) and hydrogen peroxide (H(2)O(2)). The influence of pH, redox potential and solution aging on the absorption efficiency and the consumption of chemicals was investigated. Because of the irreversible oxidation reactions of dissolved H(2)S with H(2)O(2), high H(2)S removal efficiencies were achieved while the CO(2) absorption was kept low. At an existing biogas upgrading plant an industrial-scale pilot scrubber was constructed, which efficiently desulfurizes 180m(3)/h of raw biogas with an average removal efficiency of 97%, even at relatively high and strongly fluctuating H(2)S contents in the crude gas. Copyright © 2012 Elsevier B.V. All rights reserved.

Biogasification products of water hyacinth wastewater reclamation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chynoweth, D.P.; Biljetina, R.; Srivastava, V.J.

1984-01-01

This paper describes the results of research in progress to evaluate the use of water hyacinth for wastewater treatment and subsequent conversion of hyacinth and sludge to methane by anaerobic digestion. Laboratory studies have been directed toward evaluating advanced biogasification concepts and establishing a data base for the design and operation of an experimental test unit (ETU) located at the water hyacinth wastewater treatment facility at Walt Disney World (WDW) located in Kissimmee, Florida. Laboratory-scale kinetic experiments have been conducted using continuously-stirred tank reactors (CSTR) and a novel non-mixed upflow solids reactor (USR) receiving a hyacinth/sludge blend at retention timesmore » of 15 down to 2.1 days. The data suggest that best performance is achieved in the USR which has longer solids and organism retention. A larger-scale ETU (160 cu ft) was designed and installed at WDW in 1983 and started up in 1984. The purpose of this unit is to validate laboratory experiments and to evaluate larger-scale equipment used for chopping, slurry preparation, mixing, and effluent dewatering. The ETU includes a front end designed for multiple feed processing and storage, a fully instrumented USR digester, and tanks for effluent and gas storage. The ETU is currently being operated on a 2:1 blend (dry wt basis) of water hyacinth and primary sludge. Performance is good without major operational problems. Results of laboratory studies and start-up and operation of the ETU will be presented. 7 references, 4 figures, 1 table.« less

The effect of impeller type on silica sol formation in laboratory scale agitated tank

NASA Astrophysics Data System (ADS)

Nurtono, Tantular; Suprana, Yayang Ade; Latif, Abdul; Dewa, Restu Mulya; Machmudah, Siti; Widiyastuti, Winardi, Sugeng

2016-02-01

The multiphase polymerization reaction of the silica sol formation produced from silicic acid and potassium hydroxide solutions in laboratory scale agitated tank was studied. The reactor is equipped with four segmental baffle and top entering impeller. The inside diameter of reactor is 9 cm, the baffle width is 0.9 cm, and the impeller position is 3 cm from tank bottom. The diameter of standard six blades Rushton and three blades marine propeller impellers are 5 cm. The silicic acid solution was made from 0.2 volume fraction of water glass (sodium silicate) solution in which the sodium ion was exchanged by hydrogen ion from cation resin. The reactor initially filled with 286 ml silicic acid solution was operated in semi batch mode and the temperature was kept constant in 60 °C. The 3 ml/minute of 1 M potassium hydroxide solution was added into stirred tank and the solution was stirred. The impeller rotational speed was varied from 100 until 700 rpm. This titration was stopped if the solution in stirred tank had reached the pH of 10-The morphology of the silica particles in the silica sol product was analyzed by Scanning Electron Microscope (SEM). The size of silica particles in silica sol was measured based on the SEM image. The silica particle obtained in this research was amorphous particle and the shape was roughly cylinder. The flow field generated by different impeller gave significant effect on particle size and shape. The smallest geometric mean of length and diameter of particle (4.92 µm and 2.42 µm, respectively) was generated in reactor with marine propeller at 600 rpm. The reactor with Rushton impeller produced particle which the geometric mean of length and diameter of particle was 4.85 µm and 2.36 µm, respectively, at 150 rpm.

The effect of impeller type on silica sol formation in laboratory scale agitated tank

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurtono, Tantular; Suprana, Yayang Ade; Latif, Abdul

2016-02-08

The multiphase polymerization reaction of the silica sol formation produced from silicic acid and potassium hydroxide solutions in laboratory scale agitated tank was studied. The reactor is equipped with four segmental baffle and top entering impeller. The inside diameter of reactor is 9 cm, the baffle width is 0.9 cm, and the impeller position is 3 cm from tank bottom. The diameter of standard six blades Rushton and three blades marine propeller impellers are 5 cm. The silicic acid solution was made from 0.2 volume fraction of water glass (sodium silicate) solution in which the sodium ion was exchanged by hydrogen ion from cationmore » resin. The reactor initially filled with 286 ml silicic acid solution was operated in semi batch mode and the temperature was kept constant in 60 °C. The 3 ml/minute of 1 M potassium hydroxide solution was added into stirred tank and the solution was stirred. The impeller rotational speed was varied from 100 until 700 rpm. This titration was stopped if the solution in stirred tank had reached the pH of 10-The morphology of the silica particles in the silica sol product was analyzed by Scanning Electron Microscope (SEM). The size of silica particles in silica sol was measured based on the SEM image. The silica particle obtained in this research was amorphous particle and the shape was roughly cylinder. The flow field generated by different impeller gave significant effect on particle size and shape. The smallest geometric mean of length and diameter of particle (4.92 µm and 2.42 µm, respectively) was generated in reactor with marine propeller at 600 rpm. The reactor with Rushton impeller produced particle which the geometric mean of length and diameter of particle was 4.85 µm and 2.36 µm, respectively, at 150 rpm.« less

Gimbaled-shoulder friction stir welding tool

NASA Technical Reports Server (NTRS)

Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

2010-01-01

A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

Effect of temperature on hydration kinetics and polymerization of tricalcium silicate in stirred suspensions of CaO-saturated solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant, Steven A.; Boitnott, Ginger E.; Korhonen, Charles J.

2006-04-15

Tricalcium silicate was hydrated at 274, 278, 283, 298, and 313 K in stirred suspensions of saturated CaO solutions under a nitrogen-gas atmosphere until the end of deceleratory period. The suspension conductivities and energy flows were measured continuously. The individual reaction rates for tricalcium silicate dissolution, calcium silicate hydrate precipitation, and calcium hydroxide precipitation were calculated from these measurements. The results suggest that the proportion of tricalcium silicate dissolved was determined by the rate of tricalcium silicate dissolution and the time to very rapid calcium hydroxide precipitation. The time to very rapid calcium hydroxide precipitation was more sensitive to changesmore » in temperature than was the rate of tricalcium silicate dissolution, so that the proportion of tricalcium silicate hydration dissolved by the deceleratory period increased with decreasing temperature. The average chain length of the calcium silicate hydrate ascertained by magic-angle spinning nuclear magnetic resonance spectroscopy increased with increasing temperature.« less

Quantification of Microtexture at Weld Nugget of Friction Stir-Welded Carbon Steel

NASA Astrophysics Data System (ADS)

Husain, Md M.; Sarkar, R.; Pal, T. K.; Ghosh, M.; Prabhu, N.

2017-05-01

Friction stir welding of C-Mn steel was carried out under 800-1400 rpm tool rotation. Tool traversing speed of 50 mm/min remained same for all joints. Effect of thermal state and deformation on texture and microstructure at weld nugget was investigated. Weld nugget consisted of ferrite + bainite/Widmanstatten ferrite with different matrix grain sizes depending on peak temperature. A texture around ( ϕ 2 = 0°, φ = 30°, ϕ 2 = 45°) was developed at weld nugget. Grain boundary misorientation at weld nugget indicated that continuous dynamic recrystallization influenced the development of fine equiaxed grain structure. Pole figures and orientation distribution function were used to determine crystallographic texture at weld nugget and base metal. Shear texture components D1, D2 and F were present at weld nugget. D1 shear texture was more prominent among all. Large number of high-angle grain boundaries ( 60-70%) was observed at weld nugget and was the resultant of accumulation of high amount of dislocation, followed by subgrain formation.

Microstructure Evolution and Mechanical Properties of High-Speed Friction Stir Welded Aluminum Alloy Thin Plate Joints

NASA Astrophysics Data System (ADS)

Liu, Fenjun; Fu, Li; Chen, Haiyan

2018-06-01

Sound friction stir welded (FSW) joints of 6061-T6 aluminum alloy sheets with an 0.8 mm thickness were obtained at conventional speed (2000 rpm, 300 mm/min) and high speed (11,000 rpm, 1500 mm/min). The recrystallization mechanism, precipitate evolution, mechanical properties and fracture behavior were investigated in detail. Microstructure analyses revealed that the grain structure evolution in the nugget zone (NZ) was dominated by continuous dynamic recrystallization. In the process of FSW, high speed facilitates the formation of finer equiaxed recrystallized grains, higher density of dislocations and substructures, and a larger number of precipitates in the NZ compared to the conventional speed, which further significantly improves the hardness and tensile strength of the joints. The maximum tensile strength was obtained with 292.6 MPa, 83.2% for the 6061-T6 aluminum alloy and 122.6% for the conventional-speed FSW joints. This work provides an effective method for preparing FSW aluminum alloy thin plate joints with excellent mechanical properties.

Control of fluid flow during Bridgman crystal growth using low-frequency vibrational stirring

NASA Astrophysics Data System (ADS)

Zawilski, Kevin Thomas

The goal of this research program was to develop an in depth understanding of a promising new method for stirring crystal growth melts called coupled vibrational stirring (CVS). CVS is a mixing technique that can be used in sealed systems and produces rapid mixing through vortex flows. Under normal operating conditions, CVS uses low-frequency vibrations to move the growth crucible along a circular path, producing a surface wave and convection in the melt. This research focused on the application of CVS to the vertical Bridgman technique. CVS generated flows were directly studied using a physical modeling system containing water/glycerin solutions. Sodium nitrate was chosen as a model growth system because the growth process could be directly observed using a transparent furnace. Lead magnesium niobate-lead titanate (PMNT) was chosen as the third system because of its potential application for high performance solid state transducers and actuators. In this study, the critical parameters for controlling CVS flows in cylindrical Bridgman systems were established. One of the most important results obtained was the dependence of an axial velocity gradient on the vibrational frequency. By changing the frequency, the intensity of fluid flow at a given depth can be easily manipulated. The intensity of CVS flows near the crystal-melt interface was found to be important. When flow intensity near the interface increased during growth, large growth rate fluctuations and significant changes in interface shape were observed. To eliminate such fluctuations, a constant flow rate near the crystal-melt interface was maintained by decreasing the vibrational frequency. A continuous frequency ramp was found to be essential to grow crystals of good quality under strong CVS flows. CVS generated flows were also useful in controlling the shape of the growth interface. In the sodium nitrate system without stirring, high growth rates produced a very concave interface. By adjusting the flow intensity near the interface, CVS flows were able to flatten the growth interface under these extreme growth conditions.

Improved synthesis of fine zinc borate particles using seed crystals

NASA Astrophysics Data System (ADS)

Gürhan, Deniz; Çakal, Gaye Ö.; Eroğlu, İnci; Özkar, Saim

2009-03-01

Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical compositions and structures. In this study, the production of zinc borate having the molecular formula of 2ZnO·3B 2O 3·3.5H 2O was reexamined by studying the effects of reaction parameters on the properties of product as well as the reaction kinetics. Production of zinc borate from the reaction of boric acid and zinc oxide in the presence of seed crystals was performed in a continuously stirred, temperature-controlled batch reactor having a volume of 1.5 L. Samples taken in regular time intervals during the experiments were analyzed for the concentration of zinc oxide and boron oxide in the solid as well as for the conversion of zinc oxide to zinc borate versus time. The zinc borate production reaction was fit to the logistic model. The reaction rate, reaction completion time, composition and particle size distribution of zinc borate product were determined by varying the following parameters: the boric acid to zinc oxide ratio (H 3BO 3:ZnO=3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10 and 25 μm), stirring rate (275, 400, 800 and 1600 rpm), temperature (75, 85 and 95 °C) and the size of seed crystals (10 and 2 μm). The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increases with the increase in H 3BO 3:ZnO ratio, particle size of zinc oxide, stirring rate and temperature. Concomitantly, the reaction completion time is decreased by increasing the H 3BO 3:ZnO ratio, stirring rate and temperature. The average particle sizes of the zinc borate products are in the range 4.3-16.6 μm (wet dispersion analysis).

Prospective Validation of Pre-earthquake Atmospheric Signals and Their Potential for Short–term Earthquake Forecasting

NASA Astrophysics Data System (ADS)

Ouzounov, Dimitar; Pulinets, Sergey; Hattori, Katsumi; Lee, Lou; Liu, Tiger; Kafatos, Menas

2015-04-01

We are presenting the latest development in multi-sensors observations of short-term pre-earthquake phenomena preceding major earthquakes. Our challenge question is: "Whether such pre-earthquake atmospheric/ionospheric signals are significant and could be useful for early warning of large earthquakes?" To check the predictive potential of atmospheric pre-earthquake signals we have started to validate anomalous ionospheric / atmospheric signals in retrospective and prospective modes. The integrated satellite and terrestrial framework (ISTF) is our method for validation and is based on a joint analysis of several physical and environmental parameters (Satellite thermal infrared radiation (STIR), electron concentration in the ionosphere (GPS/TEC), radon/ion activities, air temperature and seismicity patterns) that were found to be associated with earthquakes. The science rationale for multidisciplinary analysis is based on concept Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) [Pulinets and Ouzounov, 2011], which explains the synergy of different geospace processes and anomalous variations, usually named short-term pre-earthquake anomalies. Our validation processes consist in two steps: (1) A continuous retrospective analysis preformed over two different regions with high seismicity- Taiwan and Japan for 2003-2009 (2) Prospective testing of STIR anomalies with potential for M5.5+ events. The retrospective tests (100+ major earthquakes, M>5.9, Taiwan and Japan) show STIR anomalous behavior before all of these events with false negatives close to zero. False alarm ratio for false positives is less then 25%. The initial prospective testing for STIR shows systematic appearance of anomalies in advance (1-30 days) to the M5.5+ events for Taiwan, Kamchatka-Sakhalin (Russia) and Japan. Our initial prospective results suggest that our approach show a systematic appearance of atmospheric anomalies, one to several days prior to the largest earthquakes That feature could be further studied and tested for prospective early warnings based on the multi-sensors detection of pre-earthquake atmospheric signals.

Synergism of Pseudomonas aeruginosa and Fe0 for treatment of heavy metal contaminated effluents using small scale laboratory reactor.

PubMed

Singh, Rajesh; Bishnoi, Narsi R; Kirrolia, Anita; Kumar, Rajender

2013-01-01

In this study Pseudomonas aeruginosa a metal tolerant strain was not only applied for heavy metal removal but also to the solublization performance of the precipitated metal ions during effluent treatment. The synergistic effect of the isolate and Fe(0) enhanced the metal removal potential to 72.97% and 87.63% for Cr(VI) and cadmium, respectively. The decrease in cadmium ion removal to 43.65% (aeration+stirring reactors), 21.33% (aerated reactors), and 18.95% (without aerated+without stirring) with an increase in incubation period not only indicate the presence of soluble less toxic complexes, but also help in exploration of the balancing potential for valuable metal recovery. A relatively best fit and significant values of the correlation coefficient 0.912, 0.959, and 0.9314 for mixed effluent (Paint Industry effluent+CETP Wazirpur, effluent), CETP, Wazirpur, and control effluents, respectively, indicating first-order formulation and provide a reasonable description of COD kinetic data. Copyright © 2012 Elsevier Ltd. All rights reserved.

Incorporation of a two metre long PET scanner in STIR

NASA Astrophysics Data System (ADS)

Tsoumpas, C.; Brain, C.; Dyke, T.; Gold, D.

2015-09-01

The Explorer project aims to investigate the potential benefits of a total-body 2 metre long PET scanner. The following investigation incorporates this scanner in STIR library and demonstrates the capabilities and weaknesses of existing reconstruction (FBP and OSEM) and single scatter simulation algorithms. It was found that sensible images are reconstructed but at the expense of high memory and processing time demands. FBP requires 4 hours on a core; OSEM: 2 hours per iteration if ran in parallel on 15-cores of a high performance computer. The single scatter simulation algorithm shows that on a short scale, up to a fifth of the scanner length, the assumption that the scatter between direct rings is similar to the scatter between the oblique rings is approximately valid. However, for more extreme cases this assumption is not longer valid, which illustrates that consideration of the oblique rings within the single scatter simulation will be necessary, if this scatter correction is the method of choice.

Friction stir method for forming structures and materials

DOEpatents

Feng, Zhili; David, Stan A.; Frederick, David Alan

2011-11-22

Processes for forming an enhanced material or structure are disclosed. The structure typically includes a preform that has a first common surface and a recess below the first common surface. A filler is added to the recess and seams are friction stir welded, and materials may be stir mixed.

Orbital friction stir weld system

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor); Carter, Robert W. (Inventor)

2001-01-01

This invention is an apparatus for joining the ends of two cylindrical (i.e., pipe-shaped) sections together with a friction stir weld. The apparatus holds the two cylindrical sections together and provides back-side weld support as it makes a friction stir weld around the circumference of the joined ends.

Design of Linear-Quadratic-Regulator for a CSTR process

NASA Astrophysics Data System (ADS)

Meghna, P. R.; Saranya, V.; Jaganatha Pandian, B.

2017-11-01

This paper aims at creating a Linear Quadratic Regulator (LQR) for a Continuous Stirred Tank Reactor (CSTR). A CSTR is a common process used in chemical industries. It is a highly non-linear system. Therefore, in order to create the gain feedback controller, the model is linearized. The controller is designed for the linearized model and the concentration and volume of the liquid in the reactor are kept at a constant value as required.

Post-processing of metal matrix composites by friction stir processing

NASA Astrophysics Data System (ADS)

Sharma, Vipin; Singla, Yogesh; Gupta, Yashpal; Raghuwanshi, Jitendra

2018-05-01

In metal matrix composites non-uniform distribution of reinforcement particles resulted in adverse affect on the mechanical properties. It is of great interest to explore post-processing techniques that can eliminate particle distribution heterogeneity. Friction stir processing is a relatively newer technique used for post-processing of metal matrix composites to improve homogeneity in particles distribution. In friction stir processing, synergistic effect of stirring, extrusion and forging resulted in refinement of grains, reduction of reinforcement particles size, uniformity in particles distribution, reduction in microstructural heterogeneity and elimination of defects.

ELECTROMAGNETIC STIRRING IN ZONE REFINING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braun, I.; Frank, F.C.; Marshall, S.

1958-02-01

The efficiency of the zone refining process can obviously be increased by stirring the molten zone to disperse the impurity-rich layer at the solid- liquid surface. Induction heating is sometimes preferred to radiant heat because it produces more convection, but no marked improvement has been reported. Pfann and Dorsi(1967) have described a method of stirring the melt by passing an electric current through the ingot and compressing a magnetic field across the molten zone. Preliminary results obtained by using a rotating magnetic field us the stirring agent during the purification of aluminum are described. (A.C.)

Fabrication of thick multilayered steel structure using A516 Grade 70 by multipass friction stir welding †

DOE PAGES

Lim, Y. C.; Sanderson, S.; Mahoney, M.; ...

2016-04-06

Here, we fabricated a thick-sectioned multilayered steel structure by multipass friction stir welding on A516 Grade 70 steel. Tensile strength of the multilayered samples was comparable to that of the base metal. Failure was located in the base metal when a defect-free sample was tested. Charpy impact toughness was higher in the stir zone and heat affected zone than in the base metal. For higher microhardness values were found in the stir zone and heat affected zone than the base metal due to grain refinement and modification of the microstructures. As a result, improved mechanical properties compared to the basemore » metal were found in the weld zones of friction stir welded A516 Grade 70 steel.« less

Analysing the influence of FSP process parameters on IGC susceptibility of AA5083 using Sugeno - Fuzzy model

NASA Astrophysics Data System (ADS)

Jayakarthick, C.; Povendhan, A. P.; Vaira Vignesh, R.; Padmanaban, R.

2018-02-01

Aluminium alloy AA5083 was friction stir processed to improve the intergranular corrosion (IGC) resistance. FSP trials were performed by varying the process parameters as per Taguchi’s L18 orthogonal array. IGC resistance of the friction stir processed specimens were found by immersing them in concentrated nitric acid and measuring the mass loss per unit area. Results indicate that dispersion and partial dissolution of secondary phase increased IGC resistance of the friction stir processed specimens. A Sugeno fuzzy model was developed to study the effect of FSP process parameters on the IGC susceptibility of friction stir processed specimens. Tool Rotation Speed, Tool Traverse Speed and Shoulder Diameter have a significant effect on the IGC susceptibility of the friction stir processed specimens.

Diagnosis of hepatic metastasis: comparison of respiration-triggered diffusion-weighted echo-planar MRI and five t2-weighted turbo spin-echo sequences.

PubMed

Bruegel, Melanie; Gaa, Jochen; Waldt, Simone; Woertler, Klaus; Holzapfel, Konstantin; Kiefer, Berthold; Rummeny, Ernst J

2008-11-01

The purpose of this study was to compare the value of respiration-triggered diffusion-weighted (DW) single-shot echo-planar MRI (EPI) and five variants of T2-weighted turbo spin-echo (TSE) sequences in the diagnosis of hepatic metastasis. Fifty-two patients with extrahepatic primary malignant tumors underwent 1.5-T MRI that included DW EPI and the following variants of T2-weighted TSE techniques: breath-hold fat-suppressed HASTE, breath-hold fat-supressed TSE, respiration-triggered fat-suppressed TSE, breath-hold STIR, and respiration-triggered STIR. Images were reviewed independently by two blinded observers who used a 5-point confidence scale to identify lesions. Results were correlated with surgical and histopathologic findings and follow-up imaging findings. The accuracy of each technique was measured with free-response receiver operating characteristic analysis. A total of 118 hepatic metastatic lesions (mean diameter, 12.8 mm; range, 3-84 mm) were evaluated. Accuracy values were higher (p < 0.001) with DW EPI (0.91-0.92) than with the T2-weighted TSE techniques (0.47-0.67). Imaging with the HASTE sequence (0.47-0.52) was less accurate (p < 0.05) than imaging with the breath-hold TSE, breath-hold STIR, respiration-triggered TSE, and respiration-triggered STIR sequences (0.59-0.67). Sensitivity was higher (p < 0.001) with DW EPI (0.88-0.91) than with T2-weighted TSE techniques (0.45-0.62). For small (< or = 10 mm) metastatic lesions only, the differences in sensitivity between DW EPI (0.85) and T2-weighted TSE techniques (0.26-0.44) were even more pronounced. DW EPI was more sensitive and more accurate than imaging with T2-weighted TSE techniques. Because of the black-blood effect on vessels and low susceptibility to motion artifacts, DW EPI was particularly useful for the detection of small (< or = 10 mm) metastatic lesions.

Friction Stir Welding Development at NASA, Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

McGill, Preston; Gentz, Steve (Technical Monitor)

2001-01-01

Friction stir welding (FSW) is a solid state process that pan be used to join materials without melting. The process was invented by The Welding Institute (TWI), Cambridge, England. Friction stir welding exhibits several advantages over fusion welding in that it produces welds with fewer defects and higher joint efficiency and is capable of joining alloys that are generally considered non-weldable with a fusion weld process. In 1994, NASA-Marshall began collaborating with TWI to transform FSW from a laboratory curiosity to a viable metal joining process suitable for manufacturing hardware. While teamed with TWI, NASA-Marshall began its own FSW research and development effort to investigate possible aerospace applications for the FSW process. The work involved nearly all aspects of FSW development, including process modeling, scale-up issues, applications to advanced materials and development of tooling to use FSW on components of the Space Shuttle with particular emphasis on aluminum tanks. The friction stir welding process involves spinning a pin-tool at an appropriate speed, plunging it into the base metal pieces to be joined, and then translating it along the joint of the work pieces. In aluminum alloys the rotating speed typically ranges from 200 to 400 revolutions per minute and the translation speed is approximately two to five inches per minute. The pin-tool is inserted at a small lead angle from the axis normal to the work piece and requires significant loading along the axis of the tool. An anvil or reaction structure is required behind the welded material to react the load along the axis of the pin tool. The process requires no external heat input, filler material, protective shielding gas or inert atmosphere typical of fusion weld processes. The FSW solid-state weld process has resulted in aluminum welds with significantly higher strengths, higher joint efficiencies and fewer defects than fusion welds used to join similar alloys.

Optimized open-flow mixing: insights from microbubble streaming

NASA Astrophysics Data System (ADS)

Rallabandi, Bhargav; Wang, Cheng; Guo, Lin; Hilgenfeldt, Sascha

2015-11-01

Microbubble streaming has been developed into a robust and powerful flow actuation technique in microfluidics. Here, we study it as a paradigmatic system for microfluidic mixing under a continuous throughput of fluid (open-flow mixing), providing a systematic optimization of the device parameters in this practically important situation. Focusing on two-dimensional advective stirring (neglecting diffusion), we show through numerical simulation and analytical theory that mixing in steady streaming vortices becomes ineffective beyond a characteristic time scale, necessitating the introduction of unsteadiness. By duty cycling the streaming, such unsteadiness is introduced in a controlled fashion, leading to exponential refinement of the advection structures. The rate of refinement is then optimized for particular parameters of the time modulation, i.e. a particular combination of times for which the streaming is turned ``on'' and ``off''. The optimized protocol can be understood theoretically using the properties of the streaming vortices and the throughput Poiseuille flow. We can thus infer simple design principles for practical open flow micromixing applications, consistent with experiments. Current Address: Mechanical and Aerospace Engineering, Princeton University.

High-rate anaerobic co-digestion of kraft mill fibre sludge and activated sludge by CSTRs with sludge recirculation.

PubMed

Ekstrand, Eva-Maria; Karlsson, Marielle; Truong, Xu-Bin; Björn, Annika; Karlsson, Anna; Svensson, Bo H; Ejlertsson, Jörgen

2016-10-01

Kraft fibre sludge from the pulp and paper industry constitutes a new, widely available substrate for the biogas production industry, with high methane potential. In this study, anaerobic digestion of kraft fibre sludge was examined by applying continuously stirred tank reactors (CSTR) with sludge recirculation. Two lab-scale reactors (4L) were run for 800days, one on fibre sludge (R1), and the other on fibre sludge and activated sludge (R2). Additions of Mg, K and S stabilized reactor performance. Furthermore, the Ca:Mg ratio was important, and a stable process was achieved at a ratio below 16:1. Foaming was abated by short but frequent mixing. Co-digestion of fibre sludge and activated sludge resulted in more robust conditions, and high-rate operation at stable conditions was achieved at an organic loading rate of 4g volatile solids (VS)L(-1)day(-1), a hydraulic retention time of 4days and a methane production of 230±10NmL per g VS. Copyright © 2016. Published by Elsevier Ltd.

Synchronization of glycolytic oscillations in a yeast cell population.

PubMed

Danø, S; Hynne, F; De Monte, S; d'Ovidio, F; Sørensen, P G; Westerhoff, H

2001-01-01

The mechanism of active phase synchronization in a suspension of oscillatory yeast cells has remained a puzzle for almost half a century. The difficulty of the problem stems from the fact that the synchronization phenomenon involves the entire metabolic network of glycolysis and fermentation, and consequently it cannot be addressed at the level of a single enzyme or a single chemical species. In this paper it is shown how this system in a CSTR (continuous flow stirred tank reactor) can be modelled quantitatively as a population of Stuart-Landau oscillators interacting by exchange of metabolites through the extracellular medium, thus reducing the complexity of the problem without sacrificing the biochemical realism. The parameters of the model can be derived by a systematic expansion from any full-scale model of the yeast cell kinetics with a supercritical Hopf bifurcation. Some parameter values can also be obtained directly from analysis of perturbation experiments. In the mean-field limit, equations for the study of populations having a distribution of frequencies are used to simulate the effect of the inherent variations between cells.

Toluene emissions from plants

NASA Astrophysics Data System (ADS)

Heiden, A. C.; Kobel, K.; Komenda, M.; Koppmann, R.; Shao, M.; Wildt, J.

The emission of toluene from different plants was observed in continuously stirred tank reactors and in field measurements. For plants growing without stress, emission rates were low and ranged from the detection limit up to 2·10-16 mol·cm-2·s-1. Under conditions of stress, the emission rates exceeded 10-14 mol·cm-2·s-1. Exposure of sunflower (Helianthus annuus L. cv. Gigantheus) to 13CO2 resulted in 13C-labeling of the emitted toluene on a time scale of hours. Although no biochemical pathway for the production of toluene is known, these results indicate that toluene is synthesized by the plants. The emission rates of toluene from sunflower are dependent on nutrient supply and wounding. Since α-pinene emission rates are also influenced by these factors, toluene and α-pinene emissions show a high correlation. During pathogen attack on Scots pines (Pinus sylvestris L.) significant toluene emissions were observed. In this case emissions of toluene and α-pinene also show a good correlation. Toluene emissions were also found in field experiments with pines using branch enclosures.

Reduction of excess sludge production using mechanical disintegration devices.

PubMed

Strünkmann, G W; Müller, J A; Albert, F; Schwedes, J

2006-01-01

The usability of mechanical disintegration techniques for the reduction of excess sludge production in the activated sludge process was investigated. Using three different disintegration devices (ultrasonic homogeniser, stirred media mill, high pressure homogeniser) and different operational parameters of the disintegration, the effect of mechanical disintegration on the excess sludge production and on the effluent quality was studied within a continuously operated, laboratory scale wastewater treatment system with pre-denitrification. Depending on the operational conditions and the disintegration device used, a reduction of excess sludge production of up to 70% was achieved. A combination of mechanical disintegration with a membrane bioreactor process with high sludge age is more energy effective concerning reduction of sludge production than with a conventional activated sludge process at lower sludge ages. Depending on the disintegration parameters, the disintegration has no, or only minor, negative effect on the soluble effluent COD and on the COD-removal capacity of the activated sludge process. Nitrogen-removal was slightly deteriorated by the disintegration, whereas the system used was not optimised for nitrogen removal before disintegration was implemented.

Removal of hydrogen sulfide generated during anaerobic treatment of sulfate-laden wastewater using biochar: Evaluation of efficiency and mechanisms.

PubMed

Kanjanarong, Jarupat; Giri, Balendu S; Jaisi, Deb P; Oliveira, Fernanda R; Boonsawang, Piyarat; Chaiprapat, Sumate; Singh, R S; Balakrishna, Avula; Khanal, Samir Kumar

2017-06-01

Removal of hydrogen sulfide (H 2 S) from biogas was investigated in a biochar column integrated with a bench-scale continuous-stirred tank reactor (CSTR) treating sulfate-laden wastewater. Synthetic wastewater containing sulfate concentrations of 200-2000mg SO 4 2- /L was used as substrate, and the CSTR was operated at an organic loading rate of 1.5g chemical oxygen demand (COD)/L·day and a hydraulic retention time (HRT) of 20days. The biochar was able to remove about 98.0 (±1.2)% of H 2 S for the ranges of concentrations from 105-1020ppmv, especially at high moisture content (80-85%). Very high H 2 S adsorption capacity (up to 273.2±1.9mg H 2 S/g) of biochar is expected to enhance the H 2 S oxidation into S 0 and sulfate. These findings bring a potentially novel application of sulfur-rich biochar as a source of sulfur, an essential but often deficient micro-nutrient in soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evolution of microorganisms in thermophilic-dry anaerobic digestion.

PubMed

Montero, B; Garcia-Morales, J L; Sales, D; Solera, R

2008-05-01

Microbial population dynamics were studied during the start-up and stabilization periods in thermophilic-dry anaerobic digestion at lab-scale. The experimental protocol was defined to quantify Eubacteria and Archaea using Fluorescent in situ hybridization (FISH) in a continuously stirred tank reactor (CSTR), without recycling solids. The reactor was subjected to a programme of steady-state operation over a range of the retention times from 40 to 25 days, with an organic loading rate between 4.42 and 7.50 kg volatile solid/m3/day. Changes in microbial concentrations were linked to traditional performance parameters such as biogas production and VS removal. The relations of Eubacteria:Archaea and H2-utilising methanogens:acetate-utilising methanogens were 88:12 and 11:1, respectively, during start-up stage. Hydrogenotrophic methanogens, although important in the initial phase of the reactor start-up, were displaced by acetoclastic methanogens at steady-state, thus their relation were 7:32, respectively. The methane yield coefficient, the methane content in the biogas and VS removal were stabilized around 0.30 LCH4/gCOD, 50% and 80%, respectively. Methanogenic population correlated well with performance measurements.

Evolution of butyric acid and the methanogenic microbial population in a thermophilic dry anaerobic reactor.

PubMed

Montero, B; Garcia-Morales, J L; Sales, D; Solera, R

2010-10-01

Knowledge of the relationship between the evolution of butyric acid, the main precursor of methane, and the methanogenic microbial population, quantified by fluorescent in situ hybridization (FISH), is important for understating and controlling the anaerobic digestion of solid waste. In this study, a statistical analysis has been made of this relationship in a laboratory-scale continuously stirred tank reactor (CSTR) without recycling of biomass. The CSTR has been operated at four organic loading rates (OLR) between 4.42 and 7.50 kg VS m(-3)day(-1), using the Organic Fraction of Municipal Solid Waste (OFMSW) as the substrate. During the start-up stage, the consumption of butyric acid is related to the population of H(2)-utilising methanogens (R(2)=0.774), whereas in the stabilization stage, it is related to that of acetoclastic methanogens (R(2)=0.716). Therefore, it can be concluded that the methanogenic population dynamics are closely correlated with the concentration of volatile fatty acids, and in particular, with that of butyric acid. (c) 2010 Elsevier Ltd. All rights reserved.

The inhomogeneous microstructure and deformation of similar and dissimilar Al-Zn containing Mg friction stir welds

NASA Astrophysics Data System (ADS)

Hiscocks, Jessica

The magnesium-based aluminum-zinc alloys have excellent stiffness to weight ratios, and may be combined by friction stir welding to expand the possible applications. The high aluminum alloy AZ80 in particular has the advantage of being relatively stiff but still extrudable. However limited friction stir welding research is available for this alloy and extrapolation from the extensive work in aluminum alloys is impractical due differences in precipitation behaviour, and magnesium's high plastic anisotropy and tendency to form strong textures during friction stir welding. This work investigates the correlations between local friction stir welded microstructures, textures, residual strains, and the local deformation behaviour based on strain mapping during tensile tests. Covering bead-on-plate and butt configurations, joining of similar and dissimilar materials, and a range of processing conditions, many findings of interest for deformation modelling and industrial applications are presented. Synchrotron x-ray diffraction study of an entire friction stir weld was used to determine texture, residual strain and dislocation density data from a single experiment. A number of unique findings were made, mainly related to the asymmetric distribution of properties both between sides of the weld and through the depth. Particularly in the case of strain measurements, features not detectable at coarser measurement spacing or by line scan are presented and compared for multiple processing conditions. Investigation of the longitudinal material flow during welding showed that even when periodicity in grain size, precipitate distribution, or texture was not observed, periodic changes in texture intensity resulting from compaction of material behind the tool were present, providing evidence that movement of nugget material remained periodic. Strain localisation and fracture behaviour were found to be completely different between good quality similar and dissimilar friction stir welds. For similar magnesium friction stir welds, higher heat input was shown to improve mechanical performance by reducing the residual strain, while for dissimilar friction stir welds, deformation behaviour was found to be more sensitive to the final material distribution in the friction stir weld nugget. For dissimilar welds, even minor changes to the material flow were shown to have a major impact on the tensile performance.

7 CFR 58.711 - Cheddar, colby, washed or soaked curd, granular or stirred curd cheese.

Code of Federal Regulations, 2011 CFR

2011-01-01

... stirred curd cheese. 58.711 Section 58.711 Agriculture Regulations of the Department of Agriculture... soaked curd, granular or stirred curd cheese. Cheese, used in the manufacture of pasteurized process cheese products should possess a pleasing and desirable taste and odor consistent with the age of the...

7 CFR 58.711 - Cheddar, colby, washed or soaked curd, granular or stirred curd cheese.

Code of Federal Regulations, 2010 CFR

2010-01-01

... stirred curd cheese. 58.711 Section 58.711 Agriculture Regulations of the Department of Agriculture... soaked curd, granular or stirred curd cheese. Cheese, used in the manufacture of pasteurized process cheese products should possess a pleasing and desirable taste and odor consistent with the age of the...

77 FR 57596 - Government-Owned Inventions, Available for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-18

...; NASA Case No.: MFS-32940-1: Weld Nugget Temperature Control in Thermal Stir Welding; NASA Case No.: MFS-31559-2-DIV: Thermal Stir Welding Process; NASA Case No.: MFS-32611-1: Mass Gauging Demonstrator for Any....: MFS-32859-1: Pulsed Ultrasonic Stir Welding System; NASA Case No.: MFS-32655-1: Aerospace Laser...

Wiping Metal Transfer in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Nunes, Arthur C., Jr.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Much evidence suggests that as the friction stir pin-tool moves along a weld seam the displacement of metal takes place by a wiping action at the surface of a plug of metal that rotates with the tool. The wiping model is explained and some consequences for the friction stir welding process are drawn.

Effects of Laser Peening, and Shot Peening, on Friction Stir Welding

NASA Technical Reports Server (NTRS)

Hatamleh, Omar; Hackel, Lloyd; Rankin, Jon; Truong, Chanh; Walter, Matt

2006-01-01

A viewgraph presentation describing the effects of laser peening and shot peening on friction stir welding is shown. The topics include: 1) Background; 2) Friction Stir Welding (FSW); 3) Microstructure; 4) Laser & Shot Peening; 5) Residual Stresses; 6) Tensile Behavior; 7) Fatigue Life & Surface Roughness; 8) Crack Growth; and 9) Benefits.

Friction Stir Processing of Particle Reinforced Composite Materials

PubMed Central

Gan, Yong X.; Solomon, Daniel; Reinbolt, Michael

2010-01-01

The objective of this article is to provide a review of friction stir processing (FSP) technology and its application for microstructure modification of particle reinforced composite materials. The main focus of FSP was on aluminum based alloys and composites. Recently, many researchers have investigated this technology for treating other alloys and materials including stainless steels, magnesium, titanium, and copper. It is shown that FSP technology is very effective in microstructure modification of reinforced metal matrix composite materials. FSP has also been used in the processing and structure modification of polymeric composite materials. Compared with other manufacturing processes, friction stir processing has the advantage of reducing distortion and defects in materials. The layout of this paper is as follows. The friction stir processing technology will be presented first. Then, the application of this technology in manufacturing and structure modification of particle reinforced composite materials will be introduced. Future application of friction stir processing in energy field, for example, for vanadium alloy and composites will be discussed. Finally, the challenges for improving friction stir processing technology will be mentioned.

Investigation of the L-Glutamic acid polymorphism: Comparison between stirred and stagnant conditions

NASA Astrophysics Data System (ADS)

Tahri, Yousra; Gagnière, Emilie; Chabanon, Elodie; Bounahmidi, Tijani; Mangin, Denis

2016-02-01

This work highlights the effect of the stirring, the temperature and the supersaturation on the cooling crystallization of L-Glutamic acid (LGlu) polymorphs. First, solubility measurements of the metastable polymorph α and the stable polymorph β were performed. Then, crystallization experiments were carried out in stirred vessel and in stagnant cell. All these experiments were monitored by in situ devices. The effect of the temperature on the LGlu polymorphs was found to be more relevant than the supersaturation in the stirred crystallizer. In the stagnant cell, only the stable form β crystallized regardless of the operating conditions. Moreover, an unexpected and new habit of the β form was discovered and confirmed. These results suggest that the temperature and the stirring can strongly affect the nucleation and the growth kinetics of polymorphic forms.

Simultaneous removal of selected oxidized contaminants in groundwater using a continuously stirred hydrogen-based membrane biofilm reactor.

PubMed

Xia, Siqing; Liang, Jun; Xu, Xiaoyin; Shen, Shuang

2013-01-01

A laboratory trial was conducted for evaluating the capability of a continuously stirred hydrogen-based membrane biofilm reactor to simultaneously reduce nitrate (NO(3-)-N), sulfate (SO4(2-)), bromate (BrO3-), hexavalent chromium (Cr(VI)) and parachloronitrobenzene (p-CNB). The reactor contained two bundles of hollow fiber membranes functioning as an autotrophic biofilm carrier and hydrogen pipe as well. On the condition that hydrogen was supplied as electron donor and diffused into water through membrane pores, autohydrogenotrophic bacteria were capable of reducing contaminants to forms with lower toxicity. Reduction occurred within 1 day and removal fluxes for NO(3-)-N, SO4(2-), BrO3-, Cr(VI), and p-CNB reached 0.641, 2.396, 0.008, 0.016 and 0.031 g/(day x m2), respectively after 112 days of continuous operation. Except for the fact that sulfate was 37% removed under high surface loading, the other four contaminants were reduced by over 95%. The removal flux comparison between phases varying in surface loading and H2 pressure showed that decreasing surface loading or increasing H2 pressure would promote removal flux. Competition for electrons occurred among the five contaminants. Electron-equivalent flux analysis showed that the amount of utilized hydrogen was mainly controlled by NO(3-)-N and SO4(2-) reduction, which accounted for over 99% of the electron flux altogether. It also indicated the electron acceptor order, showing that nitrate was the most prior electron acceptor while suIfate was the second of the five contaminants.

The Establishment of a New Friction Stir Welding Process Development Facility at NASA/MSFC

NASA Technical Reports Server (NTRS)

Carter, Robert W.

2009-01-01

Full-scale weld process development is being performed at MSFC to develop the tools, fixtures, and facilities necessary for Ares I production. Full scale development in-house at MSFC fosters technical acuity within the NASA engineering community, and allows engineers to identify and correct tooling and equipment shortcomings before they become problems on the production floor. Finally, while the new weld process development facility is currently being outfitted in support of Ares I development, it has been established to support all future Constellation Program needs. In particular, both the RWT and VWT were sized with the larger Ares V hardware in mind.

Stability of Y–Ti–O precipitates in friction stir welded nanostructured ferritic alloys

DOE PAGES

Yu, Xinghua; Mazumder, B.; Miller, M. K.; ...

2015-01-19

Nanostructured ferritic alloys, which have complex microstructures which consist of ultrafine ferritic grains with a dispersion of stable oxide particles and nanoclusters, are promising materials for fuel cladding and structural applications in the next generation nuclear reactor. This paper evaluates microstructure of friction stir welded nanostructured ferritic alloys using electron microscopy and atom probe tomography techniques. Atom probe tomography results revealed that nanoclusters are coarsened and inhomogeneously distributed in the stir zone and thermomechanically affected zone. Three hypotheses on coarsening of nanoclusters are presented. Finally, the hardness difference in different regions of friction stir weld has been explained.

Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

2017-10-01

The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

Friction stir processing on high carbon steel U12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tarasov, S. Yu., E-mail: tsy@ispms.ru; Rubtsov, V. E., E-mail: rvy@ispms.ru; National Research Tomsk Polytechnic University, Tomsk, 634050

2015-10-27

Friction stir processing (FSP) of high carbon steel (U12) samples has been carried out using a milling machine and tools made of cemented tungsten carbide. The FSP tool has been made in the shape of 5×5×1.5 mm. The microstructural characterization of obtained stir zone and heat affected zone has been carried out. Microhardness at the level of 700 MPa has been obtained in the stir zone with microstructure consisting of large grains and cementitte network. This high-level of microhardness is explained by bainitic reaction developing from decarburization of austenitic grains during cementite network formation.

Friction Stir Weld System for Welding and Weld Repair

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor); Romine, Peter L. (Inventor); Oelgoetz, Peter A. (Inventor)

2001-01-01

A friction stir weld system for welding and weld repair has a base foundation unit connected to a hydraulically controlled elevation platform and a hydraulically adjustable pin tool. The base foundation unit may be fixably connected to a horizontal surface or may be connected to a mobile support in order to provide mobility to the friction stir welding system. The elevation platform may be utilized to raise and lower the adjustable pin tool about a particular axis. Additional components which may be necessary for the friction stir welding process include back plate tooling, fixturing and/or a roller mechanism.

Effect of stirring on the safety of flammable liquid mixtures.

PubMed

Liaw, Horng-Jang; Gerbaud, Vincent; Chen, Chan-Cheng; Shu, Chi-Min

2010-05-15

Flash point is the most important variable employed to characterize fire and explosion hazard of liquids. The models developed for predicting the flash point of partially miscible mixtures in the literature to date are all based on the assumption of liquid-liquid equilibrium. In real-world environments, however, the liquid-liquid equilibrium assumption does not always hold, such as the collection or accumulation of waste solvents without stirring, where complete stirring for a period of time is usually used to ensure the liquid phases being in equilibrium. This study investigated the effect of stirring on the flash-point behavior of binary partially miscible mixtures. Two series of partially miscible binary mixtures were employed to elucidate the effect of stirring. The first series was aqueous-organic mixtures, including water+1-butanol, water+2-butanol, water+isobutanol, water+1-pentanol, and water+octane; the second series was the mixtures of two flammable solvents, which included methanol+decane, methanol+2,2,4-trimethylpentane, and methanol+octane. Results reveal that for binary aqueous-organic solutions the flash-point values of unstirred mixtures were located between those of the completely stirred mixtures and those of the flammable component. Therefore, risk assessment could be done based on the flammable component flash-point value. However, for the assurance of safety, it is suggested to completely stir those mixtures before handling to reduce the risk. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Tensile Properties of Friction Stir Welded Joints of AA 2024-T6 Alloy at Different Welding Speeds

NASA Astrophysics Data System (ADS)

Avula, Dhananjayulu; Devuri, Venkateswarlu; Cheepu, Muralimohan; Dwivedi, Dheerendra Kumar

2018-03-01

The influence of welding speed on the friction stir welded joint properties of hardness, tensile properties, defects and microstructure characterization are studied in the present study. The friction stir welding was conducted on AA2014-T6 heat treated alloy with 5 mm thickness plate in butt joint configuration. The welding speed was varied from 8 mm/min to 120 mm/min at the fixed travel speed and load conditions. It is observed that the welding speeds at higher rate with wide range can be possible to weld this alloy at higher rates of tool revolution suggesting that the inherent capability of friction stir welding technique for aluminum 2014 alloys. The strength of the joints gradually increases with enhancing of welding speed. The micro structural observations exhibited the formation of equiaxed grains in the stir zone and slightly in the thermo-mechanically affected zone. In addition, the size of the grains decreases with increase in welding speed owing to the presence of low heat input. Hence the hardness of the joints slightly increased in the stir zones over the other zones of the weld nugget. The joint strength initially increases with the welding speed and starts to decreases after reaching to the maximum value. The relationship between the welding conditions and friction stir welded joint properties has been discussed.

Unique differentiation profile of mouse embryonic stem cells in rotary and stirred tank bioreactors.

PubMed

Fridley, Krista M; Fernandez, Irina; Li, Mon-Tzu Alice; Kettlewell, Robert B; Roy, Krishnendu

2010-11-01

Embryonic stem (ES)-cell-derived lineage-specific stem cells, for example, hematopoietic stem cells, could provide a potentially unlimited source for transplantable cells, especially for cell-based therapies. However, reproducible methods must be developed to maximize and scale-up ES cell differentiation to produce clinically relevant numbers of therapeutic cells. Bioreactor-based dynamic culture conditions are amenable to large-scale cell production, but few studies have evaluated how various bioreactor types and culture parameters influence ES cell differentiation, especially hematopoiesis. Our results indicate that cell seeding density and bioreactor speed significantly affect embryoid body formation and subsequent generation of hematopoietic stem and progenitor cells in both stirred tank (spinner flask) and rotary microgravity (Synthecon™) type bioreactors. In general, high percentages of hematopoietic stem and progenitor cells were generated in both bioreactors, especially at high cell densities. In addition, Synthecon bioreactors produced more sca-1(+) progenitors and spinner flasks generated more c-Kit(+) progenitors, demonstrating their unique differentiation profiles. cDNA microarray analysis of genes involved in pluripotency, germ layer formation, and hematopoietic differentiation showed that on day 7 of differentiation, embryoid bodies from both bioreactors consisted of all three germ layers of embryonic development. However, unique gene expression profiles were observed in the two bioreactors; for example, expression of specific hematopoietic genes were significantly more upregulated in the Synthecon cultures than in spinner flasks. We conclude that bioreactor type and culture parameters can be used to control ES cell differentiation, enhance unique progenitor cell populations, and provide means for large-scale production of transplantable therapeutic cells.

Continuous production of lactic acid from molasses by perfusion culture of Lactococcus lactis using a stirred ceramic membrane reactor.

PubMed

Ohashi, R; Yamamoto, T; Suzuki, T

1999-01-01

A perfusion culture system was used for continuous production of lactic acid by retaining cells at a high density of Lactococcus lactis in a stirred ceramic membrane reactor (SCMR). After the cell concentration increased to 248 g/l, half of the culture broth volume was replaced with the fermentation medium. Subsequently, a substrate solution containing glucose (run 1) or molasses (run 2) was continuously supplied to the cells retained in the SCMR. Simultaneously, the culture supernatant was extracted using a ceramic filter with a pore size of 0.2 mum. The dilution rate was initially set at 0.4 h(-1) and gradually decreased to 0.2 h(-1) due to reduction in the permeability of the filter. The concentration of glucose in the substrate solution was adjusted to 60 g/l for the transition and the first period until 240 h, 90 g/l for the second period from 240 h to 440 h, and 70 g/l for the third period from 440 h to 643 h. The average concentration of lactic acid in the filtrate reached 46 g/l in the first period, 43 g/l in the second period, and 33 g/l for the third period. The productivity obtained for the first period reached 15.8 g.l(-1).h(-1), twice as much as that achieved in repeated batch fermentations. Based on the results obtained in run 1, the substrate solution containing 120 g/l of molasses was continuously supplied for 240 h in run 2. The concentration and productivity of lactic acid reached 40 g/l and 10.6 g.l(-1).h(-1), respectively, by continuously replenishing the culture medium at a dilution rate of 0.26 h(-1). These results demonstrated that the filtration capacity of the SCMR was sufficient for a continuous and rapid replenishment of molasses solution from the dense cell culture and, therefore, the perfusion culture system is considered to provide a low-cost process for continuous production of lactic acid from cheap resources.

Optimization and kinetic characterization of recombinant 1,3-β-glucanase production in Escherichia coli K-12 strain BL21/pETSD10 - a bioreactor scale study.

PubMed

Zaslona, H; Trusek-Holownia, A; Radosinski, L; Hennig, J

2015-07-01

The Escherichia coli K-12 strain BL21/pETSD10 was used to produce recombinant endocellular 1,3-β-glucanase. This enzyme is responsible for the hydrolysis of the glycosidic bond in specific polysaccharides with tracts of unsubstituted β-1,3-linked glucosyl residues. Conditions for the overproduction were experimentally examined, and the optimal values of the process on a bioreactor scale were found by interpolation of the experimental data. Cell induction was preferred during log-phase with relatively high cell density at OD600 near 1·1 with 0·074 g l(-1) of Isopropyl β-D-1-thiogalactopyranoside (IPTG). The higher concentration of IPTG favors high enzyme production but with an excess of ballast protein. 1,3-β-glucanase production was favoured with moderate culture aeration (0·7-0·9 vvm) and moderate stirring (125-150 rev min(-1) ). The highest specific glucanase activity (252 U g(-1) ) was found during validated experiments carried out at aeration at 135 rev min(-1) and stirring at 0·8 vvm. Due to high-tonnage industrial applications (i.e. to hemicellulose hydrolysis), the enzymatic preparation did not need to be highly purified. After pretreatment (precipitation with ammonium sulphate and dialysis) of the crude preparation, the enzymatic protein was one of the three main proteins in the preparation. The reaction rate with respect to the substrate (CM-curdlan) was described by the first order reaction equation (k = 1·95 l h(-1 ) g(-1) ). Products formed in the reaction are composed of nine glucose units on average. In the reaction conditions, the preparation showed very good stability (t1/2 = 202 h). The results contribute to the knowledge of cultivation parameters of E. coli K-12 strain BL21/pETSD10 on a bioreactor scale to overproduce an enzyme degrading β-1,3-glucans. The optimal values of protein concentration, specific activity and total glucanase activity as a function of aeration and stirring were evaluated by numerical analysis. The obtained values were validated as positive. The protein degrades some bonds in hemicellulose. Thus, the protein could be applied as one of the degrading components for hemicellulose. © 2015 The Society for Applied Microbiology.

A Rotating Plug Model of Friction Stir Welding Heat Transfer

NASA Technical Reports Server (NTRS)

Raghulapadu J. K.; Peddieson, J.; Buchanan, G. R.; Nunes, A. C.

2006-01-01

A simplified rotating plug model is employed to study the heat transfer phenomena associated with the fiction stir welding process. An approximate analytical solution is obtained based on this idealized model and used both to demonstrate the qualitative influence of process parameters on predictions and to estimate temperatures produced in typical fiction stir welding situations.

Flame speed and self-similar propagation of expanding turbulent premixed flames.

PubMed

Chaudhuri, Swetaprovo; Wu, Fujia; Zhu, Delin; Law, Chung K

2012-01-27

In this Letter we present turbulent flame speeds and their scaling from experimental measurements on constant-pressure, unity Lewis number expanding turbulent flames, propagating in nearly homogeneous isotropic turbulence in a dual-chamber, fan-stirred vessel. It is found that the normalized turbulent flame speed as a function of the average radius scales as a turbulent Reynolds number to the one-half power, where the average radius is the length scale and the thermal diffusivity is the transport property, thus showing self-similar propagation. Utilizing this dependence it is found that the turbulent flame speeds from the present expanding flames and those from the Bunsen geometry in the literature can be unified by a turbulent Reynolds number based on flame length scales using recent theoretical results obtained by spectral closure of the transformed G equation.

Flame Speed and Self-Similar Propagation of Expanding Turbulent Premixed Flames

NASA Astrophysics Data System (ADS)

Chaudhuri, Swetaprovo; Wu, Fujia; Zhu, Delin; Law, Chung K.

2012-01-01

In this Letter we present turbulent flame speeds and their scaling from experimental measurements on constant-pressure, unity Lewis number expanding turbulent flames, propagating in nearly homogeneous isotropic turbulence in a dual-chamber, fan-stirred vessel. It is found that the normalized turbulent flame speed as a function of the average radius scales as a turbulent Reynolds number to the one-half power, where the average radius is the length scale and the thermal diffusivity is the transport property, thus showing self-similar propagation. Utilizing this dependence it is found that the turbulent flame speeds from the present expanding flames and those from the Bunsen geometry in the literature can be unified by a turbulent Reynolds number based on flame length scales using recent theoretical results obtained by spectral closure of the transformed G equation.

Systems Characterization of Temperature, Ph and Electrical Conductivity in Aerobic Biodegradation of Wheat Biomass at Differing Mixing Rates

NASA Technical Reports Server (NTRS)

Calhoun, M.; Trotman, A.; Aglan, H.

1998-01-01

The purpose of this preliminary study is to observe and relate the rate of mixing to pH and electrical conductivity in an aerobic, continuously stirred bioreactor. The objective is to use data collected from successive experiments as a means of a system characterization. Tests were conducted to obtain these data using a continuously stirred 20 L Cytostir glass reaction vessel as a bioreactor operated without built-in temperature or pH control. The tests were conducted on the lab bench at ambient temperatures. The substrate in the bioreactor was ground wheat biomass obtained from the Biomass Production Chamber at NASA Kennedy Space Center. In this study, the data reflect characteristics of the native (uninoculated) systems as well as inoculated systems. In the native systems, it was found that pi levels became stable after approximately 2 to 3 days. The electrical conductivity levels for the native systems tended to decrease over time. In contrast, ion activity was increased after the introduction of bacteria into the system. This could be correlated with the release of nutrients, due to the activity of the bacteria. Also, there were slight increases in pH in the inoculated system, a result which is expected for a system with no active pr controls. The data will be used to test a mathematical model in an automated system.

Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage.

PubMed

Shakeri Yekta, Sepehr; Lindmark, Amanda; Skyllberg, Ulf; Danielsson, Asa; Svensson, Bo H

2014-03-30

The objective of the present study was to assess major chemical reactions and chemical forms contributing to solubility and speciation of Fe(II), Co(II), and Ni(II) during anaerobic digestion of sulfur (S)-rich stillage in semi-continuous stirred tank biogas reactors (SCSTR). These metals are essential supplements for efficient and stable performance of stillage-fed SCSTR. In particular, the influence of reduced inorganic and organic S species on kinetics and thermodynamics of the metals and their partitioning between aqueous and solid phases were investigated. Solid phase S speciation was determined by use of S K-edge X-ray absorption near-edge spectroscopy. Results demonstrated that the solubility and speciation of supplemented Fe were controlled by precipitation of FeS(s) and formation of the aqueous complexes of Fe-sulfide and Fe-thiol. The relatively high solubility of Co (∼ 20% of total Co content) was attributed to the formation of compounds other than Co-sulfide and Co-thiol, presumably of microbial origin. Nickel had lower solubility than Co and its speciation was regulated by interactions with FeS(s) (e.g. co-precipitation, adsorption, and ion substitution) in addition to precipitation/dissolution of discrete NiS(s) phase and formation of aqueous Ni-sulfide complexes. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal Stir Welding Development at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Ding, Robert J.

2008-01-01

Solid state welding processes have become the focus of welding process development at NASA's Marshall Space Flight Center. Unlike fusion weld processes such as tungsten inert gas (TIG), variable polarity plasma arc (VPPA), electron beam (EB), etc., solid state welding processes do not melt the material during welding. The resultant microstructure can be characterized as a dynamically recrystallized morphology much different than the casted, dentritic structure typical of fusion weld processes. The primary benefits of solid state processes over fusion weld processes include superior mechanic properties and the elimination of thermal distortion and residual stresses. These solid state processes attributes have profoundly influenced the direction of advanced welding research and development within the NASA agency. Thermal Stir Welding (TSW) is a new solid state welding process being developed at the Marshall Space Flight Center. Unlike friction stir welding, the heating, stirring and forging elements of the weld process can be decoupled for independent control. An induction coil induces energy into a workpiece to attain a desired plastic temperature. An independently controlled stir rod, captured within non-rotating containment plates, then stirs the plasticized material followed by forging plates/rollers that work the stirred weld joint. The independent control (decoupling) of heating, stirring and forging allows, theoretically, for the precision control of microstructure morphology. The TSW process is being used to evaluate the solid state joining of Haynes 230 for ARES J-2X applications. It is also being developed for 500-in (12.5 mm) thick commercially pure grade 2 titanium for navy applications. Other interests include Inconel 718 and stainless steel. This presentation will provide metallurgical and mechanical property data for these high melting temperature alloys.

Reinforcement with alumina particles at the interface region of AA6101-T6 and AA1350 alloys during friction stir welding

NASA Astrophysics Data System (ADS)

Ashok Kumar, R.; Thansekhar, M. R.

2018-04-01

This paper deals the combinational effect of friction stir welding and friction stir processing on dissimilar AA6101-T6 and AA1350 aluminium alloys. For that, alumina particles are reinforced at interface region of AA6101-T6 and AA1350 aluminium alloys. Friction Stir Welding and Friction Stir Processing are done simultaneously for various sizes of groove. To analyze the welding quality and surface modifications, mechanical, wear and microstructural tests are carried out. Among these, smallest groove of 0.5 mm width and 1 mm depth reveals highest tensile and bending strengths and largest groove of 2 mm width and 3 mm depth gives maximum hardness and wear resistance. Taguchi technique shows that groove width is most influencing parameter. Developed second order models with interaction predict the responses with minimum error.

Investigation of heat transfer and material flow of P-FSSW: Experimental and numerical study

NASA Astrophysics Data System (ADS)

Rezazadeh, Niki; Mosavizadeh, Seyed Mostafa; Azizi, Hamed

2018-02-01

Friction stir spot welding (FSSW) is the joining process which utilizes a rotating tool consisting of a shoulder and/or a probe. In this study, the novel method of FSSW, which is called protrusion friction stir spot welding (P-FSSW), has been presented and effect of shoulder diameter parameter has been studied numerically and experimentally on the weld quality including temperature field, velocity contour, material flow, bonding length, and the depth of the stirred area. The results show that the numerical findings are in good agreement with experimental measurements. The present model could well predict the temperature distribution, velocity contour, depth of the stirred area, and the bonding length. As the shoulder diameter increases, the amount of temperature rises which leads to a rise in stirred area depth, bonding length and temperatures and velocities. Therefore, a weld of higher quality will be performed.

Effect of long residence time and high temperature over anaerobic biodegradation of Scenedesmus microalgae grown in wastewater.

PubMed

Greses, S; Zamorano-López, N; Borrás, L; Ferrer, J; Seco, A; Aguado, D

2018-07-15

Anaerobic digestion of indigenous Scenedesmus spp. microalgae was studied in continuous lab-scale anaerobic reactors at different temperatures (35 °C and 55 °C), and sludge retention time - SRT (50 and 70 days). Mesophilic digestion was performed in a continuous stirred-tank reactor (CSTR) and in an anaerobic membrane bioreactor (AnMBR). Mesophilic CSTR operated at 50 days SRT only achieved 11.9% of anaerobic biodegradability whereas in the AnMBR at 70 days SRT and 50 days HRT reached 39.5%, which is even higher than the biodegradability achieved in the thermophilic CSTR at 50 days SRT (30.4%). Microbial analysis revealed a high abundance of cellulose-degraders in both reactors, AnMBR (mainly composed of 9.4% Bacteroidetes, 10.1% Chloroflexi, 8.0% Firmicutes and 13.2% Thermotogae) and thermophilic CSTR (dominated by 23.8% Chloroflexi and 12.9% Firmicutes). However, higher microbial diversity was found in the AnMBR compared to the thermophilic CSTR which is related to the SRT. since high SRT promoted low growth-rate microorganisms, increasing the hydrolytic potential of the system. These results present the membrane technology as a promising approach to revalue microalgal biomass, suggesting that microalgae biodegradability and consequently the methane production could be improved operating at higher SRT. Copyright © 2018 Elsevier Ltd. All rights reserved.

The production of chemicals from food processing wastes using a novel fermenter separator. Annual progress report, January 1993--March 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dale, M.C.; Venkatesh, K.V.; Choi, H.

The basic objective of this project is to convert waste streams from the food processing industry to usable fuels and chemicals using novel bioreactors. These bioreactors should allow economical utilization of waste (whey, waste sugars, waste starch, bottling wastes, candy wastes, molasses, and cellulosic wastes) by the production of ethanol, acetone/butanol, organic acids (acetic, lactic, and gluconic), yeast diacetyl flavor, and antifungal compounds. Continuous processes incorporating various processing improvements such as simultaneous product separation and immobilized cells are being developed to allow commercial scale utilization of waste stream. The production of ethanol by a continuous reactor-separator is the process closestmore » to commercialization with a 7,500 liter pilot plant presently sited at an Iowa site to convert whey lactose to ethanol. Accomplishments during 1993 include installation and start-up of a 7,500 liter ICRS for ethanol production at an industry site in Iowa; Donation and installation of a 200 liter yeast pilot Plant to the project from Kenyon Enterprises; Modeling and testing of a low energy system for recovery of ethanol from vapor is using a solvent absorption/extractive distillation system; Simultaneous saccharification/fermentation of raw corn grits and starch in a stirred reactor/separator; Testing of the ability of `koji` process to ferment raw corn grits in a `no-cook` process.« less

Difficulties in maintaining long-term partial nitritation of ammonium-rich sludge digester liquids in a moving-bed biofilm reactor (MBBR).

PubMed

Fux, C; Huang, D; Monti, A; Siegrist, H

2004-01-01

Nitrogen can be eliminated effectively from sludge digester effluents by anaerobic ammonium oxidation (anammox), but 55-60% of the ammonium must first be oxidized to nitrite. Although a continuous flow stirred tank reactor (CSTR) with suspended biomass could be used, its hydraulic dilution rate is limited to 0.8-1 d(-1) (30 degrees C). Higher specific nitrite production rates can be achieved by sludge retention, as shown here for a moving-bed biofilm reactor (MBBR) with Kaldnes carriers on laboratory and pilot scales. The maximum nitrite production rate amounted to 2.7 gNO2-Nm(-2)d(-1) (3 gO2m(-3)d(-1), 30.5 degrees C), thus doubling the dilution rate compared to CSTR operation with suspended biomass for a supernatant with 700 gNH4-Nm(-3). Whenever the available alkalinity was fully consumed, an optimal amount of nitrite was produced. However, a significant amount of nitrate was produced after 11 months of operation, making the effluent unsuitable for anaerobic ammonium oxidation. Because the sludge retention time (SRT) is relatively long in biofilm systems, slow growth of nitrite oxidizers occurs. None of the selection criteria applied - a high ammonium loading rate, high free ammonia or low oxygen concentration - led to selective suppression of nitrite oxidation. A CSTR or SBR with suspended biomass is consequently recommended for full-scale operation.

Quick-start of full-scale anaerobic digestion (AD) using aeration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lagerkvist, Anders, E-mail: al@ltu.se; Pelkonen, Markku; Wikström, Tommy

Highlights: • A fast, and original, start up procedure for anaerobic digestors has been applied at full scale. • The development of a methanogenic culture has been documented using fluorescent in situ hybridization. • The technique can be widely applied. - Abstract: A conventional 1300 m{sup 3} continuously stirred anaerobic tank reactor at the city of Boden, north Sweden, which was receiving a feed of both sewage sludge and food waste, was put out of operation due to the build-up of a float phase. The reactor was emptied and cleaned. At start-up there was no methanogenic sludge available, so anmore » unconventional start-up procedure was applied: The reactor was rapidly (8 days with 1200 kg of total solids (TS) added daily) filled with thickened, and slightly acidic sewage sludge, showing only slight methane generation, which was subsequently heated to 55 °C. Then compressed air was blown into the digester and within a month a fully functional methanogenic culture was established. The transfer from acidogenic to methanogenic conditions happened in about one week. As a start-up technique this is fast and cost efficient, it only requires the access of a compressor, electricity and a source of air. In total, about 16 tonnes of oxygen were used. It is proposed that this method may also be used as an operational amendment technique, should a reactor tend to acidify.« less

Nanoscale Imaging with a Single Quantum Dot

DTIC Science & Technology

2011-12-19

mL round-bottom flask equipped with a condenser , a thermometer and a magnetic stirring bar. After the EG was heated to 160 °C in an oil bath, 0.5 mL...radiatively transferred to the wire’s SPP mode through an electric dipole interaction19. The efficiency of this process scales as the spontaneous emission...Liu, J., Gao, D., Li, H.-F. & Lin, J.-M. Controlled photopolymerization of hydrogel microstructures inside microchannels for bioassays. Lab. Chip 9

Thermo-Mechanical Processing in Friction Stir Welds

NASA Technical Reports Server (NTRS)

Schneider, J. A.; Nunes, A. C., Jr.

2002-01-01

In Friction Stir Welding (FSW) a rotating pin-tool inserted into a weld seam literally stirs the edges of the seam together. In this study, two flow paths are proposed that define the FWS zone. Studies using a longitudinal tungsten wire (0.0025 dia.) were used to visualize and document the material flow. The material flow path is described using a mathematical model.

Certification of a weld produced by friction stir welding

DOEpatents

Obaditch, Chris; Grant, Glenn J

2013-10-01

Methods, devices, and systems for providing certification of friction stir welds are disclosed. A sensor is used to collect information related to a friction stir weld. Data from the sensor is compared to threshold values provided by an extrinsic standard setting organizations using a certification engine. The certification engine subsequently produces a report on the certification status of the weld.

A Preliminary Report on the Strength and Metallography of a Bimetallic Friction Stir Weld Joint Between AA6061 and MIL-DTL-46100E High Hardness Steel Armor

DTIC Science & Technology

2012-11-26

alloy and High Hardness steel armor (MIL- STD-46100) were successfully joined by the friction stir welding (FSW) process using a tungsten- rhenium ...tungsten- rhenium stir tool. Process parameter variation experiments, which included inductive pre-heating, tool design geometry, plunge and traverse

Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

NASA Astrophysics Data System (ADS)

Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

Effects of Fusion Tack Welds on Self-Reacting Friction Stir Welds

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.; Pendleton, M. L.; Brooke, S. A.; Russell, C. K.

2012-01-01

In order to know whether fusion tack welds would affect the strength of self-reacting friction stir seam welds in 2195-T87 aluminum alloy, the fracture stresses of 144 tensile test coupons cut from 24 welded panels containing segments of friction stir welds were measured. Each of the panels was welded under unique processing conditions. A measure of the effect of the tack welds for each panel was devised. An analysis of the measures of the tack weld effect supported the hypothesis that fusion tack welds do not affect the strength of self-reacting friction stir welds to a 5% level of confidence.

Stirring of a planetesimal swarm - The role of distant encounters

NASA Technical Reports Server (NTRS)

Weidenschilling, Stuart J.

1989-01-01

The viscous stirring algorithm developed by Stewart and Wetherill (1988) to treat the random velocities induced in planetesimals by their mutual gravitational perturbations encompasses only the scattering of bodies in crossing orbits by close encounters. Expressions are presently derived for the stirring rate due to distant encounters on the basis of three-body formalism, using a stirring rate that has the same mass-dependence as that for close encounters. The relative importance of both the close encounter and distant encounter mechanisms depends on the Safronov number. Perturbations by a planetary embryo in scenarios that involve explosive growth are found capable of affecting planetesimal evolution in noncrossing orbits.

Long-term reproducibility of phantom signal intensities in nonuniformity corrected STIR-MRI examinations of skeletal muscle.

PubMed

Viddeleer, Alain R; Sijens, Paul E; van Ooijen, Peter M A; Kuypers, Paul D L; Hovius, Steven E R; Oudkerk, Matthijs

2009-08-01

Nerve regeneration could be monitored by comparing MRI image intensities in time, as denervated muscles display increased signal intensity in STIR sequences. In this study long-term reproducibility of STIR image intensity was assessed under clinical conditions and the required image intensity nonuniformity correction was improved by using phantom scans obtained at multiple positions. Three-dimensional image intensity nonuniformity was investigated in phantom scans. Next, over a three-year period, 190 clinical STIR hand scans were obtained using a standardized acquisition protocol, and corrected for intensity nonuniformity by using the results of phantom scanning. The results of correction with 1, 3, and 11 phantom scans were compared. The image intensities in calibration tubes close to the hands were measured every time to determine the reproducibility of our method. With calibration, the reproducibility of STIR image intensity improved from 7.8 to 6.4%. Image intensity nonuniformity correction with 11 phantom scans gave significantly better results than correction with 1 or 3 scans. The image intensities in clinical STIR images acquired at different times can be compared directly, provided that the acquisition protocol is standardized and that nonuniformity correction is applied. Nonuniformity correction is preferably based on multiple phantom scans.

Trace determination of volatile polycyclic aromatic hydrocarbons in natural waters by magnetic ionic liquid-based stir bar dispersive liquid microextraction.

PubMed

Benedé, Juan L; Anderson, Jared L; Chisvert, Alberto

2018-01-01

In this work, a novel hybrid approach called stir bar dispersive liquid microextraction (SBDLME) that combines the advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) has been employed for the accurate and sensitive determination of ten polycyclic aromatic hydrocarbons (PAHs) in natural water samples. The extraction is carried out using a neodymium stir bar magnetically coated with a magnetic ionic liquid (MIL) as extraction device, in such a way that the MIL is dispersed into the solution at high stirring rates. Once the stirring is ceased, the MIL is magnetically retrieved onto the stir bar, and subsequently subjected to thermal desorption (TD) coupled to a gas chromatography-mass spectrometry (GC-MS) system. The main parameters involved in TD, as well as in the extraction step affecting the extraction efficiency (i.e., MIL amount, extraction time and ionic strength) were evaluated. Under the optimized conditions, the method was successfully validated showing good linearity, limits of detection and quantification in the low ng L -1 level, good intra- and inter-day repeatability (RSD < 13%) and good enrichment factors (18 - 717). This sensitive analytical method was applied to the determination of trace amounts of PAHs in three natural water samples (river, tap and rainwater) with satisfactory relative recovery values (84-115%), highlighting that the matrices under consideration do not affect the extraction process. Copyright © 2017 Elsevier B.V. All rights reserved.

Sol-gel coated polydimethylsiloxane/beta-cyclodextrin as novel stationary phase for stir bar sorptive extraction and its application to analysis of estrogens and bisphenol A.

PubMed

Hu, Yuling; Zheng, Yanjie; Zhu, Fei; Li, Gongke

2007-04-27

A sol-gel technique was used for the preparation of a stir bar coated with a composite composed of polydimethysiloxane and beta-cyclodextrin (PDMS/beta-CD). The sol-gel mechanism during coating procedure was discussed and successful binding of beta-CD to the sol-gel network was confirmed by the IR spectra. Scanning electron micrographs of the stir bars revealed a homogeneous surface with a film thickness of 30-150 microm attributing to different coating times. Good thermal stability and solvent-resistance of the stir bar were found thanks to chemical binding formed between the stationary phase and the glass substrate. The PDMS/beta-CD coated stir bar was proved to have better selectivity to polar compounds compared to the PDMS coated stir bar, and higher extraction capacity compared to the corresponding PDMS/beta-CD coated fiber. Methods for the determinations of estrogens in environmental water, bisphenol A in drinking water and in leachate of one-off dishware by the PDMS/beta-CD coated stir bar coupled with high-performance liquid chromatography (HPLC) were developed. The limits of detection were within the range of 0.04-0.11 microg l(-1) for estrogens using UV detection and 8 ngl(-1) for bisphenol A using fluorescence detection. Reproducibility with RSD less than 9.7% for extractions of real water samples at microg l(-1) or ngl(-1) level was obtained.

Novel combined stir bar sorptive extraction coupled with ultrasonic assisted extraction for the determination of brominated flame retardants in environmental samples using high performance liquid chromatography.

PubMed

Yu, Chunhe; Hu, Bin

2007-08-10

A combined stir bar coated with poly (dimethysiloxane)-beta-cyclodextrin (PDMS-beta-CD) on single side has been prepared for the first time by sol-gel method and was coupled with ultrasonic assisted extraction (UAE) for the determination of some brominated flame-retardant compounds (BFRs) in soil and dust samples by high performance liquid chromatography (HPLC). Four different kinds of coatings including PDMS-beta-CD, PDMS, carbowax (CW)-PDMS-poly (vinyl alcohol) (PVA) and PDMS-PVA were evaluated for stir bar sorptive extraction of BFRs by orthogonal experiment design. The experimental results reveal that the PDMS-beta-CD combined stir bar exhibited the best extraction efficiency for the target analytes. The reproducibility for the preparation of PDMS-beta-CD combined stir bar ranged from 1.3% to 15.7% in one batch, and 7.2% to 15.1% among batches. Extraction time, desorption solvent, concentration of methanol and NaCl in the matrix, pH, temperature and stirring speed were optimized. The combined stir bar can avoid direct friction of the coating with the bottom of the vessel, and could be used for more than 100 times. Linearity (>0.993), repeatability (<10.5%), reproducibility (<16.5%), recovery (56-118%) and detection limits (2.9-4.2 microg L(-1)) were proper to determine the seven BFRs. The developed method was applied to the determination of BFRs in soil and dust with satisfactory results.

Effects of Stirring and Fluid Perfusion on the In Vitro Degradation of Calcium Phosphate Cement/PLGA Composites.

PubMed

An, Jie; Leeuwenburgh, Sander C G; Wolke, Joop G C; Jansen, John A

2015-11-01

In vitro degradation rates of calcium phosphate bioceramics are investigated using a large variation of soaking protocols that do not all match the dynamic conditions of the perfused physiological environment. Therefore, we studied the effect of stirring and fluid perfusion on the in vitro degradation rate of apatitic calcium phosphate cements (CPC) containing poly(lactic-co-glycolic acid) (PLGA) microspheres. The composites were soaked in phosphate-buffered saline up to 6 weeks under unstirred, stirred, or perfused conditions followed by analysis of mass loss, compression strength, porosity, crystal phase composition, and morphology of the cement composites. The results showed that fluid perfusion reduced the decrease in pH and corresponding degradation rates, while nonperfused soaking conditions (i.e., stirred and unstirred conditions) resulted into more extensive acidification, the rate of which increased with stirring. After 2 weeks, the formation of a secondary brushite phase was observed for cement composites soaked under nonperfused (i.e., stirred and unstirred) conditions, whereas this phase was not detected in cements soaked under perfused conditions. The degradation rate of cement composites decreased in the order unstirred>stirred>perfused, as evidenced by quantification of mass loss, compression strength, and pore morphology. To summarize, we have demonstrated that soaking conditions strongly affected the in vitro degradation process of CPCs. As a consequence, it can be concluded that the experimental design of current in vitro degradation studies does not allow for correlation to (pre-)clinical studies.

Grading of inflammatory disease activity in the sacroiliac joints with magnetic resonance imaging: comparison between short-tau inversion recovery and gadolinium contrast-enhanced sequences.

PubMed

Madsen, Karen Berenth; Egund, Niels; Jurik, Anne Grethe

2010-02-01

We investigated the potential concordance of 2 different magnetic resonance (MR) sequences - short-tau inversion recovery (STIR) and fat-saturated T1-weighted spin-echo after application of gadolinium (Gd) contrast medium to detect active bone marrow abnormalities at the sacroiliac joints (SIJ) in patients with spondyloarthritis (SpA). Blinded and using the Danish scoring method, we evaluated transaxial MR images of the 2 sequences in 40 patients with SpA with disease duration of 3-14 years. Both the cartilaginous and ligamentous portions of the SIJ were analyzed. There was a significant positive correlation between the activity scores obtained by STIR and Gd-enhanced sequences (p < 0.0001). Agreement in the detection of bone marrow abnormalities occurred in 60 of the 80 joints, 35 with and 25 without signs of active disease. Discordance with STIR-positive marrow activity scores occurred in only 11 joints; Gd-enhanced positive scores in 9 joints. The STIR sequence detected remnants of marrow activity in the periphery of chronic fatty replacement not seen or partly obscured on the Gd sequence. Small subchondral enhancing lesions may not be scored on the STIR sequence, mostly because of reduced image resolution. Active bone marrow abnormalities were detected nearly equally well with STIR and Gd-enhanced fat-suppressed T1 sequences in patients with SpA, with STIR being most sensitive to visualize active abnormalities in the periphery of chronic changes.

The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

NASA Astrophysics Data System (ADS)

Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

2017-02-01

This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide - cobalt chromium, chromium carbide - nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the MMC aligns with the improved dispersion of reinforcing particles throughout the aluminium matrix.

Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Xiuli, E-mail: feng.97@osu.edu; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; Liu, Huijie, E-mail: liuhj@hit.edu.cn

Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. Themore » average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging. - Highlights: • SZ grain size (∼ 1 μm) is reduced by over one order of magnitude relative to the BM. • Hardness in the SZ is lower than that of the precipitation strengthened BM. • Metastable θ′ in the base metal transforms to equilibrium θ in the stir zone. • Softening in the SZ results from a decrease of precipitation strengthening.« less

Theoretical and numerical studies of chaotic mixing

NASA Astrophysics Data System (ADS)

Kim, Ho Jun

Theoretical and numerical studies of chaotic mixing are performed to circumvent the difficulties of efficient mixing, which come from the lack of turbulence in microfluidic devices. In order to carry out efficient and accurate parametric studies and to identify a fully chaotic state, a spectral element algorithm for solution of the incompressible Navier-Stokes and species transport equations is developed. Using Taylor series expansions in time marching, the new algorithm employs an algebraic factorization scheme on multi-dimensional staggered spectral element grids, and extends classical conforming Galerkin formulations to nonconforming spectral elements. Lagrangian particle tracking methods are utilized to study particle dispersion in the mixing device using spectral element and fourth order Runge-Kutta discretizations in space and time, respectively. Comparative studies of five different techniques commonly employed to identify the chaotic strength and mixing efficiency in microfluidic systems are presented to demonstrate the competitive advantages and shortcomings of each method. These are the stirring index based on the box counting method, Poincare sections, finite time Lyapunov exponents, the probability density function of the stretching field, and mixing index inverse, based on the standard deviation of scalar species distribution. Series of numerical simulations are performed by varying the Peclet number (Pe) at fixed kinematic conditions. The mixing length (lm) is characterized as function of the Pe number, and lm ∝ ln(Pe) scaling is demonstrated for fully chaotic cases. Employing the aforementioned techniques, optimum kinematic conditions and the actuation frequency of the stirrer that result in the highest mixing/stirring efficiency are identified in a zeta potential patterned straight micro channel, where a continuous flow is generated by superposition of a steady pressure driven flow and time periodic electroosmotic flow induced by a stream-wise AC electric field. Finally, it is shown that the invariant manifold of hyperbolic periodic point determines the geometry of fast mixing zones in oscillatory flows in two-dimensional cavity.

Successful operation of continuous reactors at short retention times results in high-density, fast-rate Dehalococcoides dechlorinating cultures.

PubMed

Delgado, Anca G; Fajardo-Williams, Devyn; Popat, Sudeep C; Torres, César I; Krajmalnik-Brown, Rosa

2014-03-01

The discovery of Dehalococcoides mccartyi reducing perchloroethene and trichloroethene (TCE) to ethene was a key landmark for bioremediation applications at contaminated sites. D. mccartyi-containing cultures are typically grown in batch-fed reactors. On the other hand, continuous cultivation of these microorganisms has been described only at long hydraulic retention times (HRTs). We report the cultivation of a representative D. mccartyi-containing culture in continuous stirred-tank reactors (CSTRs) at a short, 3-d HRT, using TCE as the electron acceptor. We successfully operated 3-d HRT CSTRs for up to 120 days and observed sustained dechlorination of TCE at influent concentrations of 1 and 2 mM TCE to ≥ 97 % ethene, coupled to the production of 10(12) D. mccartyi cells Lculture (-1). These outcomes were possible in part by using a medium with low bicarbonate concentrations (5 mM) to minimize the excessive proliferation of microorganisms that use bicarbonate as an electron acceptor and compete with D. mccartyi for H2. The maximum conversion rates for the CSTR-produced culture were 0.13 ± 0.016, 0.06 ± 0.018, and 0.02 ± 0.007 mmol Cl(-) Lculture (-1) h(-1), respectively, for TCE, cis-dichloroethene, and vinyl chloride. The CSTR operation described here provides the fastest laboratory cultivation rate of high-cell density Dehalococcoides cultures reported in the literature to date. This cultivation method provides a fundamental scientific platform for potential future operations of such a system at larger scales.

Development and Validation of a Shear Punch Test Fixture

DTIC Science & Technology

2013-08-01

composites (MMC) manufactured by friction stir processing (FSP) that are being developed as part of a Technology Investment Fund (TIF) project, as the...leading a team of government departments and academics to develop a friction stir processing (FSP) based procedure to create metal matrix composite... friction stir process to fabricate surface metal matrix composites in aluminum alloys for potential application in light armoured vehicles. The

Analysis of 2-Acetyl-1-Pyrroline in rice by HSSE/GC/MS.

USDA-ARS?s Scientific Manuscript database

An alternative method for the analysis of 2-acetyl-1-pyrroline (2AP) in rice employing stir bar sorptive extraction (Twister™), is described. The Twister stir bar is placed in the headspace of a 20 ml vial containing 1 g rice kernels, 5 ml 0.1 M KOH, 2,2 g NaCl, and a second Teflon™ coated stir bar...

Estimating Bottom Water Dissolved Oxygen in the Mississippi River Gulf Outlet and Gulf Intracoastal Waterway Resulting from Proposed Structures

DTIC Science & Technology

2008-09-01

used in the analysis. The analytical approach assumes steady-state, summer conditions applied to a continuously stirred tank reactor ( CSTR ). CSTR ...constituent due to the fully mixed CSTR assumption. Thus, there is no spatial dimensionality. The DO CSTR model is solved using a spreadsheet...For this study, the CSTR represents the bottom meter of water along the reach of the channel being assessed. A unit bottom layer thickness of 1 m

Synthesis of high capacity cathodes for lithium-ion batteries by morphology-tailored hydroxide co-precipitation

NASA Astrophysics Data System (ADS)

Wang, Dapeng; Belharouak, Ilias; Ortega, Luis H.; Zhang, Xiaofeng; Xu, Rui; Zhou, Dehua; Zhou, Guangwen; Amine, Khalil

2015-01-01

Nickel manganese hydroxide co-precipitation inside a continuous stirred tank reactor was studied with sodium hydroxide and ammonium hydroxide as the precipitation agents. The ammonium hydroxide concentration had an effect on the primary and secondary particle evolution. The two-step precipitation mechanism proposed earlier was experimentally confirmed. In cell tests, Li- and Mn-rich composite cathode materials based on the hydroxide precursors demonstrated good electrochemical performance in terms of cycle life over a wide range of lithium content.

Method of chaotic mixing and improved stirred tank reactors

DOEpatents

Muzzio, F.J.; Lamberto, D.J.

1999-07-13

The invention provides a method and apparatus for efficiently achieving a homogeneous mixture of fluid components by introducing said components having a Reynolds number of between about [le]1 to about 500 into a vessel and continuously perturbing the mixing flow by altering the flow speed and mixing time until homogeneity is reached. This method prevents the components from aggregating into non-homogeneous segregated regions within said vessel during mixing and substantially reduces the time the admixed components reach homogeneity. 19 figs.

Method of chaotic mixing and improved stirred tank reactors

DOEpatents

Muzzio, Fernando J.; Lamberto, David J.

1999-01-01

The invention provides a method and apparatus for efficiently achieving a homogeneous mixture of fluid components by introducing said components having a Reynolds number of between about .ltoreq.1 to about 500 into a vessel and continuously perturbing the mixing flow by altering the flow speed and mixing time until homogeniety is reached. This method prevents the components from aggregating into non-homogeneous segregated regions within said vessel during mixing and substantially reduces the time the admixed components reach homogeneity.

Emergence of multi-scaling in fluid turbulence

NASA Astrophysics Data System (ADS)

Donzis, Diego; Yakhot, Victor

2017-11-01

We present new theoretical and numerical results on the transition to strong turbulence in an infinite fluid stirred by a Gaussian random force. The transition is defined as a first appearance of anomalous scaling of normalized moments of velocity derivatives (or dissipation rates) emerging from the low-Reynolds-number Gaussian background. It is shown that due to multi-scaling, strongly intermittent rare events can be quantitatively described in terms of an infinite number of different ``Reynolds numbers'' reflecting a multitude of anomalous scaling exponents. We found that anomalous scaling for high order moments emerges at very low Reynolds numbers implying that intense dissipative-range fluctuations are established at even lower Reynolds number than that required for an inertial range. Thus, our results suggest that information about inertial range dynamics can be obtained from dissipative scales even when the former does not exit. We discuss our further prediction that transition to fully anomalous turbulence disappears at Rλ < 3 . Support from NSF is acknowledged.

Low-Temperature Oxidation Reactions and Cool Flames at Earth and Reduced Gravity

NASA Technical Reports Server (NTRS)

Pearlman, Howard

1999-01-01

Non-isothermal studies of cool flames and low temperature oxidation reactions in unstirred closed vessels are complicated by the perturbing effects of natural convection at earth gravity. Buoyant convection due to self-heating during the course of slow reaction produces spatio-temporal variations in the thermal and thus specie concentration fields due to the Arrhenius temperature dependence of the reaction rates. Such complexities have never been quantitatively modeled and were the primary impetus for the development of CSTR's (continuously stirred tank reactors) 30 years ago. While CSTR's have been widely adopted since they offer the advantage of spatial uniformity in temperature and concentration, all gradients are necessarily destroyed along with any structure that may otherwise develop. Microgravity offers a unique environment where buoyant convection can be effectively minimized and the need for stirring eliminated. Moreover, eliminating buoyancy and the need for stirring eliminates complications associated with the induced hydrodynamic field whose influence on heat transport and hot spot formation, hence explosion limits, is not fully realized. The objective of this research is to quantitatively determine and understand the fundamental mechanisms that control the onset and evolution of low temperature reactions and cool flames in both static and flow reactors. Microgravity experiments will be conducted to obtain benchmark data on the structure (spatio-temporal temperature, concentration, flow fields), the dynamics of the chemical fronts, and the ignition diagrams (pressure vs. temperature). Ground-based experiments will be conducted to ascertain the role of buoyancy. Numerical simulations including detailed kinetics will be conducted and compared to experiment.

Weld Nugget Temperature Control in Thermal Stir Welding

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2014-01-01

A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

Friction Stir Spot Welding of Advanced High Strength Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Grant, Glenn J.; Santella, M. L.

Friction stir spot welding techniques were developed to successfully join several advanced high strength steels. Two distinct tool materials were evaluated to determine the effect of tool materials on the process parameters and joint properties. Welds were characterized primarily via lap shear, microhardness, and optical microscopy. Friction stir spot welds were compared to the resistance spot welds in similar strength alloys by using the AWS standard for resistance spot welding high strength steels. As further comparison, a primitive cost comparison between the two joining processes was developed, which included an evaluation of the future cost prospects of friction stir spotmore » welding in advanced high strength steels.« less

Friction Stir Welding of Steel Alloys

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

2001-01-01

The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

Laboratory Feasibility Study Concerning the Use of the SediMeter (trademark) to Detect Fine-Scale ( or = 1 mm) Sedimentation Resulting from Dredging Operations

DTIC Science & Technology

2013-07-01

Pages/Services.aspx). As a result of this dredging activity, bottom sediments are stirred up and resuspended into plumes. The transport of these...1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law , no...bed elevation changes as dredged material is pumped into an area such as a wetland. They could also be used to evaluate the geomorphic stability of

The Concept of Electrically Assisted Friction Stir Welding (EAFSW) and Application to the Processing of Various Metals

DTIC Science & Technology

2008-09-01

unavailability of a precise load cell. This scale was set on the machine working table. Since the shaft spindle had been placed in fixed vertical...4 Figure 4. Mill Spindle with Slip Ring and Brush Assembly, Weld Tip is in W orking Position...areas . FSW of HSLA 65 and Type 304L Processing Parameter HSLA-65 304L Spindle Speed (RPM) 850 850 Travel Speed (ipm) 6 2 Z-Load (Ibs) 3500 3500

Demonstration of a Large-Scale Tank Assembly Via Circumferential Friction Stir Welds

NASA Technical Reports Server (NTRS)

Jones, Chip; Adams, Glynn; Colligan, Kevin; McCool, A. (Technical Monitor)

2000-01-01

Five (5) each 14-foot diameter circumferential FSWelds were conducted on the modified CWT, two (2) each pathfinder and three (3) each assembly welds Tapered circumferential welds were successfully demonstrated The use of a closeout anvil was successfully demonstrated during one of the pathfinder welds Considerable difficulty maintaining joint f it-up during the weld process Anvil deflections Hardware dimensional tolerances Inadequate clamping Variations in the heat sink characteristics of the circumferential anvil as compared to the test panel anvil

Effect of FSW welding speed on microstructure and microhardness of Al-0.84Mg-0.69Si-0.76Fe alloy at moderate rotational tool velocity

NASA Astrophysics Data System (ADS)

Chand, Suresh; Vineetha, S.; Madhusudhan, D.; Sai Krishna, CH; Kusuma Devi, G.; Bhawani; Hemarao, K.; Ganesh Naidu, G.

2018-03-01

The plate of 7.0 mm thickness was double side welded using friction stir welding is investigated. The rotational velocity of friction stir welding tool is used 1400 rpm. The influence of welding speed on the microstructure and microhardness values of Al-0.84Mg-0.69Si-0.76Fe aluminum alloy is presented. Two welding speeds 25 mm/min and 31.5 mm/min are used. The microhardness values of friction stir weld are measured at various locations from the weld interface. The microhardness values in stir zone of weld are found larger than lower welding speed at constant rotational velocity of 1400 rpm of friction stir welding tool. The similar effects on microhardness values are found in the thermo-mechanically affected zone and heat affected zone. The fine microstructure is observed at 31.5 mm/min welding speed compared to the 25 mm/min welding speed at 1400 rpm.

HEAT INPUT AND POST WELD HEAT TREATMENT EFFECTS ON REDUCED-ACTIVATION FERRITIC/MARTENSITIC STEEL FRICTION STIR WELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Wei; Chen, Gaoqiang; Chen, Jian

Reduced-activation ferritic/martensitic (RAFM) steels are an important class of structural materials for fusion reactor internals developed in recent years because of their improved irradiation resistance. However, they can suffer from welding induced property degradations. In this paper, a solid phase joining technology friction stir welding (FSW) was adopted to join a RAFM steel Eurofer 97 and different FSW parameters/heat input were chosen to produce welds. FSW response parameters, joint microstructures and microhardness were investigated to reveal relationships among welding heat input, weld structure characterization and mechanical properties. In general, FSW heat input results in high hardness inside the stir zonemore » mostly due to a martensitic transformation. It is possible to produce friction stir welds similar to but not with exactly the same base metal hardness when using low power input because of other hardening mechanisms. Further, post weld heat treatment (PWHT) is a very effective way to reduce FSW stir zone hardness values.« less

Multiple pass and multiple layer friction stir welding and material enhancement processes

DOEpatents

Feng, Zhili [Knoxville, TN; David, Stan A [Knoxville, TN; Frederick, David Alan [Harriman, TN

2010-07-27

Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

Effects of the types of overlap on the mechanical properties of FSSW welded AZ series magnesium alloy joints

NASA Astrophysics Data System (ADS)

Wang, Dan; Shen, Jun; Wang, Lin-Zhi

2012-03-01

The effects of the types of overlap on the mechanical properties of the friction stir spot welding (FSSW) welded AZ series magnesium alloy joints were investigated by microstructural observations, microhardness tests, and tensile tests. The results show that the microstructure of the stir zone adjacent to the periphery of the rotating pin is mainly composed of the upper sheet. The average distance D between the longitudinal segment of the curved interface and the keyhole periphery, the tensile shear force, and the microhardness of the stir zone of the FSSW welded AZ61 alloy joint are the highest in all samples. During FSSW of AZ31 and AZ61 dissimilar magnesium alloys, the irregular deformation of the longitudinal segment of the curved interface appears, while the microhardness of the stir zone is higher when AZ61 alloy is the upper sheet. Moreover, the microhardness of the stir zone increases initially and then decreases sharply in the longitudinal test position.

Lateral position detection and control for friction stir systems

DOEpatents

Fleming, Paul; Lammlein, David; Cook, George E.; Wilkes, Don Mitchell; Strauss, Alvin M.; Delapp, David; Hartman, Daniel A.

2010-12-14

A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

Corrosion Performance of Friction Stir Linear Lap Welded AM60B Joints

NASA Astrophysics Data System (ADS)

Kish, J. R.; Birbilis, N.; McNally, E. M.; Glover, C. F.; Zhang, X.; McDermid, J. R.; Williams, G.

2017-11-01

A corrosion investigation of friction stir linear lap welded AM60B joints used to fabricate an Mg alloy-intensive automotive front end sub-assembly was performed. The stir zone exhibited a slightly refined grain size and significant break-up and re-distribution of the divorced Mg17Al12 (β-phase) relative to the base material. Exposures in NaCl (aq) environments revealed that the stir zone was more susceptible to localized corrosion than the base material. Scanning vibrating electrode technique measurements revealed differential galvanic activity across the joint. Anodic activity was confined to the stir zone surface and involved initiation and lateral propagation of localized filaments. Cathodic activity was initially confined to the base material surface, but was rapidly modified to include the cathodically-activated corrosion products in the filament wake. Site-specific surface analyses revealed that the corrosion observed across the welded joint was likely linked to variations in Al distribution across the surface film/metal interface.

Azadirachtin production by hairy root cultivation of Azadirachta indica in a modified stirred tank reactor.

PubMed

Srivastava, Smita; Srivastava, A K

2012-11-01

Present investigation involves hairy root cultivation of Azadirachta indica in a modified stirred tank reactor under optimized culture conditions for maximum volumetric productivity of azadirachtin. The selected hairy root line (Az-35) was induced via Agrobacterium rhizogenes LBA 920-mediated transformation of A. indica leaf explants (Coimbatore variety, India). Liquid culture of the hairy roots was developed in a modified Murashige and Skoog medium (MM2). To further enhance the productivity of azadirachtin, selected growth regulators (1.0 mg/l IAA and 0.025 mg/l GA(3)), permeabilizing agent (0.5 % v/v DNBP), a biotic elicitor (1 % v/v Curvularia (culture filtrate)) and an indirectly linked biosynthetic precursor (50 mg/l cholesterol) were added in the growth medium on 15th day of the hairy root cultivation period in shake flask. Highest azadirachtin production (113 mg/l) was obtained on 25th day of the growth cycle with a biomass of 21 g/l DW. Further, batch cultivation of hairy roots was carried out in a novel liquid-phase bioreactor configuration (modified stirred tank reactor with polyurethane foam as root support) to investigate the possible scale-up of the established A. indica hairy root culture. A biomass production of 15.2 g/l with azadirachtin accumulation in the hairy roots of 6.4 mg/g (97.28 mg/l) could be achieved after 25 days of the batch cultivation period, which was ~27 and ~14 % less biomass and azadirachtin concentration obtained respectively, in shake flasks. An overall volumetric productivity of 3.89 mg/(l day) of azadirachtin was obtained in the bioreactor.

Breast cancer detection using double reading of unenhanced MRI including T1-weighted, T2-weighted STIR, and diffusion-weighted imaging: a proof of concept study.

PubMed

Trimboli, Rubina M; Verardi, Nicola; Cartia, Francesco; Carbonaro, Luca A; Sardanelli, Francesco

2014-09-01

The purpose of this study was to investigate the diagnostic performance of unenhanced MRI in detecting breast cancer and to assess the impact of double reading. A total of 116 breasts of 67 women who were 36-89 years old were studied at 1.5 T using an unenhanced protocol including axial T1-weighted gradient-echo, T2-weighted STIR, and echo-planar diffusion-weighted imaging (DWI). Two blinded readers (R1 and R2) independently evaluated unenhanced images using the BIRADS scale. A combination of pathology and negative follow-up served as the reference standard. McNemar and kappa statistics were used. Per-breast cancer prevalence was 37 of 116 (32%): 30 of 37 (81%) invasive ductal carcinoma, five of 37 (13%) ductal carcinoma in situ, and two of 37 (6%) invasive lobular carcinoma. Per-breast sensitivity of unenhanced MRI was 29 of 37 (78%) for R1, 28 of 37 (76%) for R2, and 29 of 37 (78%) for double reading. Specificity was 71 of 79 (90%) for both R1 and R2 and 69 of 79 (87%) for double reading. Double reading did not provide a significant increase in sensitivity. Interobserver agreement was almost perfect (Cohen κ = 0.873). An unenhanced breast MRI protocol composed of T1-weighted gradient echo, T2-weighted STIR, and echo-planar DWI enabled breast cancer detection with sensitivity of 76-78% and specificity of 90% without a gain in sensitivity from double reading.

Scaling properties of the two-dimensional randomly stirred Navier-Stokes equation.

PubMed

Mazzino, Andrea; Muratore-Ginanneschi, Paolo; Musacchio, Stefano

2007-10-05

We inquire into the scaling properties of the 2D Navier-Stokes equation sustained by a force field with Gaussian statistics, white noise in time, and with a power-law correlation in momentum space of degree 2 - 2 epsilon. This is at variance with the setting usually assumed to derive Kraichnan's classical theory. We contrast accurate numerical experiments with the different predictions provided for the small epsilon regime by Kraichnan's double cascade theory and by renormalization group analysis. We give clear evidence that for all epsilon, Kraichnan's theory is consistent with the observed phenomenology. Our results call for a revision in the renormalization group analysis of (2D) fully developed turbulence.

Advanced Metalworking Solutions for Naval Systems that Go in Harm’s Way

DTIC Science & Technology

2010-11-10

TECHNOLOGIES An NMC project team designed, built, and demonstrated at Concurrent Technologies Corporation a low-cost, transportable friction stir welding (LC...technologies for use in shipbuilding applications. For example, NMC and its team members are currently advancing friction stir welding (FSW...lower the cost of Navy ships and improve the quality of ship components. NMC is modifying its previously designed low-cost friction stir welding

Feasibility of Underwater Friction Stir Welding of Hardenable Alloy Steel

DTIC Science & Technology

2010-12-01

Base Material CNC – Computer Numerical Controlled EDM – Electrical Discharge Machining FSP – Friction Stir Processing FSW – Friction Stir Welding...Hydrogen content was determined through vacuum hot extraction according to ASTM E 146-83. All other components were analyzed by direct current plasma ...emission spectroscopy according to ASTM E 1097-07. C. MICROSTRUCTURE ANALYSIS 1. Specimen Preparation A Charmilles Andrew EF630 CNC Wire EDM

Low-Energy Tunable Self-Modulated Nanolasers (1.1 SHORT-TERM INNOVATIVE RESEARCH (STIR) PROGRAM)

DTIC Science & Technology

2016-09-28

Optoelectronics: Low -Energy Tunable Self- Modulated Nanolasers (1.1 SHORT-TERM INNOVATIVE RESEARCH (STIR) PROGRAM) Our goal was to exploit Quantum...reviewed journals: Final Report: Optoelectronics: Low -Energy Tunable Self-Modulated Nanolasers (1.1 SHORT-TERM INNOVATIVE RESEARCH (STIR) PROGRAM...metal layer. By optimizing the thickness of the low index shield between the metal and semiconductor, the gain threshold of the laser can be

Effect of shear on performance and microbial ecology of continuously stirred anaerobic digesters treating animal manure.

PubMed

Hoffmann, Rebecca A; Garcia, Marcelo L; Veskivar, Mehul; Karim, Khursheed; Al-Dahhan, Muthanna H; Angenent, Largus T

2008-05-01

We determined the effect of different mixing intensities on the performance, methanogenic population dynamics, and juxtaposition of syntrophic microbes in anaerobic digesters treating cow manure from a dairy farm. Computer automated radioactive particle tracking in conjunction with computational fluid dynamics was performed to quantify the shear levels locally. Four continuously stirred anaerobic digesters were operated at different mixing intensities of 1,500, 500, 250, and 50 revolutions per min (RPM) over a 260-day period at a temperature of 34 +/- 1 degrees C. Animal manure at a volatile solids (VS) concentration of 50 g/L was fed into the digesters daily at five different organic loading rates between 0.6 and 3.5 g VS/L day. The different mixing intensities had no effect on the biogas production rates and yields at steady-state conditions. A methane yield of 0.241 +/- 0.007 L CH(4)/g VS fed was obtained by pooling the data of all four digesters during steady-state periods. However, digester performance was affected negatively by mixing intensity during startup of the digesters, with lower biogas production rates and higher volatile fatty acids concentrations observed for the 1,500-RPM digester. Despite similar methane production yields and rates, the acetoclastic methanogenic populations were different for the high- and low-intensity mixed digesters with Methanosarcina spp. and Methanosaeta concilii as the predominant methanogens, respectively. For all four digesters, epifluorescence microscopy revealed decreasing microbial floc sizes beginning at week 4 and continuing through week 26 after which no microbial flocs remained. This decrease in size, and subsequent loss of microbial flocs did not, however, produce any long-term upsets in digester performance. Copyright 2007 Wiley Periodicals, Inc.

Effect of three cooking methods on nutrient components and antioxidant capacities of bamboo shoot (Phyllostachys praecox C.D. Chu et C.S. Chao)*

PubMed Central

Zhang, Jin-jie; Ji, Rong; Hu, Ya-qin; Chen, Jian-chu; Ye, Xing-qian

2011-01-01

Three cooking methods, namely boiling, steaming, and stir-frying for 5 to 10 min, were used to evaluate the effect on nutrient components, free amino acids, L-ascorbic acid, total phenolic contents, and antioxidant capacities of bamboo shoots (Phyllostachys praecox). Results showed that boiling and stir-frying had a great effect on the nutrient components and they decreased the contents of protein, soluble sugar, and ash, and caused a great loss in the total free amino acids (decreased by 38.35% and 34.86%, respectively). Significant differences (P<0.05) in free amino acids were observed in the samples cooked by different methods. Stir-fried bamboo shoots had a high fat content which increased by 528.57% because of the addition of edible oil. After boiling, the L-ascorbic acid and total phenolic contents were significantly reduced, while steaming increased total phenolic content by 3.98% and stir-frying well-preserved L-ascorbic acid (78.87% of its previous content). Results of the antioxidative property study showed that stir-frying could increase antioxidant capacities of bamboo shoots. It is concluded that stir-frying is more suitable for bamboo shoots because it could obtain the maximum retention of antioxidant capacities. PMID:21887851

Comparative study of fat-suppression techniques for hip arthroplasty MR imaging.

PubMed

Molière, Sébastien; Dillenseger, Jean-Philippe; Ehlinger, Matthieu; Kremer, Stéphane; Bierry, Guillaume

2017-09-01

The goal of this study was to evaluate different fat-suppressed fluid-sensitive sequences in association with different metal artifacts reduction techniques (MARS) to determine which combination allows better fat suppression around metallic hip implants. An experimental study using an MRI fat-water phantom quantitatively evaluated contrast shift induced by metallic hip implant for different fat-suppression techniques and MARS. Then a clinical study with patients addressed to MRI unit for painful hip prosthesis compared these techniques in terms of fat suppression quality and diagnosis confidence. Among sequences without MARS, both T2 Dixon and short tau inversion recuperation (STIR) had significantly lower contrast shift (p < 0.05), Dixon offering the best fat suppression. Adding MARS (view-angle tilting or slice-encoding for metal artifact correction (SEMAC)) to STIR gave better results than Dixon alone, and also better than SPAIR and fat saturation with MARS (p < 0.05). There were no statistically significant differences between STIR with view-angle tilting and STIR with SEMAC in terms of fat suppression quality. STIR sequence is the preferred fluid-sensitive MR sequence in patients with metal implant. In combination with MARS (view-angle tilting or SEMAC), STIR appears to be the best option for high-quality fat suppression.

Evaluating the Aging of Multiple Emulsions Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry.

PubMed

Tsuda, Yukihiro; Uchimura, Tomohiro

2016-01-01

Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry was applied to measurements of multiple emulsions with no pretreatment; a method for the quantitative evaluation of aging was proposed. We prepared water-in-oil-in-water (W/O/W) multiple emulsions containing toluene and m-phenylenediamine. The samples were measured immediately following both preparation and after having been stirred for 24 h. Time profiles of the peak areas for each analyte species were obtained, and several intense spikes for toluene could be detected from each sample after stirring, which suggests that the concentration of toluene in the middle phase had increased during stirring. On the other hand, in the case of a W/O/W multiple emulsion containing phenol and m-phenylenediamine, spikes for m-phenylenediamine, rather than phenol, were detected after stirring. In the present study, the time-profile data were converted into a scatter plot in order to quantitatively evaluate the aging. As a result, the ratio of the plots where strong signal intensities of toluene were detected increased from 8.4% before stirring to 33.2% after stirring for 24 h. The present method could be a powerful tool for evaluating multiple emulsions, such as studies on the kinetics of the encapsulation and release of active ingredients.

Effect of three cooking methods on nutrient components and antioxidant capacities of bamboo shoot (Phyllostachys praecox C.D. Chu et C.S. Chao).

PubMed

Zhang, Jin-jie; Ji, Rong; Hu, Ya-qin; Chen, Jian-chu; Ye, Xing-qian

2011-09-01

Three cooking methods, namely boiling, steaming, and stir-frying for 5 to 10 min, were used to evaluate the effect on nutrient components, free amino acids, L-ascorbic acid, total phenolic contents, and antioxidant capacities of bamboo shoots (Phyllostachys praecox). Results showed that boiling and stir-frying had a great effect on the nutrient components and they decreased the contents of protein, soluble sugar, and ash, and caused a great loss in the total free amino acids (decreased by 38.35% and 34.86%, respectively). Significant differences (P<0.05) in free amino acids were observed in the samples cooked by different methods. Stir-fried bamboo shoots had a high fat content which increased by 528.57% because of the addition of edible oil. After boiling, the L-ascorbic acid and total phenolic contents were significantly reduced, while steaming increased total phenolic content by 3.98% and stir-frying well-preserved L-ascorbic acid (78.87% of its previous content). Results of the antioxidative property study showed that stir-frying could increase antioxidant capacities of bamboo shoots. It is concluded that stir-frying is more suitable for bamboo shoots because it could obtain the maximum retention of antioxidant capacities.

Process engineering and scale-up of autotrophic Clostridium strain P11 syngas fermentation

NASA Astrophysics Data System (ADS)

Kundiyana, Dimple Kumar Aiyanna

Scope and Method of Study. Biomass gasification followed by fermentation of syngas to ethanol is a potential process to produce bioenergy. The process is currently being researched under laboratory- and pilot-scale in an effort to optimize the process conditions and make the process feasible for commercial production of ethanol and other biofuels such as butanol and propanol. The broad research objectives for the research were to improve ethanol yields during syngas fermentation and to design a economical fermentation process. The research included four statistically designed experimental studies in serum bottles, bench-scale and pilot-scale fermentors to screen alternate fermentation media components, to determine the effect of process parameters such as pH, temperature and buffer on syngas fermentation, to determine the effect of key limiting nutrients of the acetyl-CoA pathway in a continuous series reactor design, and to scale-up the syngas fermentation in a 100-L pilot scale fermentor. Findings and Conclusions. The first experimental study identified cotton seed extract (CSE) as a feasible medium for Clostridium strain P11 fermentation. The study showed that CSE at 0.5 g L-1 can potentially replace all the standard Clostridium strain P11 fermentation media components while using a media buffer did not significantly improve the ethanol production when used in fermentation with CSE. Scale-up of the CSE fermentation in 2-L and 5-L stirred tank fermentors showed 25% increase in ethanol yield. The second experimental study showed that syngas fermentation at 32°C without buffer was associated with higher ethanol concentration and reduced lag time in switching to solventogenesis. Conducting fermentation at 40°C or by lowering incubation pH to 5.0 resulted in reduced cell growth and no production of ethanol or acetic acid. The third experiment studied the effect of three limiting nutrients, calcium pantothenate, vitamin B12 and CoCl2 on syngas fermentation. Results indicated that it is possible to modulate the product formation by limiting key nutrients of acetyl-CoA pathway and using a continuous fermentation in two-stage fermentor design to improve ethanol yields. The last experimental study was conducted to commission a pilot scale fermentor, and subsequently scale-up the Clostridium strain P11 fermentation from a bench-scale to a pilot scale 100-L fermentor. Results indicated a six-fold improvement in ethanol concentration (25.3 g L-1 at the end of 59 d) compared to previous Clostridium strain P11 and Clostridium carboxidivorans fermentations plus the formation of other compounds such as isopropyl alcohol, acetic acid and butanol, which are of commercial importance.

Solar-assisted synthesis of ZnO nanoparticles using lime juice: a green approach

NASA Astrophysics Data System (ADS)

Hinge, Shruti P.; Pandit, Aniruddha B.

2017-12-01

Zinc oxide (ZnO) nanoparticles are those nanoparticles which have been synthesized in various morphologies and shapes. Their size and shape dependent properties and their applications in vivid sectors of science and technology make them interesting to synthesize. Present work reports a green method for ZnO nanoparticle synthesis using lime juice and sunlight. ZnO nanoparticles were also synthesized by conventionally used methods like heating, stirring or no heating and/or stirring. The nanoparticles were characterized using different techniques like UV-vis spectroscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD) and dynamic light scattering (DLS). Thermo gravimetric analysis (TGA) was also carried out for the intermediate product to select the calcination temperature. Stoichiometric study reveals that the intermediate product formed is zinc citrate dihydrate. The synthesized calcined nanoparticles have good crystallinity, uniform shape, and high purity and were in the size range of 20-30 nm. These nanoparticles formed agglomerates of various shapes in the size range of 200-750 nm. This process is ecofriendly and is amiable for easy scale up.

Lamination and mixing in laminar flows driven by Lorentz body forces

NASA Astrophysics Data System (ADS)

Rossi, L.; Doorly, D.; Kustrin, D.

2012-01-01

We present a new approach to the design of mixers. This approach relies on a sequence of tailored flows coupled with a new procedure to quantify the local degree of striation, called lamination. Lamination translates to the distance over which the molecular diffusion needs to act to finalise mixing. A novel in situ mixing is achieved by the tailored sequence of flows. This sequence is shown with the property that material lines and lamination grow exponentially, according to processes akin to the well-known baker's map. The degree of mixing (stirring coefficient) likewise shows exponential growth before the saturation of the stirring rate. Such saturation happens when the typical striations' thickness is smaller than the diffusion's length scale. Moreover, without molecular diffusion, the predicted striations' thickness would be smaller than the size of an atom of hydrogen within 40 flow turnover times. In fact, we conclude that about 3 minutes, i.e. 15 turnover times, are sufficient to mix species with very low diffusivities, e.g. suspensions of virus, bacteria, human cells, and DNA.

Effect of Pin Tool Shape on Metal Flow During Friction Stir Welding

NASA Technical Reports Server (NTRS)

McClure, J. C.; Coronado, E.; Aloor, S.; Nowak, B.; Murr, L. M.; Nunes, Arthur C., Jr.; Munafo, Paul M. (Technical Monitor)

2002-01-01

It has been shown that metal moves behind the rotating Friction Stir Pin Tool in two separate currents or streams. One current, mostly on the advancing side, enters a zone of material that rotates with the pin tool for one or more revolutions and eventually is abandoned behind the pin tool in crescent-shaped pieces. The other current, largely on the retreating side of the pin tool is moved by a wiping process to the back of the pin tool and fills in between the pieces of the rotational zone that have been shed by the rotational zone. This process was studied by using a faying surface copper trace to clarify the metal flow. Welds were made with pin tools having various thread pitches. Decreasing the thread pitch causes the large scale top-to-bottorn flow to break up into multiple vortices along the pin and an unthreaded pin tool provides insufficient vertical motion for there to be a stable rotational zone and flow of material via the rotational zone is not possible leading to porosity on the advancing side of the weld.

Stir bar sorptive extraction of diclofenac from liquid formulations: a proof of concept study.

PubMed

Kole, Prashant Laxman; Millership, Jeff; McElnay, James C

2011-03-25

A new stir bar sorptive extraction (SBSE) technique coupled with HPLC-UV method for quantification of diclofenac in pharmaceutical formulations has been developed and validated as a proof of concept study. Commercially available polydimethylsiloxane stir bars (Twister™) were used for method development and SBSE extraction (pH, phase ratio, stirring speed, temperature, ionic strength and time) and liquid desorption (solvents, desorption method, stirring time etc) procedures were optimised. The method was validated as per ICH guidelines and was successfully applied for the estimation of diclofenac from three liquid formulations viz. Voltarol(®) Optha single dose eye drops, Voltarol(®) Ophtha multidose eye drops and Voltarol(®) ampoules. The developed method was found to be linear (r=0.9999) over 100-2000ng/ml concentration range with acceptable accuracy and precision (tested over three QC concentrations). The SBSE extraction recovery of the diclofenac was found to be 70% and the LOD and LOQ of the validated method were found to be 16.06 and 48.68ng/ml, respectively. Furthermore, a forced degradation study of a diclofenac formulation leading to the formation of structurally similar cyclic impurity (indolinone) was carried out. The developed extraction method showed comparable results to that of the reference method, i.e. method was capable of selectively extracting the indolinone and diclofenac from the liquid matrix. Data on inter and intra stir bar accuracy and precision further confirmed robustness of the method, supporting the multiple re-use of the stir bars. Copyright © 2010 Elsevier B.V. All rights reserved.

On the origin of size-dependent and size-independent crystal growth: Influence of advection and diffusion

USGS Publications Warehouse

Kile, D.E.; Eberl, D.D.

2003-01-01

Crystal growth experiments were conducted using potassium alum and calcite crystals in aqueous solution under both non-stirred and stirred conditions to elucidate the mechanism for size-dependent (proportionate) and size-independent (constant) crystal growth. Growth by these two laws can be distinguished from each other because the relative size difference among crystals is maintained during proportionate growth, leading to a constant crystal size variance (??2) for a crystal size distribution (CSD) as the mean size increases. The absolute size difference among crystals is maintained during constant growth, resulting in a decrease in size variance. Results of these experiments show that for centimeter-sized alum crystals, proportionate growth occurs in stirred systems, whereas constant growth occurs in non-stirred systems. Accordingly, the mechanism for proportionate growth is hypothesized to be related to the supply of reactants to the crystal surface by advection, whereas constant growth is related to supply by diffusion. Paradoxically, micrometer-sized calcite crystals showed proportionate growth both in stirred and in non-stirred systems. Such growth presumably results from the effects of convection and Brownian motion, which promote an advective environment and hence proportionate growth for minute crystals in non-stirred systems, thereby indicating the importance of solution velocity relative to crystal size. Calcite crystals grown in gels, where fluid motion was minimized, showed evidence for constant, diffusion-controlled growth. Additional investigations of CSDs of naturally occurring crystals indicate that proportionate growth is by far the most common growth law, thereby suggesting that advection, rather than diffusion, is the dominant process for supplying reactants to crystal surfaces.

Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia

Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation inmore » the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.« less

Determination of ultraviolet filters in bathing waters by stir bar sorptive-dispersive microextraction coupled to thermal desorption-gas chromatography-mass spectrometry.

PubMed

Benedé, Juan L; Chisvert, Alberto; Giokas, Dimosthenis L; Salvador, Amparo

2016-01-15

In this work, a new approach that combines the advantages of stir bar sorptive extraction (SBSE) and dispersive solid phase extraction (DSPE), i.e. stir bar sorptive-dispersive microextraction (SBSDµE), is employed as enrichment and clean-up technique for the sensitive determination of eight lipophilic UV filters in water samples. The extraction is accomplished using a neodymium stir bar magnetically coated with oleic acid-coated cobalt ferrite magnetic nanoparticles (MNPs) as sorbent material, which are detached and dispersed into the solution at high stirring rate. When stirring is stopped, MNPs are magnetically retrieved onto the stir bar, which is subjected to thermal desorption (TD) to release the analytes into the gas chromatography-mass spectrometry (GC-MS) system. The SBSDµE approach allows for lower extraction time than SBSE and easier post-extraction treatment than DSPE, while TD allows for an effective and solvent-free injection of the entire quantity of desorbed analytes into GC-MS, and thus achieving a high sensitivity. The main parameters involved in TD, as well as the extraction time, were evaluated. Under the optimized conditions, the method was successfully validated showing good linearity, limits of detection and quantification in the low ngL(-1) range and good intra- and inter-day repeatability (RSD<12%). This accurate and sensitive analytical method was applied to the determination of trace amounts of UV filters in three bathing water samples (river, sea and swimming pool) with satisfactory relative recovery values (80-116%). Copyright © 2015 Elsevier B.V. All rights reserved.

Different molecular signatures in magnetic resonance imaging-staged facioscapulohumeral muscular dystrophy muscles.

PubMed

Tasca, Giorgio; Pescatori, Mario; Monforte, Mauro; Mirabella, Massimiliano; Iannaccone, Elisabetta; Frusciante, Roberto; Cubeddu, Tiziana; Laschena, Francesco; Ottaviani, Pierfrancesco; Ricci, Enzo

2012-01-01

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies and is characterized by a non-conventional genetic mechanism activated by pathogenic D4Z4 repeat contractions. By muscle Magnetic Resonance Imaging (MRI) we observed that T2-short tau inversion recovery (T2-STIR) sequences identify two different conditions in which each muscle can be found before the irreversible dystrophic alteration, marked as T1-weighted sequence hyperintensity, takes place. We studied these conditions in order to obtain further information on the molecular mechanisms involved in the selective wasting of single muscles or muscle groups in this disease. Histopathology, gene expression profiling and real time PCR were performed on biopsies from FSHD muscles with different MRI pattern (T1-weighted normal/T2-STIR normal and T1-weighted normal/T2-STIR hyperintense). Data were compared with those from inflammatory myopathies, dysferlinopathies and normal controls. In order to validate obtained results, two additional FSHD samples with different MRI pattern were analyzed. Myopathic and inflammatory changes characterized T2-STIR hyperintense FSHD muscles, at variance with T2-STIR normal muscles. These two states could be easily distinguished from each other by their transcriptional profile. The comparison between T2-STIR hyperintense FSHD muscles and inflammatory myopathy muscles showed peculiar changes, although many alterations were shared among these conditions. At the single muscle level, different stages of the disease correspond to the two MRI patterns. T2-STIR hyperintense FSHD muscles are more similar to inflammatory myopathies than to T2-STIR normal FSHD muscles or other muscular dystrophies, and share with them upregulation of genes involved in innate and adaptive immunity. Our data suggest that selective inflammation, together with perturbation in biological processes such as neoangiogenesis, lipid metabolism and adipokine production, may contribute to the sequential bursts of muscle degeneration that involve individual muscles in an asynchronous manner in this disease.

Gimballed Shoulders for Friction Stir Welding

NASA Technical Reports Server (NTRS)

Carter, Robert; Lawless, Kirby

2008-01-01

In a proposed improvement of tooling for friction stir welding, gimballed shoulders would supplant shoulders that, heretofore, have been fixedly aligned with pins. The proposal is especially relevant to self-reacting friction stir welding. Some definitions of terms, recapitulated from related prior NASA Tech Briefs articles, are prerequisite to a meaningful description of the proposed improvement. In friction stir welding, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a pin that rotates with the shoulder and protrudes from the shoulder into the depth of the workpiece. In conventional friction stir welding, the main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional friction stir welding is augmented with an auto-adjustable pin-tool (APT) capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or forcecontrol system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding as practiced heretofore, there are two shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. Both shoulders rotate with the pin and remain aligned coaxially with the pin. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft into the friction-stir-welding machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. This concludes the prerequisite definitions of terms.

Bioremediation of polycyclic aromatic hydrocarbon (PAH) compounds: (acenaphthene and fluorene) in water using indigenous bacterial species isolated from the Diep and Plankenburg rivers, Western Cape, South Africa.

PubMed

Alegbeleye, Oluwadara Oluwaseun; Opeolu, Beatrice Olutoyin; Jackson, Vanessa

This study was conducted to investigate the occurrence of PAH degrading microorganisms in two river systems in the Western Cape, South Africa and their ability to degrade two PAH compounds: acenaphthene and fluorene. A total of 19 bacterial isolates were obtained from the Diep and Plankenburg rivers among which four were identified as acenaphthene and fluorene degrading isolates. In simulated batch scale experiments, the optimum temperature for efficient degradation of both compounds was determined in a shaking incubator after 14 days, testing at 25°C, 30°C, 35°C, 37°C, 38°C, 40°C and 45°C followed by experiments in a Stirred Tank Bioreactor using optimum temperature profiles from the batch experiment results. All experiments were run without the addition of supplements, bulking agents, biosurfactants or any other form of biostimulants. Results showed that Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila efficiently degraded both compounds at 37°C, 37°C, 30°C and 35°C respectively. The degradation of fluorene was more efficient and rapid compared to that of acenaphthene and degradation at Stirred Tank Bioreactor scale was more efficient for all treatments. Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila degraded a mean total of 98.60%, 95.70%, 90.20% and 99.90% acenaphthene, respectively and 99.90%, 97.90%, 98.40% and 99.50% fluorene, respectively. The PAH degrading microorganisms isolated during this study significantly reduced the concentrations of acenaphthene and fluorene and may be used on a larger, commercial scale to bioremediate PAH contaminated river systems. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Characterization of a continuous agitated cell reactor for oxygen dependent biocatalysis.

PubMed

Toftgaard Pedersen, Asbjørn; de Carvalho, Teresa Melo; Sutherland, Euan; Rehn, Gustav; Ashe, Robert; Woodley, John M

2017-06-01

Biocatalytic oxidation reactions employing molecular oxygen as the electron acceptor are difficult to conduct in a continuous flow reactor because of the requirement for high oxygen transfer rates. In this paper, the oxidation of glucose to glucono-1,5-lactone by glucose oxidase was used as a model reaction to study a novel continuous agitated cell reactor (ACR). The ACR consists of ten cells interconnected by small channels. An agitator is placed in each cell, which mixes the content of the cell when the reactor body is shaken by lateral movement. Based on tracer experiments, a hydrodynamic model for the ACR was developed. The model consisted of ten tanks-in-series with back-mixing occurring within and between each cell. The back-mixing was a necessary addition to the model in order to explain the observed phenomenon that the ACR behaved as two continuous stirred tank reactors (CSTRs) at low flow rates, while it at high flow rates behaved as the expected ten CSTRs in series. The performance of the ACR was evaluated by comparing the steady state conversion at varying residence times with the conversion observed in a stirred batch reactor of comparable size. It was found that the ACR could more than double the overall reaction rate, which was solely due to an increased oxygen transfer rate in the ACR caused by the intense mixing as a result of the spring agitators. The volumetric oxygen transfer coefficient, k L a, was estimated to be 344 h -1 in the 100 mL ACR, opposed to only 104 h -1 in a batch reactor of comparable working volume. Interestingly, the large deviation from plug flow behavior seen in the tracer experiments was found to have little influence on the conversion in the ACR, since both a plug flow reactor (PFR) model and the backflow cell model described the data sufficiently well. Biotechnol. Bioeng. 2017;114: 1222-1230. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Advanced Metalworking Solutions for Naval Systems that go in Harm’s Way

DTIC Science & Technology

2009-01-01

friction stir welding (FSW) and advanced machining and casting techniques to produce a prototype Automated weld seam facing on DDG 1000 ships will...transportable friction stir welding (FSW) machine. FSW is a solid state joining technology that offers benefits over traditional welding for several...addition, by locating FSW operation at the construction yard, the aluminum panels that will be friction stir - welded are built to the size needed instead

Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

DTIC Science & Technology

2013-01-01

REPORT Friction Stir Weld Failure Mechanisms in Aluminum -Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...Stir Weld Failure Mechanisms in Aluminum -Armor Structures Under Ballistic Impact Loading Conditions M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen...K.O. Pedersen, Fracture Mechanisms of Aluminum Alloy AA7075-T651 Under Various Loading Conditions , Int. J. Impact Eng., 2010, 37, p 537–551 24. T

STIR-Physics: Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials

DTIC Science & Technology

2016-11-02

STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials We worked on a tapered fiber in cold atomic cloud...reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber...other than abstracts): Number of Peer-Reviewed Conference Proceeding publications (other than abstracts): Books Number of Manuscripts: 0.00Number of

Psychological and Behavioral Responses to a Chemical and Biological Warfare Environment: Final Recommendations

DTIC Science & Technology

1988-09-01

transfer through contaminated areas. CB11 stirs terror in individuals both because of the particular psychological fears it arouses and the tremelidous...supply and patient transfer through contaminated areas. CBW stirs terror in individuals both because of the particular * psychological fears it arouses and...time will be required. "w Survivable Collective Protection System-Medical (SCPS-M) plays an impor at role in this task. CBW itself stirs terror in

Friction Stir Welding of Dissimilar Al/Al and Al/Non-Al Alloys: A Review

NASA Astrophysics Data System (ADS)

Wang, Xiangbin; Pan, Yi; Lados, Diana A.

2018-05-01

Friction stir welding is a solid-state welding technique that has many advantages over traditional fusion welding, and has been widely adopted in the aerospace and automotive industries. This article reviews research developments in friction stir welding of dissimilar alloys systems, including combinations of aluminum alloys with Mg alloys, Cu, and steel. Microstructural evolution, hardness, tensile and fatigue properties, residual stresses, and corrosion behavior of dissimilar welds will be reported. The effects of processing parameters such as tool rotation and traverse speeds, tool position, material position, and tool geometry on the weld quality are also presented. Discussions on future research directions in friction stir welding will also be provided in the context of existing literature and future high-integrity applications.

Effect of Heat Index on Microstructure and Mechanical Behavior of Friction Stir Processed AZ31

NASA Astrophysics Data System (ADS)

Yuan, Wei; Mishra, Rajiv S.

Friction stir processing modifies the micro structure and properties of metals through intense plastic deformation. The frictional heat input affects the microstructure evolution and resulting mechanical properties. 2 mm thick commercial AZ31B-H24 Mg alloy was friction stir processed under various process parameter combinations to investigate the effect of heat index on micro structure and properties. Recrystallized grain structure in the nugget region was observed for all processing conditions with decrease in hardness. Results indicate a reduced tensile yield strength and ultimate tensile strength compared to the as-received material in H-temper, but with an improved hardening capacity. The strain hardening behavior of friction stir processed material is discussed.

Optimization of semi-continuous anaerobic digestion of sugarcane straw co-digested with filter cake: Effects of macronutrients supplementation on conversion kinetics.

PubMed

Janke, Leandro; Weinrich, Sören; Leite, Athaydes F; Schüch, Andrea; Nikolausz, Marcell; Nelles, Michael; Stinner, Walter

2017-12-01

Anaerobic digestion of sugarcane straw co-digested with sugarcane filter cake was investigated with a special focus on macronutrients supplementation for an optimized conversion process. Experimental data from batch tests and a semi-continuous experiment operated in different supplementation phases were used for modeling the conversion kinetics based on continuous stirred-tank reactors. The semi-continuous experiment showed an overall decrease in the performance along the inoculum washout from the reactors. By supplementing nitrogen alone or in combination to phosphorus and sulfur the specific methane production significantly increased (P<0.05) by 17% and 44%, respectively. Although the two-pool one-step model has fitted well to the batch experimental data (R 2 >0.99), the use of the depicted kinetics did not provide a good estimation for process simulation of the semi-continuous process (in any supplementation phase), possibly due to the different feeding modes and inoculum source, activity and adaptation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationships between posterior ligamentous complex injury and radiographic parameters in patients with thoracolumbar burst fractures.

PubMed

Hiyama, Akihiko; Watanabe, Masahiko; Katoh, Hiroyuki; Sato, Masato; Nagai, Toshihiro; Mochida, Joji

2015-02-01

The purpose of this study was to determine whether radiographic findings associated with thoracolumbar burst fractures could also indicate the presence of posterior ligamentous complex (PLC) injuries, which were identified through short-tau inversion-recovery (STIR)-weighted MRI. Sixty-four patients were surgically treated for thoracolumbar burst fractures between April 2007 and February 2014 at our institution. Twenty-four patients were excluded from this study because of the lack of STIR-weighted MRIs, and therefore 40 patients were included in this study. The patients were divided into two groups based upon the integrity of the PLC, which was evaluated using STIR-weighted MRI: a P group with a PLC injury and a C group without such injury. The following radiographic parameters were evaluated: loss of vertebral body height (LOVBH), local kyphosis (LK), vertebral body translation, canal compromise (sagittal transverse ratio, STR), interlaminar distance (ISD), supraspinous distance (SSD) and interspinous distance (ISD). Frankel scale score and total severity score (load sharing and thoracolumbar injury classification systems, respectively) were also evaluated. Preoperative STIR-weighted MRI showed that 25 patients had a PLC injury (P group: 15 men and 10 women), and 15 patients did not have a PLC injury (C group: 8 men and 7 women). More patients in the P group had an LK>20°: 14 patients in the P group and 1 patient in the C group (p<0.01). The % SSD differed between the P and C groups (118.8%±53.4% and 88.0%±24.3%, respectively; p<0.05). Multivariate logistic analysis showed that an LK>20° was a risk factor for PLC injury in patients with thoracolumbar burst fractures (odds ratio, 55.5 [95% confidence interval, 1.30-2360.1]; p<0.05). These results demonstrate that while LOVBH, vertebral body translation, and canal compromise do not correlate significantly with the presence of a PLC injury in patients with thoracolumbar fractures, an LK>20° and increased % SSD are associated with a PLC injury. Copyright © 2014 Elsevier Ltd. All rights reserved.

SLI Complex Curvature Friction Stir Weld Risk Reduction Program

NASA Technical Reports Server (NTRS)

Hartley, Paula J.; Schneider, Jules; Jones, Chip; Lawless, Kirby; Russell, Carolyn

2003-01-01

The Space Launch Initiative Program (SLI) in conjunction with the National Center for Advanced Manufacturing (NCAM) will demonstrate the ability to produce large-scale complex curvature hardware using the self-reacting friction stir welding process. This multi-phased risk reduction program includes friction stir welding process development and manufacture of a 22-ft diameter quarter dome using a conventional tooling approach; it culminates in a 27.5-ft diameter quarter dome demonstration performed on a 5-axis Universal Weld System. The design, fabrication, and installation of the Universal Weld System is made possible through a collaboration between the State of Louisiana, NASA, and the University of New Orleans. The Universal Weld System, manufactured by MTS Systems Corporation, will be installed at the Michoud Assembly Facility in New Orleans, Louisiana, and will be capable of manufacturing domes up to 30 ft in diameter. All welding will be accomplished using the Adaptable Adjustable Pin Tool (AdAPT) weld head and controller manufactured by MTS. Weld parameters will be developed for an aluminum alloy in gauges ranging from 0.320 to 0.400 in. thick. Weld quality will be verified through radiography, mechanical property testing at ambient and LN2 temperatures, and metallurgical analysis. The AdAPT weld head will then be mounted on a 22-ft diameter dome tool, which will be modified to include a welding track and drive system for moving the AdAPT weld head along the weld joint. This tool will then be used to manufacture a 22-ft diameter dome of an aluminum alloy, with 0.320-in. constant thickness joints, consisting of three individual gore panels. Finally, the 27.5-ft diameter quarter dome will be welded on the Universal Weld System. The quarter dome will consist of three individual gore panels with weld lands tapering from 0.320 to 0.360 in. in thickness. With the demonstration of these welds, the ability to manufacture large diameter domes using the friction stir weld process in conjunction with a universal weld system provides a low risk approach to the fabrication of aluminum tanks for future launch vehicle applications.

Stable thermophilic anaerobic digestion of dissolved air flotation (DAF) sludge by co-digestion with swine manure.

PubMed

Creamer, K S; Chen, Y; Williams, C M; Cheng, J J

2010-05-01

Environmentally sound treatment of by-products in a value-adding process is an ongoing challenge in animal agriculture. The sludge produced as a result of the dissolved air flotation (DAF) wastewater treatment process in swine processing facilities is one such low-value residue. The objective of this study was to determine the fundamental performance parameters for thermophilic anaerobic digestion of DAF sludge. Testing in a semi-continuous stirred tank reactor and in batch reactors was conducted to determine the kinetics of degradation and biogas yield. Stable operation could not be achieved using pure DAF sludge as a substrate, possibly due to inhibition by long-chain fatty acids or to nutrient deficiencies. However, in a 1:1 ratio (w/w, dry basis) with swine manure, operation was both stable and productive. In the semi-continuous stirred reactor at 54.5 degrees Celsius, a hydraulic residence time of 10 days, and an organic loading rate of 4.68 gVS/day/L, the methane production rate was 2.19 L/L/day and the specific methane production rate was 0.47 L/gVS (fed). Maximum specific methanogenic activity (SMA) in batch testing was 0.15 mmoles CH(4) h(-1) gVS(-1) at a substrate concentration of 6.9 gVS L(-1). Higher substrate concentrations cause an initial lag in methane production, possibly due to long-chain fatty acid or nitrogen inhibition. Copyright 2009 Elsevier Ltd. All rights reserved.

Effects of organic loading rate on hydrogen and volatile fatty acid production and microbial community during acidogenic hydrogenesis in a continuous stirred tank reactor using molasses wastewater.

PubMed

Yun, J; Cho, K-S

2016-12-01

Microbial community associated with hydrogen production and volatile fatty acids (VFAs) accumulation was characterized in acidogenic hydrogenesis using molasses wastewater as a feedstock. Hydrogen and VFAs production were measured under an organic loading rate (OLR) from 19 to 35 g-COD l -1  day -1 . The active microbial community was analysed using RNA-based massively parallel sequencing technique, and their correlation patterns were analysed using networking analysis. The continuous stirred tank reactor achieved stable hydrogen production at different OLR conditions, and the maximum hydrogen production rate (HPR) was 1·02 L-H 2  l -1  day -1 at 31·0 g-COD l -1  day -1 . Butyrate (50%) and acetate (38%) positively increased with increase in OLR. Total VFA production stayed around 7135 mg l -1 during the operation period. Although Clostridiales and Lactobacillales were relatively abundant, the HPR was positively associated with Pseudomonadaceae and Micrococcineae. Total VFA and acetate, butyrate and propionate concentrations were positively correlated with lactic acid bacteria (LAB) such as Bacillales, Sporolactobacillus and Lactobacillus. The close relationship between Pseudomonadaceae and Micrococcineae, and LAB play important roles for stable hydrogen and VFA production from molasses wastewater. Microbial information on hydrogen and VFA production can be useful to design and operate for acidogenic hydrogenesis using high strength molasses wastewater. © 2016 The Society for Applied Microbiology.

Application of a continuously stirred tank bioreactor (CSTR) for bioremediation of hydrocarbon-rich industrial wastewater effluents.

PubMed

Gargouri, Boutheina; Karray, Fatma; Mhiri, Najla; Aloui, Fathi; Sayadi, Sami

2011-05-15

A continuously stirred tank bioreactor (CSTR) was used to optimize feasible and reliable bioprocess system in order to treat hydrocarbon-rich industrial wastewaters. A successful bioremediation was developed by an efficient acclimatized microbial consortium. After an experimental period of 225 days, the process was shown to be highly efficient in decontaminating the wastewater. The performance of the bioaugmented reactor was demonstrated by the reduction of COD rates up to 95%. The residual total petroleum hydrocarbon (TPH) decreased from 320 mg TPH l(-1) to 8 mg TPH l(-1). Analysis using gas chromatography-mass spectrometry (GC-MS) identified 26 hydrocarbons. The use of the mixed cultures demonstrated high degradation performance for hydrocarbons range n-alkanes (C10-C35). Six microbial isolates from the CSTR were characterized and species identification was confirmed by sequencing the 16S rRNA genes. The partial 16S rRNA gene sequences demonstrated that 5 strains were closely related to Aeromonas punctata (Aeromonas caviae), Bacillus cereus, Ochrobactrum intermedium, Stenotrophomonas maltophilia and Rhodococcus sp. The 6th isolate was affiliated to genera Achromobacter. Besides, the treated wastewater could be considered as non toxic according to the phytotoxicity test since the germination index of Lepidium sativum ranged between 57 and 95%. The treatment provided satisfactory results and presents a feasible technology for the treatment of hydrocarbon-rich wastewater from petrochemical industries and petroleum refineries. Copyright © 2011 Elsevier B.V. All rights reserved.

Assembly of 5.5-Meter Diameter Developmental Barrel Segments for the Ares I Upper Stage

NASA Technical Reports Server (NTRS)

Carter, Robert W.

2011-01-01

Full scale assembly welding of Ares I Upper Stage 5.5-Meter diameter cryogenic tank barrel segments has been performed at the Marshall Space Flight Center (MSFC). One full-scale developmental article produced under the Ares 1 Upper Stage project is the Manufacturing Demonstration Article (MDA) Barrel. This presentation will focus on the welded assembly of this barrel section, and associated lessons learned. Among the MDA articles planned on the Ares 1 Program, the Barrel was the first to be completed, primarily because the process of manufacture from piece parts (barrel panels) utilized the most mature friction stir process planned for use on the Ares US program: Conventional fixed pin Friction Stir Welding (FSW). This process is in use on other space launch systems, including the Shuttle s External Tank, the Delta IV common booster core, the Delta II, and the Atlas V rockets. The goals for the MDA Barrel development were several fold: 1) to prove out Marshall Space Flight Center s new Vertical Weld Tool for use in manufacture of cylindrical barrel sections, 2) to serve as a first run for weld qualification to a new weld specification, and 3) to provide a full size cylindrical section for downstream use in precision cleaning and Spray-on Foam Insulation development. The progression leading into the welding of the full size barrel included sub scale panel welding, subscale cylinder welding, a full length confidence weld, and finally, the 3 seamed MDA barrel processing. Lessons learned on this MDA program have been carried forward into the production tooling for the Ares 1 US Program, and in the use of the MSFC VWT in processing other large scale hardware, including two 8.4 meter diameter Shuttle External Tank barrel sections that are currently being used in structural analysis to validate shell buckling models.

Phase sensitive reconstruction of T1-weighted inversion recovery in the evaluation of the cervical cord lesions in multiple Sclerosis; is it similarly eligible in 1.5 T magnet fields?

PubMed

Shayganfar, A; Sarrami, A H; Fathi, S; Shaygannejad, V; Shamsian, S

2018-04-22

In primary studies with 3 T Magnets, phase sensitive reconstruction of T1-weighted inversion recovery (PSIR) have showed ability to depict the cervical multiple sclerosis (MS) lesions some of which may not be detected by short tau inversion recovery (STIR). Regarding to more availability of 1.5 T MRI, this study was designed to evaluate the eligibility of PSIR in 1.5 T for detection of spinal cord MS lesions. In a study between September 2016 till March 2017 the patients with proven diagnosis of MS enrolled to the study. The standard protocol (sagittal STIR and T2W FSE and axial T2W FSE) as well as sagittal PSIR sequences were performed using a 1.5 T magnet. The images were studied and the lesions were localized and recorded as sharp or faint on each sequence. Of 25 patients (22 females and 3 males, with mean age of 33.5 ± 9.8 years and mean disease duration of 5.4 ± 3.9 years) 69 lesions in STIR, 53 lesions in T2W FSE, 47 lesions in Magnitude reconstruction of PSIR (Magnitude), and 30 lesions in phase sensitive (real) reconstruction PSIR were detected. A Wilcoxon signed-rank test showed STIR has a statistically significant higher detection rate of the plaques rather than other three sequences. (STIR and T2W FSE, Z = -4.000, p < 0.0001, STIR and Magnitude, Z = -4.690, p < 0.0001, STIR and PSIR, Z = -6.245, p = 0.002) Also, STIR had a statistically significant superiority in the boundary definition of the plaques rather than other three sequences. This study shows that in the setting of a 1.5 T magnet field, STIR significantly has a superiority over both of the PSIR reconstructions (i.e. real and magnitude) for the detection as well as the boundary definition of the cervical cord lesions of MS. These results have a good relevance to clinical practice by using MRI scanners and sequences routinely available, however, it is discrepant with other reports performed by 3 T Magnet fields. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of Post-Weld Heat Treatment on the Mechanical Properties of Similar- and Dissimilar-Alloy Friction Stir Welded Blanks

NASA Astrophysics Data System (ADS)

Zadpoor, Amir Abbas; Sinke, Jos

2011-01-01

Friction stir welding is a solid state joining process with relatively low welding temperatures. Nevertheless, the mechanical properties of friction stir welded blanks are degraded after welding. Indeed, both strength and ductility of the welds are decreased after welding. Often, the resulting friction stir welded blanks need to be formed to their final structural shape. Therefore, the formability of friction stir welded blanks is of primary importance in the manufacturing of structural parts. This paper studies how the mechanical properties and particularly formability of friction stir welded blanks can be improved by applying a post weld heat treatment. Two aluminum alloys from 2000 and 7000 series, namely 2024-T3 and 7075-T6, are selected for the study. The sheet thickness of both materials is 2,0 mm. The selected alloys are welded in three configurations: 2024-T3 and 2024-T3, 7075-T6 and 7075-T6, and 2024-T3 and 7075-T6. The resulting welds are naturally aged for a few months. Three sets of standard dog bone shape tensile test specimens are then machined from the welds. The first set of the specimens is tested without any heat treatment. The second set of the specimens is solution heat treated and quenched before testing. The third set of the specimens is solution heat treated, quenched, and naturally aged for a week before testing. The mechanical properties of the three different sets of specimens are compared with each other. It is shown that careful selection of post weld heat-treatment can greatly improve the formability of friction stir welded blanks.

Etched poly(ether ether ketone) jacket stir bar with detachable dumbbell-shaped structure for stir bar sorptive extraction.

PubMed

Zhou, Wei; Wang, Chenlu; Wang, Xuemei; Chen, Zilin

2018-06-08

Development of stir bar sorptive extraction (SBSE) device with high stability and extraction efficiency is critical and challenging by date. In this work, etched poly(ether ether ketone) (PEEK) tube with high mechanical strength and large specific surface area was used as jacket for SBSE device. By etching with concentrated sulfuric acid, the smooth outer surface of PEEK become porous with plenty of micro holes, which was beneficial for coating of sorbents and significantly improved the extraction performance. After functionalized by bio-polydopamine method, strong hydrophobic p-naphtholbenzein molecular was immobilized onto the chemical resistant PEEK surface (PNB@E-PEEK) as stationary phase. We also firstly developed a simple detachable dumbbell-shaped structure for improving the workability of PEEK jacket stir bar. The dumbbell-shaped construction can eliminate the friction between stir bar and container, and the design of detachable structure make elution can be accomplished easier with small amount of organic solvent. It was interesting that the developed detachable dumbbell-shaped PNB@E-PEEK stir bar showed exceptional stability and extraction efficiency for SBSE enrichment of multiple analytes including several Sudan dyes, triazines, polycyclic aromatic hydrocarbons (PAHs), alkaloids and flavonoid. By coupling with high performance liquid chromatography-ultraviolet detection (HPLC-UV), PNB@E-PEEK stir bar based SBSE-HPLC-UV method was applied for the analysis of common Sudan dye pollutants. The method showed low limits of detection (0.02-0.03 ng/mL), good linearity (R 2  ≥ 0.9979) and good reproducibility (relative standard deviation ≤ 7.96%). It has been successfully applied to determine three dye pollutants in tap and lake water. Copyright © 2018 Elsevier B.V. All rights reserved.

Membrane protected C18 coated stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet detection for the determination of non-steroidal anti-inflammatory drugs in water samples.

PubMed

Mao, Xiangju; He, Man; Chen, Beibei; Hu, Bin

2016-11-11

By wrapping a porous membrane around the coated stir bar, a novel membrane protected stir bar sorptive extraction (MPSBSE) was proposed to filter out the high molecular weight interferences (such as humic acid), resulting in the analysis of real environmental water samples without filtration or centrifugation. Hydrophilic and hydrophobic membranes were compared and hydrophobic polytetrafluoroethylene (PTFE) membrane impregnated with methanol was employed to protect the C 18 coated stir bar. The impregnated methanol improves the transfer of target analytes from sample solution to the pores and lumen of the membrane, and then to the coated stir bar inside. By combining C 18 -MPSBSE with HPLC-UV, a method was proposed for the direct determination of two common non-steroidal anti-inflammatory drugs, Ketoprofen (KEP) and Naproxen (NAP) in complex water samples. Under the optimized conditions, the limit of detections of KEP and NAP are 7.89, 9.52μgL -1 in the waste water and 7.69, 6.90μgL -1 in the pure water, respectively, with the enrichment factors of 32.0-49.1-fold. Besides, the lifetime of the prepared C 18 stir bar protected by PTFE membrane (50 times) is longer than that of C 18 stir bar without membrane protection (20 times), indicating that the friction damage of SBSE coating during extraction was effectively avoided. The developed method was successfully applied to the analysis of KEP and NAP in domestic sewage and campus lake water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

On-tap passive enrichment, a new way to investigate off-flavor episodes in drinking water.

PubMed

Tondelier, Christophe; Thouvenot, Thomas; Genin, Arnaud; Benanou, David

2009-04-03

Because taste and odor events in drinking water are often fleeting and unpredictable phenomena, an innovative enrichment sampler has been developed to trap off-flavor compounds directly at the consumer's tap. The ARISTOT (Advanced Relevant Investigation Sampler for Taste & Odor at Tap) consists of a tap adapter in which seven polydimethylsiloxane (PDMS) coated stir bars are placed, allowing the stir bar sorptive extraction (SBSE) of organic compounds during each tap opening. In order to study the efficiency of ARISTOT, a private network pilot unit has been constructed in our laboratory, equipped with four faucets in parallel, solenoid valves for an automation of the system and a mixing chamber to spike drinking water with odorous compounds in order to have homogenously smelling water at each tap. After enrichment, the stir bars are taken out, in-line thermo-desorbed and analyzed by gas chromatography coupled with a mass spectrometer. The results showed the high sensitivity of ARISTOT, which was able to quickly monitor odorous compounds at the sub ng/L level. A "multishot" method was developed to analyze chemicals concentrated on the seven stir bars in only one chromatographic run, thereby increasing the sensitivity of the system. Higher enrichment factors were obtained under low water flow rates or by using longer stir bars and/or stir bars with a higher PDMS film thickness. No significant loss of extracted compounds was reported for flow rates between 2 and 4L/min. This allowed us to spike the stir bars with an internal standard prior to sampling in order to monitor the analytical variations. It was also observed that hot water increases the loss of enriched solutes but the quantification can be corrected by internal standard addition.

Polydimethylsiloxane/MIL-100(Fe) coated stir bar sorptive extraction-high performance liquid chromatography for the determination of triazines in environmental water samples.

PubMed

Lei, Yun; Chen, Beibei; You, Linna; He, Man; Hu, Bin

2017-12-01

Polydimethylsiloxane (PDMS)/MIL-100(Fe) coated stir bar was prepared by sol gel technique, and good preparation reproducibility was achieved with relative standard deviations (RSDs) ranging from 2.6% to 7.5% (n=7) and 3.6% to 10.8% (n=7) for bar-to-bar and batch-to-batch, respectively. Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/MIL-100(Fe) stir bar showed better extraction efficiency for target triazines compounds. It also exhibited relatively fast extraction/desorption kinetics and long lifespan. Based on it, a method of PDMS/MIL-100(Fe) coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for the determination of six triazines (simazine, atrazine, prometon, ametryn, prometryne and prebane) in environmental water samples. Several parameters affecting SBSE of six target triazines including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.021-0.079μgL -1 . The repeatability RSDs were in the range of 2.3-6.3% (n=7, c=0.5μgL -1 ) and the enrichment factors (EFs) ranged from 51.1 to 102-fold (theoretical EF was 200-fold). The proposed method was applied to the analysis of target triazines in environmental water samples, with recoveries of 98.0-118% and 94.0-107% for spiked East Lake water and local pond water samples, respectively. Copyright © 2017. Published by Elsevier B.V.

C18-coated stir bar sorptive extraction combined with high performance liquid chromatography-electrospray tandem mass spectrometry for the analysis of sulfonamides in milk and milk powder.

PubMed

Yu, Chunhe; Hu, Bin

2012-02-15

A simple, rapid, sensitive, inexpensive and less sample consuming method of C(18)-stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) was proposed for the determination of six sulfonamides in milk and milk powder samples. C(18) silica particles coated stir bar was prepared by adhesion method, and two kinds of adhesive glue, polydimethylsiloxane (PDMS) sol and epoxy glue were tried. It was found that the C(18)-coated stir bar prepared by PDMS sol as adhesive glue is more robust than that prepared by epoxy glue when liquid desorption was employed, in terms of both lifetime and organic solvent tolerance. The preparation of C(18) stir bar was simple with good mechanic strength and the stir bar could be reused for more than 20 times. Granular coating has relatively high specific surface area and is propitious to sorptive extraction based process. Compared to conventional PDMS SBSE coating, C(18) coating shows good affinity to the target polar/weak polar sulfonamides. To achieve optimum SBSE extraction performance, several parameters including extraction and desorption time, ionic strength, sample pH and stirring speed were investigated. The detection limits of the proposed method for six sulfonamides were in the range of 0.9-10.5 μg/L for milk and 2.7-31.5 μg/kg for milk powder. Good linearities were obtained for sulfonamides with the correlation coefficients (R) above 0.9922. Finally, the proposed method was successfully applied to the determination of sulfonamides in milk and milk powder samples and satisfied recoveries of spiked target compounds in real samples were obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

Heat Control via Torque Control in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Venable, Richard; Colligan, Kevin; Knapp, Alan

2004-01-01

In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

Concentrating membrane proteins using ultrafiltration without concentrating detergents.

PubMed

Feroz, Hasin; Vandervelden, Craig; Ikwuagwu, Bon; Ferlez, Bryan; Baker, Carol S; Lugar, Daniel J; Grzelakowski, Mariusz; Golbeck, John H; Zydney, Andrew L; Kumar, Manish

2016-10-01

Membrane proteins (MPs) are of rapidly growing interest in the design of pharmaceutical products, novel sensors, and synthetic membranes. Ultrafiltration (UF) using commercially available centrifugal concentrators is typically employed for laboratory-scale concentration of low-yield MPs, but its use is accompanied by a concomitant increase in concentration of detergent micelles. We present a detailed analysis of the hydrodynamic processes that control detergent passage during ultrafiltration of MPs and propose methods to optimize detergent passage during protein concentration in larger-scale membrane processes. Experiments were conducted using nonionic detergents, octyl-β-D glucoside (OG), and decyl-β-D maltoside (DM) with the bacterial water channel protein, Aquaporin Z (AqpZ) and the light driven chloride pump, halorhodopsin (HR), respectively. The observed sieving coefficient (So ), a measure of detergent passage, was evaluated in both stirred cell and centrifugal systems. So for DM and OG increased with increasing filtrate flux and decreasing shear rates in the stirred cell, that is, with increasing concentration polarization (CP). Similar effects were observed during filtration of MP-detergent (MPD) micelles. However, lower transmission was observed in the centrifugal system for both detergent and MPD systems. This is attributed to free convection-induced shear and hence reduced CP along the membrane surface during centrifugal UF. Thus to concentrate MPs without retention of detergent, design of UF systems that promote CP is required. Biotechnol. Bioeng. 2016;113: 2122-2130. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C

NASA Astrophysics Data System (ADS)

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-06-01

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled θ (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

A numerical investigation of grain shape and crystallographic texture effects on the plastic strain localization in friction stir weld zones

NASA Astrophysics Data System (ADS)

Romanova, V.; Balokhonov, R.; Batukhtina, E.; Shakhidjanov, V.

2015-10-01

Crystal plasticity approaches were adopted to build models accounting for the microstructure and texture observed in different friction stir weld zones. To this end, a numerical investigation of crystallographic texture and grain shape effects on the plastic strain localization in a friction stir weld of an aluminum-base alloy was performed. The presence of texture was found to give rise to pronounced mesoscale plastic strain localization.

Development of a carbon-nanoparticle-coated stirrer for stir bar sorptive extraction by a simple carbon deposition in flame.

PubMed

Feng, Juanjuan; Sun, Min; Bu, Yanan; Luo, Chuannan

2016-03-01

Stir bar sorptive extraction is an environmentally friendly microextraction technique based on a stir bar with various sorbents. A commercial stirrer is a good support, but it has not been used in stir bar sorptive extraction due to difficult modification. A stirrer was modified with carbon nanoparticles by a simple carbon deposition process in flame and characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry. A three-dimensional porous coating was formed with carbon nanoparticles. In combination with high-performance liquid chromatography, the stir bar was evaluated using five polycyclic aromatic hydrocarbons as model analytes. Conditions including extraction time and temperature, ionic strength, and desorption solvent were investigated by a factor-by-factor optimization method. The established method exhibited good linearity (0.01-10 μg/L) and low limits of quantification (0.01 μg/L). It was applied to detect model analytes in environmental water samples. No analyte was detected in river water, and five analytes were quantified in rain water. The recoveries of five analytes in two samples with spiked at 2 μg/L were in the range of 92.2-106% and 93.4-108%, respectively. The results indicated that the carbon nanoparticle-coated stirrer was an efficient stir bar for extraction analysis of some polycyclic aromatic hydrocarbons. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Automated multisyringe stir bar sorptive extraction using robust montmorillonite/epoxy-coated stir bars.

PubMed

Ghani, Milad; Saraji, Mohammad; Maya, Fernando; Cerdà, Víctor

2016-05-06

Herein we present a simple, rapid and low cost strategy for the preparation of robust stir bar coatings based on the combination of montmorillonite with epoxy resin. The composite stir bar was implemented in a novel automated multisyringe stir bar sorptive extraction system (MS-SBSE), and applied to the extraction of four chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) as model compounds, followed by high performance liquid chromatography-diode array detection. The different experimental parameters of the MS-SBSE, such as sample volume, selection of the desorption solvent, desorption volume, desorption time, sample solution pH, salt effect and extraction time were studied. Under the optimum conditions, the detection limits were between 0.02 and 0.34μgL(-1). Relative standard deviations (RSD) of the method for the analytes at 10μgL(-1) concentration level ranged from 3.5% to 4.1% (as intra-day RSD) and from 3.9% to 4.3% (as inter-day RSD at 50μgL(-1) concentration level). Batch-to-batch reproducibility for three different stir bars was 4.6-5.1%. The enrichment factors were between 30 and 49. In order to investigate the capability of the developed technique for real sample analysis, well water, wastewater and leachates from a solid waste treatment plant were satisfactorily analyzed. Copyright © 2016 Elsevier B.V. All rights reserved.

Suppressing the Neurospora crassa circadian clock while maintaining light responsiveness in continuous stirred tank reactors

PubMed Central

Cockrell, Allison L.; Pirlo, Russell K.; Babson, David M.; Cusick, Kathleen D.; Soto, Carissa M.; Petersen, Emily R.; Davis, Miah J.; Hong, Christian I.; Lee, Kwangwon; Fitzgerald, Lisa A.; Biffinger, Justin C.

2015-01-01

Neurospora crassa has been utilized as a model organism for studying biological, regulatory, and circadian rhythms for over 50 years. These circadian cycles are driven at the molecular level by gene transcription events to prepare for environmental changes. N. crassa is typically found on woody biomass and is commonly studied on agar-containing medium which mimics its natural environment. We report a novel method for disrupting circadian gene transcription while maintaining light responsiveness in N. crassa when held in a steady metabolic state using bioreactors. The arrhythmic transcription of core circadian genes and downstream clock-controlled genes was observed in constant darkness (DD) as determined by reverse transcription-quantitative PCR (RT-qPCR). Nearly all core circadian clock genes were up-regulated upon exposure to light during 11hr light/dark cycle experiments under identical conditions. Our results demonstrate that the natural timing of the robust circadian clock in N. crassa can be disrupted in the dark when maintained in a consistent metabolic state. Thus, these data lead to a path for the production of industrial scale enzymes in the model system, N. crassa, by removing the endogenous negative feedback regulation by the circadian oscillator. PMID:26031221

Method of simultaneous stir bar sorptive extraction of phenethylamines and THC metabolite from urine.

PubMed

Goto, Yoshiyuki; Takeda, Shiho; Araki, Toshinori; Fuchigami, Takayuki

2011-10-01

Stir bar sorptive extraction is a technique used for extracting target substances from various aqueous matrixes such as environmental water, food, and biological samples. This type of extraction is carried out by rotating a coated stir bar is rotated in the sample solution. In particular, Twister bar is a commercial stir bar that is coated with polydimethylsiloxane (PDMS) and used to perform sorptive extraction. In this study, we developed a method for simultaneous detection of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, and a Δ(9)-tetrahydrocannabiniol (THC) metabolite in human urine. For extracting the target analytes, the Twister bar was simply stirred in the sample in the presence of a derivatizing agent. Using this technique, phenethylamines and the acidic THC metabolite can be simultaneously extracted from human urine. This method also enables the extraction of trace amounts of these substances with good reproducibility and high selectivity. The proposed method offers many advantages over other extraction-based approaches and is therefore well suited for screening psychoactive substances in urine specimens.

Sol-gel polydimethylsiloxane/poly(vinylalcohol)-coated stir bar sorptive extraction of organophosphorus pesticides in honey and their determination by large volume injection GC.

PubMed

Yu, Chunhe; Hu, Bin

2009-01-01

A PDMS/poly(vinylalcohol) (PDMS/PVA) film prepared through a sol-gel process was coated on stir bars for sorptive extraction, followed by liquid desorption and large volume injection-GC-flame photometric detector (LVI-GC-FPD) for the determination of five organophosphorus pesticides (OPPs) (phorate, fenitrothion, malathion, parathion, and quinalphos) in honey. The preparation reproducibility of PDMS/PVA-coated stir bar ranged from 4.3 to 13.4% (n = 4) in one batch, and from 6.0 to 12.6% (n = 4) in batch to batch. And one prepared stir bar can be used for more than 50 times without apparent coating loss. The significant parameters affecting stir bar sorptive extraction (SBSE) were investigated and optimized. The LODs for five OPPs ranged from 0.013 (parathion) to 0.081 microg/L (phorate) with the RSDs ranging from 5.3 to 14.2% (c = 1 microg/L, n = 6). The proposed method was successfully applied to the analysis of five OPPs in honey.

Preparation of a polar monolithic stir bar based on methacrylic acid and divinylbenzene for the sorptive extraction of polar pharmaceuticals from complex water samples.

PubMed

Bratkowska, D; Fontanals, N; Cormack, P A G; Borrull, F; Marcé, R M

2012-02-17

A monolithic, hydrophilic stir bar coating based upon a copolymer of methacrylic acid and divinylbenzene [poly(MAA-co-DVB)] was synthesised and evaluated as a new polymeric phase for the stir bar sorptive extraction (SBSE) of polar compounds from complex environmental water samples. The experimental conditions for the extraction and liquid desorption in SBSE were optimised. Liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) was used for the determination of a group of polar pharmaceuticals in environmental water matrices. The extraction performance of the poly(MAA-co-DVB) stir bar was compared to the extraction performance of a commercially available polydimethylsiloxane stir bar; it was found that the former gave rise to significantly higher extraction efficiency of polar analytes (% recovery values near to 100% for most of the studied analytes) than the commercial product. The developed method was applied to determine the studied analytes at low ng L⁻¹ in different complex environmental water samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Production of xylanolytic enzymes by Aspergillus terricola in stirred tank and airlift tower loop bioreactors.

PubMed

Michelin, Michele; Polizeli, Maria de Lourdes Teixeira de Moraes; Silva, Daniel Pereira da; Ruzene, Denise Santos; Vicente, António Augusto; Jorge, João Atílio; Terenzi, Héctor Francisco; Teixeira, José António

2011-12-01

Fungi producing high xylanase levels have attracted considerable attention because of their potential industrial applications. Batch cultivations of Aspergillus terricola fungus were evaluated in stirred tank and airlift bioreactors, by using wheat bran particles suspended in the cultivation medium as substrate for xylanase and β-xylosidase production. In the stirred tank bioreactor, in physical conditions of 30°C, 300 rpm, and aeration of 1 vvm (1 l min⁻¹), with direct inoculation of fungal spores, 7,475 U l⁻¹ xylanase was obtained after 36 h of operation, remaining constant after 24 h. In the absence of air injection in the stirred tank reactor, limited xylanase production was observed (final concentration 740 U l⁻¹). When the fermentation process was realized in the airlift bioreactor, xylanase production was higher than that observed in the stirred tank bioreactor, being 9,265 U l⁻¹ at 0.07 vvm (0.4 l min⁻¹) and 12,845 U l⁻¹ at 0.17 vvm (1 l min⁻¹) aeration rate.

Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

NASA Technical Reports Server (NTRS)

McGill, Preston; Burkholder, Jonathan

2012-01-01

Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

Deformation During Friction Stir Welding

NASA Technical Reports Server (NTRS)

White, Henry J.

2002-01-01

Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

Chiral imprinted polymers as enantiospecific coatings of stir bar sorptive extraction devices.

PubMed

Gomez-Caballero, Alberto; Guerreiro, Antonio; Karim, Kal; Piletsky, Sergey; Goicolea, M Aranzazu; Barrio, Ramon J

2011-10-15

This paper reports the design of Molecularly Imprinted Polymers (MIP) with affinity towards (S)-citalopram using computational modeling for the selection of functional monomers and monomer:template ratio. Acrylamide was selected as functional monomer and the final complex functional monomer/template resulted in a 3:1 ratio. The polymer was synthesized by radical polymerization initiated by UV onto magnetic stir-bars in order to obtain a stir bar sorptive extraction (SBSE) device capable of selective enantiomeric recognition. After successful template removal, the parameters affecting the SBSE procedure (sample volume, ionic strength, extraction time and pH) were optimized for the effective rebinding of the target analyte. The resultant chirally imprinted polymer based stir-bar was able to selectively extract (S)-citalopram from a racemic mixture in an aqueous media with high specificity (specificity factor 4) between 25 and 500 μgL(-1). The MIP coated stir-bars can have significance for enantiospecific sample pre-concentration and subsequent analysis without the need for any chiral chromatographic separation. Copyright © 2011 Elsevier B.V. All rights reserved.

Role of Mechanical Stirring of Al-Mg Melt in the Healing of Bifilm Defect

NASA Astrophysics Data System (ADS)

Bagherpour-Torghabeh, Hamed; Raiszadeh, Ramin; Doostmohammadi, Hamid

2017-12-01

The effect of mechanical stirring of aluminum melts containing 0.3, 0.7, and 4.5 wt pct Mg with a graphite rotor with different rotation speeds of 85 and 220 RPM on the behavior of bifilms was investigated using a reduced pressure test. The results showed that the mechanical stirring at 85 RPM accelerated the healing of the bifilms by increasing the rate of formation of cracks on the bifilms and hence accelerated the consumption of their atmosphere and provided enough Mg for the transformation of the alumina layers of the bifilms to spinel. Mechanical stirring with a high speed of 220 RPM caused aspiration of the surface oxide into the melt to form new bifilms which counteracted the healing of the previously presented bifilms.

Effect of formation and state of interface on joint strength in friction stir spot welding for advanced high strength steel sheets

NASA Astrophysics Data System (ADS)

Taniguchi, Koichi; Matsushita, Muneo; Ikeda, Rinsei; Oi, Kenji

2014-08-01

The tensile shear strength and cross tension strength of friction stir spot welded joints were evaluated in the cases of lap joints of 270 N/mm2 grade and 980 N/mm2 grade cold rolled steel sheets with respect to the stir zone area, hardness distribution, and interface condition between the sheets. The results suggested that both the tensile shear strength and cross tension strength were based on the stir zone area and its hardness in both grades of steel. The "hook" shape of the interface also affected the joint strength. However, the joining that occurred across the interfaces had a significant influence on the value of the joint strength in the case of the 270 N/mm2 grade steel.

Sequential hydrogen and methane coproduction from sugary wastewater treatment by "CSTRHyd-UASBMet" system

NASA Astrophysics Data System (ADS)

Hao, Ping

2017-10-01

Potentiality of sequential hydrogen bioproduction from sugary wastewater treatment was investigated using continuous stirred tank reactor (CSTR) for various substrate COD concentrations and HRTs. At optimum substrate concentration of 6 g COD/L, hydrogen could be efficiently produced from CSTR with the highest production rate of 3.00 (±0.04) L/L reactor d at HRT of 6 h. The up flow anaerobic sludge bed (UASB) reactor was used for continuous methane bioproduction from the effluents of hydrogen bioproduction. At optimal HRT 12 h, methane could be produced with a production rate of 2.27 (±0.08) L/L reactor d and the COD removal efficiency reached up to the maximum 82.3%.

Structure of AA5056 after friction drilling

NASA Astrophysics Data System (ADS)

Eliseev, A. A.; Kalashnikova, T. A.; Fortuna, S. V.

2017-12-01

Here we present data on the structure of AA5056 alloy after friction drilling to unveil potentials of the process for use in model experiments on friction stir welding. Our analysis of the average size and volume content of precipitates shows that their content decreases immediately beneath the friction surface and that the structure of this zone is the same as the structure of stirring zones formed in friction stir welding. The data suggest that both processes provide similar metal structures.

Unraveling the Processing Parameters in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Schneider, Judy; Nunes, Arthur C., Jr.

2005-01-01

In friction stir welding (FSW), a rotating threaded pin tool is translated along a weld seam, literally stirring the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path or paths is required. In this study, various markers are used to trace the flow paths of the metal. X-ray radiographs record the segmentation and position of the wire. Several variations in the trajectories can be differentiated within the weld zone.

Protein Crystallization by Combining Laser Irradiation and Solution-Stirring Techniques

NASA Astrophysics Data System (ADS)

Adachi, Hiroaki; Niino, Ai; Murakami, Satoshi; Takano, Kazufumi; Matsumura, Hiroyoshi; Kinoshita, Takayoshi; Warizaya, Masaichi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

2005-03-01

Bovine adenosine deaminase in the absence of an inhibitor (free-ADA) does not form crystals when using conventional crystallization methods. Using a solution-stirring technique, we recently succeeded in generating a small number of free-ADA crystals. In this paper, we demonstrate the combination of laser-irradiated growth and stirring (COLAS). This technique was found to be useful for controlling crystal nucleation and growth, which led to the production of a much larger number of high-quality free-ADA crystals.

Effect of processing parameters on the corrosion behaviour of friction stir processed AA 2219 aluminum alloy

NASA Astrophysics Data System (ADS)

Surekha, K.; Murty, B. S.; Prasad Rao, K.

2009-04-01

The effect of processing parameters (rotation speed and traverse speed) on the corrosion behaviour of friction stir processed high strength precipitation hardenable AA 2219-T87 alloy was investigated. The results indicate that the rotation speed has a major influence in determining the rate of corrosion, which is attributed to the breaking down and dissolution of the intermetallic particles. Corrosion resistance of friction stir processed alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy, salt spray and immersion tests.

Characterization of Residual Stress as a Function of Friction Stir Welding Parameters in ODS Steel MA956

DTIC Science & Technology

2013-06-01

dispersion strengthened - Eurofer steel ,” J. Nucl. Mater., vol. 416 , pp. 2229, Sep 1, 2011. [10] H. J. K. Lemmen and K. J. Sudmeijer, I, “Laser beam...Reynolds and W. Tang, “Structure, properties, and residual stress of 304L stainless steel friction stir welds,” Scr. Mater., vol. 48, pp. 12891294...OF RESIDUAL STRESS AS A FUNCTION OF FRICTION STIR WELDING PARAMETERS IN ODS STEEL MA956 by Martin S. Bennett June 2013 Thesis Advisor

Attainable region analysis for continuous production of second generation bioethanol

PubMed Central

2013-01-01

Background Despite its semi-commercial status, ethanol production from lignocellulosics presents many complexities not yet fully solved. Since the pretreatment stage has been recognized as a complex and yield-determining step, it has been extensively studied. However, economic success of the production process also requires optimization of the biochemical conversion stage. This work addresses the search of bioreactor configurations with improved residence times for continuous enzymatic saccharification and fermentation operations. Instead of analyzing each possible configuration through simulation, we apply graphical methods to optimize the residence time of reactor networks composed of steady-state reactors. Although this can be easily made for processes described by a single kinetic expression, reactions under analysis do not exhibit this feature. Hence, the attainable region method, able to handle multiple species and its reactions, was applied for continuous reactors. Additionally, the effects of the sugars contained in the pretreatment liquor over the enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) were assessed. Results We obtained candidate attainable regions for separate enzymatic hydrolysis and fermentation (SHF) and SSF operations, both fed with pretreated corn stover. Results show that, despite the complexity of the reaction networks and underlying kinetics, the reactor networks that minimize the residence time can be constructed by using plug flow reactors and continuous stirred tank reactors. Regarding the effect of soluble solids in the feed stream to the reactor network, for SHF higher glucose concentration and yield are achieved for enzymatic hydrolysis with washed solids. Similarly, for SSF, higher yields and bioethanol titers are obtained using this substrate. Conclusions In this work, we demonstrated the capabilities of the attainable region analysis as a tool to assess the optimal reactor network with minimum residence time applied to the SHF and SSF operations for lignocellulosic ethanol production. The methodology can be readily modified to evaluate other kinetic models of different substrates, enzymes and microorganisms when available. From the obtained results, the most suitable reactor configuration considering residence time and rheological aspects is a continuous stirred tank reactor followed by a plug flow reactor (both in SSF mode) using washed solids as substrate. PMID:24286451

Attainable region analysis for continuous production of second generation bioethanol.

PubMed

Scott, Felipe; Conejeros, Raúl; Aroca, Germán

2013-11-29

Despite its semi-commercial status, ethanol production from lignocellulosics presents many complexities not yet fully solved. Since the pretreatment stage has been recognized as a complex and yield-determining step, it has been extensively studied. However, economic success of the production process also requires optimization of the biochemical conversion stage. This work addresses the search of bioreactor configurations with improved residence times for continuous enzymatic saccharification and fermentation operations. Instead of analyzing each possible configuration through simulation, we apply graphical methods to optimize the residence time of reactor networks composed of steady-state reactors. Although this can be easily made for processes described by a single kinetic expression, reactions under analysis do not exhibit this feature. Hence, the attainable region method, able to handle multiple species and its reactions, was applied for continuous reactors. Additionally, the effects of the sugars contained in the pretreatment liquor over the enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) were assessed. We obtained candidate attainable regions for separate enzymatic hydrolysis and fermentation (SHF) and SSF operations, both fed with pretreated corn stover. Results show that, despite the complexity of the reaction networks and underlying kinetics, the reactor networks that minimize the residence time can be constructed by using plug flow reactors and continuous stirred tank reactors. Regarding the effect of soluble solids in the feed stream to the reactor network, for SHF higher glucose concentration and yield are achieved for enzymatic hydrolysis with washed solids. Similarly, for SSF, higher yields and bioethanol titers are obtained using this substrate. In this work, we demonstrated the capabilities of the attainable region analysis as a tool to assess the optimal reactor network with minimum residence time applied to the SHF and SSF operations for lignocellulosic ethanol production. The methodology can be readily modified to evaluate other kinetic models of different substrates, enzymes and microorganisms when available. From the obtained results, the most suitable reactor configuration considering residence time and rheological aspects is a continuous stirred tank reactor followed by a plug flow reactor (both in SSF mode) using washed solids as substrate.

Validation of a simple method for predicting the disinfection performance in a flow-through contactor.

PubMed

Pfeiffer, Valentin; Barbeau, Benoit

2014-02-01

Despite its shortcomings, the T10 method introduced by the United States Environmental Protection Agency (USEPA) in 1989 is currently the method most frequently used in North America to calculate disinfection performance. Other methods (e.g., the Integrated Disinfection Design Framework, IDDF) have been advanced as replacements, and more recently, the USEPA suggested the Extended T10 and Extended CSTR (Continuous Stirred-Tank Reactor) methods to improve the inactivation calculations within ozone contactors. To develop a method that fully considers the hydraulic behavior of the contactor, two models (Plug Flow with Dispersion and N-CSTR) were successfully fitted with five tracer tests results derived from four Water Treatment Plants and a pilot-scale contactor. A new method based on the N-CSTR model was defined as the Partially Segregated (Pseg) method. The predictions from all the methods mentioned were compared under conditions of poor and good hydraulic performance, low and high disinfectant decay, and different levels of inactivation. These methods were also compared with experimental results from a chlorine pilot-scale contactor used for Escherichia coli inactivation. The T10 and Extended T10 methods led to large over- and under-estimations. The Segregated Flow Analysis (used in the IDDF) also considerably overestimated the inactivation under high disinfectant decay. Only the Extended CSTR and Pseg methods produced realistic and conservative predictions in all cases. Finally, a simple implementation procedure of the Pseg method was suggested for calculation of disinfection performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

Identifiability of sorption parameters in stirred flow-through reactor experiments and their identification with a Bayesian approach.

PubMed

Nicoulaud-Gouin, V; Garcia-Sanchez, L; Giacalone, M; Attard, J C; Martin-Garin, A; Bois, F Y

2016-10-01

This paper addresses the methodological conditions -particularly experimental design and statistical inference- ensuring the identifiability of sorption parameters from breakthrough curves measured during stirred flow-through reactor experiments also known as continuous flow stirred-tank reactor (CSTR) experiments. The equilibrium-kinetic (EK) sorption model was selected as nonequilibrium parameterization embedding the K d approach. Parameter identifiability was studied formally on the equations governing outlet concentrations. It was also studied numerically on 6 simulated CSTR experiments on a soil with known equilibrium-kinetic sorption parameters. EK sorption parameters can not be identified from a single breakthrough curve of a CSTR experiment, because K d,1 and k - were diagnosed collinear. For pairs of CSTR experiments, Bayesian inference allowed to select the correct models of sorption and error among sorption alternatives. Bayesian inference was conducted with SAMCAT software (Sensitivity Analysis and Markov Chain simulations Applied to Transfer models) which launched the simulations through the embedded simulation engine GNU-MCSim, and automated their configuration and post-processing. Experimental designs consisting in varying flow rates between experiments reaching equilibrium at contamination stage were found optimal, because they simultaneously gave accurate sorption parameters and predictions. Bayesian results were comparable to maximum likehood method but they avoided convergence problems, the marginal likelihood allowed to compare all models, and credible interval gave directly the uncertainty of sorption parameters θ. Although these findings are limited to the specific conditions studied here, in particular the considered sorption model, the chosen parameter values and error structure, they help in the conception and analysis of future CSTR experiments with radionuclides whose kinetic behaviour is suspected. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detailed Microstructural Characterization and Restoration Mechanisms of Duplex and Superduplex Stainless Steel Friction-Stir-Welded Joints

NASA Astrophysics Data System (ADS)

Santos, T. F. A.; Torres, E. A.; Lippold, J. C.; Ramirez, A. J.

2016-12-01

Duplex stainless steels are successfully used in a wide variety of applications in areas such as the food industry, petrochemical installations, and sea water desalination plants, where high corrosion resistance and high mechanical strength are required. However, during fusion welding operations, there can be changes to the favorable microstructure of these materials that compromise their performance. Friction stir welding with a non-consumable pin enables welded joints to be obtained in the solid state, which avoids typical problems associated with solidification of the molten pool, such as segregation of alloying elements and the formation of solidification and liquefaction cracks. In the case of superduplex stainless steels, use of the technique can avoid unbalanced proportions of ferrite and austenite, formation of deleterious second phases, or growth of ferritic grains in the heat-affected zone. Consolidated joints with full penetration were obtained for 6-mm-thick plates of UNS S32101 and S32205 duplex stainless steels, and S32750 and S32760 superduplex steels. The welding heat cycles employed avoided the conditions required for formation of deleterious phases, except in the case of the welded joint of the S32760 steel, where SEM images indicated the formation of secondary phases, as corroborated by decreased mechanical performance. Analysis using EBSD and transmission electron microscopy revealed continuous dynamic recrystallization by the formation of cellular arrays of dislocations in the ferrite and discontinuous dynamic recrystallization in the austenite. Microtexture evaluation indicated the presence of fibers typical of shear in the thermomechanically affected zone. These fibers were not obviously present in the stir zone, probably due to the intensity of microstructural reformulation to which this region was subjected.

A sublimate sorbent for stir-bar sorptive extraction of aqueous endocrine disruptor pesticides for gas chromatography-electron capture detection.

PubMed

Huang, Yu-Wen; Lee, Hua Kwang; Shih, Hou-Kuang; Jen, Jen-Fon

2018-06-06

A dumbbell-shaped magnetic stir-bar with sublimate sorbent was prepared for the stir bar sorptive extraction (SBSE) of pesticides in an aqueous sample prior to gas chromatography-micro-electron capture detection (GC-μECD). Cyclododecane (CDD) was coated onto a magnetic stir-bar surface as a sublimate sorbent, and steel balls were placed on both ends to form a dumbbell-shaped magnetic stir-bar for SBSE. Four EDC pesticides including chlorpyrifos, ethion, bromopropylate, and λ-cyhalothrin in aqueous samples were selected as model species to examine the proposed SBSE and the following desorption. The parameters studied were those affecting the extraction efficiencies including the coating (solvent for CDD and thickness), extraction (sample pH, stirring rate, time, and salting out effect), dissolution solvent volume, and the loss of CDD sublimated in air. The maximum extraction efficiency was obtained under the following conditions. The stir bar (with CDD thickness of 5.2 μm) was added into a 10 mL sample solution (at pH 7) for a 20-min extraction at 600 rpm. Then, the stir bar was gently removed from the sample solution, disassembled, and immersed into a 0.2 mL insert tube consisting of 3 μL hexane to dissolve; 1 μL was used for GC-ECD analysis. The linear ranges were 0.005-5 μg L -1 with coefficients of determination ranging from 0.9950 - 0.9994. Detection limits (based on S/N = 3) of the four EDCs were 0.4-4.5 ngL -1 with a relative standard deviation (RSD) of 2.4-6.3%, and quantitation limits (based on S/N = 5) were 1-15 ngL -1 . The relative recoveries of the spiked samples were in the range of 83.2-98.7% with RSDs of 2.1-8.4% in farm field waters. The proposed sublimation sorbent obtained excellent enrichment factors (101-834) and provided a simple, rapid, sensitive, and eco-friendly sample preparation method. Copyright © 2018 Elsevier B.V. All rights reserved.

Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples.

PubMed

Zhong, Cheng; He, Man; Liao, Huaping; Chen, Beibei; Wang, Cheng; Hu, Bin

2016-04-08

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Biogasification of community-derived biomass and solid wastes in a pilot-scale SOLCON reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srivastava, V.J.; Biljetina, R.; Isaacson, H.R.

1988-01-01

The Institute of Gas Technology has developed a novel, solids- concentrating (SOLCON) bioreactor to convert a variety of individual or mixed feedstocks (biomass and wastes) to methane at higher rates and efficiencies than those obtained from conventional high-rate anaerobic digesters. The biogasification studies are being conducted in a pilot-scale experimental test unit (ETU) located in the Walt Disney World Resort Complex, Orlando, Florida. This paper describes the ETU facility, the logistics of feedstock integration, the SOLCON reactor design and operating techniques, and the results obtained during 4 years of stable, uninterrupted operation with different feedstocks. The SOLCON reactor consistently outperformedmore » the conventional stirred-tank reactor by 20% to 50%.« less

Limits on fundamental limits to computation.

PubMed

Markov, Igor L

2014-08-14

An indispensable part of our personal and working lives, computing has also become essential to industries and governments. Steady improvements in computer hardware have been supported by periodic doubling of transistor densities in integrated circuits over the past fifty years. Such Moore scaling now requires ever-increasing efforts, stimulating research in alternative hardware and stirring controversy. To help evaluate emerging technologies and increase our understanding of integrated-circuit scaling, here I review fundamental limits to computation in the areas of manufacturing, energy, physical space, design and verification effort, and algorithms. To outline what is achievable in principle and in practice, I recapitulate how some limits were circumvented, and compare loose and tight limits. Engineering difficulties encountered by emerging technologies may indicate yet unknown limits.

Fiber Attachment Module Experiment (FAME): Using a Multiplexed Miniature Hollow Fiber Membrane Bioreactor Solution for Rapid Process Testing

NASA Technical Reports Server (NTRS)

Coutts, Janelle L.; Lunn, Griffin M.; Koss, Lawrence L.; Hummerick, Mary E.; Spencer, Lachelle E.; Johnsey, Marissa N.; Richards, Jeffrey T.; Ellis, Ronald; Birmele, Michele N.; Wheeler, Raymond M.

2014-01-01

Bioreactor research is mostly limited to continuous stirred-tank reactors (CSTRs) which are not an option for microgravity (g) applications due to the lack of a gravity gradient to drive aeration as described by the Archimedes principle. Bioreactors and filtration systems for treating wastewater in g could avoid the need for harsh pretreatment chemicals and improve overall water recovery. Solution: Membrane Aerated Bioreactors (MABRs) for g applications, including possible use for wastewater treatment systems for the International Space Station (ISS).

Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis Current and Futuristic Scenarios

DTIC Science & Technology

1999-07-01

handled as a dry solid. This approach was recommended by vendors and is typical of dewatering equipment used in the utility flue gas desulfurization ...in a large continuous stirred- tank reactor (CSTR). 21 H. Majdeski, personal experience in the flue gas desulfurization industry, 1998. 22 Letter to B...defined as the percentage of the feed heat that is converted to steam heat, is 62% (see Figure 15). Flue gas from the dryer cyclone enters a baghouse to

Modeling microflow and stirring around a microrotor in creeping flow using a quasi-steady-state analysis.

PubMed

Vuppu, Anil K; Garcia, Antonio A; Saha, Sanjoy K; Phelan, Patrick E; Hayes, Mark A; Calhoun, Ronald

2004-06-01

The microflow and stirring around paramagnetic particle microchains, referred to as microrotors, are modeled as a circular cylinder rotating about its radial axis at very low Reynolds number. Time scales for momentum transfer under these conditions are determined to be much smaller than those for boundary movement, hence a quasi-steady approximation can be used. The flow is derived at every instant from the case of a steady motion of a horizontally translating cylinder, with the rotation approximated to a series of differential incremental translations. A numerical simulation is used to determine the pathlines and material lines of virtual point fluid elements, which were analyzed to understand the behavior of the flow around the microrotor. The results indicate the flow to be unsteady, with chaotic advection observed in the system. The fluid motion is primarily two-dimensional, parallel to the rotational plane, with mixing limited to the immediate area around the rotating cylinder. Fluid layers, up to many cylinder diameters, in the axial direction experience the disturbance. Elliptic and star shaped pathlines, including periodic orbits, are observed depending on the fluid element's initial location. The trajectories and phase angles compare well with the experimental results, as well as with data from particle dynamics simulations. Material lines and streaklines display stretching and folding, which are indicative of the chaotic behavior and stirring characteristics of the system. The material lines have similar lengths for the same amount of rotation at different speeds, and the effect of rotational speeds appears to be primarily to change the time of mixing. The results are expected to help in the design of a particle microrotor based sensing technique.

The biogeochemical structuring role of horizontal stirring: Lagrangian perspectives on iron delivery downstream of the Kerguelen Plateau

NASA Astrophysics Data System (ADS)

d'Ovidio, F.; Della Penna, A.; Trull, T. W.; Nencioli, F.; Pujol, M.-I.; Rio, M.-H.; Park, Y.-H.; Cotté, C.; Zhou, M.; Blain, S.

2015-10-01

Field campaigns are instrumental in providing ground truth for understanding and modeling global ocean biogeochemical budgets. A survey however can only inspect a fraction of the global oceans, typically a region hundreds of kilometers wide for a temporal window of the order of (at most) several weeks. This spatiotemporal domain is also the one in which the mesoscale activity induces through horizontal stirring a strong variability in the biogeochemical tracers, with ephemeral, local contrasts which can easily mask the regional and seasonal gradients. Therefore, whenever local in situ measures are used to infer larger-scale budgets, one faces the challenge of identifying the mesoscale structuring effect, if not simply to filter it out. In the case of the KEOPS2 investigation of biogeochemical responses to natural iron fertilization, this problem was tackled by designing an adaptive sampling strategy based on regionally optimized multisatellite products analyzed in real time by specifically designed Lagrangian diagnostics. This strategy identified the different mesoscale and stirring structures present in the region and tracked the dynamical frontiers among them. It also enabled back trajectories for the ship-sampled stations to be estimated, providing important insights into the timing and pathways of iron supply, which were explored further using a model based on first-order iron removal. This context was essential for the interpretation of the field results. The mesoscale circulation-based strategy was also validated post-cruise by comparing the Lagrangian maps derived from satellites with the patterns of more than one hundred drifters, including some adaptively released during KEOPS2 and a subsequent research voyage. The KEOPS2 strategy was adapted to the specific biogeochemical characteristics of the region, but its principles are general and will be useful for future in situ biogeochemical surveys.

The biogeochemical structuring role of horizontal stirring: Lagrangian perspectives on iron delivery downstream of the Kerguelen plateau

NASA Astrophysics Data System (ADS)

d'Ovidio, F.; Della Penna, A.; Trull, T. W.; Nencioli, F.; Pujol, I.; Rio, M. H.; Park, Y.-H.; Cotté, C.; Zhou, M.; Blain, S.

2015-01-01

Field campaigns are instrumental in providing ground truth for understanding and modelling global ocean biogeochemical budgets. A survey however can only inspect a fraction of the global oceans, typically a region 100s km wide for a temporal window of the order of (at most) several weeks. This spatiotemporal domain is also the one in which the mesoscale activity induces through horizontal stirring a strong variability in the biogeochemical tracers, with ephemeral, local contrasts which can easily mask the regional and seasonal gradients. Therefore, whenever local in-situ measures are used to infer larger scale budgets one faces the challenge of identifying the mesoscale structuring effect, if not simply to filter it out. In the case of the KEOPS2 investigation of biogeochemical responses to natural iron fertilization, this problem was tackled by designing an adaptive sampling strategy based on regionally-optimized multisatellite products analyzed in real time by specifically designed Lagrangian diagnostics. This strategy identified the different mesoscale and stirring structures present in the region and tracked the dynamical frontiers among them. It also enabled back-trajectories for the ship sampled stations to be estimated, providing important insights into the timing and pathways of iron supply, which were explored further using model based on first order iron removal. This context was essential for the interpretation of the field results. The mesoscale circulation based strategy was also validated post-cruise by comparing the Lagrangian maps derived from satellite with the patterns of more than one hundred drifters adaptively released during KEOPS2 and a subsequent research voyage. The KEOPS2 strategy was adapted to the specific biogeochemical characteristics of the region, but its principles are general and will be useful for future in-situ biogeochemical surveys.

Phytase production by Sporotrichum thermophile in a cost-effective cane molasses medium in submerged fermentation and its application in bread.

PubMed

Singh, B; Satyanarayana, T

2008-12-01

Phytase production by Sporotrichum thermophile in a cost-effective cane molasses medium in submerged fermentation and its application in bread. The production of phytase by a thermophilic mould S. thermophile was investigated using free and immobilized conidiospores in cane molasses medium in shake flasks, and stirred tank and air-lift fermenters. Among surfactants tested, Tweens (Tween-20, 40 and 80) and sodium oleate increased phytase accumulation, whereas SDS and Triton X-100 inhibited the enzyme production. The mould produced phytase optimally at a(w) 0.95, and it declined sharply below this a(w) value. The enzyme production was comparable in air-lift and stirred tank reactors with a marked reduction in fermentation time. Among the matrices tried, Ca-alginate was the best for conidiospore immobilization, and fungus secreted sustained levels of enzyme titres over five cycles. The phytic acid in the dough was efficiently hydrolysed by the enzyme accompanied by the liberation of soluble phosphate in the bread. The phytase production by S. thermophile was enhanced in the presence of Tween-80 in cane molasses medium. A peak in enzyme production was attained in 48 h in the fermenter when compared with that of 96 h in shake flasks. Ca-alginate immobilized conidiospores germinated to produce fungal growth that secreted sustained levels of phytase over five cycles. The bread made with phytase contained reduced level of phytic acid and a high-soluble phosphate. The phytase accumulation by S. thermophile was increased by the surfactants. The sustainability of enzyme production in stirred tank and air-lift fermenters suggested the possibility for scaling up of phytase. The bread made with phytase contained low level of antinutrient, i.e. phytic acid.

Friction stir welding tool

DOEpatents

Tolle, Charles R.; Clark, Denis E.; Barnes, Timothy A.

2008-04-15

A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

Comparative technoeconomic analysis of a softwood ethanol process featuring posthydrolysis sugars concentration operations and continuous fermentation with cell recycle.

PubMed

Schneiderman, Steven J; Gurram, Raghu N; Menkhaus, Todd J; Gilcrease, Patrick C

2015-01-01

Economical production of second generation ethanol from Ponderosa pine is of interest due to widespread mountain pine beetle infestation in the western United States and Canada. The conversion process is limited by low glucose and high inhibitor concentrations resulting from conventional low-solids dilute acid pretreatment and enzymatic hydrolysis. Inhibited fermentations require larger fermentors (due to reduced volumetric productivity) and low sugars lead to low ethanol titers, increasing distillation costs. In this work, multiple effect evaporation (MEE) and nanofiltration (NF) were evaluated to concentrate the hydrolysate from 30 g/l to 100, 150, or 200 g/l glucose. To ferment this high gravity, inhibitor containing stream, traditional batch fermentation was compared with continuous stirred tank fermentation (CSTF) and continuous fermentation with cell recycle (CSTF-CR). Equivalent annual operating cost (EAOC = amortized capital + yearly operating expenses) was used to compare these potential improvements for a local-scale 5 MGY ethanol production facility. Hydrolysate concentration via evaporation increased EAOC over the base process due to the capital and energy intensive nature of evaporating a very dilute sugar stream; however, concentration via NF decreased EAOC for several of the cases (by 2 to 15%). NF concentration to 100 g/l glucose with a CSTF-CR was the most economical option, reducing EAOC by $0.15 per gallon ethanol produced. Sensitivity analyses on NF options showed that EAOC improvement over the base case could still be realized for even higher solids removal requirements (up to two times higher centrifuge requirement for the best case) or decreased NF performance. © 2015 American Institute of Chemical Engineers.