Effect of Nozzle Geometry on the Microstructure and Properties of HVAF-Sprayed WC-10Co4Cr and Cr3C2-25NiCr Coatings

NASA Astrophysics Data System (ADS)

Matikainen, V.; Koivuluoto, H.; Vuoristo, P.; Schubert, J.; Houdková, Š.

2018-04-01

Thermally sprayed hard metal coatings are the industrial standard solution for numerous demanding applications to improve wear resistance. In the aim of improving coating quality by utilising finer particle size distributions, several approaches have been studied to control the spray temperature. The most viable solution is to use the modern high velocity air-fuel (HVAF) spray process, which has already proven to produce high-quality coatings with dense structures. In HVAF spray process, the particle heating and acceleration can be efficiently controlled by changing the nozzle geometry. In this study, fine WC-10Co4Cr and Cr3C2-25NiCr powders were sprayed with three nozzle geometries to investigate their effect on the particle temperature, velocity and coating microstructure. The study demonstrates that the particle melting and resulting carbide dissolution can be efficiently controlled by changing the nozzle geometry from cylindrical to convergent-divergent. Moreover, the average particle velocity was increased from 780 to over 900 m/s. The increase in particle velocity significantly improved the coating structure and density. Further evaluation was carried out to resolve the effect of particle in-flight parameters on coating structure and cavitation erosion resistance, which was significantly improved in the case of WC-10Co4Cr coatings with the increasing average particle velocity.

A novel process route for the production of spherical SLS polymer powders

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

Schmidt, Jochen; Sachs, Marius; Blümel, Christina

2015-05-22

Currently, rapid prototyping gradually is transferred to additive manufacturing opening new applications. Especially selective laser sintering (SLS) is promising. One drawback is the limited choice of polymer materials available as optimized powders. Powders produced by cryogenic grinding show poor powder flowability resulting in poor device quality. Within this account we present a novel process route for the production of spherical polymer micron-sized particles of good flowability. The feasibility of the process chain is demonstrated for polystyrene e. In a first step polymer microparticles are produced by a wet grinding method. By this approach the mean particle size and the particlemore » size distribution can be tuned between a few microns and several 10 microns. The applicability of this method will be discussed for different polymers and the dependencies of product particle size distribution on stressing conditions and process temperature will be outlined. The comminution products consist of microparticles of irregular shape and poor powder flowability. An improvement of flowability of the ground particles is achieved by changing their shape: they are rounded using a heated downer reactor. The influence of temperature profile and residence time on the product properties will be addressed applying a viscous-flow sintering model. To further improve the flowability of the cohesive spherical polymer particles nanoparticles are adhered onto the microparticles’ surface. The improvement of flowability is remarkable: rounded and dry-coated powders exhibit a strongly reduced tensile strength as compared to the comminution product. The improved polymer powders obtained by the process route proposed open new possibilities in SLS processing including the usage of much smaller polymer beads.« less

Alpha spectrometric characterization of process-related particle size distributions from active particle sampling at the Los Alamos National Laboratory uranium foundry

NASA Astrophysics Data System (ADS)

Plionis, A. A.; Peterson, D. S.; Tandon, L.; LaMont, S. P.

2010-03-01

Uranium particles within the respirable size range pose a significant hazard to the health and safety of workers. Significant differences in the deposition and incorporation patterns of aerosols within the respirable range can be identified and integrated into sophisticated health physics models. Data characterizing the uranium particle size distribution resulting from specific foundry-related processes are needed. Using personal air sampling cascade impactors, particles collected from several foundry processes were sorted by activity median aerodynamic diameter onto various Marple substrates. After an initial gravimetric assessment of each impactor stage, the substrates were analyzed by alpha spectrometry to determine the uranium content of each stage. Alpha spectrometry provides rapid non-distructive isotopic data that can distinguish process uranium from natural sources and the degree of uranium contribution to the total accumulated particle load. In addition, the particle size bins utilized by the impactors provide adequate resolution to determine if a process particle size distribution is: lognormal, bimodal, or trimodal. Data on process uranium particle size values and distributions facilitate the development of more sophisticated and accurate models for internal dosimetry, resulting in an improved understanding of foundry worker health and safety.

Characterization of Calcite Mineral Precipitation Process by EICP in Porous Media

NASA Astrophysics Data System (ADS)

Kim, D.; Mahabadi, N.; Hall, C.; Jang, J.; van Paassen, L. A.

2017-12-01

One of the most prevalent ground improvement techniques is injection of synthetic materials, such as cement grout or silicates into the pore space to create cementing bonds between soil particles. Besides these traditional ground improvement methods, several biological processes have been developed to improve soil properties. Enzyme induced carbonate precipitation (EICP) is a biological process in which urea hydrolyzes into ammonia and inorganic carbon, and promotes carbonate mineral precipitation. Different morphologies and patterns of calcite mineral precipitation, such as particle surface coating, pore filling, and soil particles bonding, have been observed in the previous studies. Most of the researches have detected precipitated minerals after the completion of the treatment using SEM (Scanning Electron Microscope) imaging and XRD (X-ray Diffractometer) structural analysis. In this research, an EICP reaction medium is injected into a microfluidic chip to observe the entire process of carbonate precipitation through several cycles of EICP treatment in the porous medium. Once the process of mineral precipitation is completed, water is injected into the microfluidic chip with different flow rates to evaluate the stability of carbonates during fluid flow injection.

Measurement Comparisons Towards Improving the Understanding of Aerosol-Cloud Processing

NASA Astrophysics Data System (ADS)

Noble, Stephen R.

Cloud processing of aerosol is an aerosol-cloud interaction that is not heavily researched but could have implications on climate. The three types of cloud processing are chemical processing, collision and coalescence processing, and Brownian capture of interstitial particles. All types improve cloud condensation nuclei (CCN) in size or hygroscopicity (kappa). These improved CCN affect subsequent clouds. This dissertation focuses on measurement comparisons to improve our observations and understanding of aerosol-cloud processing. Particle size distributions measured at the continental Southern Great Plains (SGP) site were compared with ground based measurements of cloud fraction (CF) and cloud base altitude (CBA). Particle size distributions were described by a new objective shape parameter to define bimodality rather than an old subjective one. Cloudy conditions at SGP were found to be correlated with lagged shape parameter. Horizontal wind speed and regional CF explained 42%+ of this lag time. Many of these surface particle size distributions were influenced by aerosol-cloud processing. Thus, cloud processing may be more widespread with more implications than previously thought. Particle size distributions measured during two aircraft field campaigns (MArine Stratus/stratocumulus Experiment; MASE; and Ice in Cloud Experiment-Tropical; ICE-T) were compared to CCN distributions. Tuning particle size to critical supersaturation revealed hygroscopicity expressed as ? when the distributions were overlain. Distributions near cumulus clouds (ICE-T) had a higher frequency of the same ?s (48% in ICE-T to 42% in MASE) between the accumulation (processed) and Aitken (unprocessed) modes. This suggested physical processing domination in ICE-T. More MASE (stratus cloud) kappa differences between modes pointed to chemical cloud processing. Chemistry measurements made in MASE showed increases in sulfates and nitrates with distributions that were more processed. This supported chemical cloud processing in MASE. This new method to determine kappa provides the needed information without interrupting ambient measurements. MODIS derived cloud optical thickness (COT), cloud liquid water path (LWP), and cloud effective radius (re) were compared to the same in situ derived variables from cloud probe measurements of two stratus/stratocumulus cloud campaigns (MASE and Physics Of Stratocumulus Tops; POST). In situ data were from complete vertical cloud penetrations, while MODIS data were from pixels along the aircraft penetration path. Comparisons were well correlated except that MODIS LWP (14-36%) and re (20-30%) were biased high. The LWP bias was from re bias and was not improved by using the vertically stratified assumption. MODIS re bias was almost removed when compared to cloud top maximum in situ re, but, that does not describe re for the full depth of the cloud. COT is validated by in situ COT. High correlations suggest that MODIS variables are useful in self-comparisons such as gradient changes in stratus cloud re during aerosol-cloud processing.

Three-dimensional cell to tissue development process

NASA Technical Reports Server (NTRS)

Goodwin, Thomas J. (Inventor); Parker, Clayton R. (Inventor)

2008-01-01

An improved three-dimensional cell to tissue development process using a specific time varying electromagnetic force, pulsed, square wave, with minimum fluid shear stress, freedom for 3-dimensional spatial orientation of the suspended particles and localization of particles with differing or similar sedimentation properties in a similar spatial region.

Microspectroscopic Analysis of Anthropogenic- and Biogenic-Influenced Aerosol Particles during the SOAS Field Campaign

NASA Astrophysics Data System (ADS)

Ault, A. P.; Bondy, A. L.; Nhliziyo, M. V.; Bertman, S. B.; Pratt, K.; Shepson, P. B.

2013-12-01

During the summer, the southeastern United States experiences a cooling haze due to the interaction of anthropogenic and biogenic aerosol sources. An objective of the summer 2013 Southern Oxidant and Aerosol Study (SOAS) was to improve our understanding of how trace gases and aerosols are contributing to this relative cooling through light scattering and absorption. To improve understanding of biogenic-anthropogenic interactions through secondary organic aerosol (SOA) formation on primary aerosol cores requires detailed physicochemical characterization of the particles after uptake and processing. Our measurements focus on single particle analysis of aerosols in the accumulation mode (300-1000 nm) collected using a multi orifice uniform deposition impactor (MOUDI) at the Centreville, Alabama SEARCH site. Particles were characterized using an array of microscopic and spectroscopic techniques, including: scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and Raman microspectroscopy. These analyses provide detailed information on particle size, morphology, elemental composition, and functional groups. This information is combined with mapping capabilities to explore individual particle spatial patterns and how that impacts structural characteristics. The improved understanding will be used to explore how sources and processing (such as SOA coating of soot) change particle structure (i.e. core shell) and how the altered optical properties impact air quality/climate effects on a regional scale.

Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

NASA Astrophysics Data System (ADS)

Kumar, R. K.; Kamaraj, M.; Seetharamu, S.; Pramod, T.; Sampathkumaran, P.

2016-08-01

The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

A transmission and reflection coupled ultrasonic process tomography based on cylindrical miniaturized transducers using PVDF films

NASA Astrophysics Data System (ADS)

Gu, J.; Yang, H.; Fan, F.; Su, M.

2017-12-01

A transmission and reflection coupled ultrasonic process tomography has been developed, which is characterized by a proposed dual-mode (DM) reconstruction algorithm, as well as an adaptive search approach to determine an optimal image threshold during the image binarization. In respect of hardware, to improve the accuracy of time-of-flight (TOF) and extend the lowest detection limit of particle size, a cylindrical miniaturized transducer using polyvinylidene fluoride (PVDF) films is designed. Besides, the development of range-gating technique for the identification of transmission and reflection waves in scanning is discussed. A particle system with four iron particles is then investigated numerically and experimentally to evaluate these proposed methods. The sound pressure distribution in imaging area is predicted numerically, followed by the analysis of the relationship between the emitting surface width of transducer and particle size. After the processing of experimental data for effective waveform extraction and fusion, the comparison between reconstructed results from transmission-mode (TM), reflection-mode (RM), and dual-mode reconstructions is carried out and the latter manifests obvious improvements from the blurring reduction to the enhancement of particle boundary.

Enhancing Corrosion and Wear Resistance of AA6061 by Friction Stir Processing with Fe78Si9B13 Glass Particles

PubMed Central

Guo, Lingyu; Liu, Yan; Shen, Kechang; Song, Chaoqun; Yang, Min; Kim, Kibuem; Wang, Weimin

2015-01-01

The AA6061-T6 aluminum alloy samples including annealed Fe78Si9B13 particles were prepared by friction stir processing (FSP) and investigated by various techniques. The Fe78Si9B13-reinforced particles are uniformly dispersed in the aluminum alloy matrix. The XRD results indicated that the lattice parameter of α-Al increases and the preferred orientation factors F of (200) plane of α-Al reduces after friction stir processing. The coefficient of thermal expansion (CTE) for FSP samples increases at first with the temperature but then decreases as the temperature further increased, which can be explained by the dissolving of Mg and Si from β phase and Fe78Si9B13 particles. The corrosion and wear resistance of FSP samples have been improved compared with that of base metal, which can be attributed to the reduction of grain size and the CTE mismatch between the base metal and reinforced particles by FSP, and the lubrication effect of Fe78Si9B13 particles also plays a role in improving wear resistance. In particular, the FSP sample with reinforced particles in amorphous state exhibited superior corrosion and wear resistance due to the unique metastable structure. PMID:28793492

Gas-evaporation in low-gravity field (cogelation mechanism of metal vapors) (M-14)

NASA Technical Reports Server (NTRS)

Wada, N.

1993-01-01

When metal and alloy compounds are heated and vaporized in a rare gas such as helium, argon, or xenon, the vaporized substances diffused in the rare gas are supersaturated resulting in a smoke of fine particles of the material congealing as snow or fog. The gas vaporizing method is a fine particle generation method. Though the method has a variety of applications, the material vapor flow is disturbed by gravitational convection on Earth. The inability to elucidate the fine particle generation mechanism results in an obstruction to improving the method to mass production levels. As no convection occurs in microgravity in space, the fine particle generation mechanism influenced only by diffusion can be investigated. Investigators expect that excellent particles with homogeneous diameter distribution can be obtained. Experiment data and facts will assist in improving efficiency, quality, and scale or production processes including element processes such as vaporization, diffusion, and condensation. The objective of this experiment is to obtain important information related to the mechanism of particle formation in the gas atmosphere (smoke particles) and the production of submicron powders of extremely uniform size.

Single-particle cryo-EM-Improved ab initio 3D reconstruction with SIMPLE/PRIME.

PubMed

Reboul, Cyril F; Eager, Michael; Elmlund, Dominika; Elmlund, Hans

2018-01-01

Cryogenic electron microscopy (cryo-EM) and single-particle analysis now enables the determination of high-resolution structures of macromolecular assemblies that have resisted X-ray crystallography and other approaches. We developed the SIMPLE open-source image-processing suite for analysing cryo-EM images of single-particles. A core component of SIMPLE is the probabilistic PRIME algorithm for identifying clusters of images in 2D and determine relative orientations of single-particle projections in 3D. Here, we extend our previous work on PRIME and introduce new stochastic optimization algorithms that improve the robustness of the approach. Our refined method for identification of homogeneous subsets of images in accurate register substantially improves the resolution of the cluster centers and of the ab initio 3D reconstructions derived from them. We now obtain maps with a resolution better than 10 Å by exclusively processing cluster centers. Excellent parallel code performance on over-the-counter laptops and CPU workstations is demonstrated. © 2017 The Protein Society.

Atomizing nozzle and process

DOEpatents

Anderson, I.E.; Figliola, R.S.; Molnar, H.M.

1993-07-20

High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

Atomizing nozzle and process

DOEpatents

Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

1992-06-30

High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

Fuzzy logic particle tracking velocimetry

NASA Technical Reports Server (NTRS)

Wernet, Mark P.

1993-01-01

Fuzzy logic has proven to be a simple and robust method for process control. Instead of requiring a complex model of the system, a user defined rule base is used to control the process. In this paper the principles of fuzzy logic control are applied to Particle Tracking Velocimetry (PTV). Two frames of digitally recorded, single exposure particle imagery are used as input. The fuzzy processor uses the local particle displacement information to determine the correct particle tracks. Fuzzy PTV is an improvement over traditional PTV techniques which typically require a sequence (greater than 2) of image frames for accurately tracking particles. The fuzzy processor executes in software on a PC without the use of specialized array or fuzzy logic processors. A pair of sample input images with roughly 300 particle images each, results in more than 200 velocity vectors in under 8 seconds of processing time.

Improved non-invasive method for aerosol particle charge measurement employing in-line digital holography

NASA Astrophysics Data System (ADS)

Tripathi, Anjan Kumar

Electrically charged particles are found in a wide range of applications ranging from electrostatic powder coating, mineral processing, and powder handling to rain-producing cloud formation in atmospheric turbulent flows. In turbulent flows, particle dynamics is influenced by the electric force due to particle charge generation. Quantifying particle charges in such systems will help in better predicting and controlling particle clustering, relative motion, collision, and growth. However, there is a lack of noninvasive techniques to measure particle charges. Recently, a non-invasive method for particle charge measurement using in-line Digital Holographic Particle Tracking Velocimetry (DHPTV) technique was developed in our lab, where charged particles to be measured were introduced to a uniform electric field, and their movement towards the oppositely charged electrode was deemed proportional to the amount of charge on the particles (Fan Yang, 2014 [1]). However, inherent speckle noise associated with reconstructed images was not adequately removed and therefore particle tracking data was contaminated. Furthermore, particle charge calculation based on particle deflection velocity neglected the particle drag force and rebound effect of the highly charged particles from the electrodes. We improved upon the existing particle charge measurement method by: 1) hologram post processing, 2) taking drag force into account in charge calculation, 3) considering rebound effect. The improved method was first fine-tuned through a calibration experiment. The complete method was then applied to two different experiments, namely conduction charging and enclosed fan-driven turbulence chamber, to measure particle charges. In all three experiments conducted, the particle charge was found to obey non-central t-location scale family of distribution. It was also noted that the charge distribution was insensitive to the change in voltage applied between the electrodes. The range of voltage applied where reliable particle charges can be measured was also quantified by taking into account the rebound effect of highly charged particles. Finally, in the enclosed chamber experiment, it was found that using carbon conductive coating on the inner walls of the chamber minimized the charge generation inside the chamber when glass bubble particles were used. The value of electric charges obtained in calibration experiment through the improved method was found to have the same order as reported in the existing work (Y.C Ahn et al. 2004 [2]), indicating that the method is indeed effective.

Method for removing undesired particles from gas streams

DOEpatents

Durham, M.D.; Schlager, R.J.; Ebner, T.G.; Stewart, R.M.; Hyatt, D.E.; Bustard, C.J.; Sjostrom, S.

1998-11-10

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency. 11 figs.

Method and apparatus for decreased undesired particle emissions in gas streams

DOEpatents

Durham, M.D.; Schlager, R.J.; Ebner, T.G.; Stewart, R.M.; Bustard, C.J.

1999-04-13

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency. 5 figs.

Method and apparatus for decreased undesired particle emissions in gas streams

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Bustard, Cynthia Jean

1999-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Method for removing undesired particles from gas streams

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Hyatt, David E.; Bustard, Cynthia Jean; Sjostrom, Sharon

1998-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

A relativistic dissipative hydrodynamic description for systems including particle number changing processes

NASA Astrophysics Data System (ADS)

El, Andrej; Muronga, Azwinndini; Xu, Zhe; Greiner, Carsten

2010-12-01

Relativistic dissipative hydrodynamic equations are extended by taking into account particle number changing processes in a gluon system, which expands in one dimension boost-invariantly. Chemical equilibration is treated by a rate equation for the particle number density based on Boltzmann equation and Grad's ansatz for the off-equilibrium particle phase space distribution. We find that not only the particle production, but also the temperature and the momentum spectra of the gluon system, obtained from the hydrodynamic calculations, are sensitive to the rates of particle number changing processes. Comparisons of the hydrodynamic calculations with the transport ones employing the parton cascade BAMPS show the inaccuracy of the rate equation at large shear viscosity to entropy density ratio. To improve the rate equation, Grad's ansatz has to be modified beyond the second moments in momentum.

Fish tracking by combining motion based segmentation and particle filtering

NASA Astrophysics Data System (ADS)

Bichot, E.; Mascarilla, L.; Courtellemont, P.

2006-01-01

In this paper, we suggest a new importance sampling scheme to improve a particle filtering based tracking process. This scheme relies on exploitation of motion segmentation. More precisely, we propagate hypotheses from particle filtering to blobs of similar motion to target. Hence, search is driven toward regions of interest in the state space and prediction is more accurate. We also propose to exploit segmentation to update target model. Once the moving target has been identified, a representative model is learnt from its spatial support. We refer to this model in the correction step of the tracking process. The importance sampling scheme and the strategy to update target model improve the performance of particle filtering in complex situations of occlusions compared to a simple Bootstrap approach as shown by our experiments on real fish tank sequences.

Liquid additives for particulate emissions control

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Hyatt, David E.; Bustard, Cynthia Jean; Sjostrom, Sharon

1999-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Size-dependent surface phase change of lithium iron phosphate during carbon coating

NASA Astrophysics Data System (ADS)

Wang, Jiajun; Yang, Jinli; Tang, Yongji; Liu, Jian; Zhang, Yong; Liang, Guoxian; Gauthier, Michel; Karen Chen-Wiegart, Yu-Chen; Norouzi Banis, Mohammad; Li, Xifei; Li, Ruying; Wang, Jun; Sham, T. K.; Sun, Xueliang

2014-03-01

Carbon coating is a simple, effective and common technique for improving the conductivity of active materials in lithium ion batteries. However, carbon coating provides a strong reducing atmosphere and many factors remain unclear concerning the interface nature and underlying interaction mechanism that occurs between carbon and the active materials. Here, we present a size-dependent surface phase change occurring in lithium iron phosphate during the carbon coating process. Intriguingly, nanoscale particles exhibit an extremely high stability during the carbon coating process, whereas microscale particles display a direct visualization of surface phase changes occurring at the interface at elevated temperatures. Our findings provide a comprehensive understanding of the effect of particle size during carbon coating and the interface interaction that occurs on carbon-coated battery material—allowing for further improvement in materials synthesis and manufacturing processes for advanced battery materials.

Effect of In-Situ Titanium Boride Particle Addition and Friction Stir Processing on Wear Behavior of Aluminum Alloy 2219

NASA Astrophysics Data System (ADS)

Sampath, V.; Rajasekaran, N. R.

There is paucity of data on the effect of in-situ TiB2 particles on the different behavior of 2219 Al alloy. In the present work, therefore, composites with 2219 Al alloy matrix reinforced with in-situ TiB2 particles were produced by flux-assisted synthesis. Different amounts (5 and 10 wt.%) of TiB2 were incorporated. The base alloy and the composites were subjected to friction stir processing to reduce particle clustering. The wear behavior of the materials was studied. The base alloy showed considerable improvement in the wear behavior due to the in-situ particle addition which is attributed to the presence of finer particles with good interfacial bonding and high hardness. Uniform distribution of TiB2 particles and good interface between the matrix and the particles led to reduction in the wear of friction stir processed composites by 30%. The results are analyzed and discussed in detail in the paper.

Sea-urchin-like Fe3O4@C@Ag particles: an efficient SERS substrate for detection of organic pollutants

NASA Astrophysics Data System (ADS)

Ye, Yingjie; Chen, Jin; Ding, Qianqian; Lin, Dongyue; Dong, Ronglu; Yang, Liangbao; Liu, Jinhuai

2013-06-01

Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization.Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization. Electronic supplementary information (ESI) available: Additional XRD patterns and SEM images of Fe3O4@C particles, SERS spectra of 4-ATP and 4-MPY using Fe3O4@C@Ag particles as the active substrates, magnetic behaviour of Fe3O4@C and Fe3O4@C@Ag particles. See DOI: 10.1039/c3nr01273e

Theoretical and Experimental Investigations of the Process of Vibration Treatment of Liquid Metals Containing Nanoparticles

NASA Astrophysics Data System (ADS)

Vorozhtsov, S.; Kudryashova, O.; Promakhov, V.; Dammer, V.; Vorozhtsov, A.

2016-12-01

It is known that the use of external effects, such as acoustic fields (from ultrasonic to low-frequency range), help in breaking down agglomerates, improving particle wettability, providing uniform particle distribution in the melt volume, and reducing the grain size. The fragmentation of growing crystals, de-agglomeration of particles and their mixing in liquid metal under the influence of vibration (with frequencies of 10-100 Hz) are considered in this paper. The major advantage of such a technique in comparison with high-frequency methods (sonic, ultrasonic) is the capability of processing large melt volumes proportional to the wavelength. The mechanisms of the breaking down of particle agglomerates and the mixing of particles under conditions of cavitation and turbulence during the vibration treatment of the melt are considered. Expressions linking the threshold intensity and frequency with the amplitude necessary to activate mechanisms of turbulence and cavitation were obtained. The results of vibration treatment experiments for an aluminum alloy containing diamond nanoparticles are given. This treatment makes it possible to significantly reduce the grain size and to improve the casting homogeneity and thus improve the mechanical properties of the alloy.

Beam-induced motion correction for sub-megadalton cryo-EM particles.

PubMed

Scheres, Sjors Hw

2014-08-13

In electron cryo-microscopy (cryo-EM), the electron beam that is used for imaging also causes the sample to move. This motion blurs the images and limits the resolution attainable by single-particle analysis. In a previous Research article (Bai et al., 2013) we showed that correcting for this motion by processing movies from fast direct-electron detectors allowed structure determination to near-atomic resolution from 35,000 ribosome particles. In this Research advance article, we show that an improved movie processing algorithm is applicable to a much wider range of specimens. The new algorithm estimates straight movement tracks by considering multiple particles that are close to each other in the field of view, and models the fall-off of high-resolution information content by radiation damage in a dose-dependent manner. Application of the new algorithm to four data sets illustrates its potential for significantly improving cryo-EM structures, even for particles that are smaller than 200 kDa. Copyright © 2014, Scheres.

Combustion/particle sizing experiments at the Naval Postgraduate School Combustion Research Laboratory

NASA Technical Reports Server (NTRS)

Powers, John; Netzer, David

1987-01-01

Particle behavior in combustion processes is an active research area at NPS. Currently, four research efforts are being conducted: (1) There is a long standing need to better understand the soot production and combustion processes in gas turbine combustors, both from a concern for improved engine life and to minimize exhaust particulates. Soot emissions are strongly effected by fuel composition and additives; (2) A more recent need for particle sizing/behavior measurements is in the combustor of a solid fuel ramjet which uses a metallized fuel. High speed motion pictures are being used to study rather large burning particles; (3) In solid propellant rocket motors, metals are used to improve specific impulse and/or to provide damping for combustion pressure oscillations. Particle sizing experiments are being conducted using diode arrays to measure the light intensity as a function of scattering angle; (4) Once a good quality hologram is attained, a need exists for obtaining the particle distributions from hologram in a short period of time. A Quantimet 720 Image Analyzer is being used to reconstruct images.

Effects of particle packing on the sintered microstructure

NASA Astrophysics Data System (ADS)

Barringer, E. A.; Bowen, H. K.

1988-04-01

The sintering process is shown to be critically dependent on particle-packing density and porosity uniformity. Sintering experiments were conducted on compacts consisting of monodisperse, spherical TiO2 particles. Densification kinetics and microstructure evolution for two initial packing densities, 55% and 69% of theoretical, were investigated. The lower-density compacts sintered rapidly to theoretical density, yet improved particle-packing density and uniformity significantly enhanced densification.

Enhancing Aluminum Reactivity by Exploiting Surface Chemistry and Mechanical Properties

DTIC Science & Technology

2015-06-01

alter its mechanical properties . In bulk material processing , annealing and quenching metals such as Al can relieve residual stress and improve...increasing  Al  reactivity is to alter its mechanical  properties .  In bulk material  processing , annealing and quenching metals such as  Al  can relieve...mechanical properties . On a single particle level, affecting mechanical properties may also affect Al particle reactivity. Aluminum particles underwent

Electrodynamic balance-mass spectrometry of single particles as a new platform for atmospheric chemistry research

NASA Astrophysics Data System (ADS)

Birdsall, Adam W.; Krieger, Ulrich K.; Keutsch, Frank N.

2018-01-01

New analytical techniques are needed to improve our understanding of the intertwined physical and chemical processes that affect the composition of aerosol particles in the Earth's atmosphere, such as gas-particle partitioning and homogenous or heterogeneous chemistry, and their ultimate relation to air quality and climate. We describe a new laboratory setup that couples an electrodynamic balance (EDB) to a mass spectrometer (MS). The EDB stores a single laboratory-generated particle in an electric field under atmospheric conditions for an arbitrarily long length of time. The particle is then transferred via gas flow to an ionization region that vaporizes and ionizes the analyte molecules before MS measurement. We demonstrate the feasibility of the technique by tracking evaporation of polyethylene glycol molecules and finding agreement with a kinetic model. Fitting data to the kinetic model also allows determination of vapor pressures to within a factor of 2. This EDB-MS system can be used to study fundamental chemical and physical processes involving particles that are difficult to isolate and study with other techniques. The results of such measurements can be used to improve our understanding of atmospheric particles.

Improving aluminum particle reactivity by annealing and quenching treatments: Synchrotron X-ray diffraction analysis of strain

DOE PAGES

McCollum, Jena; Pantoya, Michelle L.; Tamura, Nobumichi

2015-11-06

In bulk material processing, annealing and quenching metals such as aluminum (Al) can improve mechanical properties. On a single particle level, affecting mechanical properties may also affect Al particle reactivity. Our study examines the effect of annealing and quenching on the strain of Al particles and the corresponding reactivity of aluminum and copper oxide (CuO) composites. Micron-sized Al particles were annealed and quenched according to treatments designed to affect Al mechanical properties. Furthermore, synchrotron X-ray diffraction (XRD) analysis of the particles reveals that thermal treatment increased the dilatational strain of the aluminum-core, alumina-shell particles. Flame propagation experiments also show thermalmore » treatments effect reactivity when combined with CuO. An effective annealing and quenching treatment for increasing aluminum reactivity was identified. Our results show that altering the mechanical properties of Al particles affects their reactivity.« less

Liquid additives for particulate emissions control

DOEpatents

Durham, M.D.; Schlager, R.J.; Ebner, T.G.; Stewart, R.M.; Hyatt, D.E.; Bustard, C.J.; Sjostrom, S.

1999-01-05

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency. 11 figs.

Particle formation and characterization of mackerel reaction oil by gas saturated solution process.

PubMed

Tanbirul Haque, A S M; Chun, Byung-Soo

2016-01-01

Most of the health benefits of fish oil can be attributed to the presence of omega-3 fatty acids like Docosahexenoic acid (DHA) and Eicosapentaenoic acid (EPA). There are few dietary sources of EPA and DHA other than oily fish. EPA and DHA have great potential effect on human health. In this research, Supercritical carbon dioxide (scCO2) extracted mackerel oil was reacted by enzyme at different systems to improve the EPA and DHA. Different types of immobilize enzyme TL-IM, RM-IM, Novozyme 435 were assessed for improving PUFAs. Best result was found at non-pressurized system using TL-IM. Reacted oil particle were obtained with polyethylene glycol by gas saturated solution process (PGSS). Different parameters like temperature, pressure, agitation speed and nozzle size effect on particle formulation were observed. SEM and PSA analysis showed, small size non spherical particles were obtained. It was found that after particle formation poly unsaturated fatty acids (PUFAs) were present in particle as same in oil. PUFAs release from particle was almost linear against constant time duration. Oil quality in particle not change significantly, in this contrast this study will be helpful for food and pharmaceutical industry to provide high EPA and DHA containing powder.

Fast Particle Methods for Multiscale Phenomena Simulations

NASA Technical Reports Server (NTRS)

Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew

2000-01-01

We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.

Integration of process diagnostics and three dimensional simulations in thermal spraying

NASA Astrophysics Data System (ADS)

Zhang, Wei

Thermal spraying is a group of processes in which the metallic or ceramic materials are deposited in a molten or semi-molten state on a prepared substrate. In atmospheric plasma spray process, a thermal plasma jet is used to heat up and accelerate loading particles. The process is inherently complex due to the deviation from equilibrium conditions, three dimensional nature, multitude of interrelated variables involved, and stochastic variability at different stages. This dissertation is aimed at understanding the in-flight particle state and plasma plume characteristics in atmospheric plasma spray process through the integration of process diagnostics and three-dimensional simulation. Effects of injection angle and carrier gas flow rate on in-flight particle characteristics are studied experimentally and interpreted through numerical simulation. Plasma jet perturbation by particle injection angle, carrier gas, and particle loading are also identified. Maximum particle average temperature and velocity at any given spray distance is systematically quantified. Optimum plasma plume position for particle injection which was observed in experiments was verified numerically along with description of physical mechanisms. Correlation of spray distance with in-flight particle behavior for various kinds of materials is revealed. A new strategy for visualization and representation of particle diagnostic results for thermal spray processes has been presented. Specifically, 1 st order process maps (process-particle interactions) have been addressed by converting the Temperature-Velocity of particles obtained via diagnostics into non-dimensional group parameters [Melting Index-Reynolds number]. This approach provides an improved description of the thermal and kinetic energy of particles and allows for cross-comparison of diagnostic data within a given process for different materials, comparison of a single material across different thermal spray processes, and detailed assessment of the melting behavior through recourse to analysis of the distributions. An additional group parameter, Oxidation Index, has been applied to relatively track the oxidation extent of metallic particles under different operating conditions. The new mapping strategies have also been proposed in circumstances where only ensemble particle diagnostics are available. Through the integration of process diagnostics and numerical simulation, key issues concerning in-flight particle status as well as the controlling physical mechanisms have been analyzed. A scientific and intellectual strategy for universal description of particle characteristics has been successfully developed.

Novel processing to produce polymer/ceramic nanocomposites by atomic layer deposition

NASA Astrophysics Data System (ADS)

Liang, Xinhua

Polymeric materials can be greatly influenced by nanoscale inclusions of inorganic materials. The main goal of this thesis is to fabricate novel polymer/ceramic composite materials for two different applications using atomic layer deposition (ALD) or molecular layer deposition (MLD) methods. One is to produce well-dispersed polymer/ceramic nanocomposites with improved barrier properties for packaging applications. The other is to produce porous polymer/ceramic composites with improved bioactivity for tissue engineering applications. ALD has been successfully utilized for the conformal and uniform deposition of ultra-thin alumina and titania films on primary micron-sized polymer particles. The mechanism to initiate alumina and titania ALD on polymer particles without chemical functional groups was confirmed. A nucleation period was needed for both alumina and titania ALD on high density polyethylene (HDPE) particles and no nucleation period was needed for alumina ALD on polymethyl methacrylate particles. Titania ALD films deposited at low temperatures had an amorphous structure and showed much weaker photoactivity than common pigment-grade anatase TiO2 particles. Highly uniform and conformal ultra-thin aluminum alkoxide (alucone) polymer films were deposited on primary silica and titania nanoparticles using MLD in a fluidized bed reactor. The deposition chemistry and properties of alucone MLD films were investigated. The photoactivity of pigment-grade TiO2 particles was quenched after 20 cycles of an alucone MLD film, but the films shrank and decomposed in the presence of water, which decreased the passivation effect of the photoactivity of TiO2 particles. Well-dispersed polymer/ceramic nanocomposites were obtained by extruding alumina ALD coated HDPE particles. The diffusion coefficient of the fabricated nanocomposite membranes can be reduced by half with the inclusion of 7.3 vol.% alumina flakes. However, a corresponding increase in permeability was also observed due to the voids formed at or near the interface of the polymer and alumina flakes during the extrusion process. Efforts to improve the barrier properties of the membranes included 3-aminopropyltriethoxysilane treatment and coating alucone MLD films on alumina coated particles prior to extrusion. The porous polymer/ceramic particles were synthesized by depositing ultra-thin alumina or titania films on highly porous poly(styrene-divinylbenzene) particles using a low-temperature ALD process. Analytical characterization revealed that conformal alumina and titania films were grown on internal and external polymer particle surfaces, and the pore filling mechanism was a uniform coating of the pore walls. The ALD layers can improve the bioactivity and protein adsorption of the polymer substrates.

Searching for axionlike particles in flavor-changing neutral current processes [A new flavor of searches for axion-like particles

DOE PAGES

Izaguirre, Eder; Lin, Tongyan; Shuve, Brian

2017-03-15

Here, we propose new searches for axion-like particles (ALPs) produced in flavor-changing neutral current (FCNC) processes. This proposal exploits the often-overlooked coupling of ALPs to W ± bosons, leading to FCNC production of ALPs even in the absence of a direct coupling to fermions. Our proposed searches for resonant ALP production in decays such as B→K(*)a, a→γγ, and K→πa, a→γγ could greatly improve upon the current sensitivity to ALP couplings to standard model particles. Finally, we also determine analogous constraints and discovery prospects for invisibly decaying ALPs.

Differences in fundamental and functional properties of HPMC co-processed fillers prepared by fluid-bed coating and spray drying.

PubMed

Dong, QianQian; Zhou, MiaoMiao; Lin, Xiao; Shen, Lan; Feng, Yi

2018-07-01

This study aimed to develop novel co-processed tablet fillers based on the principle of particle engineering for direct compaction and to compare the characteristics of co-processed products obtained by fluid-bed coating and co-spray drying, respectively. Water-soluble mannitol and water-insoluble calcium carbonate were selected as representative fillers for this study. Hydroxypropyl methylcellulose (HPMC), serving as a surface property modifier, was distributed on the surface of primary filler particles via the two co-processing methods. Both fundamental and functional properties of the products were comparatively investigated. The results showed that functional properties of the fillers, like flowability, compactibility, and drug-loading capacity, were effectively improved by both co-processing methods. However, fluid-bed coating showed greater advantages over co-spray drying in some aspects, which was mainly attributed to the remarkable differences in some fundamental properties of co-processed powders, like particle size, surface topology, and particle structure. For example, the more irregular surface and porous structure induced by fluid-bed coating could contribute to better compaction properties and lower lubricant sensitivity due to the increasing contact area and mechanical interlocking between particles under pressure. More effective surface distribution of HPMC during fluid-bed coating was also a contributor. In addition, such a porous agglomerate structure could also reduce the separation of drug and excipients after mixing, resulting in the improvement in drug loading capacity and tablet uniformity. In summary, fluid-bed coating appears to be more promising for co-processing than spray drying in some aspects, and co-processed excipients produced by it have a great prospect for further investigations and development. Copyright © 2018 Elsevier B.V. All rights reserved.

Structure and properties of polymer nanocomposite coatings applied by the HVOF process

NASA Astrophysics Data System (ADS)

Petrovicova, Elena

1999-11-01

A high velocity oxy-fuel (HVOF) combustion spray process was used to produce coatings from nylon 11 powders with average starting particle diameters of 30 and 60 gin. Silica and carbon black were used as nanosized reinforcements, and their nominal content was varied from 0 to 15 vol. %. Optimization of the HVOF processing parameters was based on an assessment of the degree of splatting of polymer particles, and was accomplished by varying the jet temperature (via the hydrogen/oxygen ratio). Gas mixtures with low hydrogen contents minimized polymer particle degradation. Analytical modeling of particle temperature profiles confirmed the effect of the gas velocity and temperature on the particle heating and resulting coating properties. The morphology of the polymer and the microstructure of the coatings depended on the reinforcement surface chemistry and the volume fraction of the reinforcement, as well as the initial nylon 11 particle size. Although all reinforced coatings had higher crystallinities than pure nylon 11 coatings, coatings produced from a smaller starting polymer particle size (30 mum) exhibited improved spatial distribution of the silica in the matrix and lower crystallinity. In addition, coatings produced from the smaller polymer particles had a higher density and lower porosity due to a higher degree of melting and splatting compared to coatings produced from larger particles (60 mum). Nanoreinforced coatings exhibited increased scratch and sliding wear resistance and improved mechanical and barrier properties. Improvements of up to 35% in scratch and 67% in wear resistance were obtained for coatings with nominal 15 vol. % contents of hydrophobic silica or carbon black, relative to nonreinforced coatings. Reinforcement of the polymer matrix resulted in increases of ca. 200% in the storage modulus both below and above the glass transition temperature. The increase in crystallinity seemed to further enhance the reinforcement provided by the nanoparticulates. Results also showed a decrease in the water vapor transmission rate through nanoreinforced coatings by up to 50% compared to pure polymer coatings. The aqueous permeability of coatings produced from 30 mum polymer particles was lower due to the decrease in porosity. Crystallinity seemed to have a strong influence on the mechanical properties, whereas permeability of thermally sprayed coatings was dominated by coating porosity.

Use of Iba Techniques to Characterize High Velocity Thermal Spray Coatings

NASA Astrophysics Data System (ADS)

Trompetter, W.; Markwitz, A.; Hyland, M.

Spray coatings are being used in an increasingly wide range of industries to improve the abrasive, erosive and sliding wear of machine components. Over the past decade industries have moved to the application of supersonic high velocity thermal spray techniques. These coating techniques produce superior coating quality in comparison to other traditional techniques such as plasma spraying. To date the knowledge of the bonding processes and the structure of the particles within thermal spray coatings is very subjective. The aim of this research is to improve our understanding of these materials through the use of IBA techniques in conjunction with other materials analysis techniques. Samples were prepared by spraying a widely used commercial NiCr powder onto substrates using a HVAF (high velocity air fuel) thermal spraying technique. Detailed analysis of the composition and structure of the power particles revealed two distinct types of particles. The majority was NiCr particles with a significant minority of particles composing of SiO2/CrO3. When the particles were investigated both as raw powder and in the sprayed coating, it was surprising to find that the composition of the coating meterial remained unchanged during the coating process despite the high velocity application.

A dynamic feedforward neural network based on gaussian particle swarm optimization and its application for predictive control.

PubMed

Han, Min; Fan, Jianchao; Wang, Jun

2011-09-01

A dynamic feedforward neural network (DFNN) is proposed for predictive control, whose adaptive parameters are adjusted by using Gaussian particle swarm optimization (GPSO) in the training process. Adaptive time-delay operators are added in the DFNN to improve its generalization for poorly known nonlinear dynamic systems with long time delays. Furthermore, GPSO adopts a chaotic map with Gaussian function to balance the exploration and exploitation capabilities of particles, which improves the computational efficiency without compromising the performance of the DFNN. The stability of the particle dynamics is analyzed, based on the robust stability theory, without any restrictive assumption. A stability condition for the GPSO+DFNN model is derived, which ensures a satisfactory global search and quick convergence, without the need for gradients. The particle velocity ranges could change adaptively during the optimization process. The results of a comparative study show that the performance of the proposed algorithm can compete with selected algorithms on benchmark problems. Additional simulation results demonstrate the effectiveness and accuracy of the proposed combination algorithm in identifying and controlling nonlinear systems with long time delays.

Improved silicon carbide for advanced heat engines. I - Process development for injection molding

NASA Technical Reports Server (NTRS)

Whalen, Thomas J.; Trela, Walter

1989-01-01

Alternate processing methods have been investigated as a means of improving the mechanical properties of injection-molded SiC. Various mixing processes (dry, high-sheer, and fluid) were evaluated along with the morphology and particle size of the starting beta-SiC powder. Statistically-designed experiments were used to determine significant effects and interactions of variables in the mixing, injection molding, and binder removal process steps. Improvements in mechanical strength can be correlated with the reduction in flaw size observed in the injection molded green bodies obtained with improved processing methods.

An IDEA of What's in the Air

NASA Technical Reports Server (NTRS)

2002-01-01

The Automatic Particle Fallout Monitor (APFM) is an automated instrument that assesses real-time particle contamination levels in a facility by directly imaging, sizing, and counting contamination particles. It allows personnel to respond to particle contamination before it becomes a major problem. For NASA, the APFM improves the ability to mitigate, avoid, and explain mission-compromising incidents of contamination occurring during payload processing, launch vehicle ground processing, and potentially, during flight operations. Commercial applications are in semiconductor processing and electronics fabrication, as well as aerospace, aeronautical, and medical industries. The product could also be used to measure the air quality of hotels, apartment complexes, and corporate buildings. IDEA sold and delivered its first four units to the United Space Alliance for the Space Shuttle Program at Kennedy. NASA used the APFM in the Kennedy Space Station Processing Facility to monitor contamination levels during the assembly of International Space Station components.

Identifying the hazard characteristics of powder byproducts generated from semiconductor fabrication processes.

PubMed

Choi, Kwang-Min; An, Hee-Chul; Kim, Kwan-Sick

2015-01-01

Semiconductor manufacturing processes generate powder particles as byproducts which potentially could affect workers' health. The chemical composition, size, shape, and crystal structure of these powder particles were investigated by scanning electron microscopy equipped with an energy dispersive spectrometer, Fourier transform infrared spectrometry, and X-ray diffractometry. The powders generated in diffusion and chemical mechanical polishing processes were amorphous silica. The particles in the chemical vapor deposition (CVD) and etch processes were TiO(2) and Al(2)O(3), and Al(2)O(3) particles, respectively. As for metallization, WO(3), TiO(2), and Al(2)O(3) particles were generated from equipment used for tungsten and barrier metal (TiN) operations. In photolithography, the size and shape of the powder particles showed 1-10 μm and were of spherical shape. In addition, the powders generated from high-current and medium-current processes for ion implantation included arsenic (As), whereas the high-energy process did not include As. For all samples collected using a personal air sampler during preventive maintenance of process equipment, the mass concentrations of total airborne particles were < 1 μg, which is the detection limit of the microbalance. In addition, the mean mass concentrations of airborne PM10 (particles less than 10 μm in diameter) using direct-reading aerosol monitor by area sampling were between 0.00 and 0.02 μg/m(3). Although the exposure concentration of airborne particles during preventive maintenance is extremely low, it is necessary to make continuous improvements to the process and work environment, because the influence of chronic low-level exposure cannot be excluded.

Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

NASA Astrophysics Data System (ADS)

Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

2016-08-01

The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape. Overall, the study demonstrates a substantial value of polarimetric data for improving aerosol characterization.

Characterization of complete particles (VSV-G/SIN-GFP) and empty particles (VSV-G/EMPTY) in human immunodeficiency virus type 1-based lentiviral products for gene therapy: potential applications for improvement of product quality and safety.

PubMed

Zhao, Yuan; Keating, Kenneth; Dolman, Carl; Thorpe, Robin

2008-05-01

Lentiviral vectors persist in the host and are therefore ideally suited for long-term gene therapy. To advance the use of lentiviral vectors in humans, improvement of their production, purification, and characterization has become increasingly important and challenging. In addition to cellular contaminants derived from packaging cells, empty particles without therapeutic function are the major impurities that compromise product safety and efficacy. Removal of empty particles is difficult because of their innate similarity in particle size and protein composition to the complete particles. We propose that comparison of the properties of lentiviral products with those of purposely expressed empty particles may reveal potential differences between empty and complete particles. For this, three forms of recombinant lentiviral samples, that is, recombinant vesicular stomatitis virus glycoprotein (VSV-G) proteins, empty particles (VSV-G/Empty), and complete particles (VSV-G/SIN-GFP) carrying viral RNA, were purified by size-exclusion chromatography (SEC). The SEC-purified samples were further analyzed by immunoblotting with six antibodies to examine viral and cellular proteins associated with the particles. This study has demonstrated, for the first time, important differences between VSV-G/Empty particles and complete VSV-G/SIN-GFP particles. Differences include the processing of Gag protein and the inclusion of cellular proteins in the particles. Our findings support the development of improved production, purification, and characterization methods for lentiviral products.

Improved Small-Particle Powders for Plasma Spraying

NASA Technical Reports Server (NTRS)

Nguyen, QuynhGiao, N.; Miller, Robert A.; Leissler, George W.

2005-01-01

Improved small-particle powders and powder-processing conditions have been developed for use in plasma spray deposition of thermal-barrier and environmental barrier coatings. Heretofore, plasma-sprayed coatings have typically ranged in thickness from 125 to 1,800 micrometers. As explained below, the improved powders make it possible to ensure complete coverage of substrates at unprecedently small thicknesses of the order of 25 micrometers. Plasma spraying involves feeding a powder into a hot, high-velocity plasma jet. The individual powder particles melt in the plasma jet as they are propelled towards a substrate, upon which they splat to build up a coating. In some cases, multiple coating layers are required. The size range of the powder particles necessarily dictates the minimum thickness of a coating layer needed to obtain uniform or complete coverage. Heretofore, powder particle sizes have typically ranged from 40 to 70 micrometers; as a result, the minimum thickness of a coating layer for complete coverage has been about 75 micrometers. In some applications, thinner coatings or thinner coating layers are desirable. In principle, one can reduce the minimum complete-coverage thickness of a layer by using smaller powder particles. However, until now, when powder particle sizes have been reduced, the powders have exhibited a tendency to cake, clogging powder feeder mechanisms and feed lines. Hence, the main problem is one of synthesizing smaller-particle powders having desirable flow properties. The problem is solved by use of a process that begins with a spray-drying subprocess to produce spherical powder particles having diameters of less than 30 micrometers. (Spherical-particle powders have the best flow properties.) The powder is then passed several times through a commercial sifter with a mesh to separate particles having diameters less than 15 micrometers. The resulting fine, flowable powder is passed through a commercial fluidized bed powder feeder into a plasma spray jet.

Pathogen and Particle Associations in Wastewater: Significance and Implications for Treatment and Disinfection Processes.

PubMed

Chahal, C; van den Akker, B; Young, F; Franco, C; Blackbeard, J; Monis, P

2016-01-01

Disinfection guidelines exist for pathogen inactivation in potable water and recycled water, but wastewater with high numbers of particles can be more difficult to disinfect, making compliance with the guidelines problematic. Disinfection guidelines specify that drinking water with turbidity ≥1 Nephelometric Turbidity Units (NTU) is not suitable for disinfection and therefore not fit for purpose. Treated wastewater typically has higher concentrations of particles (1-10NTU for secondary treated effluent). Two processes widely used for disinfecting wastewater are chlorination and ultraviolet radiation. In both cases, particles in wastewater can interfere with disinfection and can significantly increase treatment costs by increasing operational expenditure (chemical demand, power consumption) or infrastructure costs by requiring additional treatment processes to achieve the required levels of pathogen inactivation. Many microorganisms (viruses, bacteria, protozoans) associate with particles, which can allow them to survive disinfection processes and cause a health hazard. Improved understanding of this association will enable development of cost-effective treatment, which will become increasingly important as indirect and direct potable reuse of wastewater becomes more widespread in both developed and developing countries. This review provides an overview of wastewater and associated treatment processes, the pathogens in wastewater, the nature of particles in wastewater and how they interact with pathogens, and how particles can impact disinfection processes. Copyright © 2016 Elsevier Inc. All rights reserved.

Design of a uranium-dioxide powder spheroidization system by plasma processing

NASA Astrophysics Data System (ADS)

Cavender, Daniel

The plasma spheroidization system (PSS) is the first process in the development of a tungsten-uranium dioxide (W-UO2) ceramic-metallic (cermet) fuel for nuclear thermal rocket (NTR) propulsion. For the purposes of fissile fuel retention, UO2 spheroids ranging in size from 50 - 100 micrometers (μm) in diameter will be encapsulated in a tungsten shell. The PSS produces spherical particles by melting angular stock particles in an argon-hydrogen plasma jet where they become spherical due to surface tension. Surrogate CeO 2 powder was used in place of UO2 for system and process parameter development. Stock and spheroidized powders were micrographed using optical and scanning electron microscopy and evaluated by statistical methods to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders showed a statistically significant improvement in spherocity, with greater that 60% of the examined particles having an irregularity parameter of equal to or lower than 1.2, compared to stock powder.

Reinforcement of latex rubber by the incorporation of amphiphilic particles

USDA-ARS?s Scientific Manuscript database

Latex rubbers are fabricated from latex suspensions. During the fabrication process, latex particles are bound together while water is removed from the suspension. This report shows that the mechanical properties of latex rubbers can be improved by incorporating a small amount of amphiphilic submicr...

Nanoparticles in the pharmaceutical industry and the use of supercritical fluid technologies for nanoparticle production.

PubMed

Sheth, Pratik; Sandhu, Harpreet; Singhal, Dharmendra; Malick, Waseem; Shah, Navnit; Kislalioglu, M Serpil

2012-05-01

Poor aqueous solubility of drug candidates is a major challenge for the pharmaceutical scientists involved in drug development. Particle size reduction appears as an effective and versatile option for solubility improvement. Nanonization is an attractive solution to improve the bioavailability of the poorly soluble drugs, improved therapies, in vivo imaging, in vitro diagnostics and for the production of biomaterials and active implants. In drug delivery, application of nanotechnology is commonly referred to as Nano Drug Delivery Systems (NDDS). In this article, commercially available nanosized drugs, their dosage forms and proprietors, as well as the methods used for preparation like milling, high pressure homogenization, vacuum deposition, and high temperature evaporation were listed. Unlike the traditional methods used for the particle size reduction, supercritical fluid-processing techniques offer advantages ranging from superior particle size control to clean processing. The primary focus of this review article is the use of supercritical CO2 based technologies for small particle generation. Particles that have the smooth surfaces, small particle size and distribution and free flowing can be obtained with particular SCF techniques. In almost all techniques, the dominating process variables may be thermodynamic and aerodynamic in nature, and the design of the particle collection environment. Rapid Expansion of Supercritical Solutions (RESS), Supercritical Anti Solvent (SAS) and Particles from Gas Saturated Solutions (PGSS) are three groups of processes which lead to the production of fine and monodisperse powders. Few of them may also control crystal polymorphism. Among the aforementioned processes, RESS involves dissolving a drug in a supercritical fluid (SCF) and passing it through an appropriate nozzle. Rapid depressurization of this solution causes an extremely rapid nucleation of the product. This process has been known for a long time but its application is limited. Carbon dioxide, which is the only supercritical fluid that is preferentially used in pharmaceutical processes, is not a good solvent for many Active Pharmaceutical Ingredients (API). Various researchers have modified the RESS process to overcome its solubilizing limitations, by introducing RESOLV, RESAS, and RESS-SC. Overall, all RESS based processes are difficult to scale up. The SAS processes are based on decreasing the solvent power of a polar organic solvent in which the substrate (API & polymer of interest) is dissolved, by saturating it with carbon dioxide (CO2) at supercritical conditions. CO2 causes precipitation and recrystalization of the drug. SAS is scalable and can be applied to a wide variety of APIs and polymers. Minor modifications of basic SAS process include GAS, ASES, SAS-DEM and SAS-EM. Processes where SCF is used as an anti solvent and dispersing agent include SEDS, SAA, and A-SAIS. The mechanisms and applications of these processes were briefly discussed. In PGSS, CO2 is dissolved in organic solutions or melted compounds and it is successfully used for manufacturing drug products as well as for drying purposes. The two widely used methods, PGSSdrying and CAN-BD SCF, were also included in discussions. Among the limitations of the techniques involved, the poor solvent power of CO2, the cost and necessity of voluminous usage of the CO2 can be mentioned. There is still confusion in contribution of each variable on the particle morphology and properties regardless of the number of mechanistic studies available. The advantages of especially SAS and PGSS based techniques are the production of the nano or micro sized spherical particles with smooth surfaces and narrow particle size distribution. Regardless of its advantages, the reasons why 25 years of active research, and more than 10 years of process development could not promote the use of (SCF) technology, and produced only few commercial drug products, necessitate further evaluation of this technique.

An improved model for computing the trajectories of conductive particles in roll-type electrostatic separator for recycling metals from WEEE.

PubMed

Wu, Jiang; Li, Jia; Xu, Zhenming

2009-08-15

Electrostatic separation presents an effective and environmentally friendly way for recycling metals and nonmetals from ground waste electrical and electronic equipment (WEEE). For this process, the trajectory of conductive particle is significant and some models have been established. However, the results of previous researches are limited by some simplifying assumptions and lead to a notable discrepancy between the model prediction and the experimental results. In the present research, a roll-type corona-electrostatic separator and ground printed circuit board (PCB) wastes were used to investigate the trajectory of the conductive particle. Two factors, the air drag force and the different charging situation, were introduced into the improved model. Their effects were analyzed and an improved model for the theoretical trajectory of conductive particle was established. Compared with the previous one, the improved model shows a good agreement with the experimental results. It provides a positive guidance for designing of separator and makes a progress for recycling the metals and nonmetals from WEEE.

The Influence of Turbulent Coherent Structure on Suspended Sediment Transport

NASA Astrophysics Data System (ADS)

Huang, S. H.; Tsai, C.

2017-12-01

The anomalous diffusion of turbulent sedimentation has received more and more attention in recent years. With the advent of new instruments and technologies, researchers have found that sediment behavior may deviate from Fickian assumptions when particles are heavier. In particle-laden flow, bursting phenomena affects instantaneous local concentrations, and seems to carry suspended particles for a longer distance. Instead of the pure diffusion process in an analogy to Brownian motion, Levy flight which allows particles to move in response to bursting phenomena is suspected to be more suitable for describing particle movement in turbulence. And the fractional differential equation is a potential candidate to improve the concentration profile. However, stochastic modeling (the Differential Chapmen-Kolmogorov Equation) also provides an alternative mathematical framework to describe system transits between different states through diffusion/the jump processes. Within this framework, the stochastic particle tracking model linked with advection diffusion equation is a powerful tool to simulate particle locations in the flow field. By including the jump process to this model, a more comprehensive description for suspended sediment transport can be provided with a better physical insight. This study also shows the adaptability and expandability of the stochastic particle tracking model for suspended sediment transport modeling.

Nuevos aspectos en el estudio de la particula D en el experimento FOCUS de Fermilab

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

Quinones Gonzalez, Jose A.; /Puerto Rico U., Mayaguez

The purpose of this work is to improve the reconstruction techniques of the decays of the particles that contain charm in the quark composition using the information of the Target Silicon Detector of the experiment E831 (FOCUS). That experiment runs during 1997 to 1998 in Fermilab National Laboratory. The objective of the experiment was improving the understanding of the particles that contain charm. Adding the Target Silicon Detector information in the reconstruction process of the primary vertex the position error. This reduction produces an improvement in the mass signal and the knowledge of the charm particles properties. This ad tomore » the possibility's that in other analysis will use the techniques developed in this work.« less

Effects of magnetic fields on improving mass transfer in flue gas desulfurization using a fluidized bed

NASA Astrophysics Data System (ADS)

Zhang, Qi; Gui, Keting; Wang, Xiaobo

2016-02-01

The effects of magnetic fields on improving the mass transfer in flue gas desulfurization using a fluidized bed are investigated in the paper. In this research, the magnetically fluidized bed (MFB) is used as the reactor in which ferromagnetic particles are fluidized with simulated flue gas under the influence of an external magnetic field. Lime slurry is continuously sprayed into the reactor. As a consequence, the desulfurization reaction and the slurry drying process take place simultaneously in the MFB. In this paper, the effects of ferromagnetic particles and external magnetic fields on the desulphurization efficiency are studied and compared with that of quartz particles as the fluidized particles. Experimental results show that the ferromagnetic particles not only act as a platform for lime slurry to precipitate on like quartz particles, but also take part in the desulfurization reaction. The results also show that the specific surface area of ferromagnetic particles after reaction is enlarged as the magnetic intensity increases, and the external magnetic field promotes the oxidation of S(IV), improving the mass transfer between sulphur and its sorbent. Hence, the efficiency of desulphurization under the effects of external magnetic fields is higher than that in general fluidized beds.

Method for improving instrument response

DOEpatents

Hahn, David W.; Hencken, Kenneth R.; Johnsen, Howard A.; Flower, William L.

2000-01-01

This invention pertains generally to a method for improving the accuracy of particle analysis under conditions of discrete particle loading and particularly to a method for improving signal-to-noise ratio and instrument response in laser spark spectroscopic analysis of particulate emissions. Under conditions of low particle density loading (particles/m.sup.3) resulting from low overall metal concentrations and/or large particle size uniform sampling can not be guaranteed. The present invention discloses a technique for separating laser sparks that arise from sample particles from those that do not; that is, a process for systematically "gating" the instrument response arising from "sampled" particles from those responses which do not, is dislosed as a solution to his problem. The disclosed approach is based on random sampling combined with a conditional analysis of each pulse. A threshold value is determined for the ratio of the intensity of a spectral line for a given element to a baseline region. If the threshold value is exceeded, the pulse is classified as a "hit" and that data is collected and an average spectrum is generated from an arithmetic average of "hits". The true metal concentration is determined from the averaged spectrum.

Heterogeneous ice nucleation of α-pinene SOA particles before and after ice cloud processing

NASA Astrophysics Data System (ADS)

Wagner, Robert; Höhler, Kristina; Huang, Wei; Kiselev, Alexei; Möhler, Ottmar; Mohr, Claudia; Pajunoja, Aki; Saathoff, Harald; Schiebel, Thea; Shen, Xiaoli; Virtanen, Annele

2017-05-01

The ice nucleation ability of α-pinene secondary organic aerosol (SOA) particles was investigated at temperatures between 253 and 205 K in the Aerosol Interaction and Dynamics in the Atmosphere cloud simulation chamber. Pristine SOA particles were nucleated and grown from pure gas precursors and then subjected to repeated expansion cooling cycles to compare their intrinsic ice nucleation ability during the first nucleation event with that observed after ice cloud processing. The unprocessed α-pinene SOA particles were found to be inefficient ice-nucleating particles at cirrus temperatures, with nucleation onsets (for an activated fraction of 0.1%) as high as for the homogeneous freezing of aqueous solution droplets. Ice cloud processing at temperatures below 235 K only marginally improved the particles' ice nucleation ability and did not significantly alter their morphology. In contrast, the particles' morphology and ice nucleation ability was substantially modified upon ice cloud processing in a simulated convective cloud system, where the α-pinene SOA particles were first activated to supercooled cloud droplets and then froze homogeneously at about 235 K. As evidenced by electron microscopy, the α-pinene SOA particles adopted a highly porous morphology during such a freeze-drying cycle. When probing the freeze-dried particles in succeeding expansion cooling runs in the mixed-phase cloud regime up to 253 K, the increase in relative humidity led to a collapse of the porous structure. Heterogeneous ice formation was observed after the droplet activation of the collapsed, freeze-dried SOA particles, presumably caused by ice remnants in the highly viscous material or the larger surface area of the particles.

Pressure oscillations and instability of working processes in the combustion chambers of solid rocket motors

NASA Astrophysics Data System (ADS)

Emelyanov, V. N.; Teterina, I. V.; Volkov, K. N.; Garkushev, A. U.

2017-06-01

Metal particles are widely used in space engineering to increase specific impulse and to supress acoustic instability of intra-champber processes. A numerical analysis of the internal injection-driven turbulent gas-particle flows is performed to improve the current understanding and modeling capabilities of the complex flow characteristics in the combustion chambers of solid rocket motors (SRMs) in presence of forced pressure oscillations. The two-phase flow is simulated with a combined Eulerian-Lagrangian approach. The Reynolds-averaged Navier-Stokes equations and transport equations of k - ε model are solved numerically for the gas. The particulate phase is simulated through a Lagrangian deterministic and stochastic tracking models to provide particle trajectories and particle concentration. The results obtained highlight the crucial significance of the particle dispersion in turbulent flowfield and high potential of statistical methods. Strong coupling between acoustic oscillations, vortical motion, turbulent fluctuations and particle dynamics is observed.

Retention and Migration of Fine Organic Particles within an Agricultural Stream: Toenepi, Waikato, New Zealand

NASA Astrophysics Data System (ADS)

Drummond, J. D.; Davies-Colley, R.; Stott, R.; Sukias, J.; Nagels, J.; Sharp, A.; Packman, A. I.

2013-12-01

Fine organic particle dynamics are important to stream biogeochemistry, ecology, and transport of contaminant microbes. These particles migrate downstream through a series of deposition and resuspension events, which results in a wide range of residence times. This retention influences biogeochemical processing and in-stream stores of contaminant microbes that may mobilize during flood events and present a hazard to downstream uses such as water supplies and recreation. We are conducting studies to gain insights into organic particle dynamics in streams, with a campaign of experiments and modeling. The results should improve understanding of nutrient (C, N, P) spiraling and fine sediment movement in streams, and have particular application to microbial hazards. We directly measure microbial transport by including the indicator organism, E. coli, as a tracer, which is compared to a fluorescent inert particle tracer and conservative solute to gain insight on both microbial ecology and waterborne disease transmission. We developed a stochastic model to describe the transport and retention of fine suspended particles in rivers, including advective delivery of particles to the streambed, transport through porewaters, and reversible filtration within the streambed. Because fine particles are only episodically transported in streams, with intervening periods at rest in the bed, this transport process violates conventional advection-dispersion assumptions. Instead we adopt a stochastic mobile-immobile model formulation to describe fine particle transport. We apply this model to measurements of particle transport from multiple tracer experiments in an agricultural stream in the Waikato dairy region of New Zealand, and use the model to improve interpretation of baseflow particle dynamics. Our results show the importance of the benthic and hyporheic regions and in-stream vegetation as a reservoir for fine organic particles in streams.

Fabrication and Characterization of Surrogate Fuel Particles Using the Spark Erosion Method

NASA Astrophysics Data System (ADS)

Metzger, Kathryn E.

In light of the disaster at the Fukushima Daiichi Nuclear Plant, the Department of Energy's Advanced Fuels Program has shifted its interest from enhanced performance fuels to enhanced accident tolerance fuels. Dispersion fuels possess higher thermal conductivities than traditional light water reactor fuel and as a result, offer improved safety margins. The benefits of a dispersion fuel are due to the presence of the secondary non-fissile phase (matrix), which serves as a barrier to fission products and improves the overall thermal performance of the fuel. However, the presence of a matrix material reduces the fuel volume, which lowers the fissile content of dispersion. This issue can be remedied through the development of higher density fuel phases or through an optimization of fuel particle size and volume loading. The latter requirement necessitates the development of fabrication methods to produce small, micron-order fuel particles. This research examines the capabilities of the spark erosion process to fabricate particles on the order of 10 μm. A custom-built spark erosion device by CT Electromechanica was used to produce stainless steel surrogate fuel particles in a deionized water dielectric. Three arc intensities were evaluated to determine the effect on particle size. Particles were filtered from the dielectric using a polycarbonate membrane filter and vacuum filtration system. Fabricated particles were characterized via field emission scanning electron microscopy (FESEM), laser light particle size analysis, energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), and gas pycnometry. FESEM images reveal that the spark erosion process produces highly spherical particles on the order of 10 microns. These findings are substantiated by the results of particle size analysis. Additionally, EDS and XRD results indicate the presence of oxide phases, which suggests the dielectric reacted with the molten debris during particle formation.

Preparation and characterisation of hydrocortisone particles using a supercritical fluids extraction process.

PubMed

Velaga, Sitaram P; Ghaderi, Raouf; Carlfors, Johan

2002-01-14

Crystallisation and subsequent milling of pharmaceutical powders by traditional methods often cause variations in physicochemical properties thereby influencing bioavailability of the formulation. Crystallisation of drug substances using supercritical fluids (SFs) offers some advantages over existing traditional methods in controlling particle characteristics. The novel particle formation method, solution enhanced dispersion by supercritical (SEDS) fluids was used for the preparation of hydrocortisone (HC) particles. The influence of processing conditions on the solid-state properties of the particles was studied. HC, an anti-inflammatory corticosteroid, particles were prepared from acetone and methanol solutions using the SEDS process. The solutions were dispersed with supercritical CO(2), acting as an anti-solvent, through a specially designed co-axial nozzle into a pressured vessel maintained at a specific constant temperature and pressure. The temperatures and pressures studied were 40-90 degrees C and 90-180 bar, respectively. The relative flow rates of drug solution to CO(2) were varied between 0.002 and 0.03. Solid-state characterisation of particles included differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), solubility studies and scanning electron microscopy (SEM) examination. The aerodynamic properties of SEDS prepared particles were determined by a multistage liquid impinger (MLI). Particles produced from acetone solutions were crystalline needles, melting at 221+/-2 degrees C. Their morphology was independent of processing conditions. With methanol solutions, particles were flakes or needles depending on the processing temperature and pressure. This material melted at 216+/-1 degrees C, indicating a different crystal structure from the original material, in agreement with observed differences in the position and intensity of the XRPD peaks. The simulated lung deposition, using the MLI, for HC powder was improved after SEDS processing. It was possible to produce and control the crystallinity, morphology, and aerodynamic properties of HC particles with the SEDS technique. This method may be useful for the processing of inhalation powders.

Improved process for generating ClF/sub 3/ from ClF and F/sub 2/

DOEpatents

Reiner, R.H.; Pashley, J.H.; Barber, E.J.

The invention is an improvement in the process for producing gaseous ClF/sub 3/ by reacting ClF and F/sub 2/ at elevated temperature. The improved process comprises conducting the reaction in the presence of NiF/sub 2/, which preferably is in the form of particles or in the form of a film or layer on a particulate substrate. The nickel fluoride acts as a reaction catalyst, significantly increasing the reaction rate and thus permitting valuable reductions in process temperature, pressure, and/or reactor volume.

Enhancement of bronze alloy surface properties by FSP second-phase particle incorporation

DOE PAGES

Ajayi, O. O.; Lorenzo-Martin, Cinta

2017-06-15

This study presents results of an experimental study to evaluate friction stir processing (FSP) with and without hard second-phase particle incorporation as a means to enhance surface properties and wear performance of C86300 manganese bronze alloy. FSP of flat bronze alloy specimens was conducted with hardened H-13 tool steel to create a 3-mm-thick processed surface layer. The process was also used to incorporate B 4C particles, thereby creating a metal-matrix composite layer on the alloy surface. FSP alone was observed to produce substantial reduction in grain size (from an initial value of 350 mu m to 1-5 μm). FSP withoutmore » particle incorporation resulted in modest surface hardening due to grain refinement and dispersion hardening. Under lubricated contact in block-on-ring testing with a hardened steel counter face, FSP produced substantial reduction (about 3X) in bronze wear after polishing of processing surface roughening. FSP with hard B 4C second-phase particle incorporation further reduced wear by up to 20X. The improvement in wear behavior is attributed to grain refinement and load shielding by second-phase particles, as determined by wear mechanism analysis.« less

Morphology of diesel soot residuals from supercooled water droplets and ice crystals: Implications for optical properties

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

China, Swarup; Kulkarni, Gourihar; Scarnato, Barbara V.

Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth’s radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those frommore » supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. Lastly, these results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.« less

Morphology of diesel soot residuals from supercooled water droplets and ice crystals: Implications for optical properties

DOE PAGES

China, Swarup; Kulkarni, Gourihar; Scarnato, Barbara V.; ...

2015-11-01

Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth’s radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those frommore » supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. Lastly, these results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.« less

A deep convolutional neural network approach to single-particle recognition in cryo-electron microscopy.

PubMed

Zhu, Yanan; Ouyang, Qi; Mao, Youdong

2017-07-21

Single-particle cryo-electron microscopy (cryo-EM) has become a mainstream tool for the structural determination of biological macromolecular complexes. However, high-resolution cryo-EM reconstruction often requires hundreds of thousands of single-particle images. Particle extraction from experimental micrographs thus can be laborious and presents a major practical bottleneck in cryo-EM structural determination. Existing computational methods for particle picking often use low-resolution templates for particle matching, making them susceptible to reference-dependent bias. It is critical to develop a highly efficient template-free method for the automatic recognition of particle images from cryo-EM micrographs. We developed a deep learning-based algorithmic framework, DeepEM, for single-particle recognition from noisy cryo-EM micrographs, enabling automated particle picking, selection and verification in an integrated fashion. The kernel of DeepEM is built upon a convolutional neural network (CNN) composed of eight layers, which can be recursively trained to be highly "knowledgeable". Our approach exhibits an improved performance and accuracy when tested on the standard KLH dataset. Application of DeepEM to several challenging experimental cryo-EM datasets demonstrated its ability to avoid the selection of un-wanted particles and non-particles even when true particles contain fewer features. The DeepEM methodology, derived from a deep CNN, allows automated particle extraction from raw cryo-EM micrographs in the absence of a template. It demonstrates an improved performance, objectivity and accuracy. Application of this novel method is expected to free the labor involved in single-particle verification, significantly improving the efficiency of cryo-EM data processing.

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

Ajayi, O. O.; Lorenzo-Martin, Cinta

This study presents results of an experimental study to evaluate friction stir processing (FSP) with and without hard second-phase particle incorporation as a means to enhance surface properties and wear performance of C86300 manganese bronze alloy. FSP of flat bronze alloy specimens was conducted with hardened H-13 tool steel to create a 3-mm-thick processed surface layer. The process was also used to incorporate B 4C particles, thereby creating a metal-matrix composite layer on the alloy surface. FSP alone was observed to produce substantial reduction in grain size (from an initial value of 350 mu m to 1-5 μm). FSP withoutmore » particle incorporation resulted in modest surface hardening due to grain refinement and dispersion hardening. Under lubricated contact in block-on-ring testing with a hardened steel counter face, FSP produced substantial reduction (about 3X) in bronze wear after polishing of processing surface roughening. FSP with hard B 4C second-phase particle incorporation further reduced wear by up to 20X. The improvement in wear behavior is attributed to grain refinement and load shielding by second-phase particles, as determined by wear mechanism analysis.« less

Particle Generation and Evolution in Silane/Acetylene Flames in Microgravity

NASA Technical Reports Server (NTRS)

Keil, D. G.

2001-01-01

The objective of this new experimental program is to advance the understanding of the formation of particles from gas phase combustion processes. The work will utilize the unique SiH4/C2H2 combustion system which generates particulate products ranging from high purity, white SiC to carbonaceous soot depending on equivalence ratio. A key goal of this work is to identify gas phase or particle formation processes that provide the enthalpy release necessary to drive the combustion wave, and to locate the parts of the particle formation process that determine SiC stoichiometry and crystallinity. In a real sense, these SiH4/C2H2 flames act like "highly sooty" hydrocarbon flames, but with simpler chemistry. This simplification is expected to allow them to be used as surrogates to advance understanding of soot formation in such rich hydrocarbon flames. It is also expected that this improved understanding of SiC particle generation and evolution in these self-sustaining flames will advance the commercial potential of the flame process for the generation of high purity SiC powders.

Particle Generation And Evolution In Silane (SiH4)/Acetylene (C2H2) Flames In Microgravity

NASA Technical Reports Server (NTRS)

Keil, D. G.

2003-01-01

The objective of this experimental program is to advance the understanding of the coupling of particle formation with gas phase combustion processes. The work utilizes the unique SiH4/C2H2 combustion system which generates particulate products ranging from high purity, white SiC to carbonaceous soot depending on equivalence ratio (Ref. 1). A goal of this work is to identify gas phase or particle formation processes that provide the enthalpy release needed to drive the combustion wave, and to locate the steps of the particle formation process that determine SiC stoichiometry and crystallinity. In a real sense, these SiH4/C2H2 flames act like highly sooty hydrocarbon flames, but with simpler chemistry. This simplification is expected to allow them to be used as surrogates to advance understanding of soot formation in such rich hydrocarbon flames. It is also expected that this improved understanding of SiC particle generation and evolution in these self-sustaining flames will advance the commercial potential of the flame process for the generation of high purity SiC powders.

In-pile test results of U-silicide or U-nitride coated U-7Mo particle dispersion fuel in Al

NASA Astrophysics Data System (ADS)

Kim, Yeon Soo; Park, J. M.; Lee, K. H.; Yoo, B. O.; Ryu, H. J.; Ye, B.

2014-11-01

U-silicide or U-nitride coated U-Mo particle dispersion fuel in Al (U-Mo/Al) was in-pile tested to examine the effectiveness of the coating as a diffusion barrier between the U-7Mo fuel kernels and Al matrix. This paper reports the PIE data and analyses focusing on the effectiveness of the coating in terms of interaction layer (IL) growth and general fuel performance. The U-silicide coating showed considerable success, but it also provided evidence for additional improvement for coating process. The U-nitride coated specimen showed largely inefficient results in reducing IL growth. From the test, important observations were also made that can be utilized to improve U-Mo/Al fuel performance. The heating process for coating turned out to be beneficial to suppress fuel swelling. The use of larger fuel particles confirmed favorable effects on fuel performance.

Westinghouse modular grinding process - improvement for follow on processes

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

Fehrmann, Henning

2013-07-01

In nuclear power plants (NPP) ion exchange (IX) resins are used in several systems for water treatment. The resins can be in bead or powdered form. For waste treatment of spent IX resins, two methods are basically used: Direct immobilization (e.g. with cement, bitumen, polymer or High Integrity Container (HIC)); Thermal treatment (e.g. drying, oxidation or pyrolysis). Bead resins have some properties (e.g. particle size and density) that can have negative impacts on following waste treatment processes. Negative impacts could be: Floatation of bead resins in cementation process; Sedimentation in pipeline during transportation; Poor compaction properties for Hot Resin Supercompactionmore » (HRSC). Reducing the particle size of the bead resins can have beneficial effects enhancing further treatment processes and overcoming prior mentioned effects. Westinghouse Electric Company has developed a modular grinding process to crush/grind the bead resins. This modular process is designed for flexible use and enables a selective adjustment of particle size to tailor the grinding system to the customer needs. The system can be equipped with a crusher integrated in the process tank and if necessary a colloid mill. The crusher reduces the bead resins particle size and converts the bead resins to a pump able suspension with lower sedimentation properties. With the colloid mill the resins can be ground to a powder. Compared to existing grinding systems this equipment is designed to minimize radiation exposure of the worker during operation and maintenance. Using the crushed and/or ground bead resins has several beneficial effects like facilitating cementation process and recipe development, enhancing oxidation of resins, improving the Hot Resin Supercompaction volume reduction performance. (authors)« less

Delivery of multiple siRNAs using lipid-coated PLGA nanoparticles for treatment of prostate cancer.

PubMed

Hasan, Warefta; Chu, Kevin; Gullapalli, Anuradha; Dunn, Stuart S; Enlow, Elizabeth M; Luft, J Christopher; Tian, Shaomin; Napier, Mary E; Pohlhaus, Patrick D; Rolland, Jason P; DeSimone, Joseph M

2012-01-11

Nanotechnology can provide a critical advantage in developing strategies for cancer management and treatment by helping to improve the safety and efficacy of novel therapeutic delivery vehicles. This paper reports the fabrication of poly(lactic acid-co-glycolic acid)/siRNA nanoparticles coated with lipids for use as prostate cancer therapeutics made via a unique soft lithography particle molding process called Particle Replication In Nonwetting Templates (PRINT). The PRINT process enables high encapsulation efficiency of siRNA into neutral and monodisperse PLGA particles (32-46% encapsulation efficiency). Lipid-coated PLGA/siRNA PRINT particles were used to deliver therapeutic siRNA in vitro to knockdown genes relevant to prostate cancer. © 2011 American Chemical Society

Synthesis and thermal stability of zirconia and yttria-stabilized zirconia microspheres.

PubMed

Leib, Elisabeth W; Vainio, Ulla; Pasquarelli, Robert M; Kus, Jonas; Czaschke, Christian; Walter, Nils; Janssen, Rolf; Müller, Martin; Schreyer, Andreas; Weller, Horst; Vossmeyer, Tobias

2015-06-15

Zirconia microparticles produced by sol-gel synthesis have great potential for photonic applications. To this end, identifying synthetic methods that yield reproducible control over size uniformity is important. Phase transformations during thermal cycling can disintegrate the particles. Therefore, understanding the parameters driving these transformations is essential for enabling high-temperature applications. Particle morphology is expected to influence particle processability and stability. Yttria-doping should improve the thermal stability of the particles, as it does in bulk zirconia. Zirconia and YSZ particles were synthesized by improved sol-gel approaches using fatty acid stabilizers. The particles were heated to 1500 °C, and structural and morphological changes were monitored by SEM, ex situ XRD and high-energy in situ XRD. Zirconia particles (0.4-4.3 μm in diameter, 5-10% standard deviation) synthesized according to the modified sol-gel approaches yielded significantly improved monodispersities. As-synthesized amorphous particles transformed to the tetragonal phase at ∼450 °C with a volume decrease of up to ∼75% and then to monoclinic after heating from ∼650 to 850 °C. Submicron particles disintegrated at ∼850 °C and microparticles at ∼1200 °C due to grain growth. In situ XRD revealed that the transition from the amorphous to tetragonal phase was accompanied by relief in microstrain and the transition from tetragonal to monoclinic was correlated with the tetragonal grain size. Early crystallization and smaller initial grain sizes, which depend on the precursors used for particle synthesis, coincided with higher stability. Yttria-doping reduced grain growth, stabilized the tetragonal phase, and significantly improved the thermal stability of the particles. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Preparation and Characterization of Micronized Artemisinin via a Rapid Expansion of Supercritical Solutions (RESS) Method

PubMed Central

Yu, Huimin; Zhao, Xiuhua; Zu, Yuangang; Zhang, Xinjuan; Zu, Baishi; Zhang, Xiaonan

2012-01-01

The particle sizes of pharmaceutical substances are important for their bioavailability. Bioavailability can be improved by reducing the particle size of the drug. In this study, artemisinin was micronized by the rapid expansion of supercritical solutions (RESS). The particle size of the unprocessed white needle-like artemisinin particles was 30 to 1200 μm. The optimum micronization conditions are determined as follows: extraction temperature of 62 °C, extraction pressure of 25 MPa, precipitation temperature 45 °C and nozzle diameter of 1000 μm. Under the optimum conditions, micronized artemisinin with a (mean particle size) MPS of 550 nm is obtained. By analysis of variance (ANOVA), extraction temperature and pressure have significant effects on the MPS of the micronized artemisinin. The particle size of micronized artemisinin decreased with increasing extraction temperature and pressure. Moreover, the SEM, LC-MS, FTIR, DSC and XRD allowed the comparison between the crystalline initial state and the micronization particles obtained after the RESS process. The results showed that RESS process has not induced degradation of artemisinin and that processed artemisinin particles have lower crystallinity and melting point. The bulk density of artemisinin was determined before and after RESS process and the obtained results showed that it passes from an initial density of 0.554 to 0.128 g·cm−3 after the processing. The decrease in bulk density of the micronized powder can increase the liquidity of drug particles when they are applied for medicinal preparations. These results suggest micronized powder of artemisinin can be of great potential in drug delivery systems. PMID:22606030

Influence of Ni-P Coated SiC and Laser Scan Speed on the Microstructure and Mechanical Properties of IN625 Metal Matrix Composites

NASA Astrophysics Data System (ADS)

Sateesh, N. H.; Kumar, G. C. Mohan; Krishna, Prasad

2015-12-01

Nickel based Inconel-625 (IN625) metal matrix composites (MMCs) were prepared using pre-heated nickel phosphide (Ni-P) coated silicon carbide (SiC) reinforcement particles by Direct Metal Laser Sintering (DMLS) additive manufacturing process under inert nitrogen atmosphere to obtain interface influences on MMCs. The distribution of SiC particles and microstructures were characterized using optical and scanning electron micrographs, and the mechanical behaviours were thoroughly examined. The results clearly reveal that the interface integrity between the SiC particles and the IN625 matrix, the mixed powders flowability, the SiC ceramic particles and laser beam interaction, and the hardness, and tensile characteristics of the DMLS processed MMCs were improved effectively by the use of Ni-P coated SiC particles.

Improving particle beam acceleration in plasmas

NASA Astrophysics Data System (ADS)

C. de Sousa, M.; L. Caldas, I.

2018-04-01

The dynamics of wave-particle interactions in magnetized plasmas restricts the wave amplitude to moderate values for particle beam acceleration from rest energy. We analyze how a perturbing invariant robust barrier modifies the phase space of the system and enlarges the wave amplitude interval for particle acceleration. For low values of the wave amplitude, the acceleration becomes effective for particles with initial energy close to the rest energy. For higher values of the wave amplitude, the robust barrier controls chaos in the system and restores the acceleration process. We also determine the best position for the perturbing barrier in phase space in order to increase the final energy of the particles.

Improved particle swarm optimization algorithm for android medical care IOT using modified parameters.

PubMed

Sung, Wen-Tsai; Chiang, Yen-Chun

2012-12-01

This study examines wireless sensor network with real-time remote identification using the Android study of things (HCIOT) platform in community healthcare. An improved particle swarm optimization (PSO) method is proposed to efficiently enhance physiological multi-sensors data fusion measurement precision in the Internet of Things (IOT) system. Improved PSO (IPSO) includes: inertia weight factor design, shrinkage factor adjustment to allow improved PSO algorithm data fusion performance. The Android platform is employed to build multi-physiological signal processing and timely medical care of things analysis. Wireless sensor network signal transmission and Internet links allow community or family members to have timely medical care network services.

Observation of cosmic-ray particles with Z of 50 or greater and interpretation of the charge spectrum.

NASA Technical Reports Server (NTRS)

Blanford, G. E., Jr.; Friedlander, M. W.; Klarmann, J.; Walker, R. M.; Wefel, J. P.

1973-01-01

Large areas of plastic detectors and nuclear emulsions were exposed to the primary cosmic radiation on two high-altitude balloon flights in May 1968 and September 1969. From measurements on the tracks found in the scanning of the plastic detectors, events with charges Z greater than 50 were selected, and these data were consolidated with those from our earlier flights. Several conclusions can be drawn from the observed charge spectrum. The detection of trans-bismuth nuclei confirms earlier observations of these particles in the cosmic rays. However, no trans-uranium particles were observed. Detailed features of the charge spectrum cannot be explained by nuclei from r-process nucleosynthesis alone. Although the addition of particles following s-process abundances yields improved agreement, the spectrum appears more complicated than would result from a simple combination of r- and s-process abundances with identical propagation histories.

Performance, gut morphology and carcass characteristics of fattening rabbits as affected by particle size of pelleted diets.

PubMed

Tufarelli, Vincenzo; Desantis, Salvatore; Zizza, Sara; Laudadio, Vito

2010-10-01

A review of past literature revealed inconsistencies in recommended feed particle size for optimal growth and productive performance of rabbits. Changing diet formulation and subsequent processing conditions may improve pellet texture and potentially affect rabbit performance. In the current study, two isoenergetic and isonitrogenous pelleted diets were formulated, which varied in the particle size of the concentrates (2 and 8 mm, respectively). The objective was to evaluate the effect of different particle sizes of compound diets on performance, nutrient utilisation, gut morphology, and carcass characteristics of fattening Italian White breed rabbits. The finely ground diet led to a significant improvement in feed efficiency and apparent digestibility of crude protein, ether extract, crude fibre and NDF, without any negative effect on gut morphology. Furthermore, a smaller particle size of concentrates in pelleted diets improved carcass traits. Meat colour parameters showed significant differences in longissimus lumborum and biceps femoris due to dietary treatments, but in both muscles pH values 1 h and 24 h after slaughter remained unchanged. It is concluded that a finely ground pelleted diet can be used to improve growth performance of rabbits without affecting carcass parameters.

Production of drug nanosuspensions: effect of drug physical properties on nanosizing efficiency.

PubMed

Liu, Tao; Müller, Rainer H; Möschwitzer, Jan P

2018-02-01

Drug nanosuspension is one of the established methods to improve the bioavailability of poorly soluble drugs. Drug physical properties aspect (morphology, solid state, starting size et al) is a critical parameter determining the production efficiency. Some drug modification approaches such as spray-drying were proved to improve the millability of drug powders. However, the mechanism behind those improved performances is unclear. This study is to systematically investigate the influence of those physical properties. Five different APIs (active pharmaceutical ingredients) with different millabilities, i.e. resveratrol, hesperetin, glibenclamide, rutin, and quercetin, were processed by standard high pressure homogenization (HPH), wet bead milling (WBM), and a combinative method of spray-drying and HPH. Smaller starting sizes of certain APIs could accelerate the particle size reduction velocity during both HPH and WBM processes. Spherical particles were observed for almost all spray-dried powders (except spray-dried hesperetin) after spray-drying. The crystallinity of some spray-dried samples such as rutin and glibenclamide became much lower than their corresponding unmodified powders. Almost all spray-dried drug powders after HPH processes could lead to smaller nanocrystal particle size than unmodified APIs. The modified microstructure instead of solid state after spray-drying explained the potential reason for improved nanosizing efficiency. In addition, the contribution of starting size on the production efficiency was also critical according to both HPH and WBM results.

Parameter prediction based on Improved Process neural network and ARMA error compensation in Evaporation Process

NASA Astrophysics Data System (ADS)

Qian, Xiaoshan

2018-01-01

The traditional model of evaporation process parameters have continuity and cumulative characteristics of the prediction error larger issues, based on the basis of the process proposed an adaptive particle swarm neural network forecasting method parameters established on the autoregressive moving average (ARMA) error correction procedure compensated prediction model to predict the results of the neural network to improve prediction accuracy. Taking a alumina plant evaporation process to analyze production data validation, and compared with the traditional model, the new model prediction accuracy greatly improved, can be used to predict the dynamic process of evaporation of sodium aluminate solution components.

Engineered particles demonstrate improved flow properties at elevated drug loadings for direct compression manufacturing.

PubMed

Trementozzi, Andrea N; Leung, Cheuk-Yui; Osei-Yeboah, Frederick; Irdam, Erwin; Lin, Yiqing; MacPhee, J Michael; Boulas, Pierre; Karki, Shyam B; Zawaneh, Peter N

2017-05-15

Optimizing powder flow and compaction properties are critical for ensuring a robust tablet manufacturing process. The impact of flow and compaction properties of the active pharmaceutical ingredient (API) becomes progressively significant for higher drug load formulations, and for scaling up manufacturing processes. This study demonstrated that flow properties of a powder blend can be improved through API particle engineering, without critically impacting blend tabletability at elevated drug loadings. In studying a jet milled API (D 50 =24μm) and particle engineered wet milled API (D 50 =70μm and 90μm), flow functions of all API lots were similarly poor despite the vast difference in average particle size (ff c <4). This finding strays from the common notion that powder flow properties are directly correlated to particle size distribution. Upon adding excipients, however, clear trends in flow functions based on API particle size were observed. Wet milled API blends had a much improved flow function (ff c >10) compared with the jet milled API blends. Investigation of the compaction properties of both wet and jet milled powder blends also revealed that both jet and wet milled material produced robust tablets at the drug loadings used. The ability to practically demonstrate this uncommon observation that similarly poor flowing APIs can lead to a marked difference upon blending is important for pharmaceutical development. It is especially important in early phase development during API selection, and is advantageous particularly when material-sparing techniques are utilized. Copyright © 2017 Elsevier B.V. All rights reserved.

A highly scalable particle tracking algorithm using partitioned global address space (PGAS) programming for extreme-scale turbulence simulations

NASA Astrophysics Data System (ADS)

Buaria, D.; Yeung, P. K.

2017-12-01

A new parallel algorithm utilizing a partitioned global address space (PGAS) programming model to achieve high scalability is reported for particle tracking in direct numerical simulations of turbulent fluid flow. The work is motivated by the desire to obtain Lagrangian information necessary for the study of turbulent dispersion at the largest problem sizes feasible on current and next-generation multi-petaflop supercomputers. A large population of fluid particles is distributed among parallel processes dynamically, based on instantaneous particle positions such that all of the interpolation information needed for each particle is available either locally on its host process or neighboring processes holding adjacent sub-domains of the velocity field. With cubic splines as the preferred interpolation method, the new algorithm is designed to minimize the need for communication, by transferring between adjacent processes only those spline coefficients determined to be necessary for specific particles. This transfer is implemented very efficiently as a one-sided communication, using Co-Array Fortran (CAF) features which facilitate small data movements between different local partitions of a large global array. The cost of monitoring transfer of particle properties between adjacent processes for particles migrating across sub-domain boundaries is found to be small. Detailed benchmarks are obtained on the Cray petascale supercomputer Blue Waters at the University of Illinois, Urbana-Champaign. For operations on the particles in a 81923 simulation (0.55 trillion grid points) on 262,144 Cray XE6 cores, the new algorithm is found to be orders of magnitude faster relative to a prior algorithm in which each particle is tracked by the same parallel process at all times. This large speedup reduces the additional cost of tracking of order 300 million particles to just over 50% of the cost of computing the Eulerian velocity field at this scale. Improving support of PGAS models on major compilers suggests that this algorithm will be of wider applicability on most upcoming supercomputers.

Removal of bio-aerosols by water flow on surfaces in health-care settings

NASA Astrophysics Data System (ADS)

Yu, Han; Li, Yuguo

2016-11-01

Hand hygiene is one of the most important and efficient measures to prevent infections, however the compliance with hand hygiene remains poor especially for health-care workers. To improve this situation, the mechanisms of hand cleansing need to be explored and a detailed study on the adhesion interactions for bio-aerosols on hand surfaces and the process during particles removal by flow is significant for more efficient methods to decrease infections. The first part of presentation will focus on modelling adhesion interactions between particles, like bacteria and virus, and hand surfaces with roughness in water environment. The model presented is based on the DLVO and its extended theories. The removal process comes next, which will put forward a new model to describe the removal of particles by water flow. In this model, molecular dynamics is combined with particle motion and the results by the model will be compared with experiment results and existed models (RnR, Rock & Roll). Finally, possible improvement of the study and future design of experiments will be discussed.

Cold Spray Deposition of Ni and WC-Reinforced Ni Matrix Composite Coatings

NASA Astrophysics Data System (ADS)

Alidokht, S. A.; Vo, P.; Yue, S.; Chromik, R. R.

2017-12-01

Ni-WC composites are ideal protective coatings against wear and are often fabricated using laser cladding and thermal spray processes, but the high temperatures of these processes result in decarburization, which deteriorates the performance of the coating. Cold spray has the potential to deposit Ni-WC composite coatings and retain the composition of the initial WC feedstock. However, the insignificant plastic deformation of hard WC particles makes it difficult to build up a high WC content coating by cold spray. By using three different WC powder sizes, the effect of feedstock powder size on WC retention was tested. To improve WC retention, a WC/Ni composite powder in mixture with Ni was also sprayed. Microstructural characterization, including the deformed structure of Ni splats, retention, distribution, and fragmentation of WC, was performed by scanning electron microscopy. An improvement in WC retention was achieved using finer WC particles. Significant improvement in WC particles retention was achieved using WC/Ni composite powder, with the WC content in the coating being close to that of the feedstock.

Impacts of Future European Emission Reductions on Aerosol Particle Number Concentrations Accounting for Effects of Ammonia, Amines, and Organic Species.

PubMed

Julin, Jan; Murphy, Benjamin N; Patoulias, David; Fountoukis, Christos; Olenius, Tinja; Pandis, Spyros N; Riipinen, Ilona

2018-01-16

Although they are currently unregulated, atmospheric ultrafine particles (<100 nm) pose health risks because of, e.g., their capability to penetrate deep into the respiratory system. Ultrafine particles, often minor contributors to atmospheric particulate mass, typically dominate aerosol particle number concentrations. We simulated the response of particle number concentrations over Europe to recent estimates of future emission reductions of aerosol particles and their precursors. We used the chemical transport model PMCAMx-UF, with novel updates including state-of-the-art descriptions of ammonia and dimethylamine new particle formation (NPF) pathways and the condensation of organic compounds onto particles. These processes had notable impacts on atmospheric particle number concentrations. All three emission scenarios (current legislation, optimized emissions, and maximum technically feasible reductions) resulted in substantial (10-50%) decreases in median particle number concentrations over Europe. Consistent reductions were predicted in Central Europe, while Northern Europe exhibited smaller reductions or even increased concentrations. Motivated by the improved NPF descriptions for ammonia and methylamines, we placed special focus on the potential to improve air quality by reducing agricultural emissions, which are a major source of these species. Agricultural emission controls showed promise in reducing ultrafine particle number concentrations, although the change is nonlinear with particle size.

[Optimization of the parameters of microcirculatory structural adaptation model based on improved quantum-behaved particle swarm optimization algorithm].

PubMed

Pan, Qing; Yao, Jialiang; Wang, Ruofan; Cao, Ping; Ning, Gangmin; Fang, Luping

2017-08-01

The vessels in the microcirculation keep adjusting their structure to meet the functional requirements of the different tissues. A previously developed theoretical model can reproduce the process of vascular structural adaptation to help the study of the microcirculatory physiology. However, until now, such model lacks the appropriate methods for its parameter settings with subsequent limitation of further applications. This study proposed an improved quantum-behaved particle swarm optimization (QPSO) algorithm for setting the parameter values in this model. The optimization was performed on a real mesenteric microvascular network of rat. The results showed that the improved QPSO was superior to the standard particle swarm optimization, the standard QPSO and the previously reported Downhill algorithm. We conclude that the improved QPSO leads to a better agreement between mathematical simulation and animal experiment, rendering the model more reliable in future physiological studies.

The design and scale-up of spray dried particle delivery systems.

PubMed

Al-Khattawi, Ali; Bayly, Andrew; Phillips, Andrew; Wilson, David

2018-01-01

The rising demand for pharmaceutical particles with tailored physicochemical properties has opened new markets for spray drying especially for solubility enhancement, improving inhalation medicines and stabilization of biopharmaceuticals. Despite this, the spray drying literature is scattered and often does not address the principles underpinning robust development of pharmaceuticals. It is therefore necessary to present clearer picture of the field and highlight the factors influencing particle design and scale-up. Areas covered: The review presents a systematic analysis of the trends in development of particle delivery systems using spray drying. This is followed by exploring the mechanisms governing particle formation in the process stages. Particle design factors including those of equipment configurations and feed/process attributes were highlighted. Finally, the review summarises the current industrial approaches for upscaling pharmaceutical spray drying. Expert opinion: Spray drying provides the ability to design particles of the desired functionality. This greatly benefits the pharmaceutical sector especially as product specifications are becoming more encompassing and exacting. One of the biggest barriers to product translation remains one of scale-up/scale-down. A shift from trial and error approaches to model-based particle design helps to enhance control over product properties. To this end, process innovations and advanced manufacturing technologies are particularly welcomed.

Possibilities for preservation of coarse particles in pelleting process to improve feed quality characteristics.

PubMed

Vukmirović, D; Fišteš, A; Lević, J; Čolović, R; Rakić, D; Brlek, T; Banjac, V

2017-10-01

Poultry diets are mainly used in pelleted form because pellets have many advantages compared to mash feed. On the other hand, pelleting causes reduction of feed particle size. The aim of this research was to investigate the possibility of increasing the content of coarse particles in pellets, and, at the same time, to produce pellets with satisfactory quality. In this research, the three grinding treatments of corn were applied using hammer mill with three sieve openings diameter: 3 mm (HM-3), 6 mm (HM-6) and 9 mm (HM-9). These grinding treatments were combined in pelleting process with three gaps between rollers and the die of pellet press (roller-die gap, RDG) (0.30, 1.15 and 2.00 mm) and three moisture contents of the pelleted material (14.5, 16.0 and 17.5%). The increased coarseness of grinding by the hammer mill resulted in the increased amount of coarse particles in pellets, especially when the smallest RDG was applied (0.30 mm), but pellet quality was greatly reduced. Increasing of RDG improved the quality of pellets produced from coarsely ground corn, but reduced the content of coarse particles in pellets and increased specific energy consumption of the pellet press. Increasing the moisture content of material to be pelleted (MC) significantly reduced energy consumption of the pellet press, but there was no significant influence of MC on particle size after pelleting and on the pellet quality. The optimal values of the pelleting process parameters were determined using desirability function method. The results of optimization process showed that to achieve the highest possible quantity of coarse particles in the pellets, and to produce pellets of satisfactory quality, with the lowest possible energy consumption of the pellet press, the coarsest grinding on hammer mill (HM-9), the largest RDG (2 mm) and the highest MC (17.5%) should be applied. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

Highly compressible fluorescent particles for pressure sensing in liquids

NASA Astrophysics Data System (ADS)

Cellini, F.; Peterson, S. D.; Porfiri, M.

2017-05-01

Pressure sensing in liquids is important for engineering applications ranging from industrial processing to naval architecture. Here, we propose a pressure sensor based on highly compressible polydimethylsiloxane foam particles embedding fluorescent Nile Red molecules. The particles display pressure sensitivities as low as 0.0018 kPa-1, which are on the same order of magnitude of sensitivities reported in commercial pressure-sensitive paints for air flows. We envision the application of the proposed sensor in particle image velocimetry toward an improved understanding of flow kinetics in liquids.

An Improved Quantum-Behaved Particle Swarm Optimization Algorithm with Elitist Breeding for Unconstrained Optimization.

PubMed

Yang, Zhen-Lun; Wu, Angus; Min, Hua-Qing

2015-01-01

An improved quantum-behaved particle swarm optimization with elitist breeding (EB-QPSO) for unconstrained optimization is presented and empirically studied in this paper. In EB-QPSO, the novel elitist breeding strategy acts on the elitists of the swarm to escape from the likely local optima and guide the swarm to perform more efficient search. During the iterative optimization process of EB-QPSO, when criteria met, the personal best of each particle and the global best of the swarm are used to generate new diverse individuals through the transposon operators. The new generated individuals with better fitness are selected to be the new personal best particles and global best particle to guide the swarm for further solution exploration. A comprehensive simulation study is conducted on a set of twelve benchmark functions. Compared with five state-of-the-art quantum-behaved particle swarm optimization algorithms, the proposed EB-QPSO performs more competitively in all of the benchmark functions in terms of better global search capability and faster convergence rate.

Design Guidelines for High-Performance Particle-Based Photoanodes for Water Splitting: Lanthanum Titanium Oxynitride as a Model.

PubMed

Landsmann, Steve; Maegli, Alexandra E; Trottmann, Matthias; Battaglia, Corsin; Weidenkaff, Anke; Pokrant, Simone

2015-10-26

Semiconductor powders are perfectly suited for the scalable fabrication of particle-based photoelectrodes, which can be used to split water using the sun as a renewable energy source. This systematic study is focused on variation of the electrode design using LaTiO2 N as a model system. We present the influence of particle morphology on charge separation and transport properties combined with post-treatment procedures, such as necking and size-dependent co-catalyst loading. Five rules are proposed to guide the design of high-performance particle-based photoanodes by adding or varying several process steps. We also specify how much efficiency improvement can be achieved using each of the steps. For example, implementation of a connectivity network and surface area enhancement leads to thirty times improvement in efficiency and co-catalyst loading achieves an improvement in efficiency by a factor of seven. Some of these guidelines can be adapted to non-particle-based photoelectrodes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Itraconazole solid dispersion prepared by a supercritical fluid technique: preparation, in vitro characterization, and bioavailability in beagle dogs.

PubMed

Yin, Xuezhi; Daintree, Linda Sharon; Ding, Sheng; Ledger, Daniel Mark; Wang, Bing; Zhao, Wenwen; Qi, Jianping; Wu, Wei; Han, Jiansheng

2015-01-01

This research aimed to develop a supercritical fluid (SCF) technique for preparing a particulate form of itraconazole (ITZ) with good dissolution and bioavailability characteristics. The ITZ particulate solid dispersion was formulated with hydroxypropyl methylcellulose, Pluronic F-127, and L-ascorbic acid. Aggregated particles showed porous structure when examined by scanning electron microscopy. Powder X-ray diffraction and Fourier transform infrared spectra indicated an interaction between ITZ and excipients and showed that ITZ existed in an amorphous state in the composite solid dispersion particles. The solid dispersion obtained by the SCF process improved the dissolution of ITZ in media of pH 1.0, pH 4.5, and pH 6.8, compared with a commercial product (Sporanox(®)), which could be ascribed to the porous aggregated particle shape and amorphous solid state of ITZ. While the solid dispersion did not show a statistical improvement (P=0.50) in terms of oral bioavailability of ITZ compared with Sporanox(®), the C max (the maximum plasma concentration of ITZ in a pharmacokinetic curve) of ITZ was raised significantly (P=0.03) after oral administration. Thus, the SCF process has been shown to be an efficient, single step process to form ITZ-containing solid dispersion particles with good dissolution and oral bioavailability characteristics.

Effects of ultrasonic vibration on microstructure and mechanical properties of nano-sized SiC particles reinforced Al-5Cu composites.

PubMed

Li, Jianyu; Lü, Shulin; Wu, Shusen; Gao, Qi

2018-04-01

Ultrasonic vibration (UV) treatment has been successfully applied to improve the particles distribution of nano-sized SiC particles (SiC p ) reinforced Al-5Cu alloy matrix composites which were prepared by combined processes of dry high energy ball milling and squeeze casting. When UV treatment is applied, the distribution of nano-sized SiC p has been greatly improved. After UV for 1 min, large particles aggregates are broken up into small aggregates due to effects of cavitation and the acoustic streaming. After UV for 5 min, all the particles aggregates are dispersed and the particles are uniformly distributed in the composites. Compared with the Al-5Cu matrix alloy, the ultimate tensile strength, yield strength and elongation of the 1 wt% nano-sized SiC p /Al-5Cu composites treated by UV for 5 min are 270 MPa, 173 MPa and 13.3%, which are increased by 7.6%, 6.8% and 29%, respectively. The improvements of mechanical properties after UV are attributed to the uniform distribution of nano particles, grain refinement of aluminum matrix alloy and reduction of porosity in the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

Image segmentation for uranium isotopic analysis by SIMS: Combined adaptive thresholding and marker controlled watershed approach

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

Willingham, David G.; Naes, Benjamin E.; Heasler, Patrick G.

A novel approach to particle identification and particle isotope ratio determination has been developed for nuclear safeguard applications. This particle search approach combines an adaptive thresholding algorithm and marker-controlled watershed segmentation (MCWS) transform, which improves the secondary ion mass spectrometry (SIMS) isotopic analysis of uranium containing particle populations for nuclear safeguards applications. The Niblack assisted MCWS approach (a.k.a. SEEKER) developed for this work has improved the identification of isotopically unique uranium particles under conditions that have historically presented significant challenges for SIMS image data processing techniques. Particles obtained from five NIST uranium certified reference materials (CRM U129A, U015, U150, U500more » and U850) were successfully identified in regions of SIMS image data 1) where a high variability in image intensity existed, 2) where particles were touching or were in close proximity to one another and/or 3) where the magnitude of ion signal for a given region was count limited. Analysis of the isotopic distributions of uranium containing particles identified by SEEKER showed four distinct, accurately identified 235U enrichment distributions, corresponding to the NIST certified 235U/238U isotope ratios for CRM U129A/U015 (not statistically differentiated), U150, U500 and U850. Additionally, comparison of the minor uranium isotope (234U, 235U and 236U) atom percent values verified that, even in the absence of high precision isotope ratio measurements, SEEKER could be used to segment isotopically unique uranium particles from SIMS image data. Although demonstrated specifically for SIMS analysis of uranium containing particles for nuclear safeguards, SEEKER has application in addressing a broad set of image processing challenges.« less

A hybrid artificial bee colony algorithm for numerical function optimization

NASA Astrophysics Data System (ADS)

Alqattan, Zakaria N.; Abdullah, Rosni

2015-02-01

Artificial Bee Colony (ABC) algorithm is one of the swarm intelligence algorithms; it has been introduced by Karaboga in 2005. It is a meta-heuristic optimization search algorithm inspired from the intelligent foraging behavior of the honey bees in nature. Its unique search process made it as one of the most competitive algorithm with some other search algorithms in the area of optimization, such as Genetic algorithm (GA) and Particle Swarm Optimization (PSO). However, the ABC performance of the local search process and the bee movement or the solution improvement equation still has some weaknesses. The ABC is good in avoiding trapping at the local optimum but it spends its time searching around unpromising random selected solutions. Inspired by the PSO, we propose a Hybrid Particle-movement ABC algorithm called HPABC, which adapts the particle movement process to improve the exploration of the original ABC algorithm. Numerical benchmark functions were used in order to experimentally test the HPABC algorithm. The results illustrate that the HPABC algorithm can outperform the ABC algorithm in most of the experiments (75% better in accuracy and over 3 times faster).

Surface modification of acetaminophen particles by atomic layer deposition.

PubMed

Kääriäinen, Tommi O; Kemell, Marianna; Vehkamäki, Marko; Kääriäinen, Marja-Leena; Correia, Alexandra; Santos, Hélder A; Bimbo, Luis M; Hirvonen, Jouni; Hoppu, Pekka; George, Steven M; Cameron, David C; Ritala, Mikko; Leskelä, Markku

2017-06-15

Active pharmaceutical ingredients (APIs) are predominantly organic solid powders. Due to their bulk properties many APIs require processing to improve pharmaceutical formulation and manufacturing in the preparation for various drug dosage forms. Improved powder flow and protection of the APIs are often anticipated characteristics in pharmaceutical manufacturing. In this work, we have modified acetaminophen particles with atomic layer deposition (ALD) by conformal nanometer scale coatings in a one-step coating process. According to the results, ALD, utilizing common chemistries for Al 2 O 3 , TiO 2 and ZnO, is shown to be a promising coating method for solid pharmaceutical powders. Acetaminophen does not undergo degradation during the ALD coating process and maintains its stable polymorphic structure. Acetaminophen with nanometer scale ALD coatings shows slowed drug release. ALD TiO 2 coated acetaminophen particles show cytocompatibility whereas those coated with thicker ZnO coatings exhibit the most cytotoxicity among the ALD materials under study when assessed in vitro by their effect on intestinal Caco-2 cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Vision system and three-dimensional modeling techniques for quantification of the morphology of irregular particles

NASA Astrophysics Data System (ADS)

Smith, Lyndon N.; Smith, Melvyn L.

2000-10-01

Particulate materials undergo processing in many industries, and therefore there are significant commercial motivators for attaining improvements in the flow and packing behavior of powders. This can be achieved by modeling the effects of particle size, friction, and most importantly, particle shape or morphology. The method presented here for simulating powders employs a random number generator to construct a model of a random particle by combining a sphere with a number of smaller spheres. The resulting 3D model particle has a nodular type of morphology, which is similar to that exhibited by the atomized powders that are used in the bulk of powder metallurgy (PM) manufacture. The irregularity of the model particles is dependent upon vision system data gathered from microscopic analysis of real powder particles. A methodology is proposed whereby randomly generated model particles of various sized and irregularities can be combined in a random packing simulation. The proposed Monte Carlo technique would allow incorporation of the effects of gravity, wall friction, and inter-particle friction. The improvements in simulation realism that this method is expected to provide would prove useful for controlling powder production, and for predicting die fill behavior during the production of PM parts.

Optimizing surface finishing processes through the use of novel solvents and systems

NASA Astrophysics Data System (ADS)

Quillen, M.; Holbrook, P.; Moore, J.

2007-03-01

As the semiconductor industry continues to implement the ITRS (International Technology Roadmap for Semiconductors) node targets that go beyond 45nm [1], the need for improved cleanliness between repeated process steps continues to grow. Wafer cleaning challenges cover many applications such as Cu/low-K integration, where trade-offs must be made between dielectric damage and residue by plasma etching and CMP or moisture uptake by aqueous cleaning products. [2-5] Some surface sensitive processes use the Marangoni tool design [6] where a conventional solvent such as IPA (isopropanol), combines with water to provide improved physical properties such as reduced contact angle and surface tension. This paper introduces the use of alternative solvents and their mixtures compared to pure IPA in removing ionics, moisture, and particles using immersion bench-chemistry models of various processes. A novel Eastman proprietary solvent, Eastman methyl acetate is observed to provide improvement in ionic, moisture capture, and particle removal, as compared to conventional IPA. [7] These benefits may be improved relative to pure IPA, simply by the addition of various additives. Some physical properties of the mixtures were found to be relatively unchanged even as measured performance improved. This report presents our attempts to cite and optimize these benefits through the use of laboratory models.

Maximization of DRAM yield by control of surface charge and particle addition during high dose implantation

NASA Astrophysics Data System (ADS)

Horvath, J.; Moffatt, S.

1991-04-01

Ion implantation processing exposes semiconductor devices to an energetic ion beam in order to deposit dopant ions in shallow layers. In addition to this primary process, foreign materials are deposited as particles and surface films. The deposition of particles is a major cause of IC yield loss and becomes even more significant as device dimensions are decreased. Control of particle addition in a high-volume production environment requires procedures to limit beamline and endstation sources, control of particle transport, cleaning procedures and a well grounded preventative maintenance philosophy. Control of surface charge by optimization of the ion beam and electron shower conditions and measurement with a real-time charge sensor has been effective in improving the yield of NMOS and CMOS DRAMs. Control of surface voltages to a range between 0 and -20 V was correlated with good implant yield with PI9200 implanters for p + and n + source-drain implants.

Extended wavelet transformation to digital holographic reconstruction: application to the elliptical, astigmatic Gaussian beams.

PubMed

Remacha, Clément; Coëtmellec, Sébastien; Brunel, Marc; Lebrun, Denis

2013-02-01

Wavelet analysis provides an efficient tool in numerous signal processing problems and has been implemented in optical processing techniques, such as in-line holography. This paper proposes an improvement of this tool for the case of an elliptical, astigmatic Gaussian (AEG) beam. We show that this mathematical operator allows reconstructing an image of a spherical particle without compression of the reconstructed image, which increases the accuracy of the 3D location of particles and of their size measurement. To validate the performance of this operator we have studied the diffraction pattern produced by a particle illuminated by an AEG beam. This study used mutual intensity propagation, and the particle is defined as a chirped Gaussian sum. The proposed technique was applied and the experimental results are presented.

Blob-enhanced reconstruction technique

NASA Astrophysics Data System (ADS)

Castrillo, Giusy; Cafiero, Gioacchino; Discetti, Stefano; Astarita, Tommaso

2016-09-01

A method to enhance the quality of the tomographic reconstruction and, consequently, the 3D velocity measurement accuracy, is presented. The technique is based on integrating information on the objects to be reconstructed within the algebraic reconstruction process. A first guess intensity distribution is produced with a standard algebraic method, then the distribution is rebuilt as a sum of Gaussian blobs, based on location, intensity and size of agglomerates of light intensity surrounding local maxima. The blobs substitution regularizes the particle shape allowing a reduction of the particles discretization errors and of their elongation in the depth direction. The performances of the blob-enhanced reconstruction technique (BERT) are assessed with a 3D synthetic experiment. The results have been compared with those obtained by applying the standard camera simultaneous multiplicative reconstruction technique (CSMART) to the same volume. Several blob-enhanced reconstruction processes, both substituting the blobs at the end of the CSMART algorithm and during the iterations (i.e. using the blob-enhanced reconstruction as predictor for the following iterations), have been tested. The results confirm the enhancement in the velocity measurements accuracy, demonstrating a reduction of the bias error due to the ghost particles. The improvement is more remarkable at the largest tested seeding densities. Additionally, using the blobs distributions as a predictor enables further improvement of the convergence of the reconstruction algorithm, with the improvement being more considerable when substituting the blobs more than once during the process. The BERT process is also applied to multi resolution (MR) CSMART reconstructions, permitting simultaneously to achieve remarkable improvements in the flow field measurements and to benefit from the reduction in computational time due to the MR approach. Finally, BERT is also tested on experimental data, obtaining an increase of the signal-to-noise ratio in the reconstructed flow field and a higher value of the correlation factor in the velocity measurements with respect to the volume to which the particles are not replaced.

The effect of process parameters in Aluminum Metal Matrix Composites with Powder Metallurgy

NASA Astrophysics Data System (ADS)

Vani, Vemula Vijaya; Chak, Sanjay Kumar

2018-06-01

Metal Matrix Composites are developed in recent years as an alternative over conventional engineering materials due to their improved properties. Among all, Aluminium Matrix Composites (AMCs) are increasing their demand due to low density, high strength-to-weight ratio, high toughness, corrosion resistance, higher stiffness, improved wear resistance, increased creep resistance, low co-efficient of thermal expansion, improved high temperature properties. Major applications of these materials have been in aerospace, automobile, military. There are different processing techniques for the fabrication of AMCs. Powder metallurgy is a one of the most promising and versatile routes for fabrication of particle reinforced AMCs as compared to other manufacturing methods. This method ensures the good wettability between matrix and reinforcement, homogeneous microstructure of the fabricated MMC, and prevents the formation of any undesirable phases. This article addresses mainly on the effect of process parameters like sintering time, temperature and particle size on the microstructure of aluminum metal matrix composites.

Drug recrystallization using supercritical anti-solvent (SAS) process with impinging jets: Effect of process parameters

NASA Astrophysics Data System (ADS)

Careno, Stéphanie; Boutin, Olivier; Badens, Elisabeth

2012-03-01

The aim of this study is to improve mixing in supercritical anti-solvent process (SAS) with impinging jets in order to form finer particles of sulfathiazole, a poorly water-soluble drug. The influence of several process parameters upon the powder characteristics is studied. Parameters are jets' velocity (0.25 m s-1 to 25.92 m s-1), molar ratio solvent/CO2 (2.5% to 20%), temperature (313 K to 343 K), pressure (10 MPa to 20 MPa) and sulfathiazole concentration in the organic solution (0.5% to 1.8%). Two solvents are used: acetone and methanol. Smaller particles with a more homogeneous morphology are obtained from acetone solutions. For the smallest jets' velocity, corresponding to a non-atomized jet, the stable polymorphic form is obtained, pure or in mixture. At this velocity, pressure is the most influential parameter controlling the polymorphic nature of the powder formed. The pure stable polymorph is formed at 20 MPa. Concerning the particle size, the most influential parameters are temperature and sulfathiazole concentration. The use of impinging jets with different process parameters allows the crystallization of four polymorphs among the five known, and particle sizes are varied. This work demonstrates the studied device ability of the polymorph and the size control. A comparison with the classical SAS process shows that particle size, size distribution and morphology of particles crystallized with impinging jets are different from the ones obtained with classical SAS introduction device in similar operating conditions. Mean particle sizes are significantly smaller and size distributions are narrower with impinging jets device.

Co-processing as a tool to improve aqueous dispersibility of cellulose ethers.

PubMed

Sharma, Payal; Modi, Sameer R; Bansal, Arvind K

2015-01-01

Cellulose ethers are important materials with numerous applications in pharmaceutical industry. They are widely employed as stabilizers and viscosity enhancers for dispersed systems, binders in granulation process and as film formers for tablets. These polymers, however, exhibit challenge during preparation of their aqueous dispersions. Rapid hydration of their surfaces causes formation of a gel that prevents water from reaching the inner core of the particle. Moreover, the surfaces of these particles become sticky, thus leading to agglomeration, eventually reducing their dispersion kinetics. Numerous procedures have been tested to improve dispersibility of cellulose ethers. These include the use of cross-linking agents, alteration in the synthesis process, adjustment of water content of cellulose ether, modification by attaching hydrophobic substituents and co-processing using various excipients. Among these, co-processing has provided the most encouraging results. This review focuses on the molecular mechanisms responsible for the poor dispersibility of cellulose ethers and the role of co-processing technologies in overcoming the challenge. An attempt has been made to highlight various co-processing techniques and specific role of excipients used for co-processing.

Metal regeneration of iron chelates in nitric oxide scrubbing

DOEpatents

Chang, Shih-Ger; Littlejohn, David; Shi, Yao

1997-08-19

The present invention relates to a process of using metal particles to reduce NO to NH.sub.3. More specifically, the invention concerns an improved process to regenerate iron (II) (CHELATE) by reduction of iron (II) (CHELATE) (NO) complex, which process comprises: a) contacting an aqueous solution containing iron (II) (CHELATE) (NO) with metal particles at between about 20.degree. and 90.degree. C. to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution.

Metal regeneration of iron chelates in nitric oxide scrubbing

DOEpatents

Chang, S.G.; Littlejohn, D.; Shi, Y.

1997-08-19

The present invention relates to a process of using metal particles to reduce NO to NH{sub 3}. More specifically, the invention concerns an improved process to regenerate iron (II) (CHELATE) by reduction of iron (II) (CHELATE) (NO) complex, which process comprises: (a) contacting an aqueous solution containing iron (II) (CHELATE) (NO) with metal particles at between about 20 and 90 C to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution. 34 figs.

Synthesis, characterization, and evaluation of a superficially porous particle with unique, elongated pore channels normal to the surface.

PubMed

Wei, Ta-Chen; Mack, Anne; Chen, Wu; Liu, Jia; Dittmann, Monika; Wang, Xiaoli; Barber, William E

2016-04-01

In recent years, superficially porous particles (SPPs) have drawn great interest because of their special particle characteristics and improvement in separation efficiency. Superficially porous particles are currently manufactured by adding silica nanoparticles onto solid cores using either a multistep multilayer process or one-step coacervation process. The pore size is mainly controlled by the size of the silica nanoparticles and the tortuous pore channel geometry is determined by how those nanoparticles randomly aggregate. Such tortuous pore structure is also similar to that of all totally porous particles used in HPLC today. In this article, we report on the development of a next generation superficially porous particle with a unique pore structure that includes a thinner shell thickness and ordered pore channels oriented normal to the particle surface. The method of making the new superficially porous particles is a process called pseudomorphic transformation (PMT), which is a form of micelle templating. Porosity is no longer controlled by randomly aggregated nanoparticles but rather by micelles that have an ordered liquid crystal structure. The new particle possesses many advantages such as a narrower particle size distribution, thinner porous layer with high surface area and, most importantly, highly ordered, non-tortuous pore channels oriented normal to the particle surface. This PMT process has been applied to make 1.8-5.1μm SPPs with pore size controlled around 75Å and surface area around 100m(2)/g. All particles with different sizes show the same unique pore structure with tunable pore size and shell thickness. The impact of the novel pore structure on the performance of these particles is characterized by measuring van Deemter curves and constructing kinetic plots. Reduced plate heights as low as 1.0 have been achieved on conventional LC instruments. This indicates higher efficiency of such particles compared to conventional totally porous and superficially porous particles. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and evaluation of advanced electrocatalysts for phosphoric acid fuel cells

NASA Technical Reports Server (NTRS)

Stonehart, P.; Baris, J.; Hochmuth, J.; Pagliaro, P.

1981-01-01

Two cooperative phenomena are required the development of highly efficient porous electrocatalysts: (1) is an increase in the electrocatalytic activity of the catalyst particle; and (2) is the availability of that electrocatalyst particle for the electromechanical reaction. The two processes interact with each other so that improvements in the electrochemical activity must be coupled with improvements in the availability of the electrocatalyst for reaction. Cost effective and highly reactive electrocatalysts were developed. The utilization of the electrocatalyst particles in the porous electrode structures was analyzed. It is shown that a large percentage of the electrocatalyst in anode structures is not utilized. This low utilization translates directly into a noble metal cost penalty for the fuel cell.

Ultrasonic assisted hot metal powder compaction.

PubMed

Abedini, Rezvan; Abdullah, Amir; Alizadeh, Yunes

2017-09-01

Hot pressing of metal powders is used in production of parts with similar properties to wrought materials. During hot pressing processes, particle rearrangement, plastic deformation, creep, and diffusion are of the most effective powder densification mechanisms. Applying ultrasonic vibration is thought to result in great rates of densification and therefore higher efficiency of the process is expected. This paper deals with the effects of power ultrasonic on the densification of AA1100 aluminum powder under constant applied stress. The effects of particle size and process temperature on the densification behavior are discussed. The results show that applying ultrasonic vibration leads to an improved homogeneity and a higher relative density. Also, it is found that the effect of ultrasonic vibration is greater for finer particles. Copyright © 2016 Elsevier B.V. All rights reserved.

Selective Laser Sintering of Nano Al2O3 Infused Polyamide

PubMed Central

Warnakula, Anthony; Singamneni, Sarat

2017-01-01

Nano Al2O3 polyamide composites are evaluated for processing by selective laser sintering. A thermal characterization of the polymer composite powders allowed us to establish the possible initial settings. Initial experiments are conducted to identify the most suitable combinations of process parameters. Based on the results of the initial trials, more promising ranges of different process parameters could be identified. The post sintering characterization showed evidence of sufficient inter-particle sintering and intra-layer coalescence. While the inter-particle coalescence gradually improved, the porosity levels slightly decreased with increasing laser power. The nano-filler particles tend to agglomerate around the beads along the solid tracks, possibly due to Van der Walls forces. The tensile stress results showed an almost linear increase with increasing nano-filler content. PMID:28773220

Snow-borne nanosized particles: Abundance, distribution, composition, and significance in ice nucleation processes

NASA Astrophysics Data System (ADS)

Rangel-Alvarado, Rodrigo Benjamin; Nazarenko, Yevgen; Ariya, Parisa A.

2015-11-01

Physicochemical processes of nucleation constitute a major uncertainty in understanding aerosol-cloud interactions. To improve the knowledge of the ice nucleation process, we characterized physical, chemical, and biological properties of fresh snow using a suite of state-of-the-art techniques based on mass spectrometry, electron microscopy, chromatography, and optical particle sizing. Samples were collected at two North American Arctic sites, as part of international campaigns (2006 and 2009), and in the city of Montreal, Canada, over the last decade. Particle size distribution analyses, in the range of 3 nm to 10 µm, showed that nanosized particles are the most numerous (38-71%) in fresh snow, with a significant portion (11 to 19%) less than 100 nm in size. Particles with diameters less than 200 nm consistently exhibited relatively high ice-nucleating properties (on average ranged from -19.6 ± 2.4 to -8.1 ± 2.6°C). Chemical analysis of the nanosized fraction suggests that they contain bioorganic materials, such as amino acids, as well as inorganic compounds with similar characteristics to mineral dust. The implication of nanoparticle ubiquity and abundance in diverse snow ecosystems are discussed in the context of their importance in understanding atmospheric nucleation processes.

Improved physicochemical characteristics of felodipine solid dispersion particles by supercritical anti-solvent precipitation process.

PubMed

Won, Dong-Han; Kim, Min-Soo; Lee, Sibeum; Park, Jeong-Sook; Hwang, Sung-Joo

2005-09-14

Solid dispersions of felodipine were formulated with HPMC and surfactants by the conventional solvent evaporation (CSE) and supercritical anti-solvent precipitation (SAS) methods. The solid dispersion particles were characterized by particle size, zeta potential, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), solubility and dissolution studies. The effects of the drug/polymer ratio and surfactants on the solubility of felodipine were also studied. The mean particle size of the solid dispersions was 200-250 nm; these had a relatively regular spherical shape with a narrow size distribution. The particle size of the solid dispersions from the CSE method increased at 1 h after dispersed in distilled water. However, the particle sizes of solid dispersions from the SAS process were maintained for 6 h due to the increased solubility of felodipine. The physical state of felodipine changed from crystalline to amorphous during the CSE and SAS processes, confirmed by DSC/XRD data. The equilibrium solubility of the felodipine solid dispersion prepared by the SAS process was 1.5-20 microg/ml, while the maximum solubility was 35-110 microg/ml. Moreover, the solubility of felodipine increased with decreasing drug/polymer ratio or increasing HCO-60 content. The solid dispersions from the SAS process showed a high dissolution rate of over 90% within 2 h. The SAS process system may be used to enhance solubility or to produce oral dosage forms with high dissolution rate.

Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event

NASA Astrophysics Data System (ADS)

Xu, Lingling; Chen, Jinsheng

2016-04-01

Single particle aerosol mass spectrometer (SPAMS) was used to characterize size distribution, chemical composition, and mixing state of particles in an atmospheric pollution event during 20 Oct. - 5 Nov., 2015 in Xiamen, Southeast China. A total of 533,012 particle mass spectra were obtained and clustered into six groups, comprising of industry metal (4.5%), dust particles (2.6%), carbonaceous species (70.7%), K-Rich particles (20.7%), seasalt (0.6%) and other particles (0.9%). Carbonaceous species were further divided into EC (70.6%), OC (28.5%), and mixed ECOC (0.9%). There were 61.7%, 58.3%, 4.0%, and 14.6% of particles internally mixed with sulfate, nitrate, ammonium and C2H3O, respectively, indicating that these particles had undergone significant aging processing. Sulfate was preferentially mixed with carbonaceous particles, while nitrate tended to mix with metal-containing and dust particles. Compared to clear days, the fractions of EC-, metal- and dust particles remarkably increased, while the fraction of OC-containing particles decreased in pollution days. The mixing state of particles, excepted for OC-containing particles with secondary species was much stronger in pollution days than that in clear days, which revealed the significant influence of secondary particles in atmospheric pollution. The different activity of OC-containing particles might be related to their much smaller aerodynamic diameter. These results could improve our understanding of aerosol characteristics and could be helpful to further investigate the atmospheric process of particles.

Improved Wear Resistance of Low Carbon Steel with Plasma Melt Injection of WC Particles

NASA Astrophysics Data System (ADS)

Liu, Aiguo; Guo, Mianhuan; Hu, Hailong

2010-08-01

Surface of a low carbon steel Q235 substrate was melted by a plasma torch, and tungsten carbide (WC) particles were injected into the melt pool. WC reinforced surface metal matrix composite (MMC) was synthesized. Dry sliding wear behavior of the surface MMC was studied and compared with the substrate. The results show that dry sliding wear resistance of low carbon steel can be greatly improved by plasma melt injection of WC particles. Hardness of the surface MMC is much higher than that of the substrate. The high hardness lowers the adhesion and abrasion of the surface MMC, and also the friction coefficient of it. The oxides formed in the sliding process also help to lower the friction coefficient. In this way, the dry sliding wear resistance of the surface MMC is greatly improved.

Evaluation of minimum quantity lubrication grinding with nano-particles and recent related patents.

PubMed

Li, Changhe; Wang, Sheng; Zhang, Qiang; Jia, Dongzhou

2013-06-01

In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a supply system for the grinding fluid in nano-particle jet MQL, which produced MQL lubricant by adding solid nano-particles in degradable grinding fluid. The MQL supply device turns the lubricant to the pulse drops with fixed pressure, unchanged pulse frequency and the same drop diameter. The drops will be produced and injected in the grinding zone in the form of jet flow under high pressure gas and air seal. As people become increasingly demanding on our environment, minimum quantity lubrication has been widely used in the grinding and processing. Yet, it presents the defect of insufficient cooling performance, which confines its development. To improve the heat transfer efficiency of MQL, nano-particles of a certain mass fraction can be added in the minimum quantity of lubricant oil, which concomitantly will improve the lubrication effects in the processing. In this study, the grinding experiment corroborated the effect of nano-particles in surface grinding. In addition, compared with other forms of lubrication, the results presented that the grinding force, the friction coefficient and specific grinding energy of MQL grinding have been significantly weakened, while G ratio greatly rose. These are attributed to the friction oil-film with excellent anti-friction and anti-wear performance, which is generated nano-particles at the wheel/workpiece interface. In this research, the cooling performance of nano-particle jet MQL was analyzed. Based on tests and experiments, the surface temperature was assayed from different methods, including flood lubricating oil, dry grinding, MQL grinding and nano-particle jet MQL grinding. Because of the outstanding heat transfer performance of nano-particles, the ratio of heat delivered by grinding media was increased, leading to lower temperature in the grinding zone. Results demonstrate that nano-particle jet MQL has satisfactory cooling performance as well as a promising future of extensive application.

Tribological Characteristics of Submicron SiC(p)-GR(p)/Zn-35Al-1Mg Composites in Semisolidification Casting process

NASA Astrophysics Data System (ADS)

Liu, S.; Fang, Z. W.; Li, L. X.

2018-05-01

Uniform SiC(p)-GR(p)/Zn-35Al-1Mg composites were prepared by powder pressing and semisolidification stirring-casting process by adding submicron silicon carbide and graphite reinforcement particles in an aluminum-zinc alloy matrix. Micro Vickers hardness and microstructures of the novel composites were studied, and their wear properties and wear temperature were measured for different load and friction conditions. The results show that silicon carbide and graphite particles homogeneously mix in the matrix, while contained silicon carbide particles improve the matrix hardness to 8.4%, graphite improves the matrix hardness to 16.8%, but two of them, combined, reduce the matrix hardness to 7.6%; the rate of temperature rise of the zinc-aluminum matrix alloy is the highest than the other three composites and is up to 48.5° C/s at 1.69MPa. At 0.56MPa and sliding 26.4km, the graphite composite anti-wear effect is optimal, while at 1.13MPa, the wear resistance of silicon carbide and graphite compound particles is the best; in the other case of only silicon carbide particles, the wear resistance is increased to 35% at 1.69MPa and 26.4km, and its anti-wear effects are excellent.

Spheroidization by Plasma Processing and Characterization of Stainless Steel Powder for 3D Printing

NASA Astrophysics Data System (ADS)

Ji, Lina; Wang, Changzhen; Wu, Wenjie; Tan, Chao; Wang, Guoyu; Duan, Xuan-Ming

2017-10-01

Stainless steel 316L (SS 316L) powder was spheroidized by plasma processing to improve its suitability for powder 3D printing. The obtained spheroidized (sphero) powder was characterized in terms of its crystalline phases, elemental composition, morphology, particle size and distribution, light absorption, and flow properties. The elemental composition of the sphero powder met the Chinese standard for SS 316L except for its Si content. The volume fraction of ferrite increased after plasma processing. Furthermore, plasma processing was shown to not only reduce the mean size of the particles in the size range of 10 to 100 μm but also generate particles in the size range of 0.1 to 10 μm. The smaller particles filled the voids among larger particles, increasing the powder density. The light absorption was also increased owing to enhanced internal reflection. Although the basic flow energy decreased after plasma processing, the flow function (FF) value was smaller for the sphero powder, indicating a lower flowability of the sphero powder. However, the density of SS 316L pieces printed with commercial and sphero powders was 98.76 pct and 98.16 pct of the SS 316L bulk density, respectively, indicating the suitability of the sphero powder for 3D printing despite an FF below 10.

Optimization of Cold Spray Deposition of High-Density Polyethylene Powders

NASA Astrophysics Data System (ADS)

Bush, Trenton B.; Khalkhali, Zahra; Champagne, Victor; Schmidt, David P.; Rothstein, Jonathan P.

2017-10-01

When a solid, ductile particle impacts a substrate at sufficient velocity, the resulting heat, pressure and plastic deformation can produce bonding between the particle and the substrate. The use of a cool supersonic gas flow to accelerate these solid particles is known as cold spray deposition. The cold spray process has been commercialized for some metallic materials, but further research is required to unlock the exciting potential material properties possible with polymeric particles. In this work, a combined computational and experimental study was employed to study the cold spray deposition of high-density polyethylene powders over a wide range of particle temperatures and impact velocities. Cold spray deposition of polyethylene powders was demonstrated across a range broad range of substrate materials including several different polymer substrates with different moduli, glass and aluminum. A material-dependent window of successful deposition was determined for each substrate as a function of particle temperature and impact velocity. Additionally, a study of deposition efficiency revealed the optimal process parameters for high-density polyethylene powder deposition which yielded a deposition efficiency close to 10% and provided insights into the physical mechanics responsible for bonding while highlighting paths toward future process improvements.

Design and scale-up of a semi-industrial downer-reactor for the rounding of irregular polymer particles

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

Sachs, Marius; Schmidt, Jochen; Peukert, Wolfgang

2016-03-09

The recent development of rapid prototyping technologies towards additive manufacturing reveals some major drawbacks of processes such as laser beam melting (LBM). This contribution focuses on the lack of suitable polymer material with a fine particle size and good flowability. Polymer particles obtained by a wet grinding process 1 are treated in a heated downer reactor. This treatment changes the particles’ morphology from a chiselled state towards a spherical form by surface tension forces in a molten state 2 and leads to an improved flowability. To reach the required amount of rounded polymer powder, a downer reactor in semi-industrial scalemore » has been established and will be characterized in this article. For the purpose of particle rounding it is necessary to avoid contact of molten particles with each other and with the hot reactor walls. Furthermore, the heat distribution has been investigated as one of the key parameters of the process. Finally, a proof of concept by rounding wet grinded PBT material was successfully conducted. The product was examined to obtain data about a change in particle size and flowability.« less

The successful of finite element to invent particle cleaning system by air jet in hard disk drive

NASA Astrophysics Data System (ADS)

Jai-Ngam, Nualpun; Tangchaichit, Kaitfa

2018-02-01

Hard Disk Drive manufacturing has faced very challenging with the increasing demand of high capacity drives for Cloud-based storage. Particle adhesion has also become increasingly important in HDD to gain more reliability of storage capacity. The ability to clean on surfaces is more complicated in removing such particles without damaging the surface. This research is aim to improve the particle cleaning in HSA by using finite element to develop the air flow model then invent the prototype of air cleaning system to remove particle from surface. Surface cleaning by air pressure can be applied as alternative for the removal of solid particulate contaminants that is adhering on a solid surface. These technical and economic challenges have driven the process development from traditional way that chemical solvent cleaning. The focus of this study is to develop alternative way from scrub, ultrasonic, mega sonic on surface cleaning principles to serve as a foundation for the development of new processes to meet current state-of-the-art process requirements and minimize the waste from chemical cleaning for environment safety.

The Fireball integrated code package

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

Dobranich, D.; Powers, D.A.; Harper, F.T.

1997-07-01

Many deep-space satellites contain a plutonium heat source. An explosion, during launch, of a rocket carrying such a satellite offers the potential for the release of some of the plutonium. The fireball following such an explosion exposes any released plutonium to a high-temperature chemically-reactive environment. Vaporization, condensation, and agglomeration processes can alter the distribution of plutonium-bearing particles. The Fireball code package simulates the integrated response of the physical and chemical processes occurring in a fireball and the effect these processes have on the plutonium-bearing particle distribution. This integrated treatment of multiple phenomena represents a significant improvement in the state ofmore » the art for fireball simulations. Preliminary simulations of launch-second scenarios indicate: (1) most plutonium vaporization occurs within the first second of the fireball; (2) large non-aerosol-sized particles contribute very little to plutonium vapor production; (3) vaporization and both homogeneous and heterogeneous condensation occur simultaneously; (4) homogeneous condensation transports plutonium down to the smallest-particle sizes; (5) heterogeneous condensation precludes homogeneous condensation if sufficient condensation sites are available; and (6) agglomeration produces larger-sized particles but slows rapidly as the fireball grows.« less

A Comparative Study of Production of Glass Microspheres by using Thermal Process

NASA Astrophysics Data System (ADS)

Lee, May Yan; Tan, Jully; Heng, Jerry YY; Cheeseman, Christopher

2017-06-01

Microspheres are spherical particles that can be distinguished into two categories; solid or hollow. Microspheres typical ranges from 1 to 200 μm in diameter. Microsphere are made from glass, ceramic, carbon or plastic depending on applications. Solid glass microsphere is manufactured by direct burning of glass powders while hollow glass microspheres is produced by adding blowing agent to glass powder. This paper presented the production of glass microspheres by using the vertical thermal flame (VTF) process. Pre-treated soda lime glass powder with particle sized range from 90 to 125μm was used in this work. The results showed that glass microspheres produced by two passes through the flame have a more spherical shape as compared with the single pass. Under the Scanning Electron Microscope (SEM), it is observed that there is a morphology changed from uneven surface of glass powders to smooth spherical surface particles. Qualitative analysis for density of the pre-burned and burned particles was performed. Burned particles floats in water while pre-burned particles sank indicated the change of density of the particles. Further improvements of the VTF process in terms of the VTF set-up are required to increase the transformation of glass powders to glass microspheres.

A mechanochemical approach to get stunningly uniform particles of magnesium-aluminum-layered double hydroxides

NASA Astrophysics Data System (ADS)

Zhang, Xiaoqing; Qi, Fenglin; Li, Shuping; Wei, Shaohua; Zhou, Jiahong

2012-10-01

A mechanochemical approach is developed in preparing a series of magnesium-aluminum-layered double hydroxides (Mg-Al-LDHs). This approach includes a mechanochemical process which involved manual grinding of solid salts in an agate mortar and afterwards peptization process. In order to verify the LDHs structure synthesized in the grinding process, X-ray diffraction (XRD) patterns, transmission electron microscopy (TEM) photos and thermogravimetry/differential scanning calorimetry (TG-DSC) property of the product without peptization were characterized and the results show that amorphous particles with low crystallinity and poor thermal stability are obtained, and the effect of peptization is to improve the properties, more accurately, regular particles with high crystallinity and good thermal stability can be gained after peptization. Furthermore, the fundamental experimental parameters including grinding time, the molar ratio of Mg to Al element (defined as R value) and the water content were systematically examined in order to control the size and morphologies of LDHs particles, regular hexagonal particles or the spherical nanostructures can be efficiently obtained and the particle sizes were controlled in the range of 52-130 nm by carefully adjusting these parameters. At last, stunningly uniform Mg-Al-LDHs particles can be synthesized under proper R values, suitable grinding time and high degree of supersaturation.

Nanosizing of drugs: Effect on dissolution rate

PubMed Central

Dizaj, S. Maleki; Vazifehasl, Zh.; Salatin, S.; Adibkia, Kh.; Javadzadeh, Y.

2015-01-01

The solubility, bioavailability and dissolution rate of drugs are important parameters for achieving in vivo efficiency. The bioavailability of orally administered drugs depends on their ability to be absorbed via gastrointestinal tract. For drugs belonging to Class II of pharmaceutical classification, the absorption process is limited by drug dissolution rate in gastrointestinal media. Therefore, enhancement of the dissolution rate of these drugs will present improved bioavailability. So far several techniques such as physical and chemical modifications, changing in crystal habits, solid dispersion, complexation, solubilization and liquisolid method have been used to enhance the dissolution rate of poorly water soluble drugs. It seems that improvement of the solubility properties ofpoorly water soluble drugscan translate to an increase in their bioavailability. Nowadays nanotechnology offers various approaches in the area of dissolution enhancement of low aqueous soluble drugs. Nanosizing of drugs in the form of nanoparticles, nanocrystals or nanosuspensions not requiring expensive facilities and equipment or complicated processes may be applied as simple methods to increase the dissolution rate of poorly water soluble drugs. In this article, we attempted to review the effects of nanosizing on improving the dissolution rate of poorly aqueous soluble drugs. According to the reviewed literature, by reduction of drug particle size into nanometer size the total effective surface area is increased and thereby dissolution rate would be enhanced. Additionally, reduction of particle size leads to reduction of the diffusion layer thickness surrounding the drug particles resulting in the increment of the concentration gradient. Each of these process leads to improved bioavailability. PMID:26487886

Optimization of synthesis process of thermally-responsive poly-n-isopropylacrylamide nanoparticles for controlled release of antimicrobial hydrophobic compounds

NASA Astrophysics Data System (ADS)

Hill, Laura E.; Gomes, Carmen L.

2014-12-01

The goal of this study was to develop an effective method to synthesize poly-n-isopropylacrylamide (PNIPAAM) nanoparticles with entrapped cinnamon bark extract (CBE) to improve its delivery to foodborne pathogens and control its release with temperature stimuli. CBE was used as a model for hydrophobic natural antimicrobials. A top-down procedure using crosslinked PNIPAAM was compared to a bottom-up procedure using NIPAAM monomer. Both processes relied on self-assembly of the molecules into micelles around the CBE at 40 °C. Processing conditions were compared including homogenization time of the polymer, hydration time prior to homogenization, lyophilization, and the effect of particle ultrafiltration. The top-down versus bottom-up synthesis methods yielded particles with significantly different characteristics, especially their release profiles and antimicrobial activities. The synthesis methods affected particle size, with the bottom-up procedure resulting in smaller (P < 0.05) diameters than the top-down procedure. The controlled release profile of CBE from nanoparticles was dependent on the release media temperature. A faster, burst release was observed at 40 °C and a slower, more sustained release was observed at lower temperatures. PNIPAAM particles containing CBE were analyzed for their antimicrobial activity against Salmonella enterica serovar Typhimurium LT2 and Listeria monocytogenes Scott A. The PNIPAAM particles synthesized via the top-down procedure had a much faster release, which led to a greater (P < 0.05) antimicrobial activity. Both of the top-down nanoparticles performed similarly, therefore the 7 min homogenization time nanoparticles would be the best for this application, as the process time is shorter and little improvement was seen by using a slightly longer homogenization.

Direct position determination for digital modulation signals based on improved particle swarm optimization algorithm

NASA Astrophysics Data System (ADS)

Yu, Wan-Ting; Yu, Hong-yi; Du, Jian-Ping; Wang, Ding

2018-04-01

The Direct Position Determination (DPD) algorithm has been demonstrated to achieve a better accuracy with known signal waveforms. However, the signal waveform is difficult to be completely known in the actual positioning process. To solve the problem, we proposed a DPD method for digital modulation signals based on improved particle swarm optimization algorithm. First, a DPD model is established for known modulation signals and a cost function is obtained on symbol estimation. Second, as the optimization of the cost function is a nonlinear integer optimization problem, an improved Particle Swarm Optimization (PSO) algorithm is considered for the optimal symbol search. Simulations are carried out to show the higher position accuracy of the proposed DPD method and the convergence of the fitness function under different inertia weight and population size. On the one hand, the proposed algorithm can take full advantage of the signal feature to improve the positioning accuracy. On the other hand, the improved PSO algorithm can improve the efficiency of symbol search by nearly one hundred times to achieve a global optimal solution.

Improved electrochemical property of nanoparticle polyoxovanadate K7NiV13O38 as cathode material for lithium battery

NASA Astrophysics Data System (ADS)

Ni, Erfu; Uematsu, Shinya; Quan, Zhen; Sonoyama, Noriyuki

2013-06-01

Molecular cluster ion compound K7NiV13O38 (KNiV) has been studied as a novel cathode material for lithium ion battery. The nanoparticles are prepared by a simple re-crystallization method adding different volumes of acetone to the water solution containing the dissolved KNiV. The KNiV re-crystallized from water/acetone ratio of 1:5 shows the most uniform particle size distribution and the smallest particles with thickness of 100 nm and width of 150 nm. The nanoparticle KNiV shows significant improvement in initial discharge capacity and capacity retention after 50 cycles compared to the as-prepared micro-sized particles at various current densities. Ex situ XRD patterns demonstrate that the discharge-charge process proceeds with amorphous KNiV, which is independent from the crystal structure. Ex situ FT-IR spectra indicate that [NiV13O38]7- cluster ion is stable and reacts reversibly with lithium ion in the discharge-charge process.

Modeling particle transport and discoloration risk in drinking water distribution networks

NASA Astrophysics Data System (ADS)

van Summeren, Joost; Blokker, Mirjam

2017-10-01

Discoloration of drinking water is a worldwide phenomenon caused by accumulation and subsequent remobilization of particulate matter in drinking water distribution systems (DWDSs). It contributes a substantial fraction of customer complaints to water utilities. Accurate discoloration risk predictions could improve system operation by allowing for more effective programs on cleaning and prevention actions and field measurements, but are challenged by incomplete understanding on the origins and properties of particles and a complex and not fully understood interplay of processes in distribution networks. In this paper, we assess and describe relevant hydraulic processes that govern particle transport in turbulent pipe flow, including gravitational settling, bed-load transport, and particle entrainment into suspension. We assess which transport mechanisms are dominant for a range of bulk flow velocities, particle diameters, and particle mass densities, which includes common conditions for DWDSs in the Netherlands, the UK, and Australia. Our analysis shows that the theoretically predicted particle settling velocity and threshold shear stresses for incipient particle motion are in the same range as, but more variable than, previous estimates from lab experiments, field measurements, and modeling. The presented material will be used in the future development of a numerical modeling tool to determine and predict the spatial distribution of particulate material and discoloration risk in DWDSs. Our approach is aimed at understanding specific causalities and processes, which can complement data-driven approaches.

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.

Separating and recycling metals from mixed metallic particles of crushed electronic wastes by vacuum metallurgy.

PubMed

Zhan, Lu; Xu, Zhenming

2009-09-15

During the treatment of electronic wastes, a crushing process is usually used to strip metals from various base plates. Several methods have been applied to separate metals from nonmetals. However, mixed metallic particles obtained from these processes are still a mixture of various metals, including some toxic heavy metals such as lead and cadmium. With emphasis on recovering copper and other precious metals, there have hitherto been no satisfactory methods to recover these toxic metals. In this paper, the criterion of separating metals from mixed metallic particles by vacuum metallurgy is built. The results show that the metals with high vapor pressure have been almost recovered completely, leading to a considerable reduction of environmental pollution. In addition, the purity of copper in mixed particles has been improved from about 80 wt % to over 98 wt %.

Modeling proton and alpha elastic scattering in liquid water in Geant4-DNA

NASA Astrophysics Data System (ADS)

Tran, H. N.; El Bitar, Z.; Champion, C.; Karamitros, M.; Bernal, M. A.; Francis, Z.; Ivantchenko, V.; Lee, S. B.; Shin, J. I.; Incerti, S.

2015-01-01

Elastic scattering of protons and alpha (α) particles by water molecules cannot be neglected at low incident energies. However, this physical process is currently not available in the "Geant4-DNA" extension of the Geant4 Monte Carlo simulation toolkit. In this work, we report on theoretical differential and integral cross sections of the elastic scattering process for 100 eV-1 MeV incident protons and for 100 eV-10 MeV incident α particles in liquid water. The calculations are performed within the classical framework described by Everhart et al., Ziegler et al. and by the ICRU 49 Report. Then, we propose an implementation of the corresponding classes into the Geant4-DNA toolkit for modeling the elastic scattering of protons and α particles. Stopping powers as well as ranges are also reported. Then, it clearly appears that the account of the elastic scattering process in the slowing-down of the charged particle improves the agreement with the existing data in particular with the ICRU recommendations.

Enhancing hydrologic data assimilation by evolutionary Particle Filter and Markov Chain Monte Carlo

NASA Astrophysics Data System (ADS)

Abbaszadeh, Peyman; Moradkhani, Hamid; Yan, Hongxiang

2018-01-01

Particle Filters (PFs) have received increasing attention by researchers from different disciplines including the hydro-geosciences, as an effective tool to improve model predictions in nonlinear and non-Gaussian dynamical systems. The implication of dual state and parameter estimation using the PFs in hydrology has evolved since 2005 from the PF-SIR (sampling importance resampling) to PF-MCMC (Markov Chain Monte Carlo), and now to the most effective and robust framework through evolutionary PF approach based on Genetic Algorithm (GA) and MCMC, the so-called EPFM. In this framework, the prior distribution undergoes an evolutionary process based on the designed mutation and crossover operators of GA. The merit of this approach is that the particles move to an appropriate position by using the GA optimization and then the number of effective particles is increased by means of MCMC, whereby the particle degeneracy is avoided and the particle diversity is improved. In this study, the usefulness and effectiveness of the proposed EPFM is investigated by applying the technique on a conceptual and highly nonlinear hydrologic model over four river basins located in different climate and geographical regions of the United States. Both synthetic and real case studies demonstrate that the EPFM improves both the state and parameter estimation more effectively and reliably as compared with the PF-MCMC.

Biochar particle size, shape, and porosity act together to influence soil water properties.

PubMed

Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A; Gonnermann, Helge M

2017-01-01

Many studies report that, under some circumstances, amending soil with biochar can improve field capacity and plant-available water. However, little is known about the mechanisms that control these improvements, making it challenging to predict when biochar will improve soil water properties. To develop a conceptual model explaining biochar's effects on soil hydrologic processes, we conducted a series of well constrained laboratory experiments using a sand matrix to test the effects of biochar particle size and porosity on soil water retention curves. We showed that biochar particle size affects soil water storage through changing pore space between particles (interpores) and by adding pores that are part of the biochar (intrapores). We used these experimental results to better understand how biochar intrapores and biochar particle shape control the observed changes in water retention when capillary pressure is the main component of soil water potential. We propose that biochar's intrapores increase water content of biochar-sand mixtures when soils are drier. When biochar-sand mixtures are wetter, biochar particles' elongated shape disrupts the packing of grains in the sandy matrix, increasing the volume between grains (interpores) available for water storage. These results imply that biochars with a high intraporosity and irregular shapes will most effectively increase water storage in coarse soils.

Influence of formulation and processing variables on properties of itraconazole nanoparticles made by advanced evaporative precipitation into aqueous solution.

PubMed

Bosselmann, Stephanie; Nagao, Masao; Chow, Keat T; Williams, Robert O

2012-09-01

Nanoparticles, of the poorly water-soluble drug, itraconazole (ITZ), were produced by the Advanced Evaporative Precipitation into Aqueous Solution process (Advanced EPAS). This process combines emulsion templating and EPAS processing to provide improved control over the size distribution of precipitated particles. Specifically, oil-in-water emulsions containing the drug and suitable stabilizers are sprayed into a heated aqueous solution to induce precipitation of the drug in form of nanoparticles. The influence of processing parameters (temperature and volume of the heated aqueous solution; type of nozzle) and formulation aspects (stabilizer concentrations; total solid concentrations) on the size of suspended ITZ particles, as determined by laser diffraction, was investigated. Furthermore, freeze-dried ITZ nanoparticles were evaluated regarding their morphology, crystallinity, redispersibility, and dissolution behavior. Results indicate that a robust precipitation process was developed such that size distribution of dispersed nanoparticles was shown to be largely independent across the different processing and formulation parameters. Freeze-drying of colloidal dispersions resulted in micron-sized agglomerates composed of spherical, sub-300-nm particles characterized by reduced crystallinity and high ITZ potencies of up to 94% (w/w). The use of sucrose prevented particle agglomeration and resulted in powders that were readily reconstituted and reached high and sustained supersaturation levels upon dissolution in aqueous media.

Advanced process and defect characterization methodology to support process development of advanced patterning structures

NASA Astrophysics Data System (ADS)

Ketkar, Supriya; Lee, Junhan; Asokamani, Sen; Cho, Winston; Mishra, Shailendra

2018-03-01

This paper discusses the approach and solution adopted by GLOBALFOUNDRIES, a high volume manufacturing (HVM) foundry, for dry-etch related edge-signature surface particle defects issue facing the sub-nm node in the gate-etch sector. It is one of the highest die killers for the company in the 14-nm node. We have used different approaches to attack and rectify the edge signature surface particle defect. Several process-related & hardware changes have been successively implemented to achieve defect reduction improvement by 63%. Each systematic process and/or hardware approach has its own unique downstream issues and they have been dealt in a route-cause-effect technique to address the issue.

RB Particle Filter Time Synchronization Algorithm Based on the DPM Model.

PubMed

Guo, Chunsheng; Shen, Jia; Sun, Yao; Ying, Na

2015-09-03

Time synchronization is essential for node localization, target tracking, data fusion, and various other Wireless Sensor Network (WSN) applications. To improve the estimation accuracy of continuous clock offset and skew of mobile nodes in WSNs, we propose a novel time synchronization algorithm, the Rao-Blackwellised (RB) particle filter time synchronization algorithm based on the Dirichlet process mixture (DPM) model. In a state-space equation with a linear substructure, state variables are divided into linear and non-linear variables by the RB particle filter algorithm. These two variables can be estimated using Kalman filter and particle filter, respectively, which improves the computational efficiency more so than if only the particle filter was used. In addition, the DPM model is used to describe the distribution of non-deterministic delays and to automatically adjust the number of Gaussian mixture model components based on the observational data. This improves the estimation accuracy of clock offset and skew, which allows achieving the time synchronization. The time synchronization performance of this algorithm is also validated by computer simulations and experimental measurements. The results show that the proposed algorithm has a higher time synchronization precision than traditional time synchronization algorithms.

Quantitative proton imaging from multiple physics processes: a proof of concept

NASA Astrophysics Data System (ADS)

Bopp, C.; Rescigno, R.; Rousseau, M.; Brasse, D.

2015-07-01

Proton imaging is developed in order to improve the accuracy of charged particle therapy treatment planning. It makes it possible to directly map the relative stopping powers of the materials using the information on the energy loss of the protons. In order to reach a satisfactory spatial resolution in the reconstructed images, the position and direction of each particle is recorded upstream and downstream from the patient. As a consequence of individual proton detection, information on the transmission rate and scattering of the protons is available. Image reconstruction processes are proposed to make use of this information. A proton tomographic acquisition of an anthropomorphic head phantom was simulated. The transmission rate of the particles was used to reconstruct a map of the macroscopic cross section for nuclear interactions of the materials. A two-step iterative reconstruction process was implemented to reconstruct a map of the inverse scattering length of the materials using the scattering of the protons. Results indicate that, while the reconstruction processes should be optimized, it is possible to extract quantitative information from the transmission rate and scattering of the protons. This suggests that proton imaging could provide additional knowledge on the materials that may be of use to further improve treatment planning.

Quantitative proton imaging from multiple physics processes: a proof of concept.

PubMed

Bopp, C; Rescigno, R; Rousseau, M; Brasse, D

2015-07-07

Proton imaging is developed in order to improve the accuracy of charged particle therapy treatment planning. It makes it possible to directly map the relative stopping powers of the materials using the information on the energy loss of the protons. In order to reach a satisfactory spatial resolution in the reconstructed images, the position and direction of each particle is recorded upstream and downstream from the patient. As a consequence of individual proton detection, information on the transmission rate and scattering of the protons is available. Image reconstruction processes are proposed to make use of this information. A proton tomographic acquisition of an anthropomorphic head phantom was simulated. The transmission rate of the particles was used to reconstruct a map of the macroscopic cross section for nuclear interactions of the materials. A two-step iterative reconstruction process was implemented to reconstruct a map of the inverse scattering length of the materials using the scattering of the protons. Results indicate that, while the reconstruction processes should be optimized, it is possible to extract quantitative information from the transmission rate and scattering of the protons. This suggests that proton imaging could provide additional knowledge on the materials that may be of use to further improve treatment planning.

Preparation of 5-fluorouracil nanoparticles by supercritical antisolvents for pulmonary delivery

PubMed Central

Kalantarian, Pardis; Najafabadi, Abdolhosein Rouholamini; Haririan, Ismaeil; Vatanara, Alireza; Yamini, Yadollah; Darabi, Majid; Gilani, Kambiz

2010-01-01

This study concerns the supercritical antisolvent process which allows single-step production of 5-fluorouracil (5-FU) nanoparticles. This process enhances the physical characteristics of 5-FU in order to deliver it directly to the respiratory tract. Several mixtures of methanol with dichloromethane, acetone, or ethanol were used for particle preparation, and their effects on the physical characteristics of the final products were studied. The conditions of the experiment included pressures of 100 and 150 bar, temperature of 40°C, and a flow rate of 1 mL/min. The particles were characterized physicochemically before and after the process for their morphology and crystallinity. In spite of differences in size, the particles were not very different regarding their morphology. The resulting particles were of a regular shape, partly spherical, and appeared to have a smooth surface, whereas the mechanically milled particles showed less uniformity, had surface irregularities and a high particle size distribution, and seemed aggregated. Particles of 5-FU precipitated from methanol-dichloromethane 50:50 had a mean particle size of 248 nm. In order to evaluate the aerodynamic behavior of the nanoparticles, six 5-FU dry powder formulations containing mixtures of coarse and fine lactose of different percentages were prepared. Deposition of 5-FU was measured using a twin-stage liquid impinger and analyzed using a validated high pressure liquid chromatography method. Addition of fine lactose improved the aerodynamic performance of the drug, as determined by the fine particle fraction. PMID:21042422

The influence of different processing stages on particle size, microstructure, and appearance of dark chocolate.

PubMed

Glicerina, Virginia; Balestra, Federica; Dalla Rosa, Marco; Bergenhstål, Bjorn; Tornberg, Eva; Romani, Santina

2014-07-01

The effect of different process stages on microstructural and visual properties of dark chocolate was studied. Samples were obtained at each phase of the manufacture process: mixing, prerefining, refining, conching, and tempering. A laser light diffraction technique and environmental scanning electron microscopy (ESEM) were used to study the particle size distribution (PSD) and to analyze modifications in the network structure. Moreover, colorimetric analyses (L*, h°, and C*) were performed on all samples. Each stage influenced in stronger way the microstructural characteristic of products and above all the PSD. Sauter diameter (D [3.2]) decreased from 5.44 μm of mixed chocolate sample to 3.83 μm, of the refined one. ESEM analysis also revealed wide variations in the network structure of samples during the process, with an increase of the aggregation and contact point between particles from mixing to refining stage. Samples obtained from the conching and tempering were characterized by small PS, and a less dense aggregate structure. From color results, samples with the finest particles, having larger specific surface area and the smallest diameter, appeared lighter and more saturated than those with coarse particles. Final quality of food dispersions is affected by network and particles characteristics. The deep knowledge of the influence of single processing stage on chocolate microstructural properties is useful in order to improve or modify final product characteristics. ESEM and laser diffraction are suitable techniques to study changes in chocolate microstructure. © 2014 Institute of Food Technologists®

Application of Particle Swarm Optimization Algorithm in the Heating System Planning Problem

PubMed Central

Ma, Rong-Jiang; Yu, Nan-Yang; Hu, Jun-Yi

2013-01-01

Based on the life cycle cost (LCC) approach, this paper presents an integral mathematical model and particle swarm optimization (PSO) algorithm for the heating system planning (HSP) problem. The proposed mathematical model minimizes the cost of heating system as the objective for a given life cycle time. For the particularity of HSP problem, the general particle swarm optimization algorithm was improved. An actual case study was calculated to check its feasibility in practical use. The results show that the improved particle swarm optimization (IPSO) algorithm can more preferably solve the HSP problem than PSO algorithm. Moreover, the results also present the potential to provide useful information when making decisions in the practical planning process. Therefore, it is believed that if this approach is applied correctly and in combination with other elements, it can become a powerful and effective optimization tool for HSP problem. PMID:23935429

Particle size reduction to the nanometer range: a promising approach to improve buccal absorption of poorly water-soluble drugs

PubMed Central

Rao, Shasha; Song, Yunmei; Peddie, Frank; Evans, Allan M

2011-01-01

Poorly water-soluble drugs, such as phenylephrine, offer challenging problems for buccal drug delivery. In order to overcome these problems, particle size reduction (to the nanometer range) and cyclodextrin complexation were investigated for permeability enhancement. The apparent solubility in water and the buccal permeation of the original phenylephrine coarse powder, a phenylephrine–cyclodextrin complex and phenylephrine nanosuspensions were characterized. The particle size and particle surface properties of phenylephrine nanosuspensions were used to optimize the size reduction process. The optimized phenylephrine nanosuspension was then freeze dried and incorporated into a multi-layered buccal patch, consisting of a small tablet adhered to a mucoadhesive film, yielding a phenylephrine buccal product with good dosage accuracy and improved mucosal permeability. The design of the buccal patch allows for drug incorporation without the need to change the mucoadhesive component, and is potentially suited to a range of poorly water-soluble compounds. PMID:21753876

Particle size reduction to the nanometer range: a promising approach to improve buccal absorption of poorly water-soluble drugs.

PubMed

Rao, Shasha; Song, Yunmei; Peddie, Frank; Evans, Allan M

2011-01-01

Poorly water-soluble drugs, such as phenylephrine, offer challenging problems for buccal drug delivery. In order to overcome these problems, particle size reduction (to the nanometer range) and cyclodextrin complexation were investigated for permeability enhancement. The apparent solubility in water and the buccal permeation of the original phenylephrine coarse powder, a phenylephrine-cyclodextrin complex and phenylephrine nanosuspensions were characterized. The particle size and particle surface properties of phenylephrine nanosuspensions were used to optimize the size reduction process. The optimized phenylephrine nanosuspension was then freeze dried and incorporated into a multi-layered buccal patch, consisting of a small tablet adhered to a mucoadhesive film, yielding a phenylephrine buccal product with good dosage accuracy and improved mucosal permeability. The design of the buccal patch allows for drug incorporation without the need to change the mucoadhesive component, and is potentially suited to a range of poorly water-soluble compounds.

Process for preparing fluorine-18

DOEpatents

Winchell, Harry S.; Wells, Dale K.; Lamb, James F.; Beaudry, Samuel B.

1976-09-21

An improved process for preparation of fluorine-18 by a neon (deuteron, alpha particle) fluorine-18 nuclear reaction in a non-reactive enclosed reaction zone wherein a ultrapure product is recovered by heating the reaction zone to a high temperature and removing the product with an inert gas.

In-situ poling and structurization of piezoelectric particulate composites.

PubMed

Khanbareh, H; van der Zwaag, S; Groen, W A

2017-11-01

Composites of lead zirconate titanate particles in an epoxy matrix are prepared in the form of 0-3 and quasi 1-3 with different ceramic volume contents from 10% to 50%. Two different processing routes are tested. Firstly a conventional dielectrophoretic structuring is used to induce a chain-like particle configuration, followed by curing the matrix and poling at a high temperature and under a high voltage. Secondly a simultaneous combination of dielectrophoresis and poling is applied at room temperature while the polymer is in the liquid state followed by subsequent curing. This new processing route is practiced in an uncured thermoset system while the polymer matrix still possess a relatively high electrical conductivity. Composites with different degrees of alignment are produced by altering the magnitude of the applied electric field. A significant improvement in piezoelectric properties of quasi 1-3 composites can be achieved by a combination of dielectrophoretic alignment of the ceramic particles and poling process. It has been observed that the degree of structuring as well as the functional properties of the in-situ structured and poled composites enhance significantly compared to those of the conventionally manufactured structured composites. Improving the alignment quality enhances the piezoelectric properties of the particulate composites.

Spherical agglomerates of pure drug nanoparticles for improved pulmonary delivery in dry powder inhalers

NASA Astrophysics Data System (ADS)

Hu, Jun; Dong, Yuancai; Pastorin, Giorgia; Ng, Wai Kiong; Tan, Reginald B. H.

2013-04-01

The aim of this study was to produce micron-sized spherical agglomerates of pure drug nanoparticles to achieve improved aerosol performance in dry powder inhalers (DPIs). Sodium cromoglicate was chosen as the model drug. Pure drug nanoparticles were prepared through a bottom-up particle formation process, liquid antisolvent precipitation, and then rapidly agglomerated into porous spherical microparticles by immediate (on-line) spray drying. Nonporous spherical drug microparticles with similar geometric size distribution were prepared by conventional spray drying of the aqueous drug solution, which together with the mechanically micronized drug particles were used as the control samples. The three samples were characterized by field emission scanning electron microscopy, laser diffraction, Brunauer-Emmett-Teller analysis, density measurement, powder X-ray diffraction, and in vitro aerosol deposition measurement with a multistage liquid impinger. It was found that drug nanoparticles with a diameter of 100 nm were precipitated and agglomerated into highly porous spherical microparticles with a volume median diameter ( D 50 %) of 2.25 ± 0.08 μm and a specific surface area of 158.63 ± 3.27 m2/g. In vitro aerosol deposition studies showed the fine particle fraction of such spherical agglomerates of drug nanoparticles was increased by more than 50 % in comparison with the control samples, demonstrating significant improvements in aerosol performance. The results of this study indicated the potential of the combined particle engineering process of liquid antisolvent precipitation followed by immediate (on-line) spray drying in the development of novel DPI drug products with improved aerosol performance.

SU-F-SPS-09: Parallel MC Kernel Calculations for VMAT Plan Improvement

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

Chamberlain, S; Roswell Park Cancer Institute, Buffalo, NY; French, S

Purpose: Adding kernels (small perturbations in leaf positions) to the existing apertures of VMAT control points may improve plan quality. We investigate the calculation of kernel doses using a parallelized Monte Carlo (MC) method. Methods: A clinical prostate VMAT DICOM plan was exported from Eclipse. An arbitrary control point and leaf were chosen, and a modified MLC file was created, corresponding to the leaf position offset by 0.5cm. The additional dose produced by this 0.5 cm × 0.5 cm kernel was calculated using the DOSXYZnrc component module of BEAMnrc. A range of particle history counts were run (varying from 3more » × 10{sup 6} to 3 × 10{sup 7}); each job was split among 1, 10, or 100 parallel processes. A particle count of 3 × 10{sup 6} was established as the lower range because it provided the minimal accuracy level. Results: As expected, an increase in particle counts linearly increases run time. For the lowest particle count, the time varied from 30 hours for the single-processor run, to 0.30 hours for the 100-processor run. Conclusion: Parallel processing of MC calculations in the EGS framework significantly decreases time necessary for each kernel dose calculation. Particle counts lower than 1 × 10{sup 6} have too large of an error to output accurate dose for a Monte Carlo kernel calculation. Future work will investigate increasing the number of parallel processes and optimizing run times for multiple kernel calculations.« less

Dry powder inhalers of gentamicin and leucine: formulation parameters, aerosol performance and in vitro toxicity on CuFi1 cells.

PubMed

Aquino, R P; Prota, L; Auriemma, G; Santoro, A; Mencherini, T; Colombo, G; Russo, P

2012-04-15

The high hygroscopicity of gentamicin (G) as raw material hampers the production of respirable particles during aerosol generation and prevents its direct use as powder for inhalation in patients suffering from cystic fibrosis (CF). Therefore, this research aimed to design a new dry powder formulation of G studying dispersibility properties of an aminoacid, L-leucine (leu), and appropriate process conditions. Spray-dried powders were characterized as to water uptake, particle size distribution, morphology and stability, in correlation with process parameters. Aerodynamic properties were analyzed both by Single Stage Glass Impinger and Andersen Cascade Impactor. Moreover, the potential cytotoxicity on bronchial epithelial cells bearing a CFTR F508/F508 mutant genotype (CuFi1) were tested. Results indicated that leu may improve the aerosol performance of G-dried powders. The maximum fine particle fraction (FPF) of about 58.3% was obtained when water/isopropyl alcohol 7:3 system and 15-20% (w/w) of leu were used, compared to a FPF value of 13.4% for neat G-dried powders. The enhancement of aerosol efficiency was credited both to the improvement of the powder flowability, caused by the dispersibility enhancer (aminoacid), and to the modification of the particle surface due to the influence of the organic co-solvent on drying process. No significant degradation of the dry powder was observed up to 6 months of storage. Moreover, particle engineering did not affect either the cell viability or cell proliferation of CuFi1 over a 24 h period. Copyright © 2012 Elsevier B.V. All rights reserved.

A workflow for improving estimates of microplastic contamination in marine waters: A case study from North-Western Australia.

PubMed

Kroon, Frederieke; Motti, Cherie; Talbot, Sam; Sobral, Paula; Puotinen, Marji

2018-07-01

Plastic pollution is ubiquitous throughout the marine environment, with microplastic (i.e. <5 mm) contamination a global issue of emerging concern. The lack of universally accepted methods for quantifying microplastic contamination, including consistent application of microscopy, photography, an spectroscopy and photography, may result in unrealistic contamination estimates. Here, we present and apply an analysis workflow tailored to quantifying microplastic contamination in marine waters, incorporating stereomicroscopic visual sorting, microscopic photography and attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy. The workflow outlines step-by-step processing and associated decision making, thereby reducing bias in plastic identification and improving confidence in contamination estimates. Specific processing steps include (i) the use of a commercial algorithm-based comparison of particle spectra against an extensive commercially curated spectral library, followed by spectral interpretation to establish the chemical composition, (ii) a comparison against a customised contaminant spectral library to eliminate procedural contaminants, and (iii) final assignment of particles as either natural- or anthropogenic-derived materials, based on chemical type, a compare analysis of each particle against other particle spectra, and physical characteristics of particles. Applying this workflow to 54 tow samples collected in marine waters of North-Western Australia visually identified 248 potential anthropogenic particles. Subsequent ATR-FTIR spectroscopy, chemical assignment and visual re-inspection of photographs established 144 (58%) particles to be of anthropogenic origin. Of the original 248 particles, 97 (39%) were ultimately confirmed to be plastics, with 85 of these (34%) classified as microplastics, demonstrating that over 60% of particles may be misidentified as plastics if visual identification is not complemented by spectroscopy. Combined, this tailored analysis workflow outlines a consistent and sequential process to quantify contamination by microplastics and other anthropogenic microparticles in marine waters. Importantly, its application will contribute to more realistic estimates of microplastic contamination in marine waters, informing both ecological risk assessments and experimental concentrations in effect studies. Copyright © 2018 Australian Institute of Marine Science. Published by Elsevier Ltd.. All rights reserved.

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

Bruce S. Kang

The objective of this project was to understand and improve high-temperature structural properties of metal-silicide intermetallic alloys. Through research collaboration between the research team at West Virginia University (WVU) and Dr. J.H. Schneibel at Oak Ridge National Laboratory (ORNL), molybdenum silicide alloys were developed at ORNL and evaluated at WVU through atomistic modeling analyses, thermo-mechanical tests, and metallurgical studies. In this study, molybdenum-based alloys were ductilized by dispersing MgAl2O4 or MgO spinel particles. The addition of spinel particles is hypothesized to getter impurities such as oxygen and nitrogen from the alloy matrix with the result of ductility improvement. The introductionmore » of fine dispersions has also been postulated to improve ductility by acting as a dislocation source or reducing dislocation pile-ups at grain boundaries. The spinel particles, on the other hand, can also act as local notches or crack initiation sites, which is detrimental to the alloy mechanical properties. Optimization of material processing condition is important to develop the desirable molybdenum alloys with sufficient room-temperature ductility. Atomistic analyses were conducted to further understand the mechanism of ductility improvement of the molybdenum alloys and the results showed that trace amount of residual oxygen may be responsible for the brittle behavior of the as-cast Mo alloys. For the alloys studied, uniaxial tensile tests were conducted at different loading rates, and at room and elevated temperatures. Thermal cycling effect on the mechanical properties was also studied. Tensile tests for specimens subjected to either ten or twenty thermal cycles were conducted. For each test, a follow-up detailed fractography and microstructural analysis were carried out. The test results were correlated to the size, density, distribution of the spinel particles and processing time. Thermal expansion tests were carried out using thermo-mechanical analyzer (TMA). Results showed that the coefficient of thermal expansion (CTE) value decreases with the addition of spinel and silicide particles. Thermo-cycling tests showed that molybdenum alloy with 6% wt of spinel (MgAl2O4) developed microcracks which were caused by thermal expansion mismatch between the spinel particles and molybdenum matrix, as well as the processing conditions. Detailed post-mortem studies of microstructures and segregation of impurities to the oxide dispersion/Mo interfaces were conducted using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS).« less

Disaggregation and separation dynamics of magnetic particles in a microfluidic flow under an alternating gradient magnetic field

NASA Astrophysics Data System (ADS)

Cao, Quanliang; Li, Zhenhao; Wang, Zhen; Qi, Fan; Han, Xiaotao

2018-05-01

How to prevent particle aggregation in the magnetic separation process is of great importance for high-purity separation, while it is a challenging issue in practice. In this work, we report a novel method to solve this problem for improving the selectivity of size-based separation by use of a gradient alternating magnetic field. The specially designed magnetic field is capable of dynamically adjusting the magnetic field direction without changing the direction of magnetic gradient force acting on the particles. Using direct numerical simulations, we show that particles within a certain center-to-center distance are inseparable under a gradient static magnetic field since they are easy aggregated and then start moving together. By contrast, it has been demonstrated that alternating repulsive and attractive interaction forces between particles can be generated to avoid the formation of aggregations when the alternating gradient magnetic field with a given alternating frequency is applied, enabling these particles to be continuously separated based on size-dependent properties. The proposed magnetic separation method and simulation results have the significance for fundamental understanding of particle dynamic behavior and improving the separation efficiency.

A Brief Research Review for Improvement Methods the Wettability between Ceramic Reinforcement Particulate and Aluminium Matrix Composites

NASA Astrophysics Data System (ADS)

Razzaq, Alaa Mohammed; Majid, Dayang Laila Abang Abdul; Ishak, M. R.; B, Uday M.

2017-05-01

The development of new methods for addition fine ceramic powders to Al aluminium alloy melts, which would lead to more uniform distribution and effective incorporation of the reinforcement particles into the aluminium matrix alloy. Recently the materials engineering research has moved to composite materials from monolithic, adapting to the global need for lightweight, low cost, quality, and high performance advanced materials. Among the different methods, stir casting is one of the simplest ways of making aluminium matrix composites. However, it suffers from poor distribution and combination of the reinforcement ceramic particles in the metal matrix. These problems become significantly effect to reduce reinforcement size, more agglomeration and tendency with less wettability for the ceramic particles in the melt process. Many researchers have carried out different studies on the wettability between the metal matrix and dispersion phase, which includes added wettability agents, fluxes, preheating the reinforcement particles, coating the reinforcement particles, and use composting techniques. The enhancement of wettability of ceramic particles by the molten matrix alloy and the reinforcement particles distribution improvement in the solidified matrix is the main objective for many studies that will be discussed in this paper.

The preparation of tantalum powder using a MR-EMR combination process

NASA Astrophysics Data System (ADS)

Yoon, Jae Sik; Kim, Byung Il

2007-04-01

In the conventional metallothermic reduction (MR) process used to obtain tantalum powder in batch-type operation, it is difficult to control the morphology and location of the tantalum deposits. In contrast, an electronically mediated reaction (EMR) process is capable of overcoming this difficulty. It has the advantage of being a continuous process, but has the disadvantage of a poor reduction yield. A process known as the MR-EMR combination process is able to overcome the shortcomings of the MR and EMR processes. In this study, an MR-EMR combination process is applied to the production of tantalum powder via sodium reduction of K2TaF7. In the MR-EMR combination process, the total charge passed through an external circuit and the average particle size (FSSS) increase as the reduction temperature increases. In addition, the proportion of fine particles (-325 mesh) decreases as the reduction temperature increasess. The tantalum yield improved from 65 to 74% as the reduction temperature increased. Taking into account the charge, impurities, morphology, particle size and yield, a reduction temperature of 1123 K was found to be optimum for the MR-EMR combination process.

Synthesis of metal-polymer nanocomposites for fuel applications

NASA Astrophysics Data System (ADS)

Pontes Lima, Ricardo Jose

Metal particles have long been of interest as fuel and fuel additives for propellants and explosives because their high-density energy. In general, their volumetric energy density is higher as compared to conventional hydrocarbon-based fuel. This advantage is clearly beneficial for volume-limited rocket propulsion systems, in which the most important parameter is the density-based specific impulse. It is widely known that the reactivity of metal particles increases when particle size decreases. Significant improvements in combustion behaviors of propellant have been attributed to the use of nanosize metal particles, for example faster burning rates and shorter ignition delay time. For this reason the application of nanosize particles as fuel could be preferable than large particles. However, several difficulties limit the use of ultrafine particles in fuel applications and propellants. Most of them are attributed to the oxide layer formation on the particles that prevents good combustion performance. In boron applications, practical difficulties such as poor ignition and combustion performance, have so far limited extensive use of boron for fuel applications. Indications are that application of non-oxide coatings on particles protects them against premature oxidation and enhances their combustion properties. A number of methods have been proposed to coat metal particles with a variety of organic compounds or other metals. Common applications provides coatings of saturated hydrocarbons or fatty acids, such as oleic acid as a means to passivation the particles. Recently, high-energy ball milling, in combination with chemical reactions, was applied to fabricate nanostructured metal particles coated with organic compounds. One of the advantages of this technique is that the passivation be integrated into the production of particles as a single step. For example, the reactive milling of boron in oleic acid solution showed an improved reactivity of as-milled powders. However, the versatility of the mechanical milling technique suggests that a vast range of organic compounds could be applied to the capping of particles. Thus, developing a new method to obtain metal nanosized particles coated with chemical substances that can further improve the properties of particles is a great challenge. The first contribution of this work is to investigate the reactive milling process of metal powders, such as boron and aluminum, to better understand the experimental methodology as a means to obtain energetic-capped metal particles. To this end, a comparative experimental study was performed to evaluate two variations of the mechanical milling. In a typical procedure, metal powders and the reagents are poured into the mill vial at the start of milling. The organic reactions occur simultaneously in the milling process. In the alternative procedure, the powders are milled prior the addition of the organic reagent, thus a stepwise process is done. For both methods, an organic functionalized compound was grafted onto the particles, followed by their incorporation into an energetic polymer matrix to create a metal-polymer composite. The results highlight the differences in shape in size of particles, identifying some drawbacks for both applications, as well as analyzing the effects on combustion properties of the organic-capped powders and the binder composites. The analysis of the first results of the reactive milling showed that this way might lead to by-products and self-polymerization of organic coatings. That is the main drawback for the simultaneous milling process, preventing a better performance of as-milled powders. Considering this problem, it was necessary to modify the milling procedure to further improve the capping of metal particle. Thus, the second part of experiments applies an energetic polymer direct grafted onto particles as a means to further improvements in the energetic properties of powders. Glycidyl azide polymer (GAP) was chosen as candidate to coat the particles because of its good energetic properties. Since the mixture viscosity increases as the size of particles decreases, low-viscosity reagents are recommended to avoid very high viscosity. The molecular weight of GAP can range from 700 to 5500 and the number of hydroxyl end groups from 0 (GAP plasticizer) to 3. Among these polymers, the GAP plasticizer (700 g mol-1, low viscosity) has good properties to be applied in reactive milling. However, some functionalized groups are necessary to graft the polymer onto metal particles and the GAP plasticizer does not carry telechelic hydroxyl groups. To achieve a better reactivity of this polymer and the fresh metal surface, the GAP plasticizer was chemically modified to make some additional acid-functionalized branches in the main chain of the polymer. The direct method for coating the metal particles with the modified GAP was more effective in forming the energetic layer, which has influenced the dispersion of powders into polymers and increased the total energy release by the combustion of metal-polymer composites. The last phase of this research addressed the production of boron-polymer composites for combustion purposes. Boron has a very high gravimetric (58 kJ/g) and volumetric (136 kJ/cc) heating value. This clearly exceeds other metal or other conventional hydrocarbon fuels in both mass and volumetric energy production. Despite of this great potential energy, boron has rarely achieved its potential in propulsion systems, whereas the aluminum is the most common metal employed in the preparation of composite solid propellants. A number of studies addressed to the boron combustion attribute its reduced performance to a certain combustion property of the metal. The boron oxide (B2O3) layer, normally found on the particles is highly stable and leads to long ignition delay times. Therefore, the elemental boron ignites in a two-stage process. The first stage corresponds to the burning of boron covered with an oxide layer, and the second stage involves the completion of the combustion of the bare boron particle. The use of light metals, such as magnesium and aluminum as additives in boron formulations, has been indicated as a means to enhance its combustion efficiency. Recently, improvements of the combustion efficiency of boron were associated with the use of magnesium and aluminum as additives. The mechanism proposed for these improvements was boron oxide removal by reaction with aluminum and the additional heat release by the easy ignition of magnesium. In this work, it was proposed to apply of a layer of energetic polymer on the boron particles, which, in addition to releasing a significant amount of energy, brings other benefits in terms of the final application of the particles as fuel (i.e., the dispersion of particles into a polymer binder).

Investigation into process-induced de-aggregation of cohesive micronised API particles.

PubMed

Hoffmann, Magnus; Wray, Patrick S; Gamble, John F; Tobyn, Mike

2015-09-30

The aim of this study was to assess the impact of unit processes on the de-aggregation of a cohesive micronised API within a pharmaceutical formulation using near-infrared chemical imaging. The impact on the primary API particles was also investigated using an image-based particle characterization system with integrated Raman analysis. The blended material was shown to contain large, API rich domains which were distributed in-homogeneously across the sample, suggesting that the blending process was not aggressive enough to disperse aggregates of micronised drug particles. Cone milling, routinely used to improve the homogeneity of such cohesive formulations, was observed to substantially reduce the number and size of API rich domains; however, several smaller API domains survived the milling process. Conveyance of the cone milled formulation through the Alexanderwerk WP120 powder feed system completely dispersed all remaining aggregates. Importantly, powder feed transmission of the un-milled formulation was observed to produce an equally homogeneous API distribution. The size of the micronised primary drug particles remained unchanged during powder feed transmission. These findings provide further evidence that this powder feed system does induce shear, and is in fact better able to disperse aggregates of a cohesive micronised API within a blend than the blend-mill-blend step. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

A review on recent technologies for the manufacture of pulmonary drugs.

PubMed

Hadiwinoto, Gabriela Daisy; Lip Kwok, Philip Chi; Lakerveld, Richard

2018-01-01

This review discusses recent developments in the manufacture of inhalable dry powder formulations. Pulmonary drugs have distinct advantages compared with other drug administration routes. However, requirements of drugs properties complicate the manufacture. Control over crystallization to make particles with the desired properties in a single step is often infeasible, which calls for micronization techniques. Although spray drying produces particles in the desired size range, a stable solid state may not be attainable. Supercritical fluids may be used as a solvent or antisolvent, which significantly reduces solvent waste. Future directions include application areas such as biopharmaceuticals for dry powder inhalers and new processing strategies to improve the control over particle formation such as continuous manufacturing with in-line process analytical technologies.

Maple leaf (Acer sp.) extract mediated green process for the functionalization of ZnO powders with silver nanoparticles.

PubMed

Vivekanandhan, Singaravelu; Schreiber, Makoto; Mason, Cynthia; Mohanty, Amar Kumar; Misra, Manjusri

2014-01-01

The functionalization of ZnO powders with silver nanoparticles (AgNPs) through a novel maple leaf extract mediated biological process was demonstrated. Maple leaf extract was found to be a very effective bioreduction agent for the reduction of silver ions. The reduction rate of Ag(+) into Ag(0) was found to be much faster than other previously reported bioreduction rates and was comparable to the reduction rates obtained through chemical means. The functionalization of ZnO particles with silver nanoparticles through maple leaf extract mediated bioreduction of silver was investigated through UV-visible spectrophotometry, transmission electron microscopy (TEM), and X-ray diffraction analysis. It was found that the ZnO particles were coated with silver nanoparticles 5-20 nm in diameter. The photocatalytic ability of the ZnO particles functionalized with silver nanoparticles was found to be significantly improved compared to the photocatalytic ability of the neat ZnO particles. The silver functionalized ZnO particles reached 90% degradation of the dye an hour before the neat ZnO particles. Copyright © 2013 Elsevier B.V. All rights reserved.

Spray-drying nanocapsules in presence of colloidal silica as drying auxiliary agent: formulation and process variables optimization using experimental designs.

PubMed

Tewa-Tagne, Patrice; Degobert, Ghania; Briançon, Stéphanie; Bordes, Claire; Gauvrit, Jean-Yves; Lanteri, Pierre; Fessi, Hatem

2007-04-01

Spray-drying process was used for the development of dried polymeric nanocapsules. The purpose of this research was to investigate the effects of formulation and process variables on the resulting powder characteristics in order to optimize them. Experimental designs were used in order to estimate the influence of formulation parameters (nanocapsules and silica concentrations) and process variables (inlet temperature, spray-flow air, feed flow rate and drying air flow rate) on spray-dried nanocapsules when using silica as drying auxiliary agent. The interactions among the formulation parameters and process variables were also studied. Responses analyzed for computing these effects and interactions were outlet temperature, moisture content, operation yield, particles size, and particulate density. Additional qualitative responses (particles morphology, powder behavior) were also considered. Nanocapsules and silica concentrations were the main factors influencing the yield, particulate density and particle size. In addition, they were concerned for the only significant interactions occurring among two different variables. None of the studied variables had major effect on the moisture content while the interaction between nanocapsules and silica in the feed was of first interest and determinant for both the qualitative and quantitative responses. The particles morphology depended on the feed formulation but was unaffected by the process conditions. This study demonstrated that drying nanocapsules using silica as auxiliary agent by spray drying process enables the obtaining of dried micronic particle size. The optimization of the process and the formulation variables resulted in a considerable improvement of product yield while minimizing the moisture content.

Interface control in BaTiO3 based supercapacitors

NASA Astrophysics Data System (ADS)

Maglione, Mario; Elissalde, Catherine; Chung, U.-Chan

2010-03-01

Core shell BaTiO3 based particles sintered using advanced processes provide a high control of grain boundaries in bulk composites. As a result, supercapacitor behavior was evidenced which came from the balance between inner grain conductivity and grain boundary dielectric barrier. Thanks to the core-shell structure of the starting particles, improved control of the effective dielectric parameters can be achieved.

Direct compression of chitosan: process and formulation factors to improve powder flow and tablet performance.

PubMed

Buys, Gerhard M; du Plessis, Lissinda H; Marais, Andries F; Kotze, Awie F; Hamman, Josias H

2013-06-01

Chitosan is a polymer derived from chitin that is widely available at relatively low cost, but due to compression challenges it has limited application for the production of direct compression tablets. The aim of this study was to use certain process and formulation variables to improve manufacturing of tablets containing chitosan as bulking agent. Chitosan particle size and flow properties were determined, which included bulk density, tapped density, compressibility and moisture uptake. The effect of process variables (i.e. compression force, punch depth, percentage compaction in a novel double fill compression process) and formulation variables (i.e. type of glidant, citric acid, pectin, coating with Eudragit S®) on chitosan tablet performance (i.e. mass variation, tensile strength, dissolution) was investigated. Moisture content of the chitosan powder, particle size and the inclusion of glidants had a pronounced effect on its flow ability. Varying the percentage compaction during the first cycle of a double fill compression process produced chitosan tablets with more acceptable tensile strength and dissolution rate properties. The inclusion of citric acid and pectin into the formulation significantly decreased the dissolution rate of isoniazid from the tablets due to gel formation. Direct compression of chitosan powder into tablets can be significantly improved by the investigated process and formulation variables as well as applying a double fill compression process.

Effect of particle size on oral absorption of carvedilol nanosuspensions: in vitro and in vivo evaluation

PubMed Central

Liu, Dandan; Pan, Hao; He, Fengwei; Wang, Xiaoyu; Li, Jinyu; Yang, Xinggang; Pan, Weisan

2015-01-01

The purpose of this work was to explore the particle size reduction effect of carvedilol on dissolution and absorption. Three suspensions containing different sized particles were prepared by antisolvent precipitation method or in combination with an ultrasonication process. The suspensions were characterized for particle size, surface morphology, and crystalline state. The crystalline form of carvedilol was changed into amorphous form after antisolvent precipitation. The dissolution rate of carvedilol was significantly accelerated by a reduction in particle size. The intestinal absorption of carvedilol nanosuspensions was greatly improved in comparison with microsuspensions and solution in the in situ single-pass perfusion experiment. The in vivo evaluation demonstrated that carvedilol nanosuspensions and microsuspensions exhibited markedly increased Cmax (2.09- and 1.48-fold) and AUC0−t (2.11- and 1.51-fold), and decreased Tmax (0.34- and 0.48-fold) in contrast with carvedilol coarse suspensions. Moreover, carvedilol nanosuspensions showed good biocompatibility with the rat gastric mucosa in in vivo gastrointestinal irritation test. The entire results implicated that the dissolution rate and the oral absorption of carvedilol were significantly affected by the particle size. Particle size reduction to form nanosized particles was found to be an efficient method for improving the oral bioavailability of carvedilol. PMID:26508852

Preparation, characterization and in vivo assessment of the bioavailability of glycyrrhizic acid microparticles by supercritical anti-solvent process.

PubMed

Sui, Xiaoyu; Wei, Wei; Yang, Lei; Zu, Yuangang; Zhao, Chunjian; Zhang, Lin; Yang, Fengjian; Zhang, Zhonghua

2012-02-28

In this study, glycyrrhizic acid (GA) microparticles were successfully prepared using a supercritical anti-solvent (SAS) process. Carbon dioxide and ethanol were used as the anti-solvent and solvent, respectively. The influences of several process parameters on the mean particle size (MPS), particle size distribution (PSD) and total yield were investigated. Processed particle sizes gradually decreased as temperature and solution flow rate increased. In addition, processed particle sizes increased from 119 to 205 nm as GA concentration increased. However, CO(2) flow rate did not significantly affect particle size. The optimized process conditions were applied, those included temperature (65 °C), pressure (250 bar), CO(2) and drug solution flow rate (15 and 8 mL min(-1)), drug concentration in ethanol (20 mg mL(-1)). Microparticles with a span of PSD ranging from 95 and 174 nm, MPS of 128 nm were obtained, and total yield was 63.5%. The X-ray diffraction patterns of glycyrrhizic acid microparticles show apparent amorphous nature. Fourier transform infrared (FT-IR) spectroscopy results show that no chemical structural changes occurred. The in vitro dissolution tests showed that the GA microparticles exhibited great enhancement of dissolution performance when compared to GA original drug. Furthermore, the in vivo studies revealed that the microparticles provided improved pharmacokinetic parameter after oral administration to rats as compared with original drug. Copyright © 2011 Elsevier B.V. All rights reserved.

Passivation and alloying element retention in gas atomized powders

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

Heidloff, Andrew J.; Rieken, Joel R.; Anderson, Iver E.

A method for gas atomization of a titanium alloy, nickel alloy, or other alumina (Al.sub.2O.sub.3)-forming alloy wherein the atomized particles are exposed as they solidify and cool in a very short time to multiple gaseous reactive agents for the in-situ formation of a passivation reaction film on the atomized particles wherein the reaction film retains a precursor halogen alloying element that is subsequently introduced into a microstructure formed by subsequent thermally processing of the atomized particles to improve oxidation resistance.

Megasonic cleaning strategy for sub-10nm photomasks

NASA Astrophysics Data System (ADS)

Hsu, Jyh-Wei; Samayoa, Martin; Dress, Peter; Dietze, Uwe; Ma, Ai-Jay; Lin, Chia-Shih; Lai, Rick; Chang, Peter; Tuo, Laurent

2016-10-01

One of the main challenges in photomask cleaning is balancing particle removal efficiency (PRE) with pattern damage control. To overcome this challenge, a high frequency megasonic cleaning strategy is implemented. Apart from megasonic frequency and power, photomask surface conditioning also influences cleaning performance. With improved wettability, cleanliness is enhanced while pattern damage risk is simultaneously reduced. Therefore, a particle removal process based on higher megasonic frequencies, combined with proper surface pre-treatment, provides improved cleanliness without the unintended side effects of pattern damage, thus supporting the extension of megasonic cleaning technology into 10nm half pitch (hp) device node and beyond.

Feedback enhanced plasma spray tool

DOEpatents

Gevelber, Michael Alan; Wroblewski, Donald Edward; Fincke, James Russell; Swank, William David; Haggard, Delon C.; Bewley, Randy Lee

2005-11-22

An improved automatic feedback control scheme enhances plasma spraying of powdered material through reduction of process variability and providing better ability to engineer coating structure. The present inventors discovered that controlling centroid position of the spatial distribution along with other output parameters, such as particle temperature, particle velocity, and molten mass flux rate, vastly increases control over the sprayed coating structure, including vertical and horizontal cracks, voids, and porosity. It also allows improved control over graded layers or compositionally varying layers of material, reduces variations, including variation in coating thickness, and allows increasing deposition rate. Various measurement and system control schemes are provided.

New directions: Time for a new approach to modeling surface-atmosphere exchanges in air quality models?

NASA Astrophysics Data System (ADS)

Saylor, Rick D.; Hicks, Bruce B.

2016-03-01

Just as the exchange of heat, moisture and momentum between the Earth's surface and the atmosphere are critical components of meteorological and climate models, the surface-atmosphere exchange of many trace gases and aerosol particles is a vitally important process in air quality (AQ) models. Current state-of-the-art AQ models treat the emission and deposition of most gases and particles as separate model parameterizations, even though evidence has accumulated over time that the emission and deposition processes of many constituents are often two sides of the same coin, with the upward (emission) or downward (deposition) flux over a landscape depending on a range of environmental, seasonal and biological variables. In this note we argue that the time has come to integrate the treatment of these processes in AQ models to provide biological, physical and chemical consistency and improved predictions of trace gases and particles.

Combining microwave resonance technology to multivariate data analysis as a novel PAT tool to improve process understanding in fluid bed granulation.

PubMed

Lourenço, Vera; Herdling, Thorsten; Reich, Gabriele; Menezes, José C; Lochmann, Dirk

2011-08-01

A set of 192 fluid bed granulation batches at industrial scale were in-line monitored using microwave resonance technology (MRT) to determine moisture, temperature and density of the granules. Multivariate data analysis techniques such as multiway partial least squares (PLS), multiway principal component analysis (PCA) and multivariate batch control charts were applied onto collected batch data sets. The combination of all these techniques, along with off-line particle size measurements, led to significantly increased process understanding. A seasonality effect could be put into evidence that impacted further processing through its influence on the final granule size. Moreover, it was demonstrated by means of a PLS that a relation between the particle size and the MRT measurements can be quantitatively defined, highlighting a potential ability of the MRT sensor to predict information about the final granule size. This study has contributed to improve a fluid bed granulation process, and the process knowledge obtained shows that the product quality can be built in process design, following Quality by Design (QbD) and Process Analytical Technology (PAT) principles. Copyright © 2011. Published by Elsevier B.V.

A New Dry Flue Gas Desulfurization Process-Underfeed Circulating Spouted Bed

NASA Astrophysics Data System (ADS)

Tao, M.; Jin, B. S.; Yang, Y. P.

Applying an underfeed system, the underfeed circulating spouted bed was designed as a desulfurization reactor. The main objective of the technology is to improve the mixing effect and distribution uniformity of solid particles, and therefore to advance the desulfurization efficiency and calcium utility. In this article, a series of experimental studies were conducted to investigate the fluidization behavior of the solid-gas two-phase flow in the riser. The results show that the technology can distinctly improve the distribution of gas velocity and particle flux on sections compared with the facefeed style. Analysis of pressure fluctuation signals indicates that the operation parameters have significant influence on the flow field in the reaction bed. The existence of injecting flow near the underfeed nozzle has an evident effect on strengthening the particle mixing.

Preparation of an Ultrafine Rebamipide Ophthalmic Suspension with High Transparency.

PubMed

Matsuda, Takakuni; Hiraoka, Shogo; Urashima, Hiroki; Ogura, Ako; Ishida, Tatsuhiro

2017-01-01

A 2% commercially available, milky-white, rebamipide micro-particle suspension is used to treat dry eyes, and it causes short-term blurring of the patient's vision. In the current study, to improve the transparency of a rebamipide suspension, we attempted to obtain a clear rebamipide suspension by transforming the rebamipide particles to an ultrafine state. In the initial few efforts, various rebamipide suspensions were prepared using a neutralizing crystallization method with additives, but the suspensions retained their opaque quality. However, as a consequence of several critical improvements in the neutralizing crystallization methods such as selection of additives for crystallization, process parameters during crystallization, the dispersion method, and dialysis, we obtained an ultrafine rebamipide suspension (2%) that was highly transparent (transmittance at 640 nm: 59%). The particle size and transparency demonstrated the fewest level of changes at 25°C after 3 years, compared to initial levels. During that period, no obvious particle sedimentation was observed. The administration of this ultrafine rebamipide suspension (2%) increased the conjunctival mucin, which was comparable to the commercially available micro-particle suspension (2%). The corneal and conjunctival concentration of rebamipide following ocular administration of the ultrafine suspension was slightly higher than that of the micro-particle suspension. The ultrafine rebamipide suspension (eye-drop formulation) with a highly transparent ophthalmic clearness should improve a patient's QOL by preventing even a shortened period of blurred vision.

Particle Engulfment and Pushing

NASA Technical Reports Server (NTRS)

2001-01-01

As a liquefied metal solidifies, particles dispersed in the liquid are either pushed ahead of or engulfed by the moving solidification front. Similar effects can be seen when the ground freezes and pushes large particles out of the soil. The Particle Engulfment and Pushing (PEP) experiment, conducted aboard the fourth U.S. Microgravity Payload (USMP-4) mission in 1997, used a glass and plastic beads suspended in a transparent liquid. The liquid was then frozen, trapping or pushing the particles as the solidifying front moved. This simulated the formation of advanced alloys and composite materials. Such studies help scientists to understand how to improve the processes for making advanced materials on Earth. The principal investigator is Dr. Doru Stefanescu of the University of Alabama. This image is from a video downlink.

Ash reduction strategies in corn stover facilitated by anatomical and size fractionation

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

Lacey, Jeffrey A.; Emerson, Rachel M.; Thompson, David N.

There is growing interest internationally to produce fuels from renewable biomass resources. Inorganic components of biomass feedstocks, referred to collectively as ash, damage equipment and decrease yields in thermal conversion processes, and decrease feedstock value for biochemical conversion processes. Decreasing the ash content of feedstocks improves conversion efficiency and lowers process costs. Because physiological ash is unevenly distributed in the plant, mechanical processes can be used to separate fractions of the plant based on ash content. This study focuses on the ash separation that can be achieved by separating corn stover by particle size and anatomical fraction. Baled corn stovermore » was hand-separated into anatomical fractions, ground to <19.1 mm, and size separated using six sieves ranging from 9.5 to 0.150 mm. Size fractions were analyzed for total ash content and ash composition. Particle size distributions observed for the anatomical fractions varied considerably. Cob particles were primarily 2.0 mm or greater, while most of the sheath and husk particles were 2.0 mm and smaller. Particles of leaves greater than 0.6 mm contained the greatest amount of total ash, ranging from approximately 8 to 13% dry weight of the total original material, while the fractions with particles smaller than 0.6 mm contained less than 2% of the total ash of the original material. As a result, based on the overall ash content and the elemental ash, specific anatomical and size fractions can be separated to optimize the feedstocks being delivered to biofuels conversion processes and minimize the need for more expensive ash reduction treatments.« less

Ash reduction strategies in corn stover facilitated by anatomical and size fractionation

DOE PAGES

Lacey, Jeffrey A.; Emerson, Rachel M.; Thompson, David N.; ...

2016-04-22

There is growing interest internationally to produce fuels from renewable biomass resources. Inorganic components of biomass feedstocks, referred to collectively as ash, damage equipment and decrease yields in thermal conversion processes, and decrease feedstock value for biochemical conversion processes. Decreasing the ash content of feedstocks improves conversion efficiency and lowers process costs. Because physiological ash is unevenly distributed in the plant, mechanical processes can be used to separate fractions of the plant based on ash content. This study focuses on the ash separation that can be achieved by separating corn stover by particle size and anatomical fraction. Baled corn stovermore » was hand-separated into anatomical fractions, ground to <19.1 mm, and size separated using six sieves ranging from 9.5 to 0.150 mm. Size fractions were analyzed for total ash content and ash composition. Particle size distributions observed for the anatomical fractions varied considerably. Cob particles were primarily 2.0 mm or greater, while most of the sheath and husk particles were 2.0 mm and smaller. Particles of leaves greater than 0.6 mm contained the greatest amount of total ash, ranging from approximately 8 to 13% dry weight of the total original material, while the fractions with particles smaller than 0.6 mm contained less than 2% of the total ash of the original material. As a result, based on the overall ash content and the elemental ash, specific anatomical and size fractions can be separated to optimize the feedstocks being delivered to biofuels conversion processes and minimize the need for more expensive ash reduction treatments.« less

Utilization of Titanium Particle Impact Location to Validate a 3D Multicomponent Model for Cold Spray Additive Manufacturing

NASA Astrophysics Data System (ADS)

Faizan-Ur-Rab, M.; Zahiri, S. H.; King, P. C.; Busch, C.; Masood, S. H.; Jahedi, M.; Nagarajah, R.; Gulizia, S.

2017-12-01

Cold spray is a solid-state rapid deposition technology in which metal powder is accelerated to supersonic speeds within a de Laval nozzle and then impacts onto the surface of a substrate. It is possible for cold spray to build thick structures, thus providing an opportunity for melt-less additive manufacturing. Image analysis of particle impact location and focused ion beam dissection of individual particles were utilized to validate a 3D multicomponent model of cold spray. Impact locations obtained using the 3D model were found to be in close agreement with the empirical data. Moreover, the 3D model revealed the particles' velocity and temperature just before impact—parameters which are paramount for developing a full understanding of the deposition process. Further, it was found that the temperature and velocity variations in large-size particles before impact were far less than for the small-size particles. Therefore, an optimal particle temperature and velocity were identified, which gave the highest deformation after impact. The trajectory of the particles from the injection point to the moment of deposition in relation to propellant gas is visualized. This detailed information is expected to assist with the optimization of the deposition process, contributing to improved mechanical properties for additively manufactured cold spray titanium parts.

Thermo-mechanical characterization of siliconized E-glass fiber/hematite particles reinforced epoxy resin hybrid composite

NASA Astrophysics Data System (ADS)

V. R., Arun prakash; Rajadurai, A.

2016-10-01

In this present work hybrid polymer (epoxy) matrix composite has been strengthened with surface modified E-glass fiber and iron(III) oxide particles with varying size. The particle sizes of 200 nm and <100 nm has been prepared by high energy ball milling and sol-gel methods respectively. To enhance better dispersion of particles and improve adhesion of fibers and fillers with epoxy matrix surface modification process has been done on both fiber and filler by an amino functional silane 3-Aminopropyltrimethoxysilane (APTMS). Crystalline and functional groups of siliconized iron(III) oxide particles were characterized by XRD and FTIR spectroscopy analysis. Fixed quantity of surface treated 15 vol% E-glass fiber was laid along with 0.5 and 1.0 vol% of iron(III) oxide particles into the matrix to fabricate hybrid composites. The composites were cured by an aliphatic hardener Triethylenetetramine (TETA). Effectiveness of surface modified particles and fibers addition into the resin matrix were revealed by mechanical testing like tensile testing, flexural testing, impact testing, inter laminar shear strength and hardness. Thermal behavior of composites was evaluated by TGA, DSC and thermal conductivity (Lee's disc). The scanning electron microscopy was employed to found shape and size of iron(III) oxide particles adhesion quality of fiber with epoxy matrix. Good dispersion of fillers in matrix was achieved with surface modifier APTMS. Tensile, flexural, impact and inter laminar shear strength of composites was improved by reinforcing surface modified fiber and filler. Thermal stability of epoxy resin was improved when surface modified fiber was reinforced along with hard hematite particles. Thermal conductivity of epoxy increased with increase of hematite content in epoxy matrix.

Biochar particle size, shape, and porosity act together to influence soil water properties

PubMed Central

Dugan, Brandon; Masiello, Caroline A.; Gonnermann, Helge M.

2017-01-01

Many studies report that, under some circumstances, amending soil with biochar can improve field capacity and plant-available water. However, little is known about the mechanisms that control these improvements, making it challenging to predict when biochar will improve soil water properties. To develop a conceptual model explaining biochar’s effects on soil hydrologic processes, we conducted a series of well constrained laboratory experiments using a sand matrix to test the effects of biochar particle size and porosity on soil water retention curves. We showed that biochar particle size affects soil water storage through changing pore space between particles (interpores) and by adding pores that are part of the biochar (intrapores). We used these experimental results to better understand how biochar intrapores and biochar particle shape control the observed changes in water retention when capillary pressure is the main component of soil water potential. We propose that biochar’s intrapores increase water content of biochar-sand mixtures when soils are drier. When biochar-sand mixtures are wetter, biochar particles’ elongated shape disrupts the packing of grains in the sandy matrix, increasing the volume between grains (interpores) available for water storage. These results imply that biochars with a high intraporosity and irregular shapes will most effectively increase water storage in coarse soils. PMID:28598988

An approach to improving transporting velocity in the long-range ultrasonic transportation of micro-particles

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

Meng, Jianxin; Mei, Deqing, E-mail: meidq-127@zju.edu.cn; Yang, Keji

2014-08-14

In existing ultrasonic transportation methods, the long-range transportation of micro-particles is always realized in step-by-step way. Due to the substantial decrease of the driving force in each step, the transportation is lower-speed and stair-stepping. To improve the transporting velocity, a non-stepping ultrasonic transportation approach is proposed. By quantitatively analyzing the acoustic potential well, an optimal region is defined as the position, where the largest driving force is provided under the condition that the driving force is simultaneously the major component of an acoustic radiation force. To keep the micro-particle trapped in the optimal region during the whole transportation process, anmore » approach of optimizing the phase-shifting velocity and phase-shifting step is adopted. Due to the stable and large driving force, the displacement of the micro-particle is an approximately linear function of time, instead of a stair-stepping function of time as in the existing step-by-step methods. An experimental setup is also developed to validate this approach. Long-range ultrasonic transportations of zirconium beads with high transporting velocity were realized. The experimental results demonstrated that this approach is an effective way to improve transporting velocity in the long-range ultrasonic transportation of micro-particles.« less

Ultrasound-assisted powder-coating technique to improve content uniformity of low-dose solid dosage forms.

PubMed

Genina, Natalja; Räikkönen, Heikki; Antikainen, Osmo; Heinämäki, Jyrki; Yliruusi, Jouko

2010-09-01

An ultrasound-assisted powder-coating technique was used to produce a homogeneous powder formulation of a low-dose active pharmaceutical ingredient (API). The powdered particles of microcrystalline cellulose (MCC; Avicel® PH-200) were coated with a 4% m/V aqueous solution of riboflavin sodium phosphate, producing a uniform drug layer on the particle surfaces. It was possible to regulate the amount of API in the treated powder. The thickness of the API layer on the surface of the MCC particles increased near linearly as the number of coating cycles increased, allowing a precise control of the drug content. The tablets (n = 950) prepared from the coated powder showed significantly improved weight and content uniformity in comparison with the reference tablets compressed from a physical binary powder mixture. This was due to the coated formulation remaining uniform during the entire tabletting process, whereas the physical mixture of the powders was subject to segregation. In conclusion, the ultrasound-assisted technique presented here is an effective tool for homogeneous drug coating of powders of irregular particle shape and broad particle size distribution, improving content uniformity of low-dose API in tablets, and consequently, ensuring the safe delivery of a potent active substance to patients.

Mechanical Properties of Mg2Si/Mg Composites via Powder Metallurgy Process

NASA Astrophysics Data System (ADS)

Muramatsu, Hiroshi; Kondoh, Katsuyoshi; Yuasa, Eiji; Aizawa, Tatsuhiko

The mechanical properties of the Mg2Si/Mg composites solid-state synthesized from the mixed Mg-Si powders have been investigated. The macro-hardness (HRE) and the tensile strength of the composites increase with increasing the Si content and decreasing the Si size. The particle size of the synthesized Mg2Si depends on the initial Si size; the mechanical properties of the Mg2Si/Mg composite are remarkably improved by using fine Si particles or by decreasing the grain size of Mg matrix grains when the powder mixture was prepared via bulk mechanical alloying process.

Aluminum base alloy powder metallurgy process and product

NASA Technical Reports Server (NTRS)

Paris, Henry G. (Inventor)

1986-01-01

A metallurgical method including cooling molten aluminum particles and consolidating resulting solidified particles into a multiparticle body, wherein the improvement comprises the provision of greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn. Aluminum containing greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn.

Method and apparatus for forming ceramic oxide superconductors with ordered structure

DOEpatents

Nellis, W.J.; Maple, M.B.

1987-12-23

Disclosed are products and processes for making improved magnetic and superconducting articles from anisotropic starting materials by initially reducing the starting materials into a powdered form composed of particles of uniform directional crystal structures, forming a directionally uniform aggregate of particles by exposing the aggregate to a magnetic field of desired magnitude and direction, and then compacting the aggregate into an integral solid body. 2 Figs.

Production of pure indinavir free base nanoparticles by a supercritical anti-solvent (SAS) method.

PubMed

Imperiale, Julieta C; Bevilacqua, Gabriela; Rosa, Paulo de Tarso Vieira E; Sosnik, Alejandro

2014-12-01

This work investigated the production of pure indinavir free base nanoparticles by a supercritical anti-solvent method to improve the drug dissolution in intestine-like medium. To increase the dissolution of the drug by means of a supercritical fluid processing method. Acetone was used as solvent and supercritical CO2 as antisolvent. Products were characterized by dynamic light scattering (size, size distribution), scanning electron microscopy (morphology), differential scanning calorimetry (thermal behaviour) and X-rays diffraction (crystallinity). Processed indinavir resulted in particles of significantly smaller size than the original drug. Particles showed at least one dimension at the nanometer scale with needle or rod-like morphology. Results of X-rays powder diffraction suggested the formation of a mixture of polymorphs. Differential scanning calorimetry analysis showed a main melting endotherm at 152 °C. Less prominent transitions due to the presence of small amounts of bound water (in the raw drug) or an unstable polymorph (in processed IDV) were also visible. Finally, drug particle size reduction significantly increased the dissolution rate with respect to the raw drug. Conversely, the slight increase of the intrinsic solubility of the nanoparticles was not significant. A supercritical anti-solvent method enabled the nanonization of indinavir free base in one single step with high yield. The processing led to faster dissolution that would improve the oral bioavailability of the drug.

Low density microcellular carbon or catalytically impregnated carbon forms and process for their preparation

DOEpatents

Hopper, Robert W.; Pekala, Richard W.

1989-01-01

Machinable and structurally stable, low density microcellular carbon, and catalytically impregnated carbon, foams, and process for their preparation, are provided. Pulverized sodium chloride is classified to improve particle size uniformity, and the classified particles may be further mixed with a catalyst material. The particles are cold pressed into a compact having internal pores, and then sintered. The sintered compact is immersed and then submerged in a phenolic polymer solution to uniformly fill the pores of the compact with phenolic polymer. The compact is then heated to pyrolyze the phenolic polymer into carbon in the form of a foam. Then the sodium chloride of the compact is leached away with water, and the remaining product is freeze dried to provide the carbon, or catalytically impregnated carbon, foam.

Low density microcellular carbon or catalytically impregnated carbon foams and process for their prepartion

DOEpatents

Hopper, Robert W.; Pekala, Richard W.

1988-01-01

Machinable and structurally stable, low density microcellular carbon, and catalytically impregnated carbon, foams, and process for their preparation, are provided. Pulverized sodium chloride is classified to improve particle size uniformity, and the classified particles may be further mixed with a catalyst material. The particles are cold pressed into a compact having internal pores, and then sintered. The sintered compact is immersed and then submerged in a phenolic polymer solution to uniformly fill the pores of the compact with phenolic polymer. The compact is then heated to pyrolyze the phenolic polymer into carbon in the form of a foam. Then the sodium chloride of the compact is leached away with water, and the remaining product is freeze dried to provide the carbon, or catalytically impregnated carbon, foam.

Low density microcellular carbon or catalytically impregnated carbon foams and process for their preparation

DOEpatents

Hooper, R.W.; Pekala, R.W.

1987-04-30

Machinable and structurally stable, low density microcellular carbon, and catalytically impregnated carbon, foams, and process for their preparation, are provided. Pulverized sodium chloride is classified to improve particle size uniformity, and the classified particles may be further mixed with a catalyst material. The particles are cold pressed into a compact having internal pores, and then sintered. The sintered compact is immersed and then submerged in a phenolic polymer solution to uniformly fill the pores of the compact with phenolic polymer. The compact is then heated to pyrolyze the phenolic polymer into carbon in the form of a foam. Then the sodium chloride of the compact is leached away with water, and the remaining product is freeze dried to provide the carbon, or catalytically impregnated carbon, foam.

Selection Criteria for Sustainable Fuels for High-Efficiency Spark-Ignition Engines with Examination of their Storage Stability, Impact on Engine Knock, and Fine Particle Emissions

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

McCormick, Robert L

It is possible to significantly improve the efficiency of spark-ignition engines given fuels with improved autoignition, evaporative cooling, and particle emission properties. At the same time, a vast range of different fuel chemistries are accessible from biomass - leading to questions about how fuel chemistries outside the range available from petroleum and ethanol can impact engine operation. This presentation will briefly describe the factors leading to poor efficiency in current SI engines, and the technologies available for improving efficiency. Improved fuel properties that enable high efficiency engine designs to be pursued aggressively will be reviewed, including octane index and sensitivity.more » A screening process based on fuel properties was applied to a large set of proposed biomass-derived gasoline blendstocks, and the properties of the best blendstocks were evaluated. Some of these fuels exhibit poor stability towards oxidation in the liquid phase, and storage stability studies for alkyl furans and cyclopentanone will be presented in brief. The importance of fuel heat of vaporization for direct injection engines, along with new research on measurement of this parameter, will be presented including an SI engine study of the impact of heat of vaporization on octane index and engine knock. Fuel effects on fine particle emissions and how our understanding breaks down for oxygenates will be discussed. Engine combustion experiments, droplet evaporation simulations, and heat of vaporization measurements conducted to better understand how oxygenates affect particle emissions will be described. This research defines a process that can be used to evaluate fuels for other types of combustion such as diesel, gasoline compression ignition, or strategies with mixed modes.« less

Enhancing Data Assimilation by Evolutionary Particle Filter and Markov Chain Monte Carlo

NASA Astrophysics Data System (ADS)

Moradkhani, H.; Abbaszadeh, P.; Yan, H.

2016-12-01

Particle Filters (PFs) have received increasing attention by the researchers from different disciplines in hydro-geosciences as an effective method to improve model predictions in nonlinear and non-Gaussian dynamical systems. The implication of dual state and parameter estimation by means of data assimilation in hydrology and geoscience has evolved since 2005 from SIR-PF to PF-MCMC and now to the most effective and robust framework through evolutionary PF approach based on Genetic Algorithm (GA) and Markov Chain Monte Carlo (MCMC), the so-called EPF-MCMC. In this framework, the posterior distribution undergoes an evolutionary process to update an ensemble of prior states that more closely resemble realistic posterior probability distribution. The premise of this approach is that the particles move to optimal position using the GA optimization coupled with MCMC increasing the number of effective particles, hence the particle degeneracy is avoided while the particle diversity is improved. The proposed algorithm is applied on a conceptual and highly nonlinear hydrologic model and the effectiveness, robustness and reliability of the method in jointly estimating the states and parameters and also reducing the uncertainty is demonstrated for few river basins across the United States.

[Application of an Adaptive Inertia Weight Particle Swarm Algorithm in the Magnetic Resonance Bias Field Correction].

PubMed

Wang, Chang; Qin, Xin; Liu, Yan; Zhang, Wenchao

2016-06-01

An adaptive inertia weight particle swarm algorithm is proposed in this study to solve the local optimal problem with the method of traditional particle swarm optimization in the process of estimating magnetic resonance(MR)image bias field.An indicator measuring the degree of premature convergence was designed for the defect of traditional particle swarm optimization algorithm.The inertia weight was adjusted adaptively based on this indicator to ensure particle swarm to be optimized globally and to avoid it from falling into local optimum.The Legendre polynomial was used to fit bias field,the polynomial parameters were optimized globally,and finally the bias field was estimated and corrected.Compared to those with the improved entropy minimum algorithm,the entropy of corrected image was smaller and the estimated bias field was more accurate in this study.Then the corrected image was segmented and the segmentation accuracy obtained in this research was 10% higher than that with improved entropy minimum algorithm.This algorithm can be applied to the correction of MR image bias field.

Process optimization for particle removal on blank chrome mask plates in preparation for resist application

NASA Astrophysics Data System (ADS)

Osborne, Stephen; Smith, Eryn; Woster, Eric; Pelayo, Anthony

2002-03-01

As integrated circuits require smaller lines to provide the memory and processing capability for tomorrow's marketplace, the photomask industry is adopting higher contrast resists to improve photomask lithography. Photomask yield for several high-contrast resist recipes may be improved by coating masks at the mask shop. When coating at a mask shop, an effective method is available that uses coat/bake cluster tools to ensure blanks are clean prior to coating. Many high-contrast resists are available, and some are more susceptible to time-dependent performance factors than conventional resists. One of these factors is the time between coating and writing. Although future methods may reduce the impact of this factor, one current trend is to reduce this time by coating plates at the mask shop just prior to writing. Establishing an effective process to clean blanks prior to coating is necessary for product quality control and is a new task that is critical for maskmakers who previously purchased mask plates but have decided to begin coating them within their facility. This paper provides a strategy and method to be used within coat/bake cluster tools to remove particle contamination from mask blanks. The process uses excimer-UV ionizing radiation and ozone to remove organic contaminants, and then uses a wet process combined with megasonic agitation, surfactant, and spin forces. Megasonic agitation with surfactant lifts up particles, while the convective outflow of water enhances centripetal shear without accumulating harmful charge.

Accurate modelling of single-particle cryo-EM images quantifies the benefits expected from using Zernike phase contrast

PubMed Central

Hall, R. J.; Nogales, E.; Glaeser, R. M.

2011-01-01

The use of a Zernike-type phase plate in biological cryo-electron microscopy allows the imaging, without using defocus, of what are predominantly phase objects. It is thought that such phase-plate implementations might result in higher quality images, free from the problems of CTF correction that occur when images must be recorded at extremely high values of defocus. In single-particle cryo-electron microscopy it is hoped that these improvements in image quality will facilitate work on structures that have proved difficult to study, either because of their relatively small size or because the structures are not completely homogeneous. There is still a need, however, to quantify how much improvement can be gained by using a phase plate for single-particle cryo-electron microscopy. We present a method for quantitatively modelling the images recorded with 200 keV electrons, for single particles embedded in vitreous ice. We then investigate what difference the use of a phase-plate device could have on the processing of single-particle data. We confirm that using a phase plate results in single-particle datasets in which smaller molecules can be detected, particles can be more accurately aligned and problems of heterogeneity can be more easily addressed. PMID:21463690

Improvement of desolvation and resilience of alginate binders for Si-based anodes in a lithium ion battery by calcium-mediated cross-linking.

PubMed

Yoon, Jihee; Oh, Dongyeop X; Jo, Changshin; Lee, Jinwoo; Hwang, Dong Soo

2014-12-14

Si-based anodes in lithium ion batteries (LIBs) have exceptionally high theoretical capacity, but the use of a Si-based anode in LIBs is problematic because the charging-discharging process can fracture the Si particles. Alginate and its derivatives show promise as Si particle binders in the anode. We show that calcium-mediated "egg-box" electrostatic cross-linking of alginate improves toughness, resilience, electrolyte desolvation of the alginate binder as a Si-binder for LIBs. Consequently, the improved mechanical properties of the calcium alginate binder compared to the sodium alginate binder and other commercial binders extend the lifetime and increase the capacity of Si-based anodes in LIBs.

Optimal visual simulation of the self-tracking combustion of the infrared decoy based on the particle system

NASA Astrophysics Data System (ADS)

Hu, Qi; Duan, Jin; Wang, LiNing; Zhai, Di

2016-09-01

The high-efficiency simulation test of military weapons has a very important effect on the high cost of the actual combat test and the very demanding operational efficiency. Especially among the simulative emulation methods of the explosive smoke, the simulation method based on the particle system has generated much attention. In order to further improve the traditional simulative emulation degree of the movement process of the infrared decoy during the real combustion cycle, this paper, adopting the virtual simulation platform of OpenGL and Vega Prime and according to their own radiation characteristics and the aerodynamic characteristics of the infrared decoy, has simulated the dynamic fuzzy characteristics of the infrared decoy during the real combustion cycle by using particle system based on the double depth peeling algorithm and has solved key issues such as the interface, coordinate conversion and the retention and recovery of the Vega Prime's status. The simulation experiment has basically reached the expected improvement purpose, effectively improved the simulation fidelity and provided theoretical support for improving the performance of the infrared decoy.

Self-associated submicron IgG1 particles for pulmonary delivery: effects of non-ionic surfactants on size, shape, stability, and aerosol performance.

PubMed

Srinivasan, Asha R; Shoyele, Sunday A

2013-03-01

The ability to produce submicron particles of monoclonal antibodies of different sizes and shapes would enhance their application to pulmonary delivery. Although non-ionic surfactants are widely used as stabilizers in protein formulations, we hypothesized that non-ionic surfactants will affect the shape and size of submicron IgG particles manufactured through precipitation. Submicron particles of IgG1 were produced by a precipitation process which explores the fact that proteins have minimum solubility but maximum precipitation at the isoelectric point. Non-ionic surfactants were used for size and shape control, and as stabilizing agents. Aerosol performance of the antibody nanoparticles was assessed using Andersen Cascade Impactor. Spinhaler® and Handihaler® were used as model DPI devices. SEM micrographs revealed that the shape of the submicron particles was altered by varying the type of surfactant added to the precipitating medium. Particle size as measured by dynamic light scattering was also varied based on the type and concentration of the surfactant. The surfactants were able to stabilize the IgG during the precipitation process. Polyhedral, sponge-like, and spherical nanoparticles demonstrated improved aerosolization properties compared to irregularly shaped (>20 μm) unprocessed particles. Stable antibody submicron particles of different shapes and sizes were prepared. Careful control of the shape of such particles is critical to ensuring optimized lung delivery by dry powder inhalation.

On Characterizing Particle Shape

NASA Technical Reports Server (NTRS)

Ennis, Bryan J.; Rickman, Douglas; Rollins, A. Brent; Ennis, Brandon

2014-01-01

It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.

Influence of the size reduction of organic waste on their anaerobic digestion.

PubMed

Palmowski, L M; Müller, J A

2000-01-01

The rate-limiting step in anaerobic digestion of organic solid waste is generally their hydrolysis. A size reduction of the particles and the resulting enlargement of the available specific surface can support the biological process in two ways. Firstly, in case of substrates with a high content of fibres and a low xegradability, their comminution yields to an improved digester gas production. This leads to a decreased amount of residues to be disposed of and to an increased quantity of useful digester gas. The second effect of the particle size reduction observed with all the substrates but particularly with those of low degradability is a reduction of the technical digestion time. Furthermore, the particle size of organic waste has an influence on the dewaterability after codigestion with sewage sludge. The presence of organic waste residues improves the dewaterability measured as specific resistance to filtration but this positive effect is attenuated if the particle size of the solids is reduced.

Effect of organic additives on characteristics of carbon-coated LiCoPO4 synthesized by hydrothermal method

NASA Astrophysics Data System (ADS)

Maeyoshi, Yuta; Miyamoto, Shohei; Noda, Yusaku; Munakata, Hirokazu; Kanamura, Kiyoshi

2017-01-01

Carbon-coated LiCoPO4 particles are synthesized by one-pot hydrothermal process using three different organic additives (carboxymethylcellulose sodium salt (CMC), glucose, and ascorbic acid). The effect of the organic additives on particle size, morphology, nature of carbon coating, and electrochemical property of the resulting LiCoPO4 is investigated. CMC plays important roles to decrease the particle size and form well-covered carbon coating on the surface. Carbon-coated LiCoPO4 prepared using CMC delivers higher initial discharge capacity of 135 mA h g-1 at 0.1 C, and shows superior rate capability and cyclic performance than the other samples. The improved electrochemical characteristics are attributed to not only the fine particle which allows facile electronic and ionic transport, but also the high coverage of carbon coating which improves the electrical conductivity and prevents the irreversible reactions of the charged LiCoPO4 with electrolyte.

Enhancing Localized Evaporation through Separated Light Absorbing Centers and Scattering Centers

PubMed Central

Zhao, Dengwu; Duan, Haoze; Yu, Shengtao; Zhang, Yao; He, Jiaqing; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2015-01-01

This report investigates the enhancement of localized evaporation via separated light absorbing particles (plasmonic absorbers) and scattering particles (polystyrene nanoparticles). Evaporation has been considered as one of the most important phase-change processes in modern industries. To improve the efficiency of evaporation, one of the most feasible methods is to localize heat at the top water layer rather than heating the bulk water. In this work, the mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat. Different concentrations of both the light absorbing centers and the light scattering centers were evaluated and the evaporation performance can be largely enhanced with the balance between absorbing centers and scattering centers. The findings in this study not only provide a new way to improve evaporation efficiency in plasmonic particle-based solution, but also shed lights on the design of new solar-driven localized evaporation systems. PMID:26606898

A Support Vector Learning-Based Particle Filter Scheme for Target Localization in Communication-Constrained Underwater Acoustic Sensor Networks

PubMed Central

Zhang, Chenglin; Yan, Lei; Han, Song; Guan, Xinping

2017-01-01

Target localization, which aims to estimate the location of an unknown target, is one of the key issues in applications of underwater acoustic sensor networks (UASNs). However, the constrained property of an underwater environment, such as restricted communication capacity of sensor nodes and sensing noises, makes target localization a challenging problem. This paper relies on fractional sensor nodes to formulate a support vector learning-based particle filter algorithm for the localization problem in communication-constrained underwater acoustic sensor networks. A node-selection strategy is exploited to pick fractional sensor nodes with short-distance pattern to participate in the sensing process at each time frame. Subsequently, we propose a least-square support vector regression (LSSVR)-based observation function, through which an iterative regression strategy is used to deal with the distorted data caused by sensing noises, to improve the observation accuracy. At the same time, we integrate the observation to formulate the likelihood function, which effectively update the weights of particles. Thus, the particle effectiveness is enhanced to avoid “particle degeneracy” problem and improve localization accuracy. In order to validate the performance of the proposed localization algorithm, two different noise scenarios are investigated. The simulation results show that the proposed localization algorithm can efficiently improve the localization accuracy. In addition, the node-selection strategy can effectively select the subset of sensor nodes to improve the communication efficiency of the sensor network. PMID:29267252

A Support Vector Learning-Based Particle Filter Scheme for Target Localization in Communication-Constrained Underwater Acoustic Sensor Networks.

PubMed

Li, Xinbin; Zhang, Chenglin; Yan, Lei; Han, Song; Guan, Xinping

2017-12-21

Target localization, which aims to estimate the location of an unknown target, is one of the key issues in applications of underwater acoustic sensor networks (UASNs). However, the constrained property of an underwater environment, such as restricted communication capacity of sensor nodes and sensing noises, makes target localization a challenging problem. This paper relies on fractional sensor nodes to formulate a support vector learning-based particle filter algorithm for the localization problem in communication-constrained underwater acoustic sensor networks. A node-selection strategy is exploited to pick fractional sensor nodes with short-distance pattern to participate in the sensing process at each time frame. Subsequently, we propose a least-square support vector regression (LSSVR)-based observation function, through which an iterative regression strategy is used to deal with the distorted data caused by sensing noises, to improve the observation accuracy. At the same time, we integrate the observation to formulate the likelihood function, which effectively update the weights of particles. Thus, the particle effectiveness is enhanced to avoid "particle degeneracy" problem and improve localization accuracy. In order to validate the performance of the proposed localization algorithm, two different noise scenarios are investigated. The simulation results show that the proposed localization algorithm can efficiently improve the localization accuracy. In addition, the node-selection strategy can effectively select the subset of sensor nodes to improve the communication efficiency of the sensor network.

Flue gas conditioning for improved particle collection in electrostatic precipitators

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

Durham, M.D.

1992-04-27

The purpose of this research program is to identify and evaluate a variety of additives capable of increasing particle cohesion which could be used for improving collection efficiency in an ESP. A three-phase screening process will be used to provide the, evaluation of many additives in a logical and cost-effective manner. The three step approach involves the following experimental setups: 1. Provide a preliminary screening in the laboratory by measuring the effects of various conditioning agents on reentrainment of flyash particles in an electric field operating at simulated flue gas conditions. 2. Evaluate the successful additives using a 100 acfmmore » bench-scale ESP operating on actual flue gas. 3. Obtain the data required for scaling up the technology by testing the two or three most promising conditioning agents at the pilot scale.« less

Laboratory and Cloud Chamber Studies of Formation Processes and Properties of Atmospheric Ice Particles

NASA Astrophysics Data System (ADS)

Leisner, T.; Abdelmonem, A.; Benz, S.; Brinkmann, M.; Möhler, O.; Rzesanke, D.; Saathoff, H.; Schnaiter, M.; Wagner, R.

2009-04-01

The formation of ice in tropospheric clouds controls the evolution of precipitation and thereby influences climate and weather via a complex network of dynamical and microphysical processes. At higher altitudes, ice particles in cirrus clouds or contrails modify the radiative energy budget by direct interaction with the shortwave and longwave radiation. In order to improve the parameterisation of the complex microphysical and dynamical processes leading to and controlling the evolution of tropospheric ice, laboratory experiments are performed at the IMK Karlsruhe both on a single particle level and in the aerosol and cloud chamber AIDA. Single particle experiments in electrodynamic levitation lend themselves to the study of the interaction between cloud droplets and aerosol particles under extremely well characterized and static conditions in order to obtain microphysical parameters as freezing nucleation rates for homogeneous and heterogeneous ice formation. They also allow the observation of the freezing dynamics and of secondary ice formation and multiplication processes under controlled conditions and with very high spatial and temporal resolution. The inherent droplet charge in these experiments can be varied over a wide range in order to assess the influence of the electrical state of the cloud on its microphysics. In the AIDA chamber on the other hand, these processes are observable under the realistic dynamic conditions of an expanding and cooling cloud- parcel with interacting particles and are probed simultaneously by a comprehensive set of analytical instruments. By this means, microphysical processes can be studied in their complex interplay with dynamical processes as for example coagulation or particle evaporation and growth via the Bergeron - Findeisen process. Shortwave scattering and longwave absorption properties of the nucleating and growing ice crystals are probed by in situ polarised laser light scattering measurements and infrared extinction spectroscopy. In conjunction with ex situ single particle imaging and light scattering measurements the relation between the overall extinction and depolarization properties of the ice clouds and the morphological details of the constituent ice crystals are investigated. In our contribution we will concentrate on the parameterization of homogeneous and heterogeneous ice formation processes under various atmospheric conditions and on the optical properties of the ice crystals produced under these conditions. First attempts to parameterize the observations will be presented.

Dissolution enhancement of Deflazacort using hollow crystals prepared by antisolvent crystallization process.

PubMed

Paulino, A S; Rauber, G; Campos, C E M; Maurício, M H P; de Avillez, R R; Capobianco, G; Cardoso, S G; Cuffini, S L

2013-05-13

Deflazacort (DFZ), a derivate of prednisolone, is a poorly soluble drug which has been proposed to have major advantages over other corticosteroids. Poorly soluble drugs present limited bioavailability due to their low solubility and dissolution rate and several strategies have been developed in order to find ways to improve them. In general, pharmaceutical laboratories use a micronized process to reduce the particle size in order to increase the dissolution of the drugs. However, this process causes changes such as polymorphic transitions, particle agglomeration and a reduction in fluidity and wettability. These solid-state properties affect the dissolution behavior and stability performance of drugs. Crystallization techniques are widely used in the pharmaceutical industry and antisolvent crystallization has been used to obtain ultrafine particles. In this study, DFZ was investigated in terms of its antisolvent crystallization in different solvents and under various preparation conditions (methanol/water ratio, stirring and evaporation rate, etc.), in order to compare the physicochemical properties between crystallized samples and raw materials available on the Brazilian market with and without micronization. Crystalline structure, morphology, and particle size, and their correlation with the Intrinsic Dissolution Rate (IDR) and dissolution profile as relevant biopharmaceutical properties were studied. Crystallization conditions were achieved which provided crystalline samples of hollow-shaped crystals with internal channels, which increased the dissolution rate of DFZ. The antisolvent crystallization process allowed the formation of hollow crystals, which demonstrated a better dissolution profile than the raw material (crystalline and micronized), making this a promising technique as a crystallization strategy for improving the dissolution and thus the bioavailability of poorly soluble drugs. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of ball milling and heat treatment process on MnBi powders magnetic properties

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

Xie, Wei; Polikarpov, Evgueni; Choi, Jung-Pyung

The metallic compound MnBi has high intrinsic coercivity with large positive temperature coefficient. The coercivity of MnBi exceeds 12 kOe and 26 kOe at 300 K and 523 K, respectively. Hence MnBi is a good candidate for the hard phase in exchange coupled nanocomposite magnets. In order to maximize the loading of the soft phase, the size of the MnBi particle has to be close to 500 nm, the size of single magnetic domain. Low energy milling is the common method to reduce MnBi particle size. However, only 3-7 mu m size particle can be achieved without significant decomposition. Here,more » we report our effort on preparing submicron MnBi powders using traditional powder metallurgy methods. Mn55Bi45 magnetic powders were prepared using arc melting method, followed by a series of thermal-mechanical treatment to improve purity, and finished with low energy ball milling at cryogenic temperature to achieve submicron particle size. The Mn55Bi45 powders were decomposed during ball milling process and recovered during 24 h 290 degrees C annealing process. With increasing ball-milling time, the saturation magnetization of MnBi decreases, while the coercivity increases. Annealing after ball milling recovers some of the magnetization, indicating the decomposition occurred during the ball-milling process can be reversed. The coercivity of Mn55Bi45 powders are also improved as a result of the heat treatment at 290 degrees C for 24 h. The world record magnetization 71.2 emu/g measured applying a field of 23 kOe has been achieved via low energy ball mill at room temperature« less

Cryochemical and CVD processing of shperical carbide fuels for propulsion reactors

NASA Astrophysics Data System (ADS)

Blair, H. Thomas; Carroll, David W.; Matthews, R. Bruce

1991-01-01

Many of the nuclear propulsion reactor concepts proposed for a manned mission to Mars use a coated spherical particle fuel form similar to that used in the Rover and NERVA propulsion reactors. The formation of uranium dicarbide microspheres using a cryochemical process and the coating of the UC2 spheres with zirconium carbide using chemical vapor deposition are being developed at Los Alamos National Laboratory. The cryochemical process is described with a discussion of the variables affecting the sphere formation and carbothermic reduction to produce UC2 spheres from UO2. Emphasis is placed on minimizing the wastes produced by the process. The ability to coat particles with ZrC was recaptured, and improvements in the process and equipment were developed. Volatile organometallic precursors were investigated as alternatives to the original ZrCl4 precursor.

Single-camera three-dimensional tracking of natural particulate and zooplankton

NASA Astrophysics Data System (ADS)

Troutman, Valerie A.; Dabiri, John O.

2018-07-01

We develop and characterize an image processing algorithm to adapt single-camera defocusing digital particle image velocimetry (DDPIV) for three-dimensional (3D) particle tracking velocimetry (PTV) of natural particulates, such as those present in the ocean. The conventional DDPIV technique is extended to facilitate tracking of non-uniform, non-spherical particles within a volume depth an order of magnitude larger than current single-camera applications (i.e. 10 cm  ×  10 cm  ×  24 cm depth) by a dynamic template matching method. This 2D cross-correlation method does not rely on precise determination of the centroid of the tracked objects. To accommodate the broad range of particle number densities found in natural marine environments, the performance of the measurement technique at higher particle densities has been improved by utilizing the time-history of tracked objects to inform 3D reconstruction. The developed processing algorithms were analyzed using synthetically generated images of flow induced by Hill’s spherical vortex, and the capabilities of the measurement technique were demonstrated empirically through volumetric reconstructions of the 3D trajectories of particles and highly non-spherical, 5 mm zooplankton.

In-Situ Imaging of Particles during Rapid Thermite Deflagrations

NASA Astrophysics Data System (ADS)

Grapes, Michael; Sullivan, Kyle; Reeves, Robert; Densmore, John; Willey, Trevor; van Buuren, Tony; Fezaa, Kamel

The dynamic behavior of rapidly deflagrating thermites is a highly complex process involving rapid decomposition, melting, and outgassing of intermediate and/or product gases. Few experimental techniques are capable of probing these phenomena in situ due to the small length and time scales associated with the reaction. Here we use a recently developed extended burn tube test, where we initiate a small pile of thermite on the closed end of a clear acrylic tube. The length of the tube is sufficient to fully contain the reaction as it proceeds and flows entrained particles down the tube. This experiment was brought to the Advanced Photon Source, and the particle formation was X-ray imaged at various positions down the tube. Several formulations, as well as formulation parameters were varied to investigate the size and morphology of the particles, as well as to look for dynamic behavior attributed to the reaction. In all cases, we see evidence of particle coalescence and condensed-phase interfacial reactions. The results improve our understanding of the procession of reactants to products in these systems. Funding provided by the LLNL LDRD program (PLS-16FS-028).

Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

NASA Astrophysics Data System (ADS)

Shahidi, Nima

Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media applications such as additives to waterborne emulsions. This innovative process for the first time opened up the application of rubber particles in aqueous media. The kinetics of polymerization reaction of hydrophilic monomer mixture within the rubber particles was investigated based on the assumption of partitioning of acrylic acid monomer in the hydrophobic rubber particles. The produced PPSIPNs were used as additives to waterborne emulsions and the mechanical and physical properties of the prepared coatings were examined. It was observed that the PPSIPNs could be added in high quantities with an improvement in adhesion, enhancement of the impact strength, and hardness of the coatings. This approach aims to develop environmentally benign products from scrap rubber materials.

Astigmatism compensation in digital holographic microscopy using complex-amplitude correlation

NASA Astrophysics Data System (ADS)

Tamrin, Khairul Fikri; Rahmatullah, Bahbibi; Samuri, Suzani Mohamad

2015-07-01

Digital holographic microscopy (DHM) is a promising tool for a three-dimensional imaging of microscopic particles. It offers the possibility of wavefront processing by manipulating amplitude and phase of the recorded digital holograms. With a view to compensate for aberration in the reconstructed particle images, this paper discusses a new approach of aberration compensation based on complex amplitude correlation and the use of a priori information. The approach is applied to holograms of microscopic particles flowing inside a cylindrical micro-channel recorded using an off-axis digital holographic microscope. The approach results in improvements in the image and signal qualities.

Do wastewater treatment plants act as a potential point source of microplastics? Preliminary study in the coastal Gulf of Finland, Baltic Sea.

PubMed

Talvitie, Julia; Heinonen, Mari; Pääkkönen, Jari-Pekka; Vahtera, Emil; Mikola, Anna; Setälä, Outi; Vahala, Riku

2015-01-01

This study on the removal of microplastics during different wastewater treatment unit processes was carried out at Viikinmäki wastewater treatment plant (WWTP). The amount of microplastics in the influent was high, but it decreased significantly during the treatment process. The major part of the fibres were removed already in primary sedimentation whereas synthetic particles settled mostly in secondary sedimentation. Biological filtration further improved the removal. A proportion of the microplastic load also passed the treatment and was found in the effluent, entering the receiving water body. After the treatment process, an average of 4.9 (±1.4) fibres and 8.6 (±2.5) particles were found per litre of wastewater. The total textile fibre concentration in the samples collected from the surface waters in the Helsinki archipelago varied between 0.01 and 0.65 fibres per litre, while the synthetic particle concentration varied between 0.5 and 9.4 particles per litre. The average fibre concentration was 25 times higher and the particle concentration was three times higher in the effluent compared to the receiving body of water. This indicates that WWTPs may operate as a route for microplastics entering the sea.

Oxidation and particle deposition modeling in plasma spraying of Ti-6Al-4V/SiC fiber composites

NASA Astrophysics Data System (ADS)

Cochelin, E.; Borit, F.; Frot, G.; Jeandin, M.; Decker, L.; Jeulin, D.; Taweel, B. Al; Michaud, V.; Noël, P.

1999-03-01

Plasma spraying is known to be a promising process for the manufacturing of Ti/SiC long-fiber composites. However, some improvements remain for this process to be applied in an industrial route. These include: oxygen contamination of the sprayed material through that of titanium particles before and during spraying, damage to fibers due to a high level of thermal stresses induced at the spraying stage, adequate deposition of titanium-base powder to achieve a low-porosity matrix and good impregnation of the fiber array. This article deals with work that resulted in a threefold study of the process. Oxidation was studied using electron microprobe analysis of elementary particles quenched and trapped into a closed box at various given flight distances. Oxygen diffusion phenomena within the particles are discussed from a preliminary theoretical approach coupled with experimental data. Isothermal and thermomechanical calculations were made using the ABAQUS code to determine stresses arising from contact of a liquid Ti-6Al-4V particle onto a SiC fiber. On the scale of the sprayed powder flow, a two-dimensional new type of model simulating the deposition of droplets onto a substrate was developed. This new type of model is based on a lattice-gas automaton that reproduces the hydrodynamical behavior of fluids.

The effect of surface-bulk potential difference on the kinetics of intercalation in core-shell active cathode particles

NASA Astrophysics Data System (ADS)

Kazemiabnavi, Saeed; Malik, Rahul; Orvananos, Bernardo; Abdellahi, Aziz; Ceder, Gerbrand; Thornton, Katsuyo

2018-04-01

Surface modification of active cathode particles is commonly observed in battery research as either a surface phase evolving during the cycling process, or intentionally engineered to improve capacity retention, rate capability, and/or thermal stability of the cathode material. Here, a continuum-scale model is developed to simulate the galvanostatic charge/discharge of a cathode particle with core-shell heterostructure. The particle is assumed to be comprised of a core material encapsulated by a thin layer of a second phase that has a different open-circuit voltage. The effect of the potential difference between the surface and bulk phases (Ω) on the kinetics of lithium intercalation and the galvanostatic charge/discharge profiles is studied at different values of Ω, C-rates, and exchange current densities. The difference between the Li chemical potential in the surface and bulk phases of the cathode particle results in a concentration difference between these two phases. This leads to a charge/discharge asymmetry in the galvanostatic voltage profiles, causing a decrease in the accessible capacity of the particle. These effects are more significant at higher magnitudes of surface-bulk potential difference. The proposed model provides detailed insight into the kinetics and voltage behavior of the intercalation/de-intercalation processes in core-shell heterostructure cathode particles.

Micromechanics of Ultrafine Particle Adhesion—Contact Models

NASA Astrophysics Data System (ADS)

Tomas, Jürgen

2009-06-01

Ultrafine, dry, cohesive and compressible powders (particle diameter d<10 μm) show a wide variety of flow problems that cause insufficient apparatus and system reliability of processing plants. Thus, the understanding of the micromechanics of particle adhesion is essential to assess the product quality and to improve the process performance in particle technology. Comprehensive models are shown that describe the elastic-plastic force-displacement and frictional moment-angle behavior of adhesive contacts of isotropic smooth spheres. By the model stiff particles with soft contacts, a sphere-sphere interaction of van der Waals forces without any contact deformation describes the stiff attractive term. But, the soft micro-contact response generates a flattened contact, i.e. plate-plate interaction, and increasing adhesion. These increasing adhesion forces between particles directly depend on this frozen irreversible deformation. Thus, the adhesion force is found to be load dependent. It contributes to the tangential forces in an elastic-plastic frictional contact with partially sticking and micro-slip within the contact plane. The load dependent rolling resistance and torque of mobilized frictional contact rotation (spin around its principal axis) are also shown. This reasonable combination of particle contact micromechanics and powder continuum mechanics is used to model analytically the macroscopic friction limits of incipient powder consolidation, yield and cohesive steady-state shear flow on physical basis.

Particle Swarm Optimization With Interswarm Interactive Learning Strategy.

PubMed

Qin, Quande; Cheng, Shi; Zhang, Qingyu; Li, Li; Shi, Yuhui

2016-10-01

The learning strategy in the canonical particle swarm optimization (PSO) algorithm is often blamed for being the primary reason for loss of diversity. Population diversity maintenance is crucial for preventing particles from being stuck into local optima. In this paper, we present an improved PSO algorithm with an interswarm interactive learning strategy (IILPSO) by overcoming the drawbacks of the canonical PSO algorithm's learning strategy. IILPSO is inspired by the phenomenon in human society that the interactive learning behavior takes place among different groups. Particles in IILPSO are divided into two swarms. The interswarm interactive learning (IIL) behavior is triggered when the best particle's fitness value of both the swarms does not improve for a certain number of iterations. According to the best particle's fitness value of each swarm, the softmax method and roulette method are used to determine the roles of the two swarms as the learning swarm and the learned swarm. In addition, the velocity mutation operator and global best vibration strategy are used to improve the algorithm's global search capability. The IIL strategy is applied to PSO with global star and local ring structures, which are termed as IILPSO-G and IILPSO-L algorithm, respectively. Numerical experiments are conducted to compare the proposed algorithms with eight popular PSO variants. From the experimental results, IILPSO demonstrates the good performance in terms of solution accuracy, convergence speed, and reliability. Finally, the variations of the population diversity in the entire search process provide an explanation why IILPSO performs effectively.

Improving the API dissolution rate during pharmaceutical hot-melt extrusion I: Effect of the API particle size, and the co-rotating, twin-screw extruder screw configuration on the API dissolution rate.

PubMed

Li, Meng; Gogos, Costas G; Ioannidis, Nicolas

2015-01-15

The dissolution rate of the active pharmaceutical ingredients in pharmaceutical hot-melt extrusion is the most critical elementary step during the extrusion of amorphous solid solutions - total dissolution has to be achieved within the short residence time in the extruder. Dissolution and dissolution rates are affected by process, material and equipment variables. In this work, we examine the effect of one of the material variables and one of the equipment variables, namely, the API particle size and extruder screw configuration on the API dissolution rate, in a co-rotating, twin-screw extruder. By rapidly removing the extruder screws from the barrel after achieving a steady state, we collected samples along the length of the extruder screws that were characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) to determine the amount of undissolved API. Analyses of samples indicate that reduction of particle size of the API and appropriate selection of screw design can markedly improve the dissolution rate of the API during extrusion. In addition, angle of repose measurements and light microscopy images show that the reduction of particle size of the API can improve the flowability of the physical mixture feed and the adhesiveness between its components, respectively, through dry coating of the polymer particles by the API particles. Copyright © 2014. Published by Elsevier B.V.

New characterisation method of electrical and electronic equipment wastes (WEEE).

PubMed

Menad, N; Guignot, S; van Houwelingen, J A

2013-03-01

Innovative separation and beneficiation techniques of various materials encountered in electrical and electronic equipment wastes (WEEE) is a major improvement for its recycling. Mechanical separation-oriented characterisation of WEEE was conducted in an attempt to evaluate the amenability of mechanical separation processes. Properties such as liberation degree of fractions (plastics, metals ferrous and non-ferrous), which are essential for mechanical separation, are analysed by means of a grain counting approach. Two different samples from different recycling industries were characterised in this work. The first sample is a heterogeneous material containing different types of plastics, metals (ferrous and non-ferrous), printed circuit board (PCB), rubber and wood. The second sample contains a mixture of mainly plastics. It is found for the first sample that all aluminium particles are free (100%) in all investigated size fractions. Between 92% and 95% of plastics are present as free particles; however, 67% in average of ferromagnetic particles are liberated. It can be observed that only 42% of ferromagnetic particles are free in the size fraction larger than 20mm. Particle shapes were also quantified manually particle by particle. The results show that the particle shapes as a result of shredding, turn out to be heterogeneous, thereby complicating mechanical separation processes. In addition, the separability of various materials was ascertained by a sink-float analysis and eddy current separation. The second sample was separated by automatic sensor sorting in four different products: ABS, PC-ABS, PS and rest product. The fractions were characterised by using the methodology described in this paper. The results show that the grade and liberation degree of the plastic products ABS, PC-ABS and PS are close to 100%. Sink-float separation and infrared plastic identification equipment confirms the high plastic quality. On the basis of these findings, a global separation flow sheet is proposed to improve the plastic separation of WEEE. Copyright © 2012 Elsevier Ltd. All rights reserved.

COMMERCIALIZATION OF AN ATMOSPHERIC IRON-BASED CDCL PROCESS FOR POWER PRODUCTION. PHASE I: TECHNOECONOMIC ANALYSIS

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

Vargas, Luis

Coal Direct Chemical Looping (CDCL) is an advanced oxy-combustion technology that has potential to enable substantial reductions in the cost and energy penalty associated with carbon dioxide (CO2) capture from coal-fired power plants. Through collaborative efforts, the Babcock & Wilcox Power Generation Group (B&W) and The Ohio State University (OSU) developed a conceptual design for a 550 MWe (net) supercritical CDCL power plant with greater than 90% CO2 capture and compression. Process simulations were completed to enable an initial assessment of its technical performance. A cost estimate was developed following DOE’s guidelines as outlined in NETL’s report “Quality Guidelines formore » Energy System Studies: Cost Estimation Methodology for NETL Assessments of Power Plant Performance”, (2011/1455). The cost of electricity for the CDCL plant without CO2 Transportation and Storage cost resulted in $ $102.67 per MWh, which corresponds to a 26.8 % increase in cost of electricity (COE) when compared to an air-fired pulverized-coal supercritical power plant. The cost of electricity is strongly depending on the total plant cost and cost of the oxygen carrier particles. The CDCL process could capture further potential savings by increasing the performance of the particles and reducing the plant size. During the techno-economic analysis, the team identified technology and engineering gaps that need to be closed to bring the technology to commercialization. The technology gaps were focused in five critical areas: (i) moving bed reducer reactor, (ii) fluidized bed combustor, (iii) particle riser, (iv) oxygen-carrier particle properties, and (v) process operation. The key technology gaps are related to particle performance, particle manufacturing cost, and the operation of the reducer reactor. These technology gaps are to be addressed during Phase II of project. The project team is proposing additional lab testing to be completed on the particle and a 3MWth pilot facility be built to evaluate the reducer reactor performance among other aspects of the technology. A Phase II proposal was prepared and submitted to DOE. The project team proposed a three year program in Phase II. Year 1 includes lab testing and particle development work aimed at improving the chemical and mechanical properties of the oxygen carrier particle. In parallel, B&W will design the 3MWt pilot plant. Any improvements to the particle performance discovered in year 1 that would impact the design of the pilot will be incorporated into the final design. Year 2 will focus on procurement of materials and equipment, and construction of the pilot plant. Year 3 will include, commissioning, start-up, and testing in the pilot. Phase I work was successfully completed and a design and operating philosophy for a 550 MWe commercial scale coal-direct chemical looping power plant was developed. Based on the results of the techno-economic evaluation, B&W projects that the CDCL process can achieve 96.5% CO2 capture with a« less

Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys.

PubMed

Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

2016-12-01

Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti2Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti2Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (>99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Simulation of Plasma Jet Merger and Liner Formation within the PLX- α Project

NASA Astrophysics Data System (ADS)

Samulyak, Roman; Chen, Hsin-Chiang; Shih, Wen; Hsu, Scott

2015-11-01

Detailed numerical studies of the propagation and merger of high Mach number argon plasma jets and the formation of plasma liners have been performed using the newly developed method of Lagrangian particles (LP). The LP method significantly improves accuracy and mathematical rigor of common particle-based numerical methods such as smooth particle hydrodynamics while preserving their main advantages compared to grid-based methods. A brief overview of the LP method will be presented. The Lagrangian particle code implements main relevant physics models such as an equation of state for argon undergoing atomic physics transformation, radiation losses in thin optical limit, and heat conduction. Simulations of the merger of two plasma jets are compared with experimental data from past PLX experiments. Simulations quantify the effect of oblique shock waves, ionization, and radiation processes on the jet merger process. Results of preliminary simulations of future PLX- alpha experiments involving the ~ π / 2 -solid-angle plasma-liner configuration with 9 guns will also be presented. Partially supported by ARPA-E's ALPHA program.

Control of artificial pinning centers in REBCO coated conductors derived from the trifluoroacetate metal-organic deposition process

NASA Astrophysics Data System (ADS)

Izumi, T.; Nakaoka, K.

2018-07-01

The metal-organic deposition (MOD) process using metal trifluoroacetate salts (TFA) has the advantages of low-cost and high-scalability for the fabrication of REBa2Cu3O y (REBCO, RE: rare earth elements) superconducting coated conductors (CCs) with high critical current density, in principle, because of its non-vacuum process. For the magnetic applications of CCs such as motors, magnetic resonance imaging and superconducting magnetic energy storage, further improvement of superconducting performance under magnetic fields is required. However, the in-field superconducting performance of REBCO CCs derived from the TFA-MOD process had been inferior to those derived from the vapor-phase process. In order to improve the in-field performance, the size control of the artificial pinning centers has been known as an effective way. In the early stage, the BaZrO3 (BZO) material, which was one of the effective materials in the CCs by the vapor-phase process, was also introduced in the TFA-MOD-derived CCs. The unique feature of the BZO material in the TFA-MOD process is the shape. The BZO in the TFA-MOD process formed the particle shape, although in the vapor-phase process it has a rod shape with a long axis elongating along the thickness direction. In addition, a special heat treatment for refining the BZO particles was developed, which is called the ‘interim heat treatment’. This heating profile made the in-field characteristics higher, although they were still lower than those of the vapor-phase process. Then, the new MOD process including ‘ultra-thin once coating’ was recently developed for further refinement of the BZO particles. The characteristics of the new TFA-MOD-derived CCs in magnetic fields have become compatible with those of the CCs derived from the vapor-phase process.

[Influence of wall polymer and preparation process on the particle size and encapsulation of hemoglobin microcapsules].

PubMed

Qiu, Wei; Ma, Guang-Hui; Meng, Fan-Tao; Su, Zhi-Guo

2004-03-01

Methoxypoly (ethylene glycol)- block-poly (DL-lactide) (PELA) microcapsules containing bovine hemoglobin (BHb) were prepared by a W/O/W double emulsion-solvent diffusion process. The P50 and Hill coeffcient were 3466 Pa and 2.4 respectively, which were near to the natural bioactivity of bovine hemoglobin. The results suggested that polymer composition had significant influence on encapsulation efficiency and particle size of microcapsules. The encapsulation efficiency could reach 90% and the particle size 3 - 5 microm when the PELA copolymer containing MPEG 2000 block was used. The encapsulation efficiency and particle size increased with the concentration of PELA. Increasing the concentrations of NaCl in outer aqueous solution resulted in the increase of encapsulation efficiency and the decrease of particle size. As the concentration of stabilizer in outer aqueous solution increased in the range of 10 g/L to 20 g/L, the particle size reduced while encapsulation efficiency was increased, further increase of the stabilizer concentration would decrease encapsulation efficiency. Increasing of primary emulsion stirring rate was advantageous to the improvement of encapsulation efficiency though it had little influence on the particle size. The influence of re-emulsion stirring rate was complicated, which was not apparent in the case of large volume of re-emulsion solution. When the wall polymer and primary emulsion stirring rate were fixed, the encapsulation efficiency decreased as the particle size reduced.

Using sieving and pretreatment to separate plastics during end-of-life vehicle recycling.

PubMed

Stagner, Jacqueline A; Sagan, Barsha; Tam, Edwin Kl

2013-09-01

Plastics continue to be a challenge for recovering materials at the end-of-life for vehicles. However, it may be possible to improve the recovery of plastics by exploiting material characteristics, such as shape, or by altering their behavior, such as through temperature changes, in relation to recovery processes and handling. Samples of a 2009 Dodge Challenger front fascia were shredded in a laboratory-scale hammer mill shredder. A 2 × 2 factorial design study was performed to determine the effect of sample shape (flat versus curved) and sample temperature (room temperature versus cryogenic temperature) on the size of the particles exiting from the shredder. It was determined that sample shape does not affect the particle size; however, sample temperature does affect the particle size. At cryogenic temperatures, the distribution of particle sizes is much narrower than at room temperature. Having a more uniform particle size could make recovery of plastic particles, such as these more efficient during the recycling of end-of-life vehicles. Samples of Chrysler minivan headlights were also shredded at room temperature and at cryogenic temperatures. The size of the particles of the two different plastics in the headlights is statistically different both at room temperature and at cryogenic temperature, and the particles are distributed narrowly. The research suggests that incremental changes in end-of-life vehicle processing could be effective in aiding materials recovery.

On improving the algorithm efficiency in the particle-particle force calculations

NASA Astrophysics Data System (ADS)

Kozynchenko, Alexander I.; Kozynchenko, Sergey A.

2016-09-01

The problem of calculating inter-particle forces in the particle-particle (PP) simulation models takes an important place in scientific computing. Such simulation models are used in diverse scientific applications arising in astrophysics, plasma physics, particle accelerators, etc., where the long-range forces are considered. The inverse-square laws such as Coulomb's law of electrostatic forces and Newton's law of universal gravitation are the examples of laws pertaining to the long-range forces. The standard naïve PP method outlined, for example, by Hockney and Eastwood [1] is straightforward, processing all pairs of particles in a double nested loop. The PP algorithm provides the best accuracy of all possible methods, but its computational complexity is O (Np2), where Np is a total number of particles involved. Too low efficiency of the PP algorithm seems to be the challenging issue in some cases where the high accuracy is required. An example can be taken from the charged particle beam dynamics where, under computing the own space charge of the beam, so-called macro-particles are used (see e.g., Humphries Jr. [2], Kozynchenko and Svistunov [3]).

Emergence and Utility of Nonspherical Particles in Biomedicine

PubMed Central

Fish, Margaret B.; Thompson, Alex J.; Fromen, Catherine A.; Eniola-Adefeso, Omolola

2016-01-01

The importance of the size of targeted, spherical drug carriers has been previously explored and reviewed. Particle shape has emerged as an equally important parameter in determining the in vivo journey and efficiency of drug carrier systems. Researchers have invented techniques to better control the geometry of particles of many different materials, which have allowed for exploration of the role of particle geometry in the phases of drug delivery. The important biological processes include clearance by the immune system, trafficking to the target tissue, margination to the endothelial surface, interaction with the target cell, and controlled release of a payload. The review of current literature herein supports that particle shape can be altered to improve a system’s targeting efficiency. Non-spherical particles can harness the potential of targeted drug carriers by enhancing targeted site accumulation while simultaneously decreasing side effects and mitigating some limitations faced by spherical carriers. PMID:27182109

Use of Existing CAD Models for Radiation Shielding Analysis

NASA Technical Reports Server (NTRS)

Lee, K. T.; Barzilla, J. E.; Wilson, P.; Davis, A.; Zachman, J.

2015-01-01

The utility of a radiation exposure analysis depends not only on the accuracy of the underlying particle transport code, but also on the accuracy of the geometric representations of both the vehicle used as radiation shielding mass and the phantom representation of the human form. The current NASA/Space Radiation Analysis Group (SRAG) process to determine crew radiation exposure in a vehicle design incorporates both output from an analytic High Z and Energy Particle Transport (HZETRN) code and the properties (i.e., material thicknesses) of a previously processed drawing. This geometry pre-process can be time-consuming, and the results are less accurate than those determined using a Monte Carlo-based particle transport code. The current work aims to improve this process. Although several Monte Carlo programs (FLUKA, Geant4) are readily available, most use an internal geometry engine. The lack of an interface with the standard CAD formats used by the vehicle designers limits the ability of the user to communicate complex geometries. Translation of native CAD drawings into a format readable by these transport programs is time consuming and prone to error. The Direct Accelerated Geometry -United (DAGU) project is intended to provide an interface between the native vehicle or phantom CAD geometry and multiple particle transport codes to minimize problem setup, computing time and analysis error.

Fabrication of Oxide Dispersion Strengthened Bond Coats with Low Al2O3 Content

NASA Astrophysics Data System (ADS)

Bergholz, Jan; Pint, Bruce A.; Unocic, Kinga A.; Vaßen, Robert

2017-06-01

Nanoscale oxide dispersions have long been used to increase the oxidation and wear resistance of alloys used as bond coatings in thermal barrier coatings. Their manufacturing via mechanical alloying is often accompanied by difficulties regarding their particle size, homogeneous distribution of the oxide dispersions inside the powder, involving considerable costs, due to cold welding of the powder during milling. A significant improvement in this process can be achieved by the use of process control agent (PCA) to achieve the critical balance between cold welding and fracturing, thereby enhancing the process efficiency. In this investigation, the influence of the organic additive stearic acid on the manufacturing process of Al2O3-doped CoNiCrAlY powder was investigated. Powders were fabricated via mechanical alloying at different milling times and PCA concentrations. The results showed a decrease in particle size, without hindering the homogeneous incorporation of the oxide dispersions. Two powders manufactured with 0.5 and 1.0 wt.% PCA were deposited by high velocity oxygen fuel (HVOF) spraying. Results showed that a higher content of elongated particles in the powder with the higher PCA content led to increased surface roughness, porosity and decreased coating thickness, with areas without embedded oxide particles.

Wire Composition: Its Effect on Metal Disintegration and Particle Formation in Twin-Wire Arc-Spraying Process

NASA Astrophysics Data System (ADS)

Tillmann, W.; Abdulgader, M.

2013-03-01

The wire tips in twin-wire arc-spraying (TWAS) are heated in three different zones. A high-speed camera was used to observe the melting behavior, metal breakup, and particle formation under different operating conditions. In zone (I), the wire tips are melted (liquidus metal) and directly atomized in the form of smaller droplets. Their size is a function of the specific properties of the molten metal and the exerting aerodynamic forces. Zone (II) is directly beneath zone (I) and the origin of the extruded metal sheets at the wire tips. The extruded metal sheets in the case of cored wires are shorter than those observed while using solid wires. In this study, the effects of adjustable parameters and powder filling on melting behavior, particle formation, and process instability were revealed, and a comparison between solid and cored wires was made. The findings can improve the accuracy of the TWAS process modeling.

Improvement of Physico-mechanical Properties of Partially Amorphous Acetaminophen Developed from Hydroalcoholic Solution Using Spray Drying Technique

PubMed Central

Sadeghi, Fatemeh; Torab, Mansour; Khattab, Mostafa; Homayouni, Alireza; Afrasiabi Garekani, Hadi

2013-01-01

Objective(s): This study was performed aiming to investigate the effect of particle engineering via spray drying of hydroalcoholic solution on solid states and physico-mechanical properties of acetaminophen. Materials and Methods: Spray drying of hydroalcoholic solution (25% v/v ethanol/water) of acetaminophen (5% w/v) in the presence of small amounts of polyninylpyrrolidone K30 (PVP) (0, 1.25, 2.5 and 5% w/w based on acetaminophen weight) was carried out. The properties of spray dried particles namely morphology, surface characteristics, particle size, crystallinity, dissolution rate and compactibility were evaluated. Results: Spray drying process significantly changed the morphology of acetaminophen crystals from acicular (rod shape) to spherical microparticle. Differential scanning calorimetery (DSC) and x-ray powder diffraction (XRPD) studies ruled out any polymorphism in spray dried samples, however, a major reduction in crystallinity up to 65%, especially for those containing 5% w/w PVP was observed. Spray dried acetaminophen particles especially those obtained in the presence of PVP exhibited an obvious improvement of the dissolution and compaction properties. Tablets produced from spray dried samples exhibited excellent crushing strengths and no tendency to cap. Conclusions: The findings of this study revealed that spray drying of acetaminophen from hydroalcoholic solution in the presence of small amount of PVP produced partially amorphous particles with improved dissolution and excellent compaction properties. PMID:24379968

The influence of laser pulse duration and energy on ICP-MS signal intensity, elemental fractionation, and particle size distribution in NIR fs-LA-ICP-MS

PubMed Central

Diwakar, Prasoon K.; Harilal, Sivanandan S.; LaHaye, Nicole L.; Hassanein, Ahmed; Kulkarni, Pramod

2015-01-01

Laser parameters, typically wavelength, pulse width, irradiance, repetition rate, and pulse energy, are critical parameters which influence the laser ablation process and thereby influence the LA-ICP-MS signal. In recent times, femtosecond laser ablation has gained popularity owing to the reduction in fractionation related issues and improved analytical performance which can provide matrix-independent sampling. The advantage offered by fs-LA is due to shorter pulse duration of the laser as compared to the phonon relaxation time and heat diffusion time. Hence the thermal effects are minimized in fs-LA. Recently, fs-LA-ICP-MS demonstrated improved analytical performance as compared to ns-LA-ICP-MS, but detailed mechanisms and processes are still not clearly understood. Improvement of fs-LA-ICP-MS over ns-LA-ICP-MS elucidates the importance of laser pulse duration and related effects on the ablation process. In this study, we have investigated the influence of laser pulse width (40 fs to 0.3 ns) and energy on LA-ICP-MS signal intensity and repeatability using a brass sample. Experiments were performed in single spot ablation mode as well as rastering ablation mode to monitor the Cu/Zn ratio. The recorded ICP-MS signal was correlated with total particle counts generated during laser ablation as well as particle size distribution. Our results show the importance of pulse width effects in the fs regime that becomes more pronounced when moving from femtosecond to picosecond and nanosecond regimes. PMID:26664120

Correlation of microstructure with dynamic deformation behavior and penetration performance of tungsten heavy alloys fabricated by mechanical alloying

NASA Astrophysics Data System (ADS)

Kim, Dong-Kuk; Lee, Sunghak; Ryu, Ho Jin; Hyunghong, Soon; Noh, Joon-Woong

2000-10-01

In this study, tungsten heavy alloy specimens were fabricated by mechanical alloying (MA), and their dynamic torsional properties and penetration performance were investigated. Dynamic torsional tests were conducted on the specimens fabricated with different sintering temperatures after MA, and then the test data were compared with those of a conventionally processed specimen. Refinement of tungsten particles was obtained after MA, but contiguity was seriously increased, thereby leading to low ductility and impact energy. Specimens in which both particle size and contiguity were simultaneously reduced by MA and two-step sintering and those having higher matrix fraction by partial MA were successfully fabricated. The dynamic test results indicated that the formation of adiabatic shear bands was expected because of the plastic localization at the central area of the gage section. Upon highspeed impact testing of these specimens, self-sharpening was promoted by the adiabatic shear band formation, but their penetration performance did not improve since much of kinetic energy of the penetrators was consumed for the microcrack formation due to interfacial debonding and cleavage fracture of tungsten particles. In order to improve penetration performance as well as to achieve selfsharpening by applying MA, conditions of MA and sintering process should be established so that alloy densification, particle refinement, and contiguity reduction can be simultaneously achieved.

Microgravity

NASA Image and Video Library

2001-01-24

As a liquefied metal solidifies, particles dispersed in the liquid are either pushed ahead of or engulfed by the moving solidification front. Similar effects can be seen when the ground freezes and pushes large particles out of the soil. The Particle Engulfment and Pushing (PEP) experiment, conducted aboard the fourth U.S. Microgravity Payload (USMP-4) mission in 1997, used a glass and plastic beads suspended in a transparent liquid. The liquid was then frozen, trapping or pushing the particles as the solidifying front moved. This simulated the formation of advanced alloys and composite materials. Such studies help scientists to understand how to improve the processes for making advanced materials on Earth. The principal investigator is Dr. Doru Stefanescu of the University of Alabama. This image is from a video downlink.

Visualization of flow during cleaning process on a liquid nanofibrous filter

NASA Astrophysics Data System (ADS)

Bílek, P.

2017-10-01

This paper deals with visualization of flow during cleaning process on a nanofibrous filter. Cleaning of a filter is very important part of the filtration process which extends lifetime of the filter and improve filtration properties. Cleaning is carried out on flat-sheet filters, where particles are deposited on the filter surface and form a filtration cake. The cleaning process dislodges the deposited filtration cake, which is loose from the membrane surface to the retentate flow. The blocked pores in the filter are opened again and hydrodynamic properties are restored. The presented optical method enables to see flow behaviour in a thin laser sheet on the inlet side of a tested filter during the cleaning process. The local concentration of solid particles is possible to estimate and achieve new information about the cleaning process. In the article is described the cleaning process on nanofibrous membranes for waste water treatment. The hydrodynamic data were compared to the images of the cleaning process.

Numerical modelling of electrochemical polarization around charged metallic particles

NASA Astrophysics Data System (ADS)

Bücker, Matthias; Undorf, Sabine; Flores Orozco, Adrián; Kemna, Andreas

2017-04-01

We extend an existing analytical model and carry out numerical simulations to study the polarization process around charged metallic particles immersed in an electrolyte solution. Electro-migration and diffusion processes in the electrolyte are described by the Poisson-Nernst-Planck system of partial differential equations. To model the surface charge density, we consider a time- and frequency-invariant electric potential at the particle surface, which leads to the build-up of a static electrical double layer (EDL). Upon excitation by an external electric field at low frequencies, we observe the superposition of two polarization processes. On the one hand, the induced dipole moment on the metallic particle leads to the accumulation of opposite charges in the electrolyte. This charge polarization corresponds to the long-known response of uncharged metallic particles. On the other hand, the unequal cation and anion concentrations in the EDL give rise to a salinity gradient between the two opposite sides of the metallic particle. The resulting concentration polarization enhances the magnitude of the overall polarization response. Furthermore, we use our numerical model to study the effect of relevant model parameters such as surface charge density and ionic strength of the electrolyte on the resulting spectra of the effective conductivity of the composite model system. Our results do not only give interesting new insight into the time-harmonic variation of electric potential and ion concentrations around charged metallic particle. They are also able to reduce incongruities between earlier model predictions and geophysical field and laboratory measurements. Our model thereby improves the general understanding of IP signatures of metallic particles and represents the next step towards a quantitative interpretation of IP imaging results. Part of this research is funded by the Austrian Federal Ministry of Science, Research and Economy under the Raw Materials Initiative.

Stable carbonous catalyst particles and method for making and utilizing same

DOEpatents

Ganguli, Partha S.; Comolli, Alfred G.

2005-06-14

Stable carbonous catalyst particles composed of an inorganic catalytic metal/metal oxide powder and a carbonaceous binder material are formed having a basic inner substantially uniform-porous carbon coating of the catalytic powder, and may include an outer porous carbon coating layer. Suitable inorganic catalytic powders include zinc-chromite (ZnO/Cr.sub.2 03) and suitable carbonaceous liquid binders having molecular weight of 200-700 include partially polymerized furfuryl alcohol, which are mixed together, shaped and carbonized and partially oxidized at elevated temperature. Such stable carbonous catalyst particles such as 0.020-0.100 inch (0.51-2.54 mm) diameter extrudates, have total carbon content of 2-25 wt. % and improved crush strength of 1.0-5 1b/mn, 50-300 m.sup.2 /g surface area, and can be advantageously utilized in fixed bed or ebullated/fluidized bed reactor operations. This invention also includes method steps for making the stable carbonous catalyst particles having improved particle strength and catalytic activity, and processes for utilizing the active stable carbonous carbon-coated catalysts such as for syn-gas reactions in ebullated/fluidized bed reactors for producing alcohol products and Fischer-Tropsch synthesis liquid products.

Recovery of low volumes of wear debris from rat stifle joint tissues using a novel particle isolation method.

PubMed

Patel, J; Lal, S; Nuss, K; Wilshaw, S P; von Rechenberg, B; Hall, R M; Tipper, J L

2018-04-15

Less than optimal particle isolation techniques have impeded analysis of orthopaedic wear debris in vivo. The purpose of this research was to develop and test an improved method for particle isolation from tissue. A volume of 0.018 mm 3 of clinically relevant CoCrMo, Ti-6Al-4V or Si 3 N 4 particles was injected into rat stifle joints for seven days of in vivo exposure. Following sacrifice, particles were located within tissues using histology. The particles were recovered by enzymatic digestion of periarticular tissue with papain and proteinase K, followed by ultracentrifugation using a sodium polytungstate density gradient. Particles were recovered from all samples, observed using SEM and the particle composition was verified using EDX, which demonstrated that all isolated particles were free from contamination. Particle size, aspect ratio and circularity were measured using image analysis software. There were no significant changes to the measured parameters of CoCrMo or Si 3 N 4 particles before and after the recovery process (KS tests, p > 0.05). Titanium particles were too few before and after isolation to analyse statistically, though size and morphologies were similar. Overall the method demonstrated a significant improvement to current particle isolation methods from tissue in terms of sensitivity and efficacy at removal of protein, and has the potential to be used for the isolation of ultra-low wearing total joint replacement materials from periprosthetic tissues. This research presents a novel method for the isolation of wear particles from tissue. Methodology outlined in this work would be a valuable resource for future researchers wishing to isolate particles from tissues, either as part of preclinical testing, or from explants from patients for diagnostic purposes. It is increasingly recognised that analysis of wear particles is critical to evaluating the safety of an orthopaedic device. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Observing ice particle growth along fall streaks in mixed-phase clouds using spectral polarimetric radar data

NASA Astrophysics Data System (ADS)

Pfitzenmaier, Lukas; Unal, Christine M. H.; Dufournet, Yann; Russchenberg, Herman W. J.

2018-06-01

The growth of ice crystals in presence of supercooled liquid droplets represents the most important process for precipitation formation in the mid-latitudes. However, such mixed-phase interaction processes remain relatively unknown, as capturing the complexity in cloud dynamics and microphysical variabilities turns to be a real observational challenge. Ground-based radar systems equipped with fully polarimetric and Doppler capabilities in high temporal and spatial resolutions such as the S-band transportable atmospheric radar (TARA) are best suited to observe mixed-phase growth processes. In this paper, measurements are taken with the TARA radar during the ACCEPT campaign (analysis of the composition of clouds with extended polarization techniques). Besides the common radar observables, the 3-D wind field is also retrieved due to TARA unique three beam configuration. The novelty of this paper is to combine all these observations with a particle evolution detection algorithm based on a new fall streak retrieval technique in order to study ice particle growth within complex precipitating mixed-phased cloud systems. In the presented cases, three different growth processes of ice crystals, plate-like crystals, and needles are detected and related to the presence of supercooled liquid water. Moreover, TARA observed signatures are assessed with co-located measurements obtained from a cloud radar and radiosondes. This paper shows that it is possible to observe ice particle growth processes within complex systems taking advantage of adequate technology and state of the art retrieval algorithms. A significant improvement is made towards a conclusive interpretation of ice particle growth processes and their contribution to rain production using fall streak rearranged radar data.

Nitride Fuel Development Using Cryo-process Technique

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

O'Brien, Brandi M; Windes, William E

A new cryo-process technique has been developed for the fabrication of advanced fuel for nuclear systems. The process uses a new cryo-processing technique whereby small, porous microspheres (<2000 µm) are formed from sub-micron oxide powder. A simple aqueous particle slurry of oxide powder is pumped through a microsphere generator consisting of a vibrating needle with controlled amplitude and frequency. As the water-based droplets are formed and pass through the microsphere generator they are frozen in a bath of liquid nitrogen and promptly vacuum freeze-dried to remove the water. The resulting porous microspheres consist of half micron sized oxide particles heldmore » together by electrostatic forces and mechanical interlocking of the particles. Oxide powder microspheres ranging from 750 µm to 2000 µm are then converted into a nitride form using a high temperature fluidized particle bed. Carbon black can be added to the oxide powder before microsphere formation to augment the carbothermic reaction during conversion to a nitride. Also, the addition of ethyl alcohol to the aqueous slurry reduces the surface tension energy of the droplets resulting in even smaller droplets forming in the microsphere generator. Initial results from this new process indicate a lower impurity contamination in the final nitrides due to the single feed stream of particles, material handling and conversion are greatly simplified, a minimum of waste and personnel exposure are anticipated, and finally the conversion kinetics may be greatly increased because of the small oxide powder size (sub-micron) forming the porous microsphere. Thus far the fabrication process has been successful in demonstrating all of these improvements with surrogate ZrO2 powder. Further tests will be conducted in the future using the technique on UO2 powders.« less

A versatile model for soft patchy particles with various patch arrangements.

PubMed

Li, Zhan-Wei; Zhu, You-Liang; Lu, Zhong-Yuan; Sun, Zhao-Yan

2016-01-21

We propose a simple and general mesoscale soft patchy particle model, which can felicitously describe the deformable and surface-anisotropic characteristics of soft patchy particles. This model can be used in dynamics simulations to investigate the aggregation behavior and mechanism of various types of soft patchy particles with tunable number, size, direction, and geometrical arrangement of the patches. To improve the computational efficiency of this mesoscale model in dynamics simulations, we give the simulation algorithm that fits the compute unified device architecture (CUDA) framework of NVIDIA graphics processing units (GPUs). The validation of the model and the performance of the simulations using GPUs are demonstrated by simulating several benchmark systems of soft patchy particles with 1 to 4 patches in a regular geometrical arrangement. Because of its simplicity and computational efficiency, the soft patchy particle model will provide a powerful tool to investigate the aggregation behavior of soft patchy particles, such as patchy micelles, patchy microgels, and patchy dendrimers, over larger spatial and temporal scales.

A novel coupling of noise reduction algorithms for particle flow simulations

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

Zimoń, M.J., E-mail: malgorzata.zimon@stfc.ac.uk; James Weir Fluids Lab, Mechanical and Aerospace Engineering Department, The University of Strathclyde, Glasgow G1 1XJ; Reese, J.M.

2016-09-15

Proper orthogonal decomposition (POD) and its extension based on time-windows have been shown to greatly improve the effectiveness of recovering smooth ensemble solutions from noisy particle data. However, to successfully de-noise any molecular system, a large number of measurements still need to be provided. In order to achieve a better efficiency in processing time-dependent fields, we have combined POD with a well-established signal processing technique, wavelet-based thresholding. In this novel hybrid procedure, the wavelet filtering is applied within the POD domain and referred to as WAVinPOD. The algorithm exhibits promising results when applied to both synthetically generated signals and particlemore » data. In this work, the simulations compare the performance of our new approach with standard POD or wavelet analysis in extracting smooth profiles from noisy velocity and density fields. Numerical examples include molecular dynamics and dissipative particle dynamics simulations of unsteady force- and shear-driven liquid flows, as well as phase separation phenomenon. Simulation results confirm that WAVinPOD preserves the dimensionality reduction obtained using POD, while improving its filtering properties through the sparse representation of data in wavelet basis. This paper shows that WAVinPOD outperforms the other estimators for both synthetically generated signals and particle-based measurements, achieving a higher signal-to-noise ratio from a smaller number of samples. The new filtering methodology offers significant computational savings, particularly for multi-scale applications seeking to couple continuum informations with atomistic models. It is the first time that a rigorous analysis has compared de-noising techniques for particle-based fluid simulations.« less

Preparation of Ultraviolet Curing Type Silicone Rubbers Containing Mesoporous Silica Fillers.

PubMed

Abdullah, Nawfel; Hossain, Md Shahriar A; Fatehmulla, Amanullah; Farooq, Wazirzada Aslam; Islam, Md Tofazzal; Miyamoto, Nobuyoshi; Bando, Yoshio; Kamachi, Yuichiro; Malgras, Victor; Yamauchi, Yusuke; Suzuki, Norihiro

2018-01-01

Here we have been focusing on mesoporous silica (MPS) as inorganic filler material to improve the mechanical strength of silicone rubbers. The MPS particles are more effective in reducing the coefficient of thermal expansion (CTE) and hardening silicone rubber composites when compared to commercially available nonporous silica particles. In this study, we utilize ultraviolet curing type silicone rubbers and prepare MPS composites according to a simple single-step method. From an industrial viewpoint, simplifying the fabrication processes is critical. The thermal stability and mechanical strength are examined in detail in order to showcase the effectiveness of MPS particles as filler materials.

Optical properties of mineral dust aerosol including analysis of particle size, composition, and shape effects, and the impact of physical and chemical processing

NASA Astrophysics Data System (ADS)

Alexander, Jennifer Mary

Atmospheric mineral dust has a large impact on the earth's radiation balance and climate. The radiative effects of mineral dust depend on factors including, particle size, shape, and composition which can all be extremely complex. Mineral dust particles are typically irregular in shape and can include sharp edges, voids, and fine scale surface roughness. Particle shape can also depend on the type of mineral and can vary as a function of particle size. In addition, atmospheric mineral dust is a complex mixture of different minerals as well as other, possibly organic, components that have been mixed in while these particles are suspended in the atmosphere. Aerosol optical properties are investigated in this work, including studies of the effect of particle size, shape, and composition on the infrared (IR) extinction and visible scattering properties in order to achieve more accurate modeling methods. Studies of particle shape effects on dust optical properties for single component mineral samples of silicate clay and diatomaceous earth are carried out here first. Experimental measurements are modeled using T-matrix theory in a uniform spheroid approximation. Previous efforts to simulate the measured optical properties of silicate clay, using models that assumed particle shape was independent of particle size, have achieved only limited success. However, a model which accounts for a correlation between particle size and shape for the silicate clays offers a large improvement over earlier modeling approaches. Diatomaceous earth is also studied as an example of a single component mineral dust aerosol with extreme particle shapes. A particle shape distribution, determined by fitting the experimental IR extinction data, used as a basis for modeling the visible light scattering properties. While the visible simulations show only modestly good agreement with the scattering data, the fits are generally better than those obtained using more commonly invoked particle shape distributions. The next goal of this work is to investigate if modeling methods developed in the studies of single mineral components can be generalized to predict the optical properties of more authentic aerosol samples which are complex mixtures of different minerals. Samples of Saharan sand, Iowa loess, and Arizona road dust are used here as test cases. T-matrix based simulations of the authentic samples, using measured particle size distributions, empirical mineralogies, and a priori particle shape models for each mineral component are directly compared with the measured IR extinction spectra and visible scattering profiles. This modeling approach offers a significant improvement over more commonly applied models that ignore variations in particle shape with size or mineralogy and include only a moderate range of shape parameters. Mineral dust samples processed with organic acids and humic material are also studied in order to explore how the optical properties of dust can change after being aged in the atmosphere. Processed samples include quartz mixed with humic material, and calcite reacted with acetic and oxalic acid. Clear differences in the light scattering properties are observed for all three processed mineral dust samples when compared to the unprocessed mineral dust or organic salt products. These interactions result in both internal and external mixtures depending on the sample. In addition, the presence of these organic materials can alter the mineral dust particle shape. Overall, however, these results demonstrate the need to account for the effects of atmospheric aging of mineral dust on aerosol optical properties. Particle shape can also affect the aerodynamic properties of mineral dust aerosol. In order to account for these effects, the dynamic shape factor is used to give a measure of particle asphericity. Dynamic shape factors of quartz are measured by mass and mobility selecting particles and measuring their vacuum aerodynamic diameter. From this, dynamic shape factors in both the transition and vacuum regime can be derived. The measured dynamic shape factors of quartz agree quite well with the spheroidal shape distributions derived through studies of the optical properties.

Big Data: A Parallel Particle Swarm Optimization-Back-Propagation Neural Network Algorithm Based on MapReduce.

PubMed

Cao, Jianfang; Cui, Hongyan; Shi, Hao; Jiao, Lijuan

2016-01-01

A back-propagation (BP) neural network can solve complicated random nonlinear mapping problems; therefore, it can be applied to a wide range of problems. However, as the sample size increases, the time required to train BP neural networks becomes lengthy. Moreover, the classification accuracy decreases as well. To improve the classification accuracy and runtime efficiency of the BP neural network algorithm, we proposed a parallel design and realization method for a particle swarm optimization (PSO)-optimized BP neural network based on MapReduce on the Hadoop platform using both the PSO algorithm and a parallel design. The PSO algorithm was used to optimize the BP neural network's initial weights and thresholds and improve the accuracy of the classification algorithm. The MapReduce parallel programming model was utilized to achieve parallel processing of the BP algorithm, thereby solving the problems of hardware and communication overhead when the BP neural network addresses big data. Datasets on 5 different scales were constructed using the scene image library from the SUN Database. The classification accuracy of the parallel PSO-BP neural network algorithm is approximately 92%, and the system efficiency is approximately 0.85, which presents obvious advantages when processing big data. The algorithm proposed in this study demonstrated both higher classification accuracy and improved time efficiency, which represents a significant improvement obtained from applying parallel processing to an intelligent algorithm on big data.

Characterization of Ice and Snow In-Situ Properties During the Main Weather Regimes Observed in The Olympic Mountain Experiment

NASA Astrophysics Data System (ADS)

Borque, P.; Finlon, J.; Nesbitt, S. W.; McFarquhar, G. M.

2017-12-01

Observations from the Olympic Mountain Experiment (OLYMPEX) present a unique opportunity to analyze a vast catalogue of in-situ microphysical information over a variety of mid-latitude precipitation types. Data collected by the Citation Research Aircraft was processed using the University of Illinois/Oklahoma Optical Array Probe Processing Software to give not only bulk cloud properties (e.g., total number concentration, ice water content (IWC), and parameters describing gamma fits to observed size distributions) but also particle-by-particle properties (e.g., aspect ratio, perimeter, and projected area). In this work, we analyzed these properties in association with the different processes (e.g., aggregation, riming and accretion) occurring under the three main weather sectors (warm, prefrontal, and postfrontal) present over the OLYMPEX region. Bulk and particle properties present statistically different characteristics over the different sectors of the weather system analyzed. For example, the IWC over the warm sector presents a bimodal distribution with the primary maximum present at 0.055 g m-3 and a secondary maximum at 0.235 g m-3; whereas over the postfrontal sector the IWC has a unique maximum at 0.005 g m-3. The higher frequency of occurrence of mass-weighted mean crystal diameter (Dm) occurs at 1.57mm for the warm sector and 0.125mm for the postfrontal sector. In summary, the warm sector is characterized by large IWC, large Dm, shape parameter of the gamma distribution (μ) close to zero, and lighter particles (following a simple mass-diameter relation), all consistent with aggregation being the dominant process. In contrast, observations from the postfrontal sector show smaller IWCs, smaller Dm, negative μ, and heavier particles, all consistent with rimed particles dominating the region. Evidence for this was also seen with particle images from the in-situ probes showing large aggregates present in the warm sector and rimed particles in the postfrontal sector. The characterization of this extensive catalog of observations leads to a better understanding of the dominating microphysical process present in each region, which will improve GPM algorithms as bulk and particle information are of fundamental importance to relate ice cloud particle shape properties to mass-related information

Intercomparison and Evaluation of Global Aerosol Microphysical Properties Among Aerocom Models of a Range of Complexity

NASA Technical Reports Server (NTRS)

Mann, G. W.; Carslaw, K. S.; Reddington, C. L.; Pringle, K. J.; Schulz, M.; Asmi, A.; Spracklen, D. V.; Ridley, D. A.; Woodhouse, M. T.; Lee, L. A.;

Implementing Molecular Dynamics on Hybrid High Performance Computers - Particle-Particle Particle-Mesh

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

Brown, W Michael; Kohlmeyer, Axel; Plimpton, Steven J

The use of accelerators such as graphics processing units (GPUs) has become popular in scientific computing applications due to their low cost, impressive floating-point capabilities, high memory bandwidth, and low electrical power requirements. Hybrid high-performance computers, machines with nodes containing more than one type of floating-point processor (e.g. CPU and GPU), are now becoming more prevalent due to these advantages. In this paper, we present a continuation of previous work implementing algorithms for using accelerators into the LAMMPS molecular dynamics software for distributed memory parallel hybrid machines. In our previous work, we focused on acceleration for short-range models with anmore » approach intended to harness the processing power of both the accelerator and (multi-core) CPUs. To augment the existing implementations, we present an efficient implementation of long-range electrostatic force calculation for molecular dynamics. Specifically, we present an implementation of the particle-particle particle-mesh method based on the work by Harvey and De Fabritiis. We present benchmark results on the Keeneland InfiniBand GPU cluster. We provide a performance comparison of the same kernels compiled with both CUDA and OpenCL. We discuss limitations to parallel efficiency and future directions for improving performance on hybrid or heterogeneous computers.« less

Purification process of natural graphite as anode for Li-ion batteries: chemical versus thermal

NASA Astrophysics Data System (ADS)

Zaghib, K.; Song, X.; Guerfi, A.; Rioux, R.; Kinoshita, K.

The intercalation of Li ions in natural graphite that was purified by chemical and thermal processes was investigated. A new chemical process was developed that involved a mixed aqueous solution containing 30% H 2SO 4 and 30% NH xF y heated to 90 °C. The results of this process are compared to those obtained by heating the natural graphite from 1500 to 2400 °C in an inert environment (thermal process). The first-cycle coulombic efficiency of the purified natural graphite obtained by the chemical process is 91 and 84% after the thermal process at 2400 °C. Grinding the natural graphite before or after purification had no significant effect on electrochemical performance at low currents. However, grinding to a very small particle size before purification permitted optimization of the size distribution of the particles, which gives rise to a more homogenous electrode. The impurities in the graphite play a role as microabrasion agents during grinding which enhances its hardness and improves its mechanical properties. Grinding also modifies the particle morphology from a 2- to a 3-D structure (similar in shape to a potato). This potato-shaped natural graphite shows high reversible capacity at high current densities (about 90% at 1 C rate). Our analysis suggests that thermal processing is considerably more expensive than the chemical process to obtain purified natural graphite.

Improving a Spectral Bin Microphysical Scheme Using TRMM Satellite Observations

NASA Technical Reports Server (NTRS)

Li, Xiaowen; Tao, Wei-Kuo; Matsui, Toshihisa; Liu, Chuntao; Masunaga, Hirohiko

2010-01-01

Comparisons between cloud model simulations and observations are crucial in validating model performance and improving physical processes represented in the mod Tel.hese modeled physical processes are idealized representations and almost always have large rooms for improvements. In this study, we use data from two different sensors onboard TRMM (Tropical Rainfall Measurement Mission) satellite to improve the microphysical scheme in the Goddard Cumulus Ensemble (GCE) model. TRMM observed mature-stage squall lines during late spring, early summer in central US over a 9-year period are compiled and compared with a case simulation by GCE model. A unique aspect of the GCE model is that it has a state-of-the-art spectral bin microphysical scheme, which uses 33 different bins to represent particle size distribution of each of the seven hydrometeor species. A forward radiative transfer model calculates TRMM Precipitation Radar (PR) reflectivity and TRMM Microwave Imager (TMI) 85 GHz brightness temperatures from simulated particle size distributions. Comparisons between model outputs and observations reveal that the model overestimates sizes of snow/aggregates in the stratiform region of the squall line. After adjusting temperature-dependent collection coefficients among ice-phase particles, PR comparisons become good while TMI comparisons worsen. Further investigations show that the partitioning between graupel (a high-density form of aggregate), and snow (a low-density form of aggregate) needs to be adjusted in order to have good comparisons in both PR reflectivity and TMI brightness temperature. This study shows that long-term satellite observations, especially those with multiple sensors, can be very useful in constraining model microphysics. It is also the first study in validating and improving a sophisticated spectral bin microphysical scheme according to long-term satellite observations.

Fox-7 for Insensitive Boosters

DTIC Science & Technology

2010-08-01

cavitation , and therefore nucleation, to occur at each frequency. As well as producing ultrasound at different frequencies, the method of delivery of...processing techniques using ultrasound , designed to optimise FOX-7 crystal size and morphology to improve booster formulations, and results from these...7 booster formulations. Also included are particle processing techniques using ultrasound , designed to optimise FOX-7 crystal size and morphology

Perspective: Aerosol microphysics: From molecules to the chemical physics of aerosols

NASA Astrophysics Data System (ADS)

Bzdek, Bryan R.; Reid, Jonathan P.

2017-12-01

Aerosols are found in a wide diversity of contexts and applications, including the atmosphere, pharmaceutics, and industry. Aerosols are dispersions of particles in a gas, and the coupling of the two phases results in highly dynamic systems where chemical and physical properties like size, composition, phase, and refractive index change rapidly in response to environmental perturbations. Aerosol particles span a wide range of sizes from 1 nm to tens of micrometres or from small molecular clusters that may more closely resemble gas phase molecules to large particles that can have similar qualities to bulk materials. However, even large particles with finite volumes exhibit distinct properties from the bulk condensed phase, due in part to their higher surface-to-volume ratio and their ability to easily access supersaturated solute states inaccessible in the bulk. Aerosols represent a major challenge for study because of the facile coupling between the particle and gas, the small amounts of sample available for analysis, and the sheer breadth of operative processes. Time scales of aerosol processes can be as short as nanoseconds or as long as years. Despite their very different impacts and applications, fundamental chemical physics processes serve as a common theme that underpins our understanding of aerosols. This perspective article discusses challenges in the study of aerosols and highlights recent chemical physics advancements that have enabled improved understanding of these complex systems.

A new sol-gel processing routine without chelating agents for preparing highly transparent solutions and nanothin films: engineering the role of chemistry to design the process

NASA Astrophysics Data System (ADS)

Ashiri, Rouholah

2015-01-01

The great sensitivity of titanium alkoxides to hydrolysis makes their sol-gel transformation very fast and thus difficult to control. A method was proposed to alleviate this drawback. Preparation of highly transparent solutions and nanothin films is another objective of the present research. Employing nanoemulsion method and optimizing the processing conditions, a clear solution of well-dispersed nanosized particles was obtained. With the proposed process BaTiO3 precursor sols and nanothin films with enhanced optical transparency towards the visible were prepared. The optimal formulation of the sol consists of acetic acid, barium acetate, 2-propanol, TTIP and deionized water with 6:1:1:1:150 M ratios, respectively. It was found that the reduction of the temperature in the initial stage of mixing of precursors controls the size of the forming species and accordingly improves the stability and transparency of the sol. The results also showed that the applied modifications and optimizations significantly downsize the particles within the sol to the nanometric scale and accordingly result in a significant improvement in the optical response of the products.

Revealing the jet substructure in a compressed spectrum of new physics

NASA Astrophysics Data System (ADS)

Han, Chengcheng; Park, Myeonghun

2016-07-01

The physics beyond the Standard Model with parameters of the compressed spectrum is well motivated both in the theory side and with phenomenological reasons, especially related to dark matter phenomenology. In this letter, we propose a method to tag soft final state particles from a decaying process of a new particle in this parameter space. By taking a supersymmetric gluino search as an example, we demonstrate how the Large Hadron Collider experimental collaborations can improve sensitivity in these nontrivial search regions.

Improving quality of an innovative pea puree by high hydrostatic pressure.

PubMed

Klug, Tâmmila Venzke; Martínez-Sánchez, Ascensión; Gómez, Perla A; Collado, Elena; Aguayo, Encarna; Artés, Francisco; Artés-Hernández, Francisco

2017-10-01

The food industry is continuously innovating to fulfill consumer demand for new, healthy, ready-to-eat products. Pea purees could satisfy this trend by increasing the intake of legumes, which are an important source of nutrients. Moreover, sensorial properties like viscosity could be improved by high hydrostatic pressure (HHP). In this study the effect of a boiling treatment (10 min) followed by HHP at 550 kPa (0, 5 or 10 min) on the rheological properties, associated with enzymatic activity and particle size, as well as on the microbial and sensory quality of a pea-based puree stored for 36 days at 5 °C, has been assessed. The particle size of pea puree decreased after all processing treatments, but increased during storage in HHP-treated samples. Conversely, boiling treatment showed an increase in polygalacturonase activity at the end of the storage period, with a decrease in particle size, viscosity and stability. However, 5 min of 550 kPa HHP showed the highest mean particle size, mean surface diameter and viscosity regarding the remaining treatments. The microbial load remained low during storage. HHP treatment can be used by the food industry to improve the rheological properties, viscosity and stability of pea purees. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Coating agents affected toward magnetite nanoparticles properties

NASA Astrophysics Data System (ADS)

Petcharoen, Karat; Sirivat, Anuvat

2012-02-01

Magnetite nanoparticles --MNPs-- are innovative materials used in biological and medical applications. They respond to magnetic field through the superparamagnetic behavior at room temperature. In this study, the MNPs were synthesized via the chemical co-precipitation method using various coating agents. Fatty acids, found naturally in the animal fats, can be used as a coating agent. Oleic acid and hexanoic acid were chosen as the surface modification agents to study the improvement in the suspension of MNPs in water and the magnetite properties. Suspension stability, particle size, and electrical conductivity of MNPs are critically affected by the modification process. The well-dispersed MNPs in water can be improved by the surface modification and the oleic acid coated MNPs possess excellent suspension stability over 1 week. The particle size of MNPs increases up to 40 nm using oleic acid coated MNPs. The electrical conductivity of the smallest particle size is 1.3x10-3 S/cm, which is 5 times higher than that of the largest particle, suggesting potential applications as a biomedical material under both of the electrical and magnetic fields.

Tracking Algorithm of Multiple Pedestrians Based on Particle Filters in Video Sequences

PubMed Central

Liu, Yun; Wang, Chuanxu; Zhang, Shujun; Cui, Xuehong

2016-01-01

Pedestrian tracking is a critical problem in the field of computer vision. Particle filters have been proven to be very useful in pedestrian tracking for nonlinear and non-Gaussian estimation problems. However, pedestrian tracking in complex environment is still facing many problems due to changes of pedestrian postures and scale, moving background, mutual occlusion, and presence of pedestrian. To surmount these difficulties, this paper presents tracking algorithm of multiple pedestrians based on particle filters in video sequences. The algorithm acquires confidence value of the object and the background through extracting a priori knowledge thus to achieve multipedestrian detection; it adopts color and texture features into particle filter to get better observation results and then automatically adjusts weight value of each feature according to current tracking environment. During the process of tracking, the algorithm processes severe occlusion condition to prevent drift and loss phenomena caused by object occlusion and associates detection results with particle state to propose discriminated method for object disappearance and emergence thus to achieve robust tracking of multiple pedestrians. Experimental verification and analysis in video sequences demonstrate that proposed algorithm improves the tracking performance and has better tracking results. PMID:27847514

Visualizing turbulent mixing of gases and particles

NASA Technical Reports Server (NTRS)

Ma, Kwan-Liu; Smith, Philip J.; Jain, Sandeep

1995-01-01

A physical model and interactive computer graphics techniques have been developed for the visualization of the basic physical process of stochastic dispersion and mixing from steady-state CFD calculations. The mixing of massless particles and inertial particles is visualized by transforming the vector field from a traditionally Eulerian reference frame into a Lagrangian reference frame. Groups of particles are traced through the vector field for the mean path as well as their statistical dispersion about the mean position by using added scalar information about the root mean square value of the vector field and its Lagrangian time scale. In this way, clouds of particles in a turbulent environment are traced, not just mean paths. In combustion simulations of many industrial processes, good mixing is required to achieve a sufficient degree of combustion efficiency. The ability to visualize this multiphase mixing can not only help identify poor mixing but also explain the mechanism for poor mixing. The information gained from the visualization can be used to improve the overall combustion efficiency in utility boilers or propulsion devices. We have used this technique to visualize steady-state simulations of the combustion performance in several furnace designs.

Exposure to Airborne Particles and Volatile Organic Compounds from Polyurethane Molding, Spray Painting, Lacquering, and Gluing in a Workshop

PubMed Central

Mølgaard, Bjarke; Viitanen, Anna-Kaisa; Kangas, Anneli; Huhtiniemi, Marika; Larsen, Søren Thor; Vanhala, Esa; Hussein, Tareq; Boor, Brandon E.; Hämeri, Kaarle; Koivisto, Antti Joonas

2015-01-01

Due to the health risk related to occupational air pollution exposure, we assessed concentrations and identified sources of particles and volatile organic compounds (VOCs) in a handcraft workshop producing fishing lures. The work processes in the site included polyurethane molding, spray painting, lacquering, and gluing. We measured total VOC (TVOC) concentrations and particle size distributions at three locations representing the various phases of the manufacturing and assembly process. The mean working-hour TVOC concentrations in three locations studied were 41, 37, and 24 ppm according to photo-ionization detector measurements. The mean working-hour particle number concentration varied between locations from 3000 to 36,000 cm−3. Analysis of temporal and spatial variations of TVOC concentrations revealed that there were at least four substantial VOC sources: spray gluing, mold-release agent spraying, continuous evaporation from various lacquer and paint containers, and either spray painting or lacquering (probably both). The mold-release agent spray was indirectly also a major source of ultrafine particles. The workers’ exposure can be reduced by improving the local exhaust ventilation at the known sources and by increasing the ventilation rate in the area with the continuous source. PMID:25849539

Sol–gel method as a way of carbonyl iron powder surface modification for interaction improvement

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

Małecki, P., E-mail: pawel.malecki@pwr.edu.pl; Kolman, K.; Pigłowski, J.

2015-03-15

This article presents a method for modification of carbonyl iron particles’ surface (CIP), (d{sub 50}=4–9 µm) by silica coatings obtained using the sol–gel method. Reaction parameters were determined to obtain dry magnetic powder with homogeneous silica coatings without further processing and without any by-product in the solid or liquid phase. This approach is new among the commonly used methods of silica coating of iron particles. No attempt has been made to cover a carbonyl iron surface by silica in a waste-free method, up to date. In the current work two different silica core/shell structures were made by the sol–gel process,more » based on different silica precursors: tetraethoxy-silane (TEOS) and tetramethoxy-silane (TMOS). The dependence between the synthesis procedure and thickness of silica shell covering carbonyl iron particles has been described. Surface morphology of the modified magnetic particles and the coating thickness were characterized with the use of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Determination of the physicochemical structure of the obtained materials was performed by the energy-dispersive X-ray spectroscope (EDS), and the infrared technique (IR). The surface composition was analyzed using X-ray photoelectron spectroscopy (XPS). Additionally, distribution of particle size was measured using light microscopy. The new, efficient process of covering micro-size CIP with a nanometric silica layer was shown. Results of a performed analysis confirm the effectiveness of the presented method. - Highlights: • Proper covering CIP by sol–gel silica layer avoids agglomeration. • A new solid waste-free method of CIP coating is proposed. • Examination of the properties of modified CIP in depends on washing process. • Coatings on CIP particles doesn’t change the magnetic properties of particles.« less

Processing of Aluminum-Graphite Particulate Metal Matrix Composites by Advanced Shear Technology

NASA Astrophysics Data System (ADS)

Barekar, N.; Tzamtzis, S.; Dhindaw, B. K.; Patel, J.; Hari Babu, N.; Fan, Z.

2009-12-01

To extend the possibilities of using aluminum/graphite composites as structural materials, a novel process is developed. The conventional methods often produce agglomerated structures exhibiting lower strength and ductility. To overcome the cohesive force of the agglomerates, a melt conditioned high-pressure die casting (MC-HPDC) process innovatively adapts the well-established, high-shear dispersive mixing action of a twin screw mechanism. The distribution of particles and properties of composites are quantitatively evaluated. The adopted rheo process significantly improved the distribution of the reinforcement in the matrix with a strong interfacial bond between the two. A good combination of improved ultimate tensile strength (UTS) and tensile elongation (ɛ) is obtained compared with composites produced by conventional processes.

Hydrocracking with a zeolite in an alumina binder peptized in the presence of a surfactant

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

O'Hara, M.J.

A process for the conversion of a hydrocarbon charge stock is disclosed. The process comprises reacting the charge stock with hydrogen at hydrocracking conditions in contact with a catalytic composite having improved selectivity to middle distillate product during hydrocracking. The catalyst composite comprises alumina, a crystalline aluminosilicate, a Group VIB metal component and a Group VIII metal component and is prepared by the method comprising: admixing the alumina and crystalline aluminosilicate with a peptizing agent and an aqueous solution of a modified linear aliphatic polyether surfactant to form a dough; extruding the dough into discrete particles; and calcining and dryingmore » the particles.« less

A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films

NASA Astrophysics Data System (ADS)

Revaux, Amelie; Dantelle, Geraldine; George, Nathan; Seshadri, Ram; Gacoin, Thierry; Boilot, Jean-Pierre

2011-05-01

A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 °C), which result in increased particle size and aggregation, and lead to oxidation of Ce(iii) to Ce(iv). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 °C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 °C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 +/- 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing.A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 °C), which result in increased particle size and aggregation, and lead to oxidation of Ce(iii) to Ce(iv). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 °C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 °C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 +/- 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing. Electronic supplementary information (ESI) available: Thermogravimetric analysis curve, picture of a YAG:Ce3+ thin film. See DOI: 10.1039/c0nr01000f

Application of particle splitting method for both hydrostatic and hydrodynamic cases in SPH

NASA Astrophysics Data System (ADS)

Liu, W. T.; Sun, P. N.; Ming, F. R.; Zhang, A. M.

2018-01-01

Smoothed particle hydrodynamics (SPH) method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid-solid interaction problems. However, in most simulations, uniform particle distributions are used and the multi-resolution, which can obviously improve the local accuracy and the overall computational efficiency, has seldom been applied. In this paper, a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems. The splitting algorithm is that, when a coarse (mother) particle enters the splitting region, it will be split into four daughter particles, which inherit the physical parameters of the mother particle. In the particle splitting process, conservations of mass, momentum and energy are ensured. Based on the error analysis, the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases. Finally, the scheme is validated by five basic cases, which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic problems.

Constraining particle size-dependent plume sedimentation from the 17 June 1996 eruption of Ruapehu Volcano, New Zealand, using geophysical inversions

NASA Astrophysics Data System (ADS)

Klawonn, M.; Frazer, L. N.; Wolfe, C. J.; Houghton, B. F.; Rosenberg, M. D.

2014-03-01

Weak subplinian-plinian plumes pose frequent hazards to populations and aviation, yet many key parameters of these particle-laden plumes are, to date, poorly constrained. This study recovers the particle size-dependent mass distribution along the trajectory of a well-constrained weak plume by inverting the dispersion process of tephra fallout. We use the example of the 17 June 1996 Ruapehu eruption in New Zealand and base our computations on mass per unit area tephra measurements and grain size distributions at 118 sample locations. Comparisons of particle fall times and time of sampling collection, as well as observations during the eruption, reveal that particles smaller than 250 μm likely settled as aggregates. For simplicity we assume that all of these fine particles fell as aggregates of constant size and density, whereas we assume that large particles fell as individual particles at their terminal velocity. Mass fallout along the plume trajectory follows distinct trends between larger particles (d≥250 μm) and the fine population (d<250 μm) that are likely due to the two different settling behaviors (aggregate settling versus single-particle settling). In addition, we computed the resulting particle size distribution within the weak plume along its axis and find that the particle mode shifts from an initial 1φ mode to a 2.5φ mode 10 km from the vent and is dominated by a 2.5 to 3φ mode 10-180 km from vent, where the plume reaches the coastline and we do not have further field constraints. The computed particle distributions inside the plume provide new constraints on the mass transport processes within weak plumes and improve previous models. The distinct decay trends between single-particle settling and aggregate settling may serve as a new tool to identify particle sizes that fell as aggregates for other eruptions.

THOR Field and Wave Processor - FWP

NASA Astrophysics Data System (ADS)

Soucek, Jan; Rothkaehl, Hanna; Balikhin, Michael; Zaslavsky, Arnaud; Nakamura, Rumi; Khotyaintsev, Yuri; Uhlir, Ludek; Lan, Radek; Yearby, Keith; Morawski, Marek; Winkler, Marek

2016-04-01

If selected, Turbulence Heating ObserveR (THOR) will become the first mission ever flown in space dedicated to plasma turbulence. The Fields and Waves Processor (FWP) is an integrated electronics unit for all electromagnetic field measurements performed by THOR. FWP will interface with all fields sensors: electric field antennas of the EFI instrument, the MAG fluxgate magnetometer and search-coil magnetometer (SCM) and perform data digitization and on-board processing. FWP box will house multiple data acquisition sub-units and signal analyzers all sharing a common power supply and data processing unit and thus a single data and power interface to the spacecraft. Integrating all the electromagnetic field measurements in a single unit will improve the consistency of field measurement and accuracy of time synchronization. The feasibility of making highly sensitive electric and magnetic field measurements in space has been demonstrated by Cluster (among other spacecraft) and THOR instrumentation complemented by a thorough electromagnetic cleanliness program will further improve on this heritage. Taking advantage of the capabilities of modern electronics, FWP will provide simultaneous synchronized waveform and spectral data products at high time resolution from the numerous THOR sensors, taking advantage of the large telemetry bandwidth of THOR. FWP will also implement a plasma a resonance sounder and a digital plasma quasi-thermal noise analyzer designed to provide high cadence measurements of plasma density and temperature complementary to data from particle instruments. FWP will be interfaced with the particle instrument data processing unit (PPU) via a dedicated digital link which will enable performing on board correlation between waves and particles, quantifying the transfer of energy between waves and particles. The FWP instrument shall be designed and built by an international consortium of scientific institutes from Czech Republic, Poland, France, UK, Sweden and Austria.

Fabrication of oxide dispersion strengthened bond coats with low Al 2O 3 content [Fabrication of ODS bond coats with low Al 2O 3 content

DOE PAGES

Bergholz, Jan; Pint, Bruce A.; Unocic, Kinga A.; ...

2017-03-23

Here, nanoscale oxide dispersions have long been used to increase the oxidation and wear resistance of alloys used as bond coatings in thermal barrier coatings. Their manufacturing via mechanical alloying is often accompanied by difficulties regarding their particle size, homogeneous distribution of the oxide dispersions inside the powder, involving considerable costs, due to cold welding of the powder during milling. A significant improvement in this process can be achieved by the use of process control agent (PCA) to achieve the critical balance between cold welding and fracturing, thereby enhancing the process efficiency. In this investigation, the influence of the organicmore » additive stearic acid on the manufacturing process of Al 2O 3-doped CoNiCrAlY powder was investigated. Powders were fabricated via mechanical alloying at different milling times and PCA concentrations. The results showed a decrease in particle size, without hindering the homogeneous incorporation of the oxide dispersions. Two powders manufactured with 0.5 and 1.0 wt.% PCA were deposited by high velocity oxygen fuel (HVOF) spraying. Results showed that a higher content of elongated particles in the powder with the higher PCA content led to increased surface roughness, porosity and decreased coating thickness, with areas without embedded oxide particles.« less

Effect of Mg content on the thermal stability and mechanical behaviour of PLLA/Mg composites processed by hot extrusion.

PubMed

Cifuentes, S C; Lieblich, M; López, F A; Benavente, R; González-Carrasco, J L

2017-03-01

In the field of bioabsorbable composites for biomedical applications, extrusion has been employed as a method to prepare homogeneous blends of polymeric matrices with bioactive ceramic fillers. In this work, the suitability of processing poly-l-lactic acid/Magnesium (PLLA/Mg) composites by hot extrusion has been assessed by a systematic characterization of PLLA/Mg composites containing different amounts of Mg particles up to 7wt%. The results show that extrusion causes a reduction of almost 20% in the viscosity average molecular weight of PLLA, which further decreases with increasing Mg content. Extrusion gave always rise to a homogeneous distribution of Mg particles within the PLLA matrix. This composite processing was not compromised by the degradation of the polymeric matrix because the processing temperature was always below the onset degradation temperature. In the processing conditions employed in the present work, degradation of the composite slightly increases as more Mg is added up to 5wt%, but is very high at 7wt%. This was also evident from the mechanical behaviour, so that Mg particles improved the stiffness and compression strength of neat PLLA until 5wt% of Mg content, which dropped drastically when the material had 7wt% of Mg. The filler strengthening factor decreases with the increment in Mg content. In order to obtain an optimised contribution of Mg particles, a balance between thermal degradation and mechanical resistance of PLLA must be achieved. Copyright © 2016 Elsevier B.V. All rights reserved.

Additive Manufacturing/Diagnostics via the High Frequency Induction Heating of Metal Powders: The Determination of the Power Transfer Factor for Fine Metallic Spheres

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

Rios, Orlando; Radhakrishnan, Balasubramaniam; Caravias, George

2015-03-11

Grid Logic Inc. is developing a method for sintering and melting fine metallic powders for additive manufacturing using spatially-compact, high-frequency magnetic fields called Micro-Induction Sintering (MIS). One of the challenges in advancing MIS technology for additive manufacturing is in understanding the power transfer to the particles in a powder bed. This knowledge is important to achieving efficient power transfer, control, and selective particle heating during the MIS process needed for commercialization of the technology. The project s work provided a rigorous physics-based model for induction heating of fine spherical particles as a function of frequency and particle size. This simulationmore » improved upon Grid Logic s earlier models and provides guidance that will make the MIS technology more effective. The project model will be incorporated into Grid Logic s power control circuit of the MIS 3D printer product and its diagnostics technology to optimize the sintering process for part quality and energy efficiency.« less

Dynamic effect of total solid content, low substrate/inoculum ratio and particle size on solid-state anaerobic digestion.

PubMed

Motte, J-C; Escudié, R; Bernet, N; Delgenes, J-P; Steyer, J-P; Dumas, C

2013-09-01

Among all the process parameters of solid-state anaerobic digestion (SS-AD), total solid content (TS), inoculation (S/X ratio) and size of the organic solid particles can be optimized to improve methane yield and process stability. To evaluate the effects of each parameter and their interactions on methane production, a three level Box-Behnken experimental design was implemented in SS-AD batch tests degrading wheat straw by adjusting: TS content from 15% to 25%, S/X ratio (in volatile solids) between 28 and 47 and particle size with a mean diameter ranging from 0.1 to 1.4mm. A dynamic analysis of the methane production indicates that the S/X ratio has only an effect during the start-up phase of the SS-AD. During the growing phase, TS content becomes the main parameter governing the methane production and its strong interaction with the particle size suggests the important role of water compartmentation on SS-AD. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modeling Remineralization of Desalinated Water by Micronized Calcite Dissolution.

PubMed

Hasson, David; Fine, Larissa; Sagiv, Abraham; Semiat, Raphael; Shemer, Hilla

2017-11-07

A widely used process for remineralization of desalinated water consists of dissolution of calcite particles by flow of acidified desalinated water through a bed packed with millimeter-size calcite particles. An alternative process consists of calcite dissolution by slurry flow of micron-size calcite particles with acidified desalinated water. The objective of this investigation is to provide theoretical models enabling design of remineralization by calcite slurry dissolution with carbonic and sulfuric acids. Extensive experimental results are presented displaying the effects of acid concentration, slurry feed concentration, and dissolution contact time. The experimental data are shown to be in agreement within less than 10% with theoretical predictions based on the simplifying assumption that the slurry consists of uniform particles represented by the surface mean diameter of the powder. Agreement between theory and experiment is improved by 1-8% by taking into account the powder size distribution. Apart from the practical value of this work in providing a hitherto lacking design tool for a novel technology. The paper has the merit of being among the very few publications providing experimental confirmation to the theory describing reaction kinetics in a segregated flow system.

Quality comparison of continuous steam sterilization segmented-flow aseptic processing versus conventional canning of whole and sliced mushrooms.

PubMed

Anderson, N M; Walker, P N

2011-08-01

This study was carried out to investigate segmented-flow aseptic processing of particle foods. A pilot-scale continuous steam sterilization unit capable of producing shelf stable aseptically processed whole and sliced mushrooms was developed. The system utilized pressurized steam as the heating medium to achieve high temperature-short time processing conditions with high and uniform heat transfer that will enable static temperature penetration studies for process development. Segmented-flow technology produced a narrower residence time distribution than pipe-flow aseptic processing; thus, whole and sliced mushrooms were processed only as long as needed to achieve the target F₀  = 7.0 min and were not overcooked. Continuous steam sterilization segmented-flow aseptic processing produced shelf stable aseptically processed mushrooms of superior quality to conventionally canned mushrooms. When compared to conventionally canned mushrooms, aseptically processed yield (weight basis) increased 6.1% (SD = 2.9%) and 6.6% (SD = 2.2%), whiteness (L) improved 3.1% (SD = 1.9%) and 4.7% (SD = 0.7%), color difference (ΔE) improved 6.0% (SD = 1.3%) and 8.5% (SD = 1.5%), and texture improved 3.9% (SD = 1.7%) and 4.6% (SD = 4.2%), for whole and sliced mushrooms, respectively. Segmented-flow aseptic processing eliminated a separate blanching step, eliminated the unnecessary packaging of water and promoted the use of bag-in-box and other versatile aseptic packaging methods. Segmented-flow aseptic processing is capable of producing shelf stable aseptically processed particle foods of superior quality to a conventionally canned product. This unique continuous steam sterilization process eliminates the need for a separate blanching step, reduces or eliminates the need for a liquid carrier, and promotes the use of bag-in-box and other versatile aseptic packaging methods. © 2011 Institute of Food Technologists®

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

Effect of ultrasonic frequency on degradation of methylene blue in the presence of particle

NASA Astrophysics Data System (ADS)

Kobayashi, Daisuke; Suzuki, Atsushi; Takahashi, Tomoki; Matsumoto, Hideyuki; Kuroda, Chiaki; Otake, Katsuto; Shono, Atsushi

2012-05-01

Techniques for the degradation of hazardous organic compounds have been investigated such as solvent extraction, incineration, chemical dehalogenation and biodegradation, etc. Ultrasound has been found to be an attractive advanced technology for the degradation of hazardous organic compounds in water. In addition, the sonochemical reaction is enhanced by particle addition. However, the enhancement mechanism of particle addition has not been investigated well, because ultrasound enhances not only chemical reaction but also mass transfer. In this study, the degradation process of methylene blue as the model hazardous organic compound by ultrasonic irradiation was investigated. The effects of ultrasonic irradiation condition on degradation rate were investigated. The effect of ultrasonic frequency on improvement of degradation reaction by particle addition was also investigated. In addition, the effects of ultrasonic frequency on ultrasonic power and chemical efficiency were investigated by calorimetry and SE value. The degradation rate constants were estimated from the results of temporal change of the concentration of methylene blue assuming first order kinetics for the decomposition. There was a linear relation in the degradation rate and the ultrasonic power. In addition, the degradation rates at 127 kHz and 490 kHz were much larger than that at 22.8 kHz. The effect of ultrasonic frequency on sonochemical efficiency has been investigated, and the sonochemical effects in the range of frequency of 200 - 500 kHz are 10 times larger than those in the lower or higher frequency regions. Therefore, the degradation rate of methylene blue was considered to estimate using sonochemical efficiency. The degradation process of methylene blue was intensified by particle addition, and the degradation rate increased with increasing amount of particle. On the other hand, the enhancement of degradation rate by particle addition was influenced by both ultrasonic frequency and species of particle. The relationship between particle size and resonance diameter of ultrasound is considered to influence the enhancement of ultrasonic degradation process.

Local Cloudiness Development Forecast Based on Simulation of Solid Phase Formation Processes in the Atmosphere

NASA Astrophysics Data System (ADS)

Barodka, Siarhei; Kliutko, Yauhenia; Krasouski, Alexander; Papko, Iryna; Svetashev, Alexander; Turishev, Leonid

2013-04-01

Nowadays numerical simulation of thundercloud formation processes is of great interest as an actual problem from the practical point of view. Thunderclouds significantly affect airplane flights, and mesoscale weather forecast has much to contribute to facilitate the aviation forecast procedures. An accurate forecast can certainly help to avoid aviation accidents due to weather conditions. The present study focuses on modelling of the convective clouds development and thunder clouds detection on the basis of mesoscale atmospheric processes simulation, aiming at significantly improving the aeronautical forecast. In the analysis, the primary weather radar information has been used to be further adapted for mesoscale forecast systems. Two types of domains have been selected for modelling: an internal one (with radius of 8 km), and an external one (with radius of 300 km). The internal domain has been directly applied to study the local clouds development, and the external domain data has been treated as initial and final conditions for cloud cover formation. The domain height has been chosen according to the civil aviation forecast data (i.e. not exceeding 14 km). Simulations of weather conditions and local clouds development have been made within selected domains with the WRF modelling system. In several cases, thunderclouds are detected within the convective clouds. To specify the given category of clouds, we employ a simulation technique of solid phase formation processes in the atmosphere. Based on modelling results, we construct vertical profiles indicating the amount of solid phase in the atmosphere. Furthermore, we obtain profiles demonstrating the amount of ice particles and large particles (hailstones). While simulating the processes of solid phase formation, we investigate vertical and horizontal air flows. Consequently, we attempt to separate the total amount of solid phase into categories of small ice particles, large ice particles and hailstones. Also, we strive to reveal and differentiate the basic atmospheric parameters of sublimation and coagulation processes, aiming to predict ice particles precipitation. To analyze modelling results we apply the VAPOR three-dimensional visualization package. For the chosen domains, a diurnal synoptic situation has been simulated, including rain, sleet, ice pellets, and hail. As a result, we have obtained a large scope of data describing various atmospheric parameters: cloud cover, major wind components, basic levels of isobaric surfaces, and precipitation rate. Based on this data, we show both distinction in precipitation formation due to various heights and its differentiation of the ice particles. The relation between particle rise in the atmosphere and its size is analyzed: at 8-10 km altitude large ice particles, resulted from coagulation, dominate, while at 6-7 km altitude one can find snow and small ice particles formed by condensation growth. Also, mechanical trajectories of solid precipitation particles for various ice formation processes have been calculated.

Systemic characterization and evaluation of particle packings as initial sets for discrete element simulations

NASA Astrophysics Data System (ADS)

Morfa, Carlos Recarey; Cortés, Lucía Argüelles; Farias, Márcio Muniz de; Morales, Irvin Pablo Pérez; Valera, Roberto Roselló; Oñate, Eugenio

2018-07-01

A methodology that comprises several characterization properties for particle packings is proposed in this paper. The methodology takes into account factors such as dimension and shape of particles, space occupation, homogeneity, connectivity and isotropy, among others. This classification and integration of several properties allows to carry out a characterization process to systemically evaluate the particle packings in order to guarantee the quality of the initial meshes in discrete element simulations, in both the micro- and the macroscales. Several new properties were created, and improvements in existing ones are presented. Properties from other disciplines were adapted to be used in the evaluation of particle systems. The methodology allows to easily characterize media at the level of the microscale (continuous geometries—steels, rocks microstructures, etc., and discrete geometries) and the macroscale. A global, systemic and integral system for characterizing and evaluating particle sets, based on fuzzy logic, is presented. Such system allows researchers to have a unique evaluation criterion based on the aim of their research. Examples of applications are shown.

Hygroscopic analysis of individual Beijing haze aerosol particles by environmental scanning electron microscopy

NASA Astrophysics Data System (ADS)

Bai, Zhangpeng; Ji, Yuan; Pi, Yiqun; Yang, Kaixiang; Wang, Li; Zhang, Yinqi; Zhai, Yadi; Yan, Zhengguang; Han, Xiaodong

2018-01-01

Investigating the hygroscopic behavior of haze aerosol particles is essential for understanding their physicochemical properties and their impacts on regional weather and visibility. An environmental scanning electron microscope equipped with a home-made transmission-scattering electron imaging setup and an energy dispersive spectrometer was used for in-situ observations of pure water-soluble (WS) salts and Beijing haze particles. This imaging setup showed obvious advantages for improving the resolution and acquiring internal information of mixed particles in hydrated environments. We measured the deliquescence relative humidity of pure NaCl, NH4NO3, and (NH4)2SO4 by deliquescence-crystallization processes with an accuracy of up to 0.3% RH. The mixed haze particles showed hygroscopic activation like water uptake and morphological changes when they included WS components such as nitrates, sulfates, halides, ammoniums, and alkali metal salts. In addition, the hygroscopic behavior provides complementary information for analyzing possible phases in mixed haze particles.

Numerical simulation of hemorrhage in human injury

NASA Astrophysics Data System (ADS)

Chong, Kwitae; Jiang, Chenfanfu; Santhanam, Anand; Benharash, Peyman; Teran, Joseph; Eldredge, Jeff

2015-11-01

Smoothed Particle Hydrodynamics (SPH) is adapted to simulate hemorrhage in the injured human body. As a Lagrangian fluid simulation, SPH uses fluid particles as computational elements and thus mass conservation is trivially satisfied. In order to ensure anatomical fidelity, a three-dimensional reconstruction of a portion of the human body -here, demonstrated on the lower leg- is sampled as skin, bone and internal tissue particles from the CT scan image of an actual patient. The injured geometry is then generated by simulation of ballistic projectiles passing through the anatomical model with the Material Point Method (MPM) and injured vessel segments are identified. From each such injured segment, SPH is used to simulate bleeding, with inflow boundary condition obtained from a coupled 1-d vascular tree model. Blood particles interact with impermeable bone and skin particles through the Navier-Stokes equations and with permeable internal tissue particles through the Brinkman equations. The SPH results are rendered in post-processing for improved visual fidelity. The overall simulation strategy is demonstrated on several injury scenarios in the lower leg.

Systemic characterization and evaluation of particle packings as initial sets for discrete element simulations

NASA Astrophysics Data System (ADS)

Morfa, Carlos Recarey; Cortés, Lucía Argüelles; Farias, Márcio Muniz de; Morales, Irvin Pablo Pérez; Valera, Roberto Roselló; Oñate, Eugenio

2017-10-01

A methodology that comprises several characterization properties for particle packings is proposed in this paper. The methodology takes into account factors such as dimension and shape of particles, space occupation, homogeneity, connectivity and isotropy, among others. This classification and integration of several properties allows to carry out a characterization process to systemically evaluate the particle packings in order to guarantee the quality of the initial meshes in discrete element simulations, in both the micro- and the macroscales. Several new properties were created, and improvements in existing ones are presented. Properties from other disciplines were adapted to be used in the evaluation of particle systems. The methodology allows to easily characterize media at the level of the microscale (continuous geometries—steels, rocks microstructures, etc., and discrete geometries) and the macroscale. A global, systemic and integral system for characterizing and evaluating particle sets, based on fuzzy logic, is presented. Such system allows researchers to have a unique evaluation criterion based on the aim of their research. Examples of applications are shown.

Steady-state configuration and tension calculations of marine cables under complex currents via separated particle swarm optimization

NASA Astrophysics Data System (ADS)

Xu, Xue-song

2014-12-01

Under complex currents, the motion governing equations of marine cables are complex and nonlinear, and the calculations of cable configuration and tension become difficult compared with those under the uniform or simple currents. To obtain the numerical results, the usual Newton-Raphson iteration is often adopted, but its stability depends on the initial guessed solution to the governing equations. To improve the stability of numerical calculation, this paper proposed separated the particle swarm optimization, in which the variables are separated into several groups, and the dimension of search space is reduced to facilitate the particle swarm optimization. Via the separated particle swarm optimization, these governing nonlinear equations can be solved successfully with any initial solution, and the process of numerical calculation is very stable. For the calculations of cable configuration and tension of marine cables under complex currents, the proposed separated swarm particle optimization is more effective than the other particle swarm optimizations.

Modifying Silicates for Better Dispersion in Nanocomposites

NASA Technical Reports Server (NTRS)

Campbell, Sandi

2005-01-01

An improved chemical modification has been developed to enhance the dispersion of layered silicate particles in the formulation of a polymer/silicate nanocomposite material. The modification involves, among other things, the co-exchange of an alkyl ammonium ion and a monoprotonated diamine with interlayer cations of the silicate. The net overall effects of the improved chemical modification are to improve processability of the nanocomposite and maximize the benefits of dispersing the silicate particles into the polymer. Some background discussion is necessary to give meaning to a description of this development. Polymer/silicate nanocomposites are also denoted polymer/clay composites because the silicate particles in them are typically derived from clay particles. Particles of clay comprise layers of silicate platelets separated by gaps called "galleries." The platelet thickness is 1 nm. The length varies from 30 nm to 1 m, depending on the silicate. In order to fully realize the benefits of polymer/silicate nanocomposites, it is necessary to ensure that the platelets become dispersed in the polymer matrices. Proper dispersion can impart physical and chemical properties that make nanocomposites attractive for a variety of applications. In order to achieve nanometer-level dispersion of a layered silicate into a polymer matrix, it is typically necessary to modify the interlayer silicate surfaces by attaching organic functional groups. This modification can be achieved easily by ion exchange between the interlayer metal cations found naturally in the silicate and protonated organic cations - typically protonated amines. Long-chain alkyl ammonium ions are commonly chosen as the ion-exchange materials because they effectively lower the surface energies of the silicates and ease the incorporation of organic monomers or polymers into the silicate galleries. This completes the background discussion. In the present improved modification of the interlayer silicate surfaces, the co-ion exchange strengthens the polymer/silicate interface and ensures irreversible separation of the silicate layers. One way in which it does this is to essentially tether one amine of each diamine molecule to a silicate surface, leaving the second amine free for reaction with monomers during the synthesis of a polymer. In addition, the incorporation of alkyl ammonium ions into the galleries at low concentration helps to keep low the melt viscosity of the oligomer formed during synthesis of the polymer and associated processing - a consideration that is particularly important in the case of a highly cross-linked, thermosetting polymer. Because of the chemical bonding between the surface-modifying amines and the monomers, even when the alkyl ammonium ions become degraded at high processing temperature, the silicate layers do not aggregate and, hence, nanometer-level dispersion is maintained.

Evaluation of the performance of the cross-flow air classifier in manufactured sand processing via CFD-DEM simulations

NASA Astrophysics Data System (ADS)

Petit, H. A.; Irassar, E. F.; Barbosa, M. R.

2018-01-01

Manufactured sands are particulate materials obtained as by product of rock crushing. Particle sizes in the sand can be as high as 6 mm and as low as a few microns. The concrete industry has been increasingly using these sands as fine aggregates to replace natural sands. The main shortcoming is the excess of particles smaller than <0.075 mm (Dust). This problem has been traditionally solved by a washing process. Air classification is being studied to replace the washing process and avoid the use of water. The complex classification process can only been understood with the aid of CFD-DEM simulations. This paper evaluates the applicability of a cross-flow air classifier to reduce the amount of dust in manufactured sands. Computational fluid dynamics (CFD) and discrete element modelling (DEM) were used for the assessment. Results show that the correct classification set up improves the size distribution of the raw materials. The cross-flow air classification is found to be influenced by the particle size distribution and the turbulence inside the chamber. The classifier can be re-designed to work at low inlet velocities to produce manufactured sand for the concrete industry.

F-T process using an iron on mixed zirconia-titania supported catalyst

DOEpatents

Dyer, Paul N.; Nordquist, Andrew F.; Pierantozzi, Ronald

1987-01-01

A Fischer-Tropsch catalyst comprising iron co-deposited with or deposited on particles comprising a mixture of zirconia and titania, preferably formed by co-precipitation of compounds convertible to zirconia and titania, such as zirconium and titanium alkoxide. The invention also comprises the method of making this catalyst and an improved Fischer-Tropsch reaction process in which the catalyst is utilized.

Optimization of PID Parameters Utilizing Variable Weight Grey-Taguchi Method and Particle Swarm Optimization

NASA Astrophysics Data System (ADS)

Azmi, Nur Iffah Mohamed; Arifin Mat Piah, Kamal; Yusoff, Wan Azhar Wan; Romlay, Fadhlur Rahman Mohd

2018-03-01

Controller that uses PID parameters requires a good tuning method in order to improve the control system performance. Tuning PID control method is divided into two namely the classical methods and the methods of artificial intelligence. Particle swarm optimization algorithm (PSO) is one of the artificial intelligence methods. Previously, researchers had integrated PSO algorithms in the PID parameter tuning process. This research aims to improve the PSO-PID tuning algorithms by integrating the tuning process with the Variable Weight Grey- Taguchi Design of Experiment (DOE) method. This is done by conducting the DOE on the two PSO optimizing parameters: the particle velocity limit and the weight distribution factor. Computer simulations and physical experiments were conducted by using the proposed PSO- PID with the Variable Weight Grey-Taguchi DOE and the classical Ziegler-Nichols methods. They are implemented on the hydraulic positioning system. Simulation results show that the proposed PSO-PID with the Variable Weight Grey-Taguchi DOE has reduced the rise time by 48.13% and settling time by 48.57% compared to the Ziegler-Nichols method. Furthermore, the physical experiment results also show that the proposed PSO-PID with the Variable Weight Grey-Taguchi DOE tuning method responds better than Ziegler-Nichols tuning. In conclusion, this research has improved the PSO-PID parameter by applying the PSO-PID algorithm together with the Variable Weight Grey-Taguchi DOE method as a tuning method in the hydraulic positioning system.

Characterization of Al/crystallized Al-based metallic glass composites produced by repeated roll bonding process

NASA Astrophysics Data System (ADS)

Alizadeh, Morteza; Khoramkhorshid, Saba; Taghvaei, Amir Hossein; Gokuldoss, Prashanth Konda

2017-07-01

Devitrified Al84Gd6Ni7Co3 glassy particles have been used to reinforce Al-matrix composites through repeated roll bonding (RRB) process. Microstructural characterization of the produced composites after various rolling cycles was performed by scanning electron microscopy. Mechanical properties of the fabricated composites were evaluated by the tensile and microhardness tests. The results indicate that the RRB process is successful to produce composites with the negligible amount of flaws and porosity, and it is followed by homogeneous distribution of Al84Gd6Ni7Co3 particles in the Al matrix after nine rolling passes. Elongation of the composites improves significantly upon RRB cycles and the tensile strength and microhardness of them increase more than two times compared to unreinforced Al. According to fractography results, the enhanced mechanical properties are correlated with formation of excellent bonding at the interface of Al84Gd6Ni7Co3 particles and Al matrix. The theoretical values of composites hardness and yield strength calculated based on iso-strain model show a good agreement with respect to the experimental results.

An Application of X-Ray Fluorescence as Process Analytical Technology (PAT) to Monitor Particle Coating Processes.

PubMed

Nakano, Yoshio; Katakuse, Yoshimitsu; Azechi, Yasutaka

2018-06-01

An attempt to apply X-Ray Fluorescence (XRF) analysis to evaluate small particle coating process as a Process Analytical Technologies (PAT) was made. The XRF analysis was used to monitor coating level in small particle coating process with at-line manner. The small particle coating process usually consists of multiple coating processes. This study was conducted by a simple coating particles prepared by first coating of a model compound (DL-methionine) and second coating by talc on spherical microcrystalline cellulose cores. The particles with two layered coating are enough to demonstrate the small particle coating process. From the result by the small particle coating process, it was found that the XRF signal played different roles, resulting that XRF signals by first coating (layering) and second coating (mask coating) could demonstrate the extent with different mechanisms for the coating process. Furthermore, the particle coating of the different particle size has also been investigated to evaluate size effect of these coating processes. From these results, it was concluded that the XRF could be used as a PAT in monitoring particle coating processes and become powerful tool in pharmaceutical manufacturing.

Aerosol gels

NASA Technical Reports Server (NTRS)

Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

2010-01-01

An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

Granular flows: fundamentals and applications

NASA Astrophysics Data System (ADS)

Cleary, Paul W.

DEM allows the prediction of complex industrial and geophysical particle flows. The importance of particle shape is demonstrated through a series of simple examples. Shape controls resistance to shear, the magnitude of collision stress, dilation and the angle of repose. We use a periodic flow of a bed of particles to demonstrate the different states of granular matter, the generation of dilute granular flow when granular temperature is high and the flow dependent nature of the granular thermodynamic boundary conditions. A series of industrial case studies examines how DEM can be used to understand and improve processes such as separation, mixing, grinding, excavation, hopper discharge, metering and conveyor interchange. Finally, an example of landslide motion over real topography is presented.

SMIF capability at Intel Mask Operation improves yield

NASA Astrophysics Data System (ADS)

Dam, Thuc H.; Pekny, Matt; Millino, Jim; Luu, Gibson; Melwani, Nitesh; Venkatramani, Aparna; Tavassoli, Malahat

2003-08-01

At Intel Mask Operations (IMO), Standard Mechanical Interface (SMIF) processing has been employed to reduce environmental particle contamination from manual handling-related activities. SMIF handling entailed the utilization of automated robotic transfers of photoblanks/reticles between SMIF pods, whereas conventional handling utilized manual pick transfers of masks between SMIF pods with intermediate storage in Toppan compacts. The SMIF-enabling units in IMO's process line included: (1) coater, (2) exposure, (3) developer, (4) dry etcher, and (5) inspection. Each unit is equipped with automated I/O port, environmentally enclosed processing chamber, and SMIF pods. Yield metrics were utilized to demonstrate the effectiveness and advantages of SMIF processing compared to manual processing. The areas focused in this paper were blank resist coating, binary front-end reticle processing and 2nd level PSM reticle processing. Results obtained from the investigation showed yield improvements in these areas.

Improvements of the particle-in-cell code EUTERPE for petascaling machines

NASA Astrophysics Data System (ADS)

Sáez, Xavier; Soba, Alejandro; Sánchez, Edilberto; Kleiber, Ralf; Castejón, Francisco; Cela, José M.

2011-09-01

In the present work we report some performance measures and computational improvements recently carried out using the gyrokinetic code EUTERPE (Jost, 2000 [1] and Jost et al., 1999 [2]), which is based on the general particle-in-cell (PIC) method. The scalability of the code has been studied for up to sixty thousand processing elements and some steps towards a complete hybridization of the code were made. As a numerical example, non-linear simulations of Ion Temperature Gradient (ITG) instabilities have been carried out in screw-pinch geometry and the results are compared with earlier works. A parametric study of the influence of variables (step size of the time integrator, number of markers, grid size) on the quality of the simulation is presented.

Optimisation on processing parameters for minimising warpage on side arm using response surface methodology (RSM) and particle swarm optimisation (PSO)

NASA Astrophysics Data System (ADS)

Rayhana, N.; Fathullah, M.; Shayfull, Z.; Nasir, S. M.; Hazwan, M. H. M.; Sazli, M.; Yahya, Z. R.

2017-09-01

This study presents the application of optimisation method to reduce the warpage of side arm part. Autodesk Moldflow Insight software was integrated into this study to analyse the warpage. The design of Experiment (DOE) for Response Surface Methodology (RSM) was constructed and by using the equation from RSM, Particle Swarm Optimisation (PSO) was applied. The optimisation method will result in optimised processing parameters with minimum warpage. Mould temperature, melt temperature, packing pressure, packing time and cooling time was selected as the variable parameters. Parameters selection was based on most significant factor affecting warpage stated by previous researchers. The results show that warpage was improved by 28.16% for RSM and 28.17% for PSO. The warpage improvement in PSO from RSM is only by 0.01 %. Thus, the optimisation using RSM is already efficient to give the best combination parameters and optimum warpage value for side arm part. The most significant parameters affecting warpage are packing pressure.

Emulsion design to improve the delivery of functional lipophilic components.

PubMed

McClements, David Julian

2010-01-01

The food industry has used emulsion science and technology for many years to create a diverse range of food products, such as milk, cream, soft drinks, nutritional beverages, dressings, mayonnaise, sauces, dips, deserts, ice cream, margarine, and butter. The majority of these food products are conventional oil-in-water (O/W) or water-in-oil (W/O) type emulsions. Recently, there has been increasing interest within the food industry in either improving or extending the functional performance of foods using novel structured emulsions. This article reviews recent developments in the creation of structured emulsions that could be used by the food and other industries, including nanoemulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. These structured emulsions can be produced from food-grade [generally recognized as safe (GRAS)] ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals), using simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, production, performance, and potential applications of each type of structured emulsion system are discussed.

The effect of hydrogen on B4C coatings fabrication in inductively coupled plasma torch

NASA Astrophysics Data System (ADS)

Guo, Q. J.; Zhao, P.; Li, L.; Zhou, Q. J.; Ni, G. H.; Meng, Y. D.

2018-02-01

Boron carbide (B4C) coatings are prepared by an RF inductively coupled plasma (ICP) torch with different amounts of hydrogen introduced into the sheath gas. The effects of the added hydrogen on the characteristics of the plasma are diagnosed by optical emission spectroscopy and high speed photography. The effects on the melting of B4C particles in the plasma are studied by scanning electron microscopy (SEM). The microstructure of the B4C coatings was determined with SEM imaging and x-ray diffraction analysis. The results show that adding hydrogen to the sheath gas leads to plasma contraction, which results in higher gas temperature of plasma. It also enhances B4C particles spheroidizing and improves the compactness of B4C coatings. Plasma processing does not change the main phase of boron carbide. The obtained results on B4C coatings on Cu substrates allows for improving the B4C coatings fabrication process.

Enhancing speech recognition using improved particle swarm optimization based hidden Markov model.

PubMed

Selvaraj, Lokesh; Ganesan, Balakrishnan

2014-01-01

Enhancing speech recognition is the primary intention of this work. In this paper a novel speech recognition method based on vector quantization and improved particle swarm optimization (IPSO) is suggested. The suggested methodology contains four stages, namely, (i) denoising, (ii) feature mining (iii), vector quantization, and (iv) IPSO based hidden Markov model (HMM) technique (IP-HMM). At first, the speech signals are denoised using median filter. Next, characteristics such as peak, pitch spectrum, Mel frequency Cepstral coefficients (MFCC), mean, standard deviation, and minimum and maximum of the signal are extorted from the denoised signal. Following that, to accomplish the training process, the extracted characteristics are given to genetic algorithm based codebook generation in vector quantization. The initial populations are created by selecting random code vectors from the training set for the codebooks for the genetic algorithm process and IP-HMM helps in doing the recognition. At this point the creativeness will be done in terms of one of the genetic operation crossovers. The proposed speech recognition technique offers 97.14% accuracy.

Antisolvent crystallization of a cardiotonic drug in ionic liquids: Effect of mixing on the crystal properties

NASA Astrophysics Data System (ADS)

de Azevedo Jacqueline, Resende; Fabienne, Espitalier; Jean-Jacques, Letourneau; Inês, Ré Maria

2017-08-01

LASSBio-294 (3,4-methylenedioxybenzoyl-2-thienylhydrazon) is a poorly soluble drug which has been proposed to have major advantages over other cardiotonic drugs. Poorly water soluble drugs present limited bioavailability due to their low solubility and dissolution rate. An antisolvent crystallization processing can improve the dissolution rate by decreasing the crystals particle size. However, LASSBio-294 is also poorly soluble in organic solvents and this operation is limited. In order to open new perspectives to improve dissolution rate, this work has investigated LASSBio-294 in terms of its antisolvent crystallization in 1-ethyl-3-methylimidazolium methyl phosphonate [emim][CH3O(H)PO2] as solvent and water as antisolvent. Two modes of mixing are tested in stirred vessel with different pre-mixers (Roughton or T-mixers) in order to investigate the mixing effect on the crystal properties (crystalline structure, particle size distribution, residual solvent and in vitro dissolution rate). Smaller drug particles with unchanged crystalline structure were obtained. Despite the decrease of the elementary particles size, the recrystallized particles did not achieve a better dissolution profile. However, this study was able to highlight a certain number of findings such as the impact of the hydrodynamic conditions on the crystals formation and the presence of a gel phase limiting the dissolution rate.

Aerosol Particle Interfacial Thermodynamics and Phase Partitioning Measurements Using Biphasic Microfluidics

NASA Astrophysics Data System (ADS)

Dutcher, Cari; Metcalf, Andrew

2015-03-01

Secondary organic aerosol particles are nearly ubiquitous in the atmosphere and yet there remain large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. Interfacial properties affect the ambient aerosol morphology, or internal structure of the particle, which in turn can affect the way a particle interacts with an environment of condensable clusters and organic vapors. To improve our ability to accurately predict ambient aerosol morphology, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Unfortunately, many techniques employed to measure interfacial properties do so in bulk solutions or in the presence of a ternary (e.g. solid) phase. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface or interfacial tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred.

The effect of rotating magnetic field on the microstructure of in situ TiB2/Cu composites

NASA Astrophysics Data System (ADS)

Zou, C.; Kang, H.; Li, R.; Li, M.; Wang, W.; Chen, Z.; Wang, T.

2016-03-01

Nano ceramic particulate reinforced metal matrix composites are confronted with the problem of particle aggregation emerging in the process of solidification. It sharply deteriorates the mechanical properties of the composites. In order to improve the microstructure and particle distribution, in situ TiB2/Cu composites were prepared using Ti and Cu-B master alloys in a vacuum medium frequency induction furnace equipped with a rotating magnetic field (RMF). The effect of RMF magnetic field intensity employed on the microstructure and particles distribution of the TiB2/Cu composites were investigated. The results show that with the applied RMF, TiB2 particles are homogeneously distributed in the copper matrix, which significantly improves the mechanical properties of TiB2/Cu composites. The mechanism of RMF may be ascribed to the following two aspects. On the one hand, the electromagnetic body force generated by appropriate RMF drives forced convection in the equatorial plane of composite melt during solidification. On the other hand, a secondary flow in the meridional plane is engendered by a radial pressure gradient, thus making a strong agitation in the melt. These two effects result in a homogenous dispersion of TiB2 particles in the copper matrix, and hence excellent properties of TiB2/Cu composites were obtained.

Measuring the specific surface area of natural and manmade glasses: effects of formation process, morphology, and particle size

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

Papelis, Charalambos; Um, Wooyong; Russel, Charles E.

2003-03-28

The specific surface area of natural and manmade solid materials is a key parameter controlling important interfacial processes in natural environments and engineered systems, including dissolution reactions and sorption processes at solid-fluid interfaces. To improve our ability to quantify the release of trace elements trapped in natural glasses, the release of hazardous compounds trapped in manmade glasses, or the release of radionuclides from nuclear melt glass, we measured the specific surface area of natural and manmade glasses as a function of particle size, morphology, and composition. Volcanic ash, volcanic tuff, tektites, obsidian glass, and in situ vitrified rock were analyzed.more » Specific surface area estimates were obtained using krypton as gas adsorbent and the BET model. The range of surface areas measured exceeded three orders of magnitude. A tektite sample had the highest surface area (1.65 m2/g), while one of the samples of in situ vitrified rock had the lowest surf ace area (0.0016 m2/g). The specific surface area of the samples was a function of particle size, decreasing with increasing particle size. Different types of materials, however, showed variable dependence on particle size, and could be assigned to one of three distinct groups: (1) samples with low surface area dependence on particle size and surface areas approximately two orders of magnitude higher than the surface area of smooth spheres of equivalent size. The specific surface area of these materials was attributed mostly to internal porosity and surface roughness. (2) samples that showed a trend of decreasing surface area dependence on particle size as the particle size increased. The minimum specific surface area of these materials was between 0.1 and 0.01 m2/g and was also attributed to internal porosity and surface roughness. (3) samples whose surface area showed a monotonic decrease with increasing particle size, never reaching an ultimate surface area limit within the particle size range examined. The surface area results were consistent with particle morphology, examined by scanning electron microscopy, and have significant implications for the release of radionuclides and toxic metals in the environment.« less

Azores 2017 Field Campaign Report

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

Wehner, Birgit; Chevallier, Karine; Weinhold, Kay

Aerosol particles play an important role for the regional and global climate. Therefore, a network of measurement sites has been established worldwide, but only a small fraction of them is capturing the marine boundary layer (MBL) while approximately 70% of the Earth’s surface is covered with water. The main focus of this project is to improve the knowledge of sources and exchange processes of aerosol particles in general (German Research Foundation [DFG] project WE 2757/2-1) and of cloud condensation nuclei in particular (DFG project HE 6770/2-1) in the MBL in the northeastern Atlantic Ocean where the influence of local anthropogenicmore » sources is negligible. The main hypothesis of the project is that long-range transport of aerosols from North America as well as new particle formation in the free troposphere (FT) and at cloud edges followed by vertical transport contribute significantly to the aerosol budget in the MBL. The knowledge of sources and sinks of aerosol particles in combination with vertical exchange between FT and MBL is a prerequisite to predict aerosol particle number concentrations in the lowest regions of the MBL and its influence on the formation of clouds. These processes are not sufficiently quantified over the ocean up to now. To verify the hypothesis stated above, vertical exchange processes and particle sources over the Azores will be quantified using data of 17 measurement flights with high spatial resolution using a helicopter-borne platform developed at the Leibniz Institute for Tropospheric Research (TROPOS). Here, aerosol particle number concentration and vertical wind speed have been measured with a temporal resolution allowing the direct estimate of the vertical turbulent flux of aerosol particles in different heights for the first time. In addition, aerosol particle number size distributions, number concentrations of cloud condensation nuclei (CCN), cloud droplet number concentration (CDNC), and particle absorption at three different wavelengths have been determined. The data analysis is ongoing and final results are not available yet. The detailed analysis of these data will be used to conclude sources and origin of the investigated aerosol particles.« less

Identification of Particles in Parenteral Drug Raw Materials.

PubMed

Lee, Kathryn; Lankers, Markus; Valet, Oliver

2018-04-18

Particles in drug products are not good and are therefore regulated. These particles can come from the very beginning of the manufacturing process, from the raw materials. To prevent particles, it is important to understand what they are and where they come from so the raw material quality, processing, and shipping can be improved. Thus, it is important to correctly identify particles seen in raw materials. Raw materials need to be of a certain quality with respect to physical and chemical composition, and need to have no contaminants in the form of particles which could contaminate the product or indicate the raw materials are not pure enough to make a good quality product. Particles are often seen when handling raw materials due to color, size, or shape characteristics different from those in the raw materials. Particles may appear to the eye to be very different things than they actually are, so microscope, chemical, and elemental analyses are required for accuracy in proper identification. This paper shows how using three different spectroscopy tools correctly and together can be used to identify particles from extrinsic, intrinsic, and inherent particles. Sources of materials can be humans and the environment (extrinsic), from within the process (intrinsic), and part of the formulation (inherent). Microscope versions of Raman spectroscopy, laser-induced breakdown spectroscopy (LIBS), and IR spectroscopy are excellent tools for identifying particles because they are fast and accurate techniques needing minimal sample preparation that can provide chemical composition as well as images that can be used for identification. The micro analysis capabilities allow for easy analysis of different portions of samples so multiple components can be identified and sample preparation can be reduced. Using just one of these techniques may not be sufficient to give adequate identification results so that the source of contamination can be adequately identified. The complementarity of the techniques provides the advantage of identifying various chemical and molecular components, as well as elemental and image analyses. Correct interpretation of the results from these techniques is also very important. Copyright © 2018, Parenteral Drug Association.

Lungs deposition and pharmacokinetic study of submicron budesonide particles in Wistar rats intended for immediate effect in asthma.

PubMed

Rauf, Abdul; Bhatnagar, Aseem; Sisodia, S S; Khar, Roop K; Ahmad, Farhan J

2017-01-01

The purpose of the present investigation was to study the aerosolization, lungs deposition and pharmacokinetic study of inhalable submicron particles of budesonide in male Wistar rats. Submicron particles were prepared by antisolvent nanoprecipitation method and freeze-dried to obtain free flowing powder. The freeze-drying process yielded dry powder with desirable aerodynamic properties for inhalation therapy. An in-house model inhaler was designed to deliver medicine to lungs, optimized at dose level of 10 mg for 30 sec of fluidization. The in vitro aerosolization study demonstrates that submicron particles dissolve faster with improved aerosolization effect as compared to micronized budesonide. Both submicron and micron particles were compared for in vivo lungs deposition. The results showed that relatively high quantity of submicron particles reaches deep into the lungs as compared to micron particles. Most pronounced effect observed with submicron particles from pharmacokinetic parameters was the enhancement in peak plasma concentration (C max ) by 28.85 %, and increase in area under concentration curve (AUC 0-8h ) by 30.33 % compared to micron sized particles. The results suggested that developed submicronized formulation of budesonide can be used for pulmonary drug delivery for high deposition to deep lungs tissues.

Improved Silica-Guanidiniumthiocyanate DNA Isolation Procedure Based on Selective Binding of Bovine Alpha-Casein to Silica Particles

PubMed Central

Boom, René; Sol, Cees; Beld, Marcel; Weel, Jan; Goudsmit, Jaap; Wertheim-van Dillen, Pauline

1999-01-01

DNA purified from clinical cerebrospinal fluid and urine specimens by a silica-guanidiniumthiocyanate procedure frequently contained an inhibitor(s) of DNA-processing enzymes which may have been introduced by the purification procedure itself. Inhibition could be relieved by the use of a novel lysis buffer containing alpha-casein. When the novel lysis buffer was used, alpha-casein was bound by the silica particles in the first step of the procedure and eluted together with DNA in the last step, after which it exerted its beneficial effects for DNA-processing enzymes. In the present study we have compared the novel lysis buffer with the previously described lysis buffer with respect to double-stranded DNA yield (which was nearly 100%) and the performance of DNA-processing enzymes. PMID:9986822

Nickel ferrite aerogels with monodisperse nanoscale building blocks--the importance of processing temperature and atmosphere.

PubMed

Pettigrew, Katherine A; Long, Jeffrey W; Carpenter, Everett E; Baker, Colin C; Lytle, Justin C; Chervin, Christopher N; Logan, Michael S; Stroud, Rhonda M; Rolison, Debra R

2008-04-01

Using two-step (air/argon) thermal processing, sol-gel-derived nickel-iron oxide aerogels are transformed into monodisperse, networked nanocrystalline magnetic oxides of NiFe(2)O(4) with particle diameters that can be ripened with increasing temperature under argon to 4.6, 6.4, and 8.8 nm. Processing in air alone yields poorly crystalline materials; heating in argon alone leads to single phase, but diversiform, polydisperse NiFe(2)O(4), which hampers interpretation of the magnetic properties of the nanoarchitectures. The two-step method yields an improved model system to study magnetic effects as a function of size on the nanoscale while maintaining the particles within the size regime of single domain magnets, as networked building blocks, not agglomerates, and without stabilizing ligands capping the surface.

Hybrid 3D printing by bridging micro/nano processes

NASA Astrophysics Data System (ADS)

Yoon, Hae-Sung; Jang, Ki-Hwan; Kim, Eunseob; Lee, Hyun-Taek; Ahn, Sung-Hoon

2017-06-01

A hybrid 3D printing process was developed for multiple-material/freeform nano-scale manufacturing. The process consisted of aerodynamically focused nanoparticle (AFN) printing, micro-machining, focused ion beam milling, and spin-coating. Theoretical and experimental investigations were carried out to improve the compatibility of each of the processes, enabling bridging of various different techniques. The resulting hybrid process could address the limitations of individual processes, enabling improved process scaling and dimensional degrees of freedom, without losing the advantages of the existing processes. The minimum structure width can be reduced to 50 nm using undercut structures. In addition, AFN printing employs particle impact for adhesion, and various inorganic materials are suitable for printing, including metals and functional ceramics. Using the developed system, we fabricated bi-material cantilevers for applications as a thermal actuator. The mechanical and thermal properties of the structure were investigated using an in situ measurement system, and irregular thermal phenomena due to the fabrication process were analyzed. We expect that this work will lead to improvements in the area of customized nano-scale manufacturing, as well as further improvements in manufacturing technology by combining different fabrication techniques.

Effects of wheat source and particle size in meal and pelleted diets on finishing pig growth performance, carcass characteristics, and nutrient digestibility.

PubMed

De Jong, J A; DeRouchey, J M; Tokach, M D; Dritz, S S; Goodband, R D; Paulk, C B; Woodworth, J C; Jones, C K; Stark, C R

2016-08-01

Two experiments were conducted to test the effects of wheat source and particle size in meal and pelleted diets on finishing pig performance, carcass characteristics, and diet digestibility. In Exp. 1, pigs (PIC 327 × 1050; = 288; initially 43.8 kg BW) were balanced by initial BW and randomly allotted to 1 of 3 treatments with 8 pigs per pen (4 barrows and 4 gilts) and 12 pens per treatment. The 3 dietary treatments were hard red winter wheat ground with a hammer mill to 728, 579, or 326 μm, respectively. From d 0 to 40, decreasing wheat particle size decreased (linear, < 0.033) ADFI but improved (quadratic, < 0.014) G:F. From d 40 to 83, decreasing wheat particle size increased (quadratic, < 0.018) ADG and improved (linear, < 0.002) G:F. Overall from d 0 to 83, reducing wheat particle size improved (linear, < 0.002) G:F. In Exp. 2, pigs (PIC 327 × 1050; = 576; initially 43.4 ± 0.02 kg BW) were used to determine the effects of wheat source and particle size of pelleted diets on finishing pig growth performance and carcass characteristics. Pigs were randomly allotted to pens, and pens of pigs were balanced by initial BW and randomly allotted to 1 of 6 dietary treatments with 12 replications per treatment and 8 pigs/pen. The experimental diets used the same wheat-soybean meal formulation, with the 6 treatments using hard red winter or soft white winter wheat that were processed to 245, 465, and 693 μm and 258, 402, and 710 μm, respectively. All diets were pelleted. Overall, feeding hard red winter wheat increased ( < 0.05) ADG and ADFI when compared with soft white winter wheat. There was a tendency ( < 0.10) for a quadratic particle size × wheat source interaction for ADG, ADFI, and both DM and GE digestibility, as they were decreased for pigs fed 465-μm hard red winter wheat and were greatest for pigs fed 402-μm soft white winter wheat. There were no main or interactive effects of particle size or wheat source on carcass characteristics. In summary, fine grinding hard red winter wheat fed in meal form improved G:F and nutrient digestibility, whereas reducing particle size of wheat from approximately 700 to 250 μm in pelleted diets did not influence growth or carcass traits. Finally, feeding hard red winter wheat improved ADG and ADFI compared with feeding soft white winter wheat.

Effect of ethanol as a co-solvent on the aerosol performance and stability of spray-dried lysozyme.

PubMed

Ji, Shuying; Thulstrup, Peter Waaben; Mu, Huiling; Hansen, Steen Honoré; van de Weert, Marco; Rantanen, Jukka; Yang, Mingshi

2016-11-20

In the spray drying process, organic solvents can be added to facilitate drying, accommodate certain functional excipients, and modify the final particle characteristics. In this study, lysozyme was used as a model pharmaceutical protein to study the effect of ethanol as a co-solvent on the stability and aerosol performance of spray-dried protein. Lysozyme was dissolved in solutions with various ratios of ethanol and water, and subsequently spray-dried. A change from spherical particles into wrinkled and folded particles was observed upon increasing the ratio of ethanol in the feed. The aerosol performance of the spray-dried lysozyme from ethanol-water solution was improved compared to that from pure water. The conformation of lysozyme in the ethanol-water solution and spray dried powder was altered, but the native structure of lysozyme was restored upon reconstitution in water after the spray drying process. The enzymatic activities of the spray-dried lysozyme showed no significant impact of ethanol; however, the lysozyme enzymatic activity was ca. 25% lower compared to the starting material. In conclusion, the addition of ethanol as a co-solvent in the spray drying feed for lysozyme did not compromise the conformation of the protein after drying, while it improved the inhaled aerosol performance. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of fine-celled bio-fiber composite foams using physical blowing agents and nano-particles

NASA Astrophysics Data System (ADS)

Guo, Gangjian

As one of eco-friendly bio-fibers, wood-fiber has been incorporated in plastics to make wood-fiber/plastic composites (WPC) with an increased stiffness, durability and lowered cost. However, these improvements are usually accompanied by loss in the ductility and impact strength of the composites. These shortcomings can be significantly improved by incorporating a fine-cell foam structure in the composites. This thesis presents the development of the foaming technology for the manufacture of fine-cell WPC foams with environmentally benign physical blowing agents (PBAs), and focuses on the elucidation of the fundamental foaming mechanisms and the related issues involved. One critical issue comes from the volatiles evolved from the wood-fiber during high temperature processing. The volatiles, as a blowing agent, can contribute to the foaming process. However, they lead to gross deterioration of the cell structure of WPC foams. The presence of volatiles makes foaming of WPC "a poorly understood black art". With the use of PBAs, a strategy of lowering processing temperature becomes feasible, to suppress the generation of volatiles. A series of PBA-based experiments were designed using a statistical design of experiments (DOE) technique, and were performed to establish the relationship of processing and material variables with the structure of WPC foams. Fundamental foaming behaviors for two different PBAs and two different polymer systems were identified. WPC foams with a fine-cell morphology and a desired density were successfully obtained at the optimized conditions. Another limitation for the wider application of WPC is their flammability. Innovative use of a small amount of nano-clay in WPC significantly improved the flame-retarding property of WPC, and the key issue was to achieve a high degree of exfoliation of nano-particles in the polymer matrix, to achieve a desired flammability reduction. The synergistic effects of nano-particles in foaming of WPC were identified as well.

Conformational and Thermal Stability Improvements for the Large-Scale Production of Yeast-Derived Rabbit Hemorrhagic Disease Virus-Like Particles as Multipurpose Vaccine

PubMed Central

Méndez, Lídice; González, Nemecio; Parra, Francisco; Martín-Alonso, José M.; Limonta, Miladys; Sánchez, Kosara; Cabrales, Ania; Estrada, Mario P.; Rodríguez-Mallón, Alina; Farnós, Omar

2013-01-01

Recombinant virus-like particles (VLP) antigenically similar to rabbit hemorrhagic disease virus (RHDV) were recently expressed at high levels inside Pichia pastoris cells. Based on the potential of RHDV VLP as platform for diverse vaccination purposes we undertook the design, development and scale-up of a production process. Conformational and stability issues were addressed to improve process control and optimization. Analyses on the structure, morphology and antigenicity of these multimers were carried out at different pH values during cell disruption and purification by size-exclusion chromatography. Process steps and environmental stresses in which aggregation or conformational instability can be detected were included. These analyses revealed higher stability and recoveries of properly assembled high-purity capsids at acidic and neutral pH in phosphate buffer. The use of stabilizers during long-term storage in solution showed that sucrose, sorbitol, trehalose and glycerol acted as useful aggregation-reducing agents. The VLP emulsified in an oil-based adjuvant were subjected to accelerated thermal stress treatments. None to slight variations were detected in the stability of formulations and in the structure of recovered capsids. A comprehensive analysis on scale-up strategies was accomplished and a nine steps large-scale production process was established. VLP produced after chromatographic separation protected rabbits against a lethal challenge. The minimum protective dose was identified. Stabilized particles were ultimately assayed as carriers of a foreign viral epitope from another pathogen affecting a larger animal species. For that purpose, a linear protective B-cell epitope from Classical Swine Fever Virus (CSFV) E2 envelope protein was chemically coupled to RHDV VLP. Conjugates were able to present the E2 peptide fragment for immune recognition and significantly enhanced the peptide-specific antibody response in vaccinated pigs. Overall these results allowed establishing improved conditions regarding conformational stability and recovery of these multimers for their production at large-scale and potential use on different animal species or humans. PMID:23460801

Improvements of the Radiation Code "MstrnX" in AORI/NIES/JAMSTEC Models

NASA Astrophysics Data System (ADS)

Sekiguchi, M.; Suzuki, K.; Takemura, T.; Watanabe, M.; Ogura, T.

2015-12-01

There is a large demand for an accurate yet rapid radiation transfer scheme accurate for general climate models. The broadband radiative transfer code "mstrnX", ,which was developed by Atmosphere and Ocean Research Institute (AORI) and was implemented in several global and regional climate models cooperatively developed in the Japanese research community, for example, MIROC (the Model for Interdisciplinary Research on Climate) [Watanabe et al., 2010], NICAM (Non-hydrostatic Icosahedral Atmospheric Model) [Satoh et al, 2008], and CReSS (Cloud Resolving Storm Simulator) [Tsuboki and Sakakibara, 2002]. In this study, we improve the gas absorption process and the scattering process of ice particles. For update of gas absorption process, the absorption line database is replaced by the latest versions of the Harvard-Smithsonian Center, HITRAN2012. An optimization method is adopted in mstrnX to decrease the number of integration points for the wavenumber integration using the correlated k-distribution method and to increase the computational efficiency in each band. The integration points and weights of the correlated k-distribution are optimized for accurate calculation of the heating rate up to altitude of 70 km. For this purpose we adopted a new non-linear optimization method of the correlated k-distribution and studied an optimal initial condition and the cost function for the non-linear optimization. It is known that mstrnX has a considerable bias in case of quadrapled carbon dioxide concentrations [Pincus et al., 2015], however, the bias is decreased by this improvement. For update of scattering process of ice particles, we adopt a solid column as an ice crystal habit [Yang et al., 2013]. The single scattering properties are calculated and tabulated in advance. The size parameter of this table is ranged from 0.1 to 1000 in mstrnX, we expand the maximum to 50000 in order to correspond to large particles, like fog and rain drop. Those update will be introduced to MIROC and adopted for CMIP6 experiment.

Enhanced stab resistance of armor composites with functionalized silica nanoparticles

NASA Astrophysics Data System (ADS)

Mahfuz, Hassan; Clements, Floria; Rangari, Vijaya; Dhanak, Vinod; Beamson, Graham

2009-03-01

Traditionally shear thickening fluid (STF) reinforced with Kevlar has been used to develop flexible armor. At the core of the STF-Kevlar composites is a mixture of polyethylene glycol (PEG) and silica particles. This mixture is often known as STF and is consisted of approximately 45 wt % PEG and 55 wt % silica. During rheological tests, STF shows instantaneous spike in viscosity above a critical shear rate. Fabrication of STF-Kevlar composites requires preparation of STF, dilution with ethanol, and then impregnation with Kevlar. In the current approach, nanoscale silica particles were dispersed directly into a mixture of PEG and ethanol through a sonic cavitation process. Two types of silica nanoparticles were used in the investigation: 30 nm crystalline silica and 7 nm amorphous silica. The admixture was then reinforced with Kevlar fabric to produce flexible armor composites. In the next step, silica particles are functionalized with a silane coupling agent to enhance bonding between silica and PEG. The performance of the resulting armor composites improved significantly. As evidenced by National Institute of Justice spike tests, the energy required for zero-layer penetration (i.e., no penetration) jumped twofold: from 12 to 25 J cm2/g. The source of this improvement has been traced to the formation of siloxane (Si-O-Si) bonds between silica and PEG and superior coating of Kevlar filaments with particles. Fourier transform infrared, x-ray photoemission spectroscopy, and scanning electron microscopy studies were performed to examine chemical bonds, elemental composition, and particle dispersion responsible for such improvement. In summary, our experiments have demonstrated that functionalization of silica particles followed by direct dispersion into PEG resulted in superior Kevlar composites having much higher spike resistance.

Do we really need a large number of particles to simulate bimolecular reactive transport with random walk methods? A kernel density estimation approach

NASA Astrophysics Data System (ADS)

Rahbaralam, Maryam; Fernàndez-Garcia, Daniel; Sanchez-Vila, Xavier

2015-12-01

Random walk particle tracking methods are a computationally efficient family of methods to solve reactive transport problems. While the number of particles in most realistic applications is in the order of 106-109, the number of reactive molecules even in diluted systems might be in the order of fractions of the Avogadro number. Thus, each particle actually represents a group of potentially reactive molecules. The use of a low number of particles may result not only in loss of accuracy, but also may lead to an improper reproduction of the mixing process, limited by diffusion. Recent works have used this effect as a proxy to model incomplete mixing in porous media. In this work, we propose using a Kernel Density Estimation (KDE) of the concentrations that allows getting the expected results for a well-mixed solution with a limited number of particles. The idea consists of treating each particle as a sample drawn from the pool of molecules that it represents; this way, the actual location of a tracked particle is seen as a sample drawn from the density function of the location of molecules represented by that given particle, rigorously represented by a kernel density function. The probability of reaction can be obtained by combining the kernels associated to two potentially reactive particles. We demonstrate that the observed deviation in the reaction vs time curves in numerical experiments reported in the literature could be attributed to the statistical method used to reconstruct concentrations (fixed particle support) from discrete particle distributions, and not to the occurrence of true incomplete mixing. We further explore the evolution of the kernel size with time, linking it to the diffusion process. Our results show that KDEs are powerful tools to improve computational efficiency and robustness in reactive transport simulations, and indicates that incomplete mixing in diluted systems should be modeled based on alternative mechanistic models and not on a limited number of particles.

Engineering and evaluating drug delivery particles in microfluidic devices.

PubMed

Björnmalm, Mattias; Yan, Yan; Caruso, Frank

2014-09-28

The development of new and improved particle-based drug delivery is underpinned by an enhanced ability to engineer particles with high fidelity and integrity, as well as increased knowledge of their biological performance. Microfluidics can facilitate these processes through the engineering of spatiotemporally highly controlled environments using designed microstructures in combination with physical phenomena present at the microscale. In this review, we discuss microfluidics in the context of addressing key challenges in particle-based drug delivery. We provide an overview of how microfluidic devices can: (i) be employed to engineer particles, by providing highly controlled interfaces, and (ii) be used to establish dynamic in vitro models that mimic in vivo environments for studying the biological behavior of engineered particles. Finally, we discuss how the flexible and modular nature of microfluidic devices provides opportunities to create increasingly realistic models of the in vivo milieu (including multi-cell, multi-tissue and even multi-organ devices), and how ongoing developments toward commercialization of microfluidic tools are opening up new opportunities for the engineering and evaluation of drug delivery particles. Copyright © 2014 Elsevier B.V. All rights reserved.

Resolving occlusion and segmentation errors in multiple video object tracking

NASA Astrophysics Data System (ADS)

Cheng, Hsu-Yung; Hwang, Jenq-Neng

2009-02-01

In this work, we propose a method to integrate the Kalman filter and adaptive particle sampling for multiple video object tracking. The proposed framework is able to detect occlusion and segmentation error cases and perform adaptive particle sampling for accurate measurement selection. Compared with traditional particle filter based tracking methods, the proposed method generates particles only when necessary. With the concept of adaptive particle sampling, we can avoid degeneracy problem because the sampling position and range are dynamically determined by parameters that are updated by Kalman filters. There is no need to spend time on processing particles with very small weights. The adaptive appearance for the occluded object refers to the prediction results of Kalman filters to determine the region that should be updated and avoids the problem of using inadequate information to update the appearance under occlusion cases. The experimental results have shown that a small number of particles are sufficient to achieve high positioning and scaling accuracy. Also, the employment of adaptive appearance substantially improves the positioning and scaling accuracy on the tracking results.

Motion-Blurred Particle Image Restoration for On-Line Wear Monitoring

PubMed Central

Peng, Yeping; Wu, Tonghai; Wang, Shuo; Kwok, Ngaiming; Peng, Zhongxiao

2015-01-01

On-line images of wear debris contain important information for real-time condition monitoring, and a dynamic imaging technique can eliminate particle overlaps commonly found in static images, for instance, acquired using ferrography. However, dynamic wear debris images captured in a running machine are unavoidably blurred because the particles in lubricant are in motion. Hence, it is difficult to acquire reliable images of wear debris with an adequate resolution for particle feature extraction. In order to obtain sharp wear particle images, an image processing approach is proposed. Blurred particles were firstly separated from the static background by utilizing a background subtraction method. Second, the point spread function was estimated using power cepstrum to determine the blur direction and length. Then, the Wiener filter algorithm was adopted to perform image restoration to improve the image quality. Finally, experiments were conducted with a large number of dynamic particle images to validate the effectiveness of the proposed method and the performance of the approach was also evaluated. This study provides a new practical approach to acquire clear images for on-line wear monitoring. PMID:25856328

Improved Energetic-Behaviors of Spontaneously Surface-Mediated Al Particles.

PubMed

Kim, Dong Won; Kim, Kyung Tae; Min, Tae Sik; Kim, Kyung Ju; Kim, Soo Hyung

2017-07-05

Surface-mediated Al particles are synthesized by incorporating the stable fluoride reaction of Al-F on a pure Al surface in place of natural oxides. Al particles with fluoro-polymer directly adsorbed on the surface show a considerable capability to overcome limitations caused by the surface oxide. Here, we report that Al fluoride when spontaneously formed at the poly(vinylidene fluoride)/Al interface serves as an oxidation-protecting layer while also providing an efficient combustion path along which the internal Al rapidly reacts with external oxygen atoms. Both thermal oxidation and explosion tests of the poly(vinylidene fluoride)/Al particles show superior exothermic enthalpy energy and simultaneously rapid oxidation reactivity compared to those of Al 2 O 3 passivated Al particles. It is clearly elucidated that the enhanced energetic properties of Al particles mediated by poly(vinylidene fluoride) originate from the extraordinary pyrolytic process of Al fluoride occurring at a low temperature compared to Al 2 O 3 passivated Al. Hence, these results clarify that the surface mediation of Al particles can be significantly considered as advanced technology for many energetic applications.

Big Data: A Parallel Particle Swarm Optimization-Back-Propagation Neural Network Algorithm Based on MapReduce

PubMed Central

Cao, Jianfang; Cui, Hongyan; Shi, Hao; Jiao, Lijuan

2016-01-01

A back-propagation (BP) neural network can solve complicated random nonlinear mapping problems; therefore, it can be applied to a wide range of problems. However, as the sample size increases, the time required to train BP neural networks becomes lengthy. Moreover, the classification accuracy decreases as well. To improve the classification accuracy and runtime efficiency of the BP neural network algorithm, we proposed a parallel design and realization method for a particle swarm optimization (PSO)-optimized BP neural network based on MapReduce on the Hadoop platform using both the PSO algorithm and a parallel design. The PSO algorithm was used to optimize the BP neural network’s initial weights and thresholds and improve the accuracy of the classification algorithm. The MapReduce parallel programming model was utilized to achieve parallel processing of the BP algorithm, thereby solving the problems of hardware and communication overhead when the BP neural network addresses big data. Datasets on 5 different scales were constructed using the scene image library from the SUN Database. The classification accuracy of the parallel PSO-BP neural network algorithm is approximately 92%, and the system efficiency is approximately 0.85, which presents obvious advantages when processing big data. The algorithm proposed in this study demonstrated both higher classification accuracy and improved time efficiency, which represents a significant improvement obtained from applying parallel processing to an intelligent algorithm on big data. PMID:27304987

In situ affinity purification of his-tagged protein A from Bacillus megaterium cultivation using recyclable superparamagnetic iron oxide nanoparticles.

PubMed

Gädke, Johannes; Kleinfeldt, Lennart; Schubert, Chris; Rohde, Manfred; Biedendieck, Rebekka; Garnweitner, Georg; Krull, Rainer

2017-01-20

This paper discusses the use of recyclable functionalized nanoparticles for an improved downstream processing of recombinant products. The Gram-positive bacterium Bacillus megaterium was used to secrete recombinant protein A fused to a histidine tag into the culture supernatant in shaker flasks. Superparamagnetic iron oxide nanoparticles functionalized with 3-glycidoxypropyl-trimethoxysilane-coupled-nitrilotriacetic-acid groups (GNTA-SPION) were synthesized and added directly to the growing culture. After 10min incubation time, >85% of the product was adsorbed onto the particles. The particles were magnetically separated using handheld neodymium magnets and the product was eluted. The GNTA-SPION were successfully regenerated and reused in five consecutive cycles. In the one-step purification, the purity of the product reached >99.9% regarding protein A. A very low particle concentration of 0.5g/L was sufficient for effective product separation. Bacterial growth was not influenced negatively by this concentration. Particle analysis showed similar properties between freshly synthesized and regenerated GNTA-SPION. The overall process efficiency was however influenced by partial disintegration of particle agglomerates and thus loss of particles. The demonstration of very fast in situ product removal from growing bacterial culture combined with a very high product purity within one step shows possibilities for automated large scale purification combined with recycling of biomass. Copyright © 2016 Elsevier B.V. All rights reserved.

Validation of a low field Rheo-NMR instrument and application to shear-induced migration of suspended non-colloidal particles in Couette flow

NASA Astrophysics Data System (ADS)

Colbourne, A. A.; Blythe, T. W.; Barua, R.; Lovett, S.; Mitchell, J.; Sederman, A. J.; Gladden, L. F.

2018-01-01

Nuclear magnetic resonance rheology (Rheo-NMR) is a valuable tool for studying the transport of suspended non-colloidal particles, important in many commercial processes. The Rheo-NMR imaging technique directly and quantitatively measures fluid displacement as a function of radial position. However, the high field magnets typically used in these experiments are unsuitable for the industrial environment and significantly hinder the measurement of shear stress. We introduce a low field Rheo-NMR instrument (1 H resonance frequency of 10.7MHz), which is portable and suitable as a process monitoring tool. This system is applied to the measurement of steady-state velocity profiles of a Newtonian carrier fluid suspending neutrally-buoyant non-colloidal particles at a range of concentrations. The large particle size (diameter > 200 μm) in the system studied requires a wide-gap Couette geometry and the local rheology was expected to be controlled by shear-induced particle migration. The low-field results are validated against high field Rheo-NMR measurements of consistent samples at matched shear rates. Additionally, it is demonstrated that existing models for particle migration fail to adequately describe the solid volume fractions measured in these systems, highlighting the need for improvement. The low field implementation of Rheo-NMR is complementary to shear stress rheology, such that the two techniques could be combined in a single instrument.

A combined acidification/PEO flocculation process to improve the lignin removal from the pre-hydrolysis liquor of kraft-based dissolving pulp production process.

PubMed

Shi, Haiqiang; Fatehi, Pedram; Xiao, Huining; Ni, Yonghao

2011-04-01

The presence of lignin impairs the utilization of the hemicelluloses dissolved in the pre-hydrolysis liquor (PHL) of the kraft-based dissolving pulp production process. In this paper, a novel process was developed by combining the acidification and poly ethylene oxide (PEO) flocculation concepts to improve the lignin removal. The results showed that the lignin removal was improved by the addition of PEO to the acidified PHL, particularly at a low pH of 1.5. The main mechanisms involved are the lignin/PEO complex formation and the bridging of the formed complexes. This hypothesis was supported by the turbidity, FTIR and particle size measurements. Interestingly, the hemicelluloses removal from the acidification/PEO flocculation was marginal, which would be beneficial for the down-stream ethanol production from the PHL. Additionally, a process flow diagram was proposed that incorporates this new concept into the existing configuration of kraft-based dissolving pulp production process. Copyright © 2011 Elsevier Ltd. All rights reserved.

Cellulose nanofibers from banana peels as a Pickering emulsifier: High-energy emulsification processes.

PubMed

Costa, Ana Letícia Rodrigues; Gomes, Andresa; Tibolla, Heloisa; Menegalli, Florencia Cecilia; Cunha, Rosiane Lopes

2018-08-15

Cellulose nanofibers (CNFs) from banana peels was evaluated as promising stabilizer for oil-in-water emulsions. CNFs were treated using ultrasound and high-pressure homogenizer. Changes on the size, crystallinity index and zeta potential of CNFs were associated with the intense effects of cavitation phenomenon and shear forces promoted by mechanical treatments. CNFs-stabilized emulsions were produced under the same process conditions as the particles. Coalescence phenomenon was observed in the emulsions produced using high-pressure homogenizer, whereas droplets flocculation occurred in emulsions processed by ultrasound. In the latter, coalescence stability was associated with effects of cavitation forces acting on the CNFs breakup. Thus, smaller droplets created during the ultrasonication process could be recovered by particles that acted as an effective barrier against droplets coalescence. Our results improved understanding about the relationship between the choice of emulsification process and their effects on the CNFs properties influencing the potential application of CNFs as a food emulsifier. Copyright © 2018 Elsevier Ltd. All rights reserved.

The xylooligosaccharide addition and sodium reduction in requeijão cremoso processed cheese.

PubMed

Ferrão, Luana L; Ferreira, Marcus Vinícius S; Cavalcanti, Rodrigo N; Carvalho, Ana Flávia A; Pimentel, Tatiana C; Silva, Hugo L A; Silva, Ramon; Esmerino, Erick A; Neto, Roberto P C; Tavares, Maria Inês B; Freitas, Mônica Q; Menezes, Jaqueline C V; Cabral, Lúcio M; Moraes, Jeremias; Silva, Márcia C; Mathias, Simone P; Raices, Renata S L; Pastore, Gláucia M; Cruz, Adriano G

2018-05-01

The addition of xylooligosaccharide (XOS), sodium reduction and flavor enhancers (arginine and yeast extract) on the manufacture of requeijão cremoso processed cheese was investigated. The addition of XOS resulted in a denser and compact structure, with increased apparent viscosity, elasticity (G') and firmness (G*). The addition of XOS and yeast extract improved the rheological and physicochemical properties (decrease in viscosity and particle size and increase in melting rate) and sensory characteristics (improvement in salty and acid taste, greater homogeneity, and lower bitter taste). In addition, a positive effect of arginine was observed in the sensory characteristics of the requeijão cremoso processed cheese, but without improvements in the physicochemical and rheological characteristics. Overall, the XOS addition and sodium reduction proportionated the development of a healthier processed cheese formulation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Method For Enhanced Gas Monitoring In High Density Flow Streams

DOEpatents

Von Drasek, William A.; Mulderink, Kenneth A.; Marin, Ovidiu

2005-09-13

A method for conducting laser absorption measurements in high temperature process streams having high levels of particulate matter is disclosed. An impinger is positioned substantially parallel to a laser beam propagation path and at upstream position relative to the laser beam. Beam shielding pipes shield the beam from the surrounding environment. Measurement is conducted only in the gap between the two shielding pipes where the beam propagates through the process gas. The impinger facilitates reduced particle presence in the measurement beam, resulting in improved SNR (signal-to-noise) and improved sensitivity and dynamic range of the measurement.

Digital Correlation In Laser-Speckle Velocimetry

NASA Technical Reports Server (NTRS)

Gilbert, John A.; Mathys, Donald R.

1992-01-01

Periodic recording helps to eliminate spurious results. Improved digital-correlation process extracts velocity field of two-dimensional flow from laser-speckle images of seed particles distributed sparsely in flow. Method which involves digital correlation of images recorded at unequal intervals, completely automated and has potential to be fastest yet.

Surfactant-assisted coal liquefaction

NASA Technical Reports Server (NTRS)

Hsu, G. C.

1977-01-01

Improved process of coal liquefaction utilizing nonaqueous surfactant has increased oil yield from 50 to about 80%. Asphaltene molecule formation of colloid particles is prevented by surfactant. Separated molecules present more surface area for hydrogenation reaction. Lower requirements for temperature, pressure, and hydrogen lead to reduction in capital and operation costs.

Recent Advances in Superhydrophobic Electrodeposits

PubMed Central

Tam, Jason; Palumbo, Gino; Erb, Uwe

2016-01-01

In this review, we present an extensive summary of research on superhydrophobic electrodeposits reported in the literature over the past decade. As a synthesis technique, electrodeposition is a simple and scalable process to produce non-wetting metal surfaces. There are three main categories of superhydrophobic surfaces made by electrodeposition: (i) electrodeposits that are inherently non-wetting due to hierarchical roughness generated from the process; (ii) electrodeposits with plated surface roughness that are further modified with low surface energy material; (iii) composite electrodeposits with co-deposited inert and hydrophobic particles. A recently developed strategy to improve the durability during the application of superhydrophobic electrodeposits by controlling the microstructure of the metal matrix and the co-deposition of hydrophobic ceramic particles will also be addressed. PMID:28773278

Pulmonary aerosol delivery and the importance of growth dynamics.

PubMed

Haddrell, Allen E; Lewis, David; Church, Tanya; Vehring, Reinhard; Murnane, Darragh; Reid, Jonathan P

2017-12-01

Aerosols are dynamic systems, responding to variations in the surrounding environmental conditions by changing in size, composition and phase. Although, widely used in inhalation therapies, details of the processes occurring on aerosol generation and during inhalation have received little attention. Instead, research has focused on improvements to the formulation of the drug prior to aerosolization and the resulting clinical efficacy of the treatment. Here, we highlight the processes that occur during aerosol generation and inhalation, affecting aerosol disposition when deposited and, potentially, impacting total and regional doses. In particular, we examine the response of aerosol particles to the humid environment of the respiratory tract, considering both the capacity of particles to grow by absorbing moisture and the timescale for condensation to occur. [Formula: see text].

On improving the fracture toughness of a NiAl-based alloy by mechanical alloying

NASA Technical Reports Server (NTRS)

Kostrubanic, J.; Koss, D. A.; Locci, I. E.; Nathal, M.

1991-01-01

Mechanical alloying (MA) has been used to process the NiAl-based alloy Ni-35Al-20Fe, such that a fine-grain (about 2 microns) microstructure is obtained through the addition of 2 vol pct Y2O3 particles. When compared to a conventionally processed, coarse-grained (about 28 microns) Ni-35-20 alloy without the Y2O3 particles, the MA alloy exhibits two to three times higher fracture toughness values, despite a 50-percent increase in yield strength. Room-temperature K(O) values as high as 34 MPa sq rt m are observed, accompanied by a yield strength in excess of 1100 MPa. Fractography confirms a change in fracture characteristics of the fine-grained MA alloy.

Recent Advances in Superhydrophobic Electrodeposits.

PubMed

Tam, Jason; Palumbo, Gino; Erb, Uwe

2016-03-03

In this review, we present an extensive summary of research on superhydrophobic electrodeposits reported in the literature over the past decade. As a synthesis technique, electrodeposition is a simple and scalable process to produce non-wetting metal surfaces. There are three main categories of superhydrophobic surfaces made by electrodeposition: (i) electrodeposits that are inherently non-wetting due to hierarchical roughness generated from the process; (ii) electrodeposits with plated surface roughness that are further modified with low surface energy material; (iii) composite electrodeposits with co-deposited inert and hydrophobic particles. A recently developed strategy to improve the durability during the application of superhydrophobic electrodeposits by controlling the microstructure of the metal matrix and the co-deposition of hydrophobic ceramic particles will also be addressed.

Particle dispersing system and method for testing semiconductor manufacturing equipment

DOEpatents

Chandrachood, Madhavi; Ghanayem, Steve G.; Cantwell, Nancy; Rader, Daniel J.; Geller, Anthony S.

1998-01-01

The system and method prepare a gas stream comprising particles at a known concentration using a particle disperser for moving particles from a reservoir of particles into a stream of flowing carrier gas. The electrostatic charges on the particles entrained in the carrier gas are then neutralized or otherwise altered, and the resulting particle-laden gas stream is then diluted to provide an acceptable particle concentration. The diluted gas stream is then split into a calibration stream and the desired output stream. The particles in the calibration stream are detected to provide an indication of the actual size distribution and concentration of particles in the output stream that is supplied to a process chamber being analyzed. Particles flowing out of the process chamber within a vacuum pumping system are detected, and the output particle size distribution and concentration are compared with the particle size distribution and concentration of the calibration stream in order to determine the particle transport characteristics of a process chamber, or to determine the number of particles lodged in the process chamber as a function of manufacturing process parameters such as pressure, flowrate, temperature, process chamber geometry, particle size, particle charge, and gas composition.

Techniques for precise energy calibration of particle pixel detectors

NASA Astrophysics Data System (ADS)

Kroupa, M.; Campbell-Ricketts, T.; Bahadori, A.; Empl, A.

2017-03-01

We demonstrate techniques to improve the accuracy of the energy calibration of Timepix pixel detectors, used for the measurement of energetic particles. The typical signal from such particles spreads among many pixels due to charge sharing effects. As a consequence, the deposited energy in each pixel cannot be reconstructed unless the detector is calibrated, limiting the usability of such signals for calibration. To avoid this shortcoming, we calibrate using low energy X-rays. However, charge sharing effects still occur, resulting in part of the energy being deposited in adjacent pixels and possibly lost. This systematic error in the calibration process results in an error of about 5% in the energy measurements of calibrated devices. We use FLUKA simulations to assess the magnitude of charge sharing effects, allowing a corrected energy calibration to be performed on several Timepix pixel detectors and resulting in substantial improvement in energy deposition measurements. Next, we address shortcomings in calibration associated with the huge range (from kiloelectron-volts to megaelectron-volts) of energy deposited per pixel which result in a nonlinear energy response over the full range. We introduce a new method to characterize the non-linear response of the Timepix detectors at high input energies. We demonstrate improvement using a broad range of particle types and energies, showing that the new method reduces the energy measurement errors, in some cases by more than 90%.

Techniques for precise energy calibration of particle pixel detectors.

PubMed

Kroupa, M; Campbell-Ricketts, T; Bahadori, A; Empl, A

2017-03-01

We demonstrate techniques to improve the accuracy of the energy calibration of Timepix pixel detectors, used for the measurement of energetic particles. The typical signal from such particles spreads among many pixels due to charge sharing effects. As a consequence, the deposited energy in each pixel cannot be reconstructed unless the detector is calibrated, limiting the usability of such signals for calibration. To avoid this shortcoming, we calibrate using low energy X-rays. However, charge sharing effects still occur, resulting in part of the energy being deposited in adjacent pixels and possibly lost. This systematic error in the calibration process results in an error of about 5% in the energy measurements of calibrated devices. We use FLUKA simulations to assess the magnitude of charge sharing effects, allowing a corrected energy calibration to be performed on several Timepix pixel detectors and resulting in substantial improvement in energy deposition measurements. Next, we address shortcomings in calibration associated with the huge range (from kiloelectron-volts to megaelectron-volts) of energy deposited per pixel which result in a nonlinear energy response over the full range. We introduce a new method to characterize the non-linear response of the Timepix detectors at high input energies. We demonstrate improvement using a broad range of particle types and energies, showing that the new method reduces the energy measurement errors, in some cases by more than 90%.

Prospective Symbiosis of Green Chemistry and Energetic Materials.

PubMed

Kuchurov, Ilya V; Zharkov, Mikhail N; Fershtat, Leonid L; Makhova, Nina N; Zlotin, Sergey G

2017-10-23

A global increase in environmental pollution demands the development of new "cleaner" chemical processes. Among urgent improvements, the replacement of traditional hydrocarbon-derived toxic organic solvents with neoteric solvents less harmful for the environment is one of the most vital issues. As a result of the favorable combination of their unique properties, ionic liquids (ILs), dense gases, and supercritical fluids (SCFs) have gained considerable attention as suitable green chemistry media for the preparation and modification of important chemical compounds and materials. In particular, they have a significant potential in a specific and very important area of research associated with the manufacture and processing of high-energy materials (HEMs). These large-scale manufacturing processes, in which hazardous chemicals and extreme conditions are used, produce a huge amount of hard-to-dispose-of waste. Furthermore, they are risky to staff, and any improvements that would reduce the fire and explosion risks of the corresponding processes are highly desirable. In this Review, useful applications of almost nonflammable ILs, dense gases, and SCFs (first of all, CO 2 ) for nitration and other reactions used for manufacturing HEMs are considered. Recent advances in the field of energetic (oxygen-balanced and hypergolic) ILs are summarized. Significant attention is paid to the SCF-based micronization techniques, which improve the energetic performance of HEMs through an efficient control of the morphology and particle size distribution of the HEM fine particles, and to useful applications of SCFs in HEM processing that makes them less hazardous. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Review on Biomass Torrefaction Process and Product Properties for Energy Applications

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

Jaya Shankar Tumuluru; Shahab Sokhansanj; J. Richard Hess

2011-10-01

Torrefaction of biomass can be described as a mild form of pyrolysis at temperatures typically ranging between 200 and 300 C in an inert and reduced environment. Common biomass reactions during torrefaction include devolatilization, depolymerization, and carbonization of hemicellulose, lignin and cellulose. Torrefaction process produces a brown to black solid uniform product and also condensable (water, organics, and lipids) and non condensable gases (CO2, CO, and CH4). Typically during torrefaction, 70% of the mass is retained as a solid product, containing 90% of the initial energy content, and 30% of the lost mass is converted into condensable and non-condensable products.more » The system's energy efficiency can be improved by reintroducing the material lost during torrefaction as a source of heat. Torrefaction of biomass improves its physical properties like grindability; particle shape, size, and distribution; pelletability; and proximate and ultimate composition like moisture, carbon and hydrogen content, and calorific value. Carbon and calorific value of torrefied biomass increases by 15-25%, and moisture content reduces to <3% (w.b.). Torrefaction reduces grinding energy by about 70%, and the ground torrefied biomass has improved sphericity, particle surface area, and particle size distribution. Pelletization of torrefied biomass at temperatures of 225 C reduces specific energy consumption by two times and increases the capacity of the mill by two times. The loss of the OH group during torrefaction makes the material hydrophobic (loses the ability to attract water molecules) and more stable against chemical oxidation and microbial degradation. These improved properties make torrefied biomass particularly suitable for cofiring in power plants and as an upgraded feedstock for gasification.« less

Experimental Studies of the Effects of Anode Composition and Process Parameters on Anode Slime Adhesion and Cathode Copper Purity by Performing Copper Electrorefining in a Pilot-Scale Cell

NASA Astrophysics Data System (ADS)

Zeng, Weizhi; Wang, Shijie; Free, Michael L.

2016-10-01

Copper electrorefining tests were conducted in a pilot-scale cell under commercial tankhouse environment to study the effects of anode compositions, current density, cathode blank width, and flow rate on anode slime behavior and cathode copper purity. Three different types of anodes (high, mid, and low impurity levels) were used in the tests and were analyzed under SEM/EDS. The harvested copper cathodes were weighed and analyzed for impurities concentrations using DC Arc. The adhered slimes and released slimes were collected, weighed, and analyzed for compositions using ICP. It was shown that the lead-to-arsenic ratio in the anodes affects the sintering and coalescence of slime particles. High current density condition can improve anode slime adhesion and cathode purity by intensifying slime particles' coalescence and dissolving part of the particles. Wide cathode blanks can raise the anodic current densities significantly and result in massive release of large slime particle aggregates, which are not likely to contaminate the cathode copper. Low flow rate can cause anode passivation and increase local temperatures in front of the anode, which leads to very intense sintering and coalescence of slime particles. The results and analyses of the tests present potential solutions for industrial copper electrorefining process.

Effects of irradiation intensity and pH on nutrients release and solids destruction of waste activated sludge using the microwave-enhanced advanced oxidation process.

PubMed

Chan, W I; Liao, P H; Lo, K V

2010-11-01

Using the microwave-enhanced advanced oxidation process (MW/H2O2-AOP), the pH and irradiation intensity on waste activated sludge samples were investigated to provide insight to the athermal effects on nutrients release, solids destruction, particle size distribution and dewaterability, and to demonstrate their interrelationships. Carbonaceous matters and nutrients released into solution depended on the irradiation intensity and time. Higher irradiation levels tended to be more effective in the solubilization of nutrients and had more pronounced effects in the dewaterability of sludge. In terms of particle size distribution, detectable particles increased in size for treatments in acidic conditions, while the dewaterability of treated sludge was improved. In treatments under neutral and alkaline conditions, the particle size range increased, with more small particles formed, thereby significantly deteriorating the dewaterability of sludge treated in alkaline conditions. The best results for the solubilization of nutrients were in alkaline conditions with high irradiation power, but dewaterability of the sludge was compromised. Sludge treatment with the MW/H2O2-AOP in acidic conditions with high irradiation power yielded the best dewaterable sludge and significant nutrient solubilization; therefore, it is the recommended treatment condition for activated sludge.

Plackett-Burman experimental design for bacterial cellulose-silica composites synthesis.

PubMed

Guzun, Anicuta Stoica; Stroescu, Marta; Jinga, Sorin Ion; Voicu, Georgeta; Grumezescu, Alexandru Mihai; Holban, Alina Maria

2014-09-01

Bacterial cellulose-silica hybrid composites were prepared starting from wet bacterial cellulose (BC) membranes using Stöber reaction. The structure and surface morphology of hybrid composites were examined by FTIR and SEM. The SEM pictures revealed that the silica particles are attached to BC fibrils and are well dispersed in the BC matrix. The influence of silica particles upon BC crystallinity was studied using XRD analysis. Thermogravimetric (TG) analysis showed that the composites are stable up to 300°C. A Plackett-Burman design was applied in order to investigate the influence of process parameters upon silica particle sizes and silica content of BC-silica composites. The statistical model predicted that it is possible for silica particles size to vary the synthesis parameters in order to obtain silica particles deposed on BC membranes in the range from 34.5 to 500 nm, the significant parameters being ammonia concentration, reaction time and temperature. The silica content also varies depending on process parameters, the statistical model predicting that the most influential parameters are water-tetraethoxysilane (TEOS) ratio and reaction temperature. The antimicrobial behavior on Staphylococcus aureus of BC-silica composites functionalized with usnic acid (UA) was also studied, in order to create improved surfaces with antiadherence and anti-biofilm properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Simulating coupled dynamics of a rigid-flexible multibody system and compressible fluid

NASA Astrophysics Data System (ADS)

Hu, Wei; Tian, Qiang; Hu, HaiYan

2018-04-01

As a subsequent work of previous studies of authors, a new parallel computation approach is proposed to simulate the coupled dynamics of a rigid-flexible multibody system and compressible fluid. In this approach, the smoothed particle hydrodynamics (SPH) method is used to model the compressible fluid, the natural coordinate formulation (NCF) and absolute nodal coordinate formulation (ANCF) are used to model the rigid and flexible bodies, respectively. In order to model the compressible fluid properly and efficiently via SPH method, three measures are taken as follows. The first is to use the Riemann solver to cope with the fluid compressibility, the second is to define virtual particles of SPH to model the dynamic interaction between the fluid and the multibody system, and the third is to impose the boundary conditions of periodical inflow and outflow to reduce the number of SPH particles involved in the computation process. Afterwards, a parallel computation strategy is proposed based on the graphics processing unit (GPU) to detect the neighboring SPH particles and to solve the dynamic equations of SPH particles in order to improve the computation efficiency. Meanwhile, the generalized-alpha algorithm is used to solve the dynamic equations of the multibody system. Finally, four case studies are given to validate the proposed parallel computation approach.

In-Situ Imaging of Particles during Rapid Thermite Deflagrations

NASA Astrophysics Data System (ADS)

Grapes, Michael; Reeves, Robert; Densmore, John; Fezzaa, Kamel; van Buuren, Tony; Willey, Trevor; Sullivan, Kyle

2017-06-01

The dynamic behavior of rapidly deflagrating thermites is a highly complex process involving rapid decomposition, melting, and outgassing of intermediate and/or product gases. Few experimental techniques are capable of probing these phenomena in situ due to the small length and time scales associated with the reaction. Here we use a recently developed extended burn tube test, where we initiate a small pile of thermite on the closed end of a clear acrylic tube. The length of the tube is sufficient to fully contain the reaction as it proceeds and flows entrained particles down the tube. This experiment was brought to the Advanced Photon Source, and the particle formation was X-ray imaged at various positions down the tube. Several formulations, as well as formulation parameters were varied to investigate the size and morphology of the particles, as well as to look for dynamic behavior attributed to the reaction. In all cases, we see evidence of particle coalescence and condensed-phase interfacial reactions. The results improve our understanding of the procession of reactants to products in these systems. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-691140.

Interphase and particle dispersion correlations in polymer nanocomposites

NASA Astrophysics Data System (ADS)

Senses, Erkan

Particle dispersion in polymer matrices is a major parameter governing the mechanical performance of polymer nanocomposites. Controlling particle dispersion and understanding aging of composites under large shear and temperature variations determine the processing conditions and lifetime of composites which are very important for diverse applications in biomedicine, highly reinforced materials and more importantly for the polymer composites with adaptive mechanical responses. This thesis investigates the role of interphase layers between particles and polymer matrices in two bulk systems where particle dispersion is altered upon deformation in repulsive composites, and good-dispersion of particles is retained after multiple oscillatory shearing and aging cycles in attractive composites. We demonstrate that chain desorption and re-adsorption processes in attractive composites under shear can effectively enhance the bulk microscopic mechanical properties, and long chains of adsorbed layers lead to a denser entangled interphase layer. We further designed experiments where particles are physically adsorbed with bimodal lengths of homopolymer chains to underpin the entanglement effect in interphases. Bimodal adsorbed chains are shown to improve the interfacial strength and used to modulate the elastic properties of composites without changing the particle loading, dispersion state or polymer conformation. Finally, the role of dynamic asymmetry (different mobilities in polymer blends) and chemical heterogeneity in the interphase layer are explored in systems of poly(methyl methacrylate) adsorbed silica nanoparticles dispersed in poly(ethylene oxide) matrix. Such nanocomposites are shown to exhibit unique thermal-stiffening behavior at temperatures above glass transitions of both polymers. These interesting findings suggest that the mobility of the surface-bound polymer is essential for reinforcement in polymer nanocomposites, contrary to existing glassy layer theories for polymers on attractive particle surfaces. The shown thermally-induced stiffening behavior is reversible and makes this interfacial mechanism highly attractive in developing new active, remotely controllable engineered materials from non-responsive components.

Influence of membrane material on the production of colloidal emulsions by premix membrane emulsification.

PubMed

Gehrmann, Sandra; Bunjes, Heike

2018-05-01

Premix membrane emulsification is a possibility to produce colloidal emulsions as carrier systems for poorly water soluble drugs. During the extrusion of a coarse pre-emulsion through a porous membrane, the emulsion droplets are disrupted into smaller droplets. The influence of the membrane material on the emulsification success was investigated in dependence on the emulsifier. Premixed medium chain triglyceride (MCT) emulsions stabilized with five different emulsifiers were extruded through seven different hydrophilic polymeric membrane materials with pore sizes of 200nm. The resulting emulsions differed strongly in particle size and particle size distribution with a range of median particle sizes between 0.08μm and 11μm. The particle size of the emulsions did not depend mainly on the structure or thickness of the membrane but on the combination of emulsifier and membrane material. Contact angle measurements indicated that the wetting of the membrane with the continuous phase of the emulsion was decisive for achieving emulsions with colloidal particle sizes. The type of dispersed phase was of minor importance as basically the same results were obtained with peanut oil instead of MCT. To prove the assumption that only sufficiently hydrophilic membrane materials led to emulsions with colloidal particle sizes, two membrane materials were hydrophilized by plasma treatment. After hydrophilization, the emulsifying process led to emulsions with smaller particle sizes. The use of an alumina membrane (Anodisc®) improved the process even more. With this type of membrane, emulsions with a median particle size below 250nm and a narrow particle size distribution could be obtained with all investigated emulsifiers. Copyright © 2016 Elsevier B.V. All rights reserved.

A New Role of Fine Excipient Materials in Carrier-Based Dry Powder Inhalation Mixtures: Effect on Deagglomeration of Drug Particles During Mixing Revealed.

PubMed

Shalash, Ahmed O; Elsayed, Mustafa M A

2017-11-01

The potential of fine excipient materials to improve the performance of carrier-based dry powder inhalation mixtures is well acknowledged. The mechanisms underlying this potential are, however, open to question till date. Elaborate understanding of these mechanisms is a requisite for rational rather than empirical development of ternary dry powder inhalation mixtures. While effects of fine excipient materials on drug adhesion to and detachment from surfaces of carrier particle have been extensively investigated, effects on other processes, such as carrier-drug mixing, capsule/blister/device filling, or aerosolization in inhaler devices, have received little attention. We investigated the influence of fine excipient materials on the outcome of the carrier-drug mixing process. We studied the dispersibility of micronized fluticasone propionate particles after mixing with α-lactose monohydrate blends comprising different fine particle concentrations. Increasing the fine (D < 10.0 μm) excipient fraction from 1.84 to 8.70% v/v increased the respirable drug fraction in the excipient-drug mixture from 56.42 to 67.80% v/v (p < 0.05). The results suggest that low concentrations of fine excipient particles bind to active sites on and fill deep crevices in coarse carrier particles. As the concentration of fine excipient particles increases beyond that saturating active sites, they fill the spaces between and adhere to the surfaces of coarse carrier particles, creating projections and micropores. They thereby promote deagglomeration of drug particles during carrier-drug mixing. The findings pave the way for a comprehensive understanding of contributions of fine excipient materials to the performance of carrier-based dry powder inhalation mixtures.

Improving particle filters in rainfall-runoff models: application of the resample-move step and development of the ensemble Gaussian particle filter

NASA Astrophysics Data System (ADS)

Plaza Guingla, D. A.; Pauwels, V. R.; De Lannoy, G. J.; Matgen, P.; Giustarini, L.; De Keyser, R.

2012-12-01

The objective of this work is to analyze the improvement in the performance of the particle filter by including a resample-move step or by using a modified Gaussian particle filter. Specifically, the standard particle filter structure is altered by the inclusion of the Markov chain Monte Carlo move step. The second choice adopted in this study uses the moments of an ensemble Kalman filter analysis to define the importance density function within the Gaussian particle filter structure. Both variants of the standard particle filter are used in the assimilation of densely sampled discharge records into a conceptual rainfall-runoff model. In order to quantify the obtained improvement, discharge root mean square errors are compared for different particle filters, as well as for the ensemble Kalman filter. First, a synthetic experiment is carried out. The results indicate that the performance of the standard particle filter can be improved by the inclusion of the resample-move step, but its effectiveness is limited to situations with limited particle impoverishment. The results also show that the modified Gaussian particle filter outperforms the rest of the filters. Second, a real experiment is carried out in order to validate the findings from the synthetic experiment. The addition of the resample-move step does not show a considerable improvement due to performance limitations in the standard particle filter with real data. On the other hand, when an optimal importance density function is used in the Gaussian particle filter, the results show a considerably improved performance of the particle filter.

Composition and mixing states of brown haze particle over the Himalayas along two transboundary south-north transects

NASA Astrophysics Data System (ADS)

Dong, Zhiwen; Kang, Shichang; Guo, Junming; Zhang, Qianggong; Wang, Xuejia; Qin, Dahe

2017-05-01

Pollutants that are usually transported from southern Asia to the Tibetan Plateau deposit on the Plateau surface, change snow albedo and thereby surface radiative flux. This results numerous climatic implications like as erratic monsoon, perturbation in hydrological cycle, etc. However, the accurate estimation of these climatic implications is not well understood, because the atmospheric pollution is a heterogeneous mixture of various particle types. Therefore, this part of climate research requires a detailed investigation of physical and chemical properties of atmospheric pollutants. This study aimed to examine the physical and chemical properties of atmospheric pollutants across the Himalayan regions along two transboundary south-north transects. The information of individual-particles was obtained using microscopy-based techniques that comprises transmission electron microscope (TEM) and Energy-dispersive X-ray spectrometer (EDX). Study capture the signatures of various types of atmospheric species such as black carbon (BC), mineral dust, fly ash, organic matter, sulfate, nitrite, ammonium, and NaCl. Microscopy-based techniques confirm that these particles were generally in mixing state, for example salt-coated particles accounting for 25-56% of the total particles in sampled locations. Our analysis shows that urban and rural locations are characterized with atmospheric particles which sourced from anthropogenic activities, whereas remote locations with those released from natural crustal. However, the relative contributions of anthropogenic particles were higher than that of particles released from natural crustal. The presence of such particles over remote locations of Himalayan region provides an evidence of prevailing atmospheric transport processes, which further need to be well understood. It is expected that this work would be helpful in understanding the regional atmospheric conditions and the transboundary transport process of haze particles. As these informations are of great importance in modeling studies, which further lead to improve understanding of haze particles climate effects.

Accelerating population balance-Monte Carlo simulation for coagulation dynamics from the Markov jump model, stochastic algorithm and GPU parallel computing

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

Xu, Zuwei; Zhao, Haibo, E-mail: klinsmannzhb@163.com; Zheng, Chuguang

2015-01-15

This paper proposes a comprehensive framework for accelerating population balance-Monte Carlo (PBMC) simulation of particle coagulation dynamics. By combining Markov jump model, weighted majorant kernel and GPU (graphics processing unit) parallel computing, a significant gain in computational efficiency is achieved. The Markov jump model constructs a coagulation-rule matrix of differentially-weighted simulation particles, so as to capture the time evolution of particle size distribution with low statistical noise over the full size range and as far as possible to reduce the number of time loopings. Here three coagulation rules are highlighted and it is found that constructing appropriate coagulation rule providesmore » a route to attain the compromise between accuracy and cost of PBMC methods. Further, in order to avoid double looping over all simulation particles when considering the two-particle events (typically, particle coagulation), the weighted majorant kernel is introduced to estimate the maximum coagulation rates being used for acceptance–rejection processes by single-looping over all particles, and meanwhile the mean time-step of coagulation event is estimated by summing the coagulation kernels of rejected and accepted particle pairs. The computational load of these fast differentially-weighted PBMC simulations (based on the Markov jump model) is reduced greatly to be proportional to the number of simulation particles in a zero-dimensional system (single cell). Finally, for a spatially inhomogeneous multi-dimensional (multi-cell) simulation, the proposed fast PBMC is performed in each cell, and multiple cells are parallel processed by multi-cores on a GPU that can implement the massively threaded data-parallel tasks to obtain remarkable speedup ratio (comparing with CPU computation, the speedup ratio of GPU parallel computing is as high as 200 in a case of 100 cells with 10 000 simulation particles per cell). These accelerating approaches of PBMC are demonstrated in a physically realistic Brownian coagulation case. The computational accuracy is validated with benchmark solution of discrete-sectional method. The simulation results show that the comprehensive approach can attain very favorable improvement in cost without sacrificing computational accuracy.« less

Impact of aromatic concentration in marine fuels on particle emissions

NASA Astrophysics Data System (ADS)

Zetterdahl, Maria; Salo, Kent; Fridell, Erik; Sjöblom, Jonas

2017-09-01

The fuel sulfur content in marine fuels has been regulated in Sulfur Emission Control Areas (SECAs) since January 2015. However, other fuel characteristics are also believed to have an impact on particle emissions, particularly on the number of particles emitted. This study investigates the impact of the content of aromatics in fuel. To achieve fuel blends with concentrations of aromatics similar to those found in marine fuel oils, i.e. 20%-30% by volume (%vol.), normal diesel oil (4%-5% vol. aromatics) is doped with a mixture of aromatics. Emission measurements are conducted in test-bed engine facilities and particle emissions over a wide size range are analyzed. Results show a decreased number of particles emitted (or not change) with an increase in the aromatic concentration in fuel. This is because there is a reduction in the cetane number of the fuel with an increased aromatic content, which effects the combustion process and results in decreased particle formation. However, when ignition improver is used to increase the cetane number, particle emissions remain at a lower level than for normal diesel oil; thereby emphasizing the presence of other factors in the formation of particles.

Three-Dimensional Stereoscopic Tracking Velocimetry and Experimental/Numerical Comparison of Directional Solidification

NASA Technical Reports Server (NTRS)

Lee, David; Ge, Yi; Cha, Soyoung Stephen; Ramachandran, Narayanan; Rose, M. Franklin (Technical Monitor)

2001-01-01

Measurement of three-dimensional (3-D) three-component velocity fields is of great importance in both ground and space experiments for understanding materials processing and fluid physics. The experiments in these fields most likely inhibit the application of conventional planar probes for observing 3-D phenomena. Here, we present the investigation results of stereoscopic tracking velocimetry (STV) for measuring 3-D velocity fields, which include diagnostic technology development, experimental velocity measurement, and comparison with analytical and numerical computation. STV is advantageous in system simplicity for building compact hardware and in software efficiency for continual near-real-time monitoring. It has great freedom in illuminating and observing volumetric fields from arbitrary directions. STV is based on stereoscopic observation of particles-Seeded in a flow by CCD sensors. In the approach, part of the individual particle images that provide data points is likely to be lost or cause errors when their images overlap and crisscross each other especially under a high particle density. In order to maximize the valid recovery of data points, neural networks are implemented for these two important processes. For the step of particle overlap decomposition, the back propagation neural network is utilized because of its ability in pattern recognition with pertinent particle image feature parameters. For the step of particle tracking, the Hopfield neural network is employed to find appropriate particle tracks based on global optimization. Our investigation indicates that the neural networks are very efficient and useful for stereoscopically tracking particles. As an initial assessment of the diagnostic technology performance, laminar water jets with and without pulsation are measured. The jet tip velocity profiles are in good agreement with analytical predictions. Finally, for testing in material processing applications, a simple directional solidification apparatus is built for experimenting with a metal analog of succinonitrile. Its 3-D velocity field at the liquid phase is then measured to be compared with those from numerical computation. Our theoretical, numerical, and experimental investigations have proven STV to be a viable candidate for reliably measuring 3-D flow velocities. With current activities are focused on further improving the processing efficiency, overall accuracy, and automation, the eventual efforts of broad experimental applications and concurrent numerical modeling validation will be vital to many areas in fluid flow and materials processing.

Control of the plume induced during high-power fiber laser welding with a transverse arc

NASA Astrophysics Data System (ADS)

Wu, Shikai; Zou, Jianglin; Xiao, Rongshi; Li, Fei

2015-04-01

In this letter, the addition of the transverse arc into high-power fiber welding is proposed. The effects of the transverse arc on the laser-induced plume, the morphology of the weld, and the stability of the welding process are investigated. The experimental results indicate that, by introducing the transverse arc, the slender plume disappears, the temperature of the plasma plume increases then decreases with the rise in height, the weld width is reduced by around 42%, and the weld depth and the melting area are enhanced by about 28 and 12%, respectively. Moreover, the stability of the welding process is improved remarkably. As concluded from further analysis, the Mie scattering of the incident laser, induced by the particles in the plume, is responsible for the adverse effects induced by the plume. With the addition of the transverse arc, the particles in the plume are gasified and, thus, do not impact the energy transmission of the fiber laser. Consequently, the adverse effects induced by the plume can be significantly suppressed while the laser energy utilization efficiency and the stability of the welding process are improved.

Studies on Microstructure and Thermoelectric Properties of p-Type Bi-Sb-Te Based Alloys by Gas Atomization and Hot Extrusion Processes

NASA Astrophysics Data System (ADS)

Park, Ki-Chan; Madavali, Babu; Kim, Eun-Bin; Koo, Kyung-Wan; Hong, Soon-Jik

2017-05-01

p-Type Bi2Te3 + 75% Sb2Te3 based thermoelectric materials were fabricated via gas atomization and the hot extrusion process. The gas atomized powder showed a clean surface with a spherical shape, and expanded in a wide particle size distribution (average particle size 50 μm). The phase of the fabricated extruded and R-extruded bars was identified using x-ray diffraction. The relative densities of both the extruded and R-extruded samples were measured by Archimedes principle with ˜98% relative density. The R-extruded bar exhibited finer grain microstructure than that of single extrusion process, which was attributed to a recrystallization mechanism during the fabrication. The R-extruded sample showed improved Vickers hardness compared to the extruded sample due to its fine grain microstructure. The electrical conductivity improved for the extruded sample whereas the Seebeck coefficient decreases due to its high carrier concentration. The peak power factor, ˜4.26 × 10-3 w/mK2 was obtained for the single extrusion sample, which is higher than the R-extrusion sample owing to its high electrical properties.

Enhancement of the recycling of waste Ni-Cd and Ni-MH batteries by mechanical treatment.

PubMed

Huang, Kui; Li, Jia; Xu, Zhenming

2011-06-01

A serious environmental problem was presented by waste batteries resulting from lack of relevant regulations and effective recycling technologies in China. The present work considered the enhancement of waste Ni-Cd and Ni-MH batteries recycling by mechanical treatment. In the process of characterization, two types of waste batteries (Ni-Cd and Ni-MH batteries) were selected and their components were characterized in relation to their elemental chemical compositions. In the process of mechanical separation and recycling, waste Ni-Cd and Ni-MH batteries were processed by a recycling technology without a negative impact on the environment. The technology contained mechanical crushing, size classification, gravity separation, and magnetic separation. The results obtained demonstrated that: (1) Mechanical crushing was an effective process to strip the metallic parts from separators and pastes. High liberation efficiency of the metallic parts from separators and pastes was attained in the crushing process until the fractions reached particle sizes smaller than 2mm. (2) The classified materials mainly consisted of the fractions with the size of particles between 0.5 and 2mm after size classification. (3) The metallic concentrates of the samples were improved from around 75% to 90% by gravity separation. More than 90% of the metallic materials were separated into heavy fractions when the particle sizes were larger than 0.5mm. (4) The size of particles between 0.5 and 2mm and the rotational speed of the separator between 30 and 60 rpm were suitable for magnetic separation during industrial application, with the recycling efficiency exceeding 95%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Development of a real-time PCR protocol for the species origin confirmation of isolated animal particles detected by NIRM.

PubMed

Fumière, O; Marien, A; Fernández Pierna, J A; Baeten, V; Berben, G

2010-08-01

At present, European legislation prohibits totally the use of processed animal proteins in feed for all farmed animals (Commission Regulation (EC) No. 1234/2003-extended feed ban). A softening of the feed ban for non-ruminants would nevertheless be considered if alternative methods could be used to gain more information concerning the species origin of processed animal proteins than that which can be provided by classical optical microscopy. This would allow control provisions such as the ban of feeding animals with proteins from the same species or intra-species recycling (Regulation (EC) No. 1774/2002). Two promising alternative methods, near-infrared microscopy (NIRM) and real-time polymerase chain reaction (PCR), were combined to authenticate, at the species level, the presence of animal particles. The paper describes the improvements of the real-time PCR method made to the DNA extraction protocol, allowing five PCR analyses to be performed with the DNA extracted from a single particle.

Improved silicon nitride for advanced heat engines

NASA Technical Reports Server (NTRS)

Yeh, H. C.; Wimmer, J. M.; Huang, H. H.; Rorabaugh, M. E.; Schienle, J.; Styhr, K. H.

1985-01-01

The AiResearch Casting Company baseline silicon nitride (92 percent GTE SN-502 Si sub 3 N sub 4 plus 6 percent Y sub 2 O sub 3 plus 2 percent Al sub 2 O sub 3) was characterized with methods that included chemical analysis, oxygen content determination, electrophoresis, particle size distribution analysis, surface area determination, and analysis of the degree of agglomeration and maximum particle size of elutriated powder. Test bars were injection molded and processed through sintering at 0.68 MPa (100 psi) of nitrogen. The as-sintered test bars were evaluated by X-ray phase analysis, room and elevated temperature modulus of rupture strength, Weibull modulus, stress rupture, strength after oxidation, fracture origins, microstructure, and density from quantities of samples sufficiently large to generate statistically valid results. A series of small test matrices were conducted to study the effects and interactions of processing parameters which included raw materials, binder systems, binder removal cycles, injection molding temperatures, particle size distribution, sintering additives, and sintering cycle parameters.

Temperature-Switchable Agglomeration of Magnetic Particles Designed for Continuous Separation Processes in Biotechnology.

PubMed

Paulus, Anja S; Heinzler, Raphael; Ooi, Huey Wen; Franzreb, Matthias

2015-07-08

The purpose of this work was the synthesis and characterization of thermally switchable magnetic particles for use in biotechnological applications such as protein purification and enzymatic conversions. Reversible addition-fragmentation chain-transfer polymerization was employed to synthesize poly(N-isopropylacrylamide) brushes via a "graft-from" approach on the surface of magnetic microparticles. The resulting particles were characterized by infrared spectroscopy and thermogravimetric analysis and their temperature-dependent agglomeration behavior was assessed. The influence of several factors on particle agglomeration (pH, temperature, salt type, and particle concentration) was evaluated. The results showed that a low pH value (pH 3-4), a kosmotropic salt (ammonium sulfate), and a high particle concentration (4 g/L) resulted in improved agglomeration at elevated temperature (40 °C). Recycling of particles and reversibility of the temperature-switchable agglomeration were successfully demonstrated for ten heating-cooling cycles. Additionally, enhanced magnetic separation was observed for the modified particles. Ionic monomers were integrated into the polymer chain to create end-group functionalized particles as well as two- and three-block copolymer particles for protein binding. The adsorption of lactoferrin, bovine serum albumin, and lysozyme to these ion exchange particles was evaluated and showed a binding capacity of up to 135 mg/g. The dual-responsive particles combined magnetic and thermoresponsive properties for switchable agglomeration, easy separability, and efficient protein adsorption.

Visualization assisted by parallel processing

NASA Astrophysics Data System (ADS)

Lange, B.; Rey, H.; Vasques, X.; Puech, W.; Rodriguez, N.

2011-01-01

This paper discusses the experimental results of our visualization model for data extracted from sensors. The objective of this paper is to find a computationally efficient method to produce a real time rendering visualization for a large amount of data. We develop visualization method to monitor temperature variance of a data center. Sensors are placed on three layers and do not cover all the room. We use particle paradigm to interpolate data sensors. Particles model the "space" of the room. In this work we use a partition of the particle set, using two mathematical methods: Delaunay triangulation and Voronoý cells. Avis and Bhattacharya present these two algorithms in. Particles provide information on the room temperature at different coordinates over time. To locate and update particles data we define a computational cost function. To solve this function in an efficient way, we use a client server paradigm. Server computes data and client display this data on different kind of hardware. This paper is organized as follows. The first part presents related algorithm used to visualize large flow of data. The second part presents different platforms and methods used, which was evaluated in order to determine the better solution for the task proposed. The benchmark use the computational cost of our algorithm that formed based on located particles compared to sensors and on update of particles value. The benchmark was done on a personal computer using CPU, multi core programming, GPU programming and hybrid GPU/CPU. GPU programming method is growing in the research field; this method allows getting a real time rendering instates of a precompute rendering. For improving our results, we compute our algorithm on a High Performance Computing (HPC), this benchmark was used to improve multi-core method. HPC is commonly used in data visualization (astronomy, physic, etc) for improving the rendering and getting real-time.

Cermets from molten metal infiltration processing

DOEpatents

Landingham, Richard Lee

2012-09-18

New cermets with improved properties and applications are provided. These new cermets have lower density and/or higher hardness than B4C cermet. By incorporating other new ceramics into B4C powders or as a substitute for B4C, lower densities and/or higher hardness cermets result. The ceramic powders have much finer particle size than those previously used which significantly reduces grain size of the cermet microstructure and improves the cermet properties.

Cermets from molten metal infiltration processing

DOEpatents

Landingham, Richard L.

2013-09-10

New cermets with improved properties and applications are provided. These new cermets have lower density and/or higher hardness than B4C cermet. By incorporating other new ceramics into B4C powders or as a substitute for B4C, lower densities and/or higher hardness cermets result. The ceramic powders have much finer particle size than those previously used which significantly reduces grain size of the cermet microstructure and improves the cermet properties.

Application of aqueous two-phase micellar system to improve extraction of adenoviral particles from cell lysate.

PubMed

Molino, João Vitor Dutra; Lopes, André Moreni; Viana Marques, Daniela de Araújo; Mazzola, Priscila Gava; da Silva, Joas Lucas; Hirata, Mario Hiroyuki; Hirata, Rosário Dominguez Crespo; Gatti, Maria Silvia Viccari; Pessoa, Adalberto

2017-12-04

Viral vectors are important in medical approaches, such as disease prevention and gene therapy, and their production depends on efficient prepurification steps. In the present study, an aqueous two-phase micellar system (ATPMS) was evaluated to extract human adenovirus type 5 particles from a cell lysate. Adenovirus was cultured in human embryonic kidney 293 (HEK-293) cells to a concentration of 1.4 × 10 10 particles/mL. Cells were lysed, and the system formed by direct addition of Triton X-114 in a 2 3 full factorial design with center points. The systems were formed with Triton X-114 at a final concentration of 1.0, 6.0, and 11.0% (w/w), cell lysate pH of 6.0, 6.5, and 7.0, and incubation temperatures at 33, 35, and 37 °C. Adenovirus particles recovered from partition phases were measured by qPCR. The best system condition was with 11.0% (w/w) of Triton X-114, a cell lysate pH of 7.0, and an incubation temperature at 33 °C, yielding 3.51 × 10 10 adenovirus particles/mL, which increased the initial adenovirus particles concentration by 2.3-fold, purifying it by 2.2-fold from the cell lysate, and removing cell debris. In conclusion, these results demonstrated that the use of an aqueous two-phase micellar system in the early steps of downstream processing could improve viral particle extraction from cultured cells while integrating clarification, concentration, and prepurification steps. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

New Photocatalysis for Effective Degradation of Organic Pollutants in Water

NASA Astrophysics Data System (ADS)

Zarei Chaleshtori, M.; Saupe, G. B.; Masoud, S.

2009-12-01

The presence of harmful compounds in water supplies and in the discharge of wastewater from chemical industries, power plants, and agricultural sources is a topic of global concern. The processes and technologies available at the present time for the treatment of polluted water are varied that include traditional water treatment processes such as biological, thermal and chemical treatment. All these water treatment processes, have limitations of their own and none is cost effective. Advanced oxidation processes have been proposed as an alternative for the treatment of this kind of wastewater. Heterogeneous photocatalysis has recently emerged as an efficient method for purifying water. TiO2 has generally been demonstrated to be the most active semiconductor material for decontamination water. One significant factor is the cost of separation TiO2, which is generally a powder having a very small particle size from the water after treatment by either sedimentation or ultrafiltration. The new photocatalyst, HTiNbO5, has been tested to determine whether its photocatalytic efficiency is good enough for use in photocatalytic water purification since it has high surface area and relatively large particle size. The larger particle sizes of the porous materials facilitate catalyst removal from a solution, after purification has taken place. It can be separated from water easily than TiO2, a significant technical improvement that might eliminate the tedious final filtration necessary with a slurry. These materials are characterized and tested as water decontamination photocatalysts. The new catalyst exhibited excellent catalytic activity, but with a strong pH dependence on the photo efficiency. These results suggest that elimination of the ion exchange character of the catalyst may greatly improve its performance at various pHs. This new research proposes to study the effects of a topotactic dehydration reaction on these new porous material catalysts.

A novel method for isolation and recovery of ceramic nanoparticles and metal wear debris from serum lubricants at ultra-low wear rates.

PubMed

Lal, S; Hall, R M; Tipper, J L

2016-09-15

Ceramics have been used to deliver significant improvements in the wear properties of orthopaedic bearing materials, which has made it challenging to isolate wear debris from simulator lubricants. Ceramics such as silicon nitride, as well as ceramic-like surface coatings on metal substrates have been explored as potential alternatives to conventional implant materials. Current isolation methods were designed for isolating conventional metal, UHMWPE and ceramic wear debris. In this paper, we describe a methodology for isolation and recovery of ceramic or ceramic-like coating particles and metal wear particles from serum lubricants under ultra-low and low wear performance. Enzymatic digestion was used to digest the serum proteins and sodium polytungstate was used as a novel density gradient medium to isolate particles from proteins and other contaminants by ultracentrifugation. This method demonstrated over 80% recovery of particles and did not alter the size or morphology of ceramic and metal particles during the isolation process. Improvements in resistance to wear and mechanical damage of the articulating surfaces have a large influence on longevity and reliability of joint replacement devices. Modern ceramics have demonstrated ultra-low wear rates for hard-on-hard total hip replacements. Generation of very low concentrations of wear debris in simulator lubricants has made it challenging to isolate the particles for characterisation and further analysis. We have introduced a novel method to isolate ceramic and metal particles from serum-based lubricants using enzymatic digestion and novel sodium polytungstate gradients. This is the first study to demonstrate the recovery of ceramic and metal particles from serum lubricants at lowest detectable in vitro wear rates reported in literature. Copyright © 2016. Published by Elsevier Ltd.

How small bugs tie down big rocks: Measuring and modeling the forces acting between nets spun by Caddisfly larvae (Hydropsychidae) and gravel particles at the onset of motion

NASA Astrophysics Data System (ADS)

Mclaughlin, M. K.; Tumolo, B.; Sklar, L. S.; Albertson, L.; Daniels, M.

2017-12-01

The influence of life on geomorphic processes is commonly inferred from correlations between the size and abundance of individual organisms and the change in process thresholds and rates from abiotic conditions. However, to understand and model the underlying mechanisms, it is helpful to make direct measurements of the forces acting between organisms and the earth materials they inhabit. For example, flume studies have found that the presence of net-spinning caddisfly larvae (Trichoptera: Hydropsychidae) can increase the shear stress required to initiate particle motion by more than a factor of two, with potentially significant implications for the timing and magnitude of bedload sediment transport in gravel-bedded rivers. To explore the underlying mechanics we conducted flume experiments at the Stroud Water Research center in Avonadale, Pennsylvania, using strain gages to measure the forces acting between caddisfly nets and sediment particles of various sizes, during the process of initial particle motion. We combine these measurements with high-speed video images to document for the first time, the three dimensional dynamics of net stretching, tearing, and detachment that govern the magnitude of the increase in critical shear stress. We are using these data and insights to substantially improve a previously published theoretical model for the mechanics of sediment stabilization by caddisfly larvae. In particular, we seek to constrain the range of particle sizes potentially stabilized by caddisfly larvae and explain mechanistically why the effect of caddisfly nets varies with particle size. These predictions have implications for understanding feedbacks between bed stabilization by caddisflies, insect density, inter-specific niche partitioning, and the movement of sediment that shapes gravel-bed channels.

Strain Rate Dependency of Bronze Metal Matrix Composite Mechanical Properties as a Function of Casting Technique

NASA Astrophysics Data System (ADS)

Brown, Lloyd; Joyce, Peter; Radice, Joshua; Gregorian, Dro; Gobble, Michael

2012-07-01

Strain rate dependency of mechanical properties of tungsten carbide (WC)-filled bronze castings fabricated by centrifugal and sedimentation-casting techniques are examined, in this study. Both casting techniques are an attempt to produce a functionally graded material with high wear resistance at a chosen surface. Potential applications of such materials include shaft bushings, electrical contact surfaces, and brake rotors. Knowledge of strain rate-dependent mechanical properties is recommended for predicting component response due to dynamic loading or impact events. A brief overview of the casting techniques for the materials considered in this study is followed by an explanation of the test matrix and testing techniques. Hardness testing, density measurement, and determination of the volume fraction of WC particles are performed throughout the castings using both image analysis and optical microscopy. The effects of particle filling on mechanical properties are first evaluated through a microhardness survey of the castings. The volume fraction of WC particles is validated using a thorough density survey and a rule-of-mixtures model. Split Hopkinson Pressure Bar (SHPB) testing of various volume fraction specimens is conducted to determine strain dependence of mechanical properties and to compare the process-property relationships between the two casting techniques. The baseline performances of C95400 bronze are provided for comparison. The results show that the addition of WC particles improves microhardness significantly for the centrifugally cast specimens, and, to a lesser extent, in the sedimentation-cast specimens, largely because the WC particles are more concentrated as a result of the centrifugal-casting process. Both metal matrix composites (MMCs) demonstrate strain rate dependency, with sedimentation casting having a greater, but variable, effects on material response. This difference is attributed to legacy effects from the casting process, namely, porosity and localized WC particle grouping.

Fast proton decay

NASA Astrophysics Data System (ADS)

Li, Tianjun; Nanopoulos, Dimitri V.; Walker, Joel W.

2010-10-01

We consider proton decay in the testable flipped SU(5)×U(1)X models with TeV-scale vector-like particles which can be realized in free fermionic string constructions and F-theory model building. We significantly improve upon the determination of light threshold effects from prior studies, and perform a fresh calculation of the second loop for the process p→eπ from the heavy gauge boson exchange. The cumulative result is comparatively fast proton decay, with a majority of the most plausible parameter space within reach of the future Hyper-Kamiokande and DUSEL experiments. Because the TeV-scale vector-like particles can be produced at the LHC, we predict a strong correlation between the most exciting particle physics experiments of the coming decade.

TRAPPED PROTON FLUXES AT LOW EARTH ORBITS MEASURED BY THE PAMELA EXPERIMENT

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

Adriani, O.; Bongi, M.; Barbarino, G. C.

2015-01-20

We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above ∼70 MeV performed by the PAMELA mission at low Earth orbits (350 ÷ 610 km). Data were analyzed in the frame of the adiabatic theory of charged particle motion in the geomagnetic field. Flux properties were investigated in detail, providing a full characterization of the particle radiation in the South Atlantic Anomaly region, including locations, energy spectra, and pitch angle distributions. PAMELA results significantly improve the description of the Earth's radiation environment at low altitudes, placing important constraints on the trapping and interaction processes, and can be usedmore » to validate current trapped particle radiation models.« less

Preparation, characterization, and application of titanium nano-tube array in dye-sensitized solar cells

PubMed Central

2012-01-01

The vertically orientated TiO2 nanotube array (TNA) decorated with TiO2 nano-particles was successfully fabricated by electrochemically anodizing titanium (Ti) foils followed by Ti-precursor post-treatment and annealing process. The TNA morphology characterized by SEM and TEM was found to be filled with TiO2 nano-particles interior and exterior of the TiO2 nano-tubes after titanium (IV) n-butoxide (TnB) treatment, whereas TiO2 nano-particles were only found inside of TiO2 nano-tubes upon titanium tetrachloride (TiCl4) treatment. The efficiency in TNA-based DSSCs was improved by both TnB and TiCl4 treatment presumably due to the increase of dye adsorption. PMID:22353282

Novel Application of Confocal Laser Scanning Microscopy and 3D Volume Rendering toward Improving the Resolution of the Fossil Record of Charcoal

PubMed Central

Belcher, Claire M.; Punyasena, Surangi W.; Sivaguru, Mayandi

2013-01-01

Variations in the abundance of fossil charcoals between rocks and sediments are assumed to reflect changes in fire activity in Earth’s past. These variations in fire activity are often considered to be in response to environmental, ecological or climatic changes. The role that fire plays in feedbacks to such changes is becoming increasingly important to understand and highlights the need to create robust estimates of variations in fossil charcoal abundance. The majority of charcoal based fire reconstructions quantify the abundance of charcoal particles and do not consider the changes in the morphology of the individual particles that may have occurred due to fragmentation as part of their transport history. We have developed a novel application of confocal laser scanning microscopy coupled to image processing that enables the 3-dimensional reconstruction of individual charcoal particles. This method is able to measure the volume of both microfossil and mesofossil charcoal particles and allows the abundance of charcoal in a sample to be expressed as total volume of charcoal. The method further measures particle surface area and shape allowing both relationships between different size and shape metrics to be analysed and full consideration of variations in particle size and size sorting between different samples to be studied. We believe application of this new imaging approach could allow significant improvement in our ability to estimate variations in past fire activity using fossil charcoals. PMID:23977267

A regularized auxiliary particle filtering approach for system state estimation and battery life prediction

NASA Astrophysics Data System (ADS)

Liu, Jie; Wang, Wilson; Ma, Fai

2011-07-01

System current state estimation (or condition monitoring) and future state prediction (or failure prognostics) constitute the core elements of condition-based maintenance programs. For complex systems whose internal state variables are either inaccessible to sensors or hard to measure under normal operational conditions, inference has to be made from indirect measurements using approaches such as Bayesian learning. In recent years, the auxiliary particle filter (APF) has gained popularity in Bayesian state estimation; the APF technique, however, has some potential limitations in real-world applications. For example, the diversity of the particles may deteriorate when the process noise is small, and the variance of the importance weights could become extremely large when the likelihood varies dramatically over the prior. To tackle these problems, a regularized auxiliary particle filter (RAPF) is developed in this paper for system state estimation and forecasting. This RAPF aims to improve the performance of the APF through two innovative steps: (1) regularize the approximating empirical density and redraw samples from a continuous distribution so as to diversify the particles; and (2) smooth out the rather diffused proposals by a rejection/resampling approach so as to improve the robustness of particle filtering. The effectiveness of the proposed RAPF technique is evaluated through simulations of a nonlinear/non-Gaussian benchmark model for state estimation. It is also implemented for a real application in the remaining useful life (RUL) prediction of lithium-ion batteries.

ELECTROSTATIC SURFACE STRUCTURES OF COAL AND MINERAL PARTICLES

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

NONE

It is the purpose of this research to study electrostatic charging mechanisms related to electrostatic beneficiation of coal with the goal of improving models of separation and the design of electrostatic separators. Areas addressed in this technical progress report are (a) electrostatic beneficiation of Pittsburgh #8 coal powders as a function of grind size and processing atmosphere; (b) the use of fluorescent micro-spheres to probe the charge distribution on the surfaces of coal particles; (c) the use of electrostatic beneficiation to recover unburned carbon from flyash; (d) the development of research instruments for investigation of charging properties of coal. Pittsburghmore » #8 powders were beneficiated as a function of grind size and under three atmosphere conditions: fresh ground in air , after 24 hours of air exposure, or under N2 atmosphere. The feed and processed powders were analyzed by a variety of methods including moisture, ash, total sulfur, and pyritic sulfur content. Mass distribution and cumulative charge of the processed powders were also measured. Fresh ground coal performed the best in electrostatic beneficiation. Results are compared with those of similar studies conducted on Pittsburgh #8 powders last year (April 1, 1997 to September 30, 1997). Polystyrene latex spheres were charged and deposited onto coal particles that had been passed through the electrostatic separator and collected onto insulating filters. The observations suggest bipolar charging of individual particles and patches of charge on the particles which may be associated with particular maceral types or with mineral inclusions. A preliminary investigation was performed on eletrostatic separation of unburned carbon particles from flyash. Approximately 25% of the flyash acquired positive charge in the copper tribocharger. This compares with 75% of fresh ground coal. The negatively charged material had a slightly reduced ash content suggesting some enrichment of carbonaceous material. There was also evidence that the carbon is present at a higher ratio in larger particles than in small particles. An ultraviolet photoelectron counter for use in ambient atmosphere is nearing completion. The counter will be used to measure work functions of different maceral and mineral types in the coal matrix. A Particle Image Analyzer for measuring size and charge of airborne particles is also under contruction and its current status is presented. A charged, monodisperse, droplet generator is also being constructed for calibration of the Particle Image Analyzer and other airborne particle analyzers in our labs.« less

Numerical simulations of regolith sampling processes

NASA Astrophysics Data System (ADS)

Schäfer, Christoph M.; Scherrer, Samuel; Buchwald, Robert; Maindl, Thomas I.; Speith, Roland; Kley, Wilhelm

2017-07-01

We present recent improvements in the simulation of regolith sampling processes in microgravity using the numerical particle method smooth particle hydrodynamics (SPH). We use an elastic-plastic soil constitutive model for large deformation and failure flows for dynamical behaviour of regolith. In the context of projected small body (asteroid or small moons) sample return missions, we investigate the efficiency and feasibility of a particular material sampling method: Brushes sweep material from the asteroid's surface into a collecting tray. We analyze the influence of different material parameters of regolith such as cohesion and angle of internal friction on the sampling rate. Furthermore, we study the sampling process in two environments by varying the surface gravity (Earth's and Phobos') and we apply different rotation rates for the brushes. We find good agreement of our sampling simulations on Earth with experiments and provide estimations for the influence of the material properties on the collecting rate.

Pharmaceutical spray drying: solid-dose process technology platform for the 21st century.

PubMed

Snyder, Herman E

2012-07-01

Requirement for precise control of solid-dosage particle properties created with a scalable process technology are continuing to expand in the pharmaceutical industry. Alternate methods of drug delivery, limited active drug substance solubility and the need to improve drug product stability under room-temperature conditions are some of the pharmaceutical applications that can benefit from spray-drying technology. Used widely for decades in other industries with production rates up to several tons per hour, pharmaceutical uses for spray drying are expanding beyond excipient production and solvent removal from crystalline material. Creation of active pharmaceutical-ingredient particles with combinations of unique target properties are now more common. This review of spray-drying technology fundamentals provides a brief perspective on the internal process 'mechanics', which combine with both the liquid and solid properties of a formulation to enable high-throughput, continuous manufacturing of precision powder properties.

Feed-Forward Neural Network Soft-Sensor Modeling of Flotation Process Based on Particle Swarm Optimization and Gravitational Search Algorithm

PubMed Central

Wang, Jie-Sheng; Han, Shuang

2015-01-01

For predicting the key technology indicators (concentrate grade and tailings recovery rate) of flotation process, a feed-forward neural network (FNN) based soft-sensor model optimized by the hybrid algorithm combining particle swarm optimization (PSO) algorithm and gravitational search algorithm (GSA) is proposed. Although GSA has better optimization capability, it has slow convergence velocity and is easy to fall into local optimum. So in this paper, the velocity vector and position vector of GSA are adjusted by PSO algorithm in order to improve its convergence speed and prediction accuracy. Finally, the proposed hybrid algorithm is adopted to optimize the parameters of FNN soft-sensor model. Simulation results show that the model has better generalization and prediction accuracy for the concentrate grade and tailings recovery rate to meet the online soft-sensor requirements of the real-time control in the flotation process. PMID:26583034

Bayesian parameter inference for stochastic biochemical network models using particle Markov chain Monte Carlo

PubMed Central

Golightly, Andrew; Wilkinson, Darren J.

2011-01-01

Computational systems biology is concerned with the development of detailed mechanistic models of biological processes. Such models are often stochastic and analytically intractable, containing uncertain parameters that must be estimated from time course data. In this article, we consider the task of inferring the parameters of a stochastic kinetic model defined as a Markov (jump) process. Inference for the parameters of complex nonlinear multivariate stochastic process models is a challenging problem, but we find here that algorithms based on particle Markov chain Monte Carlo turn out to be a very effective computationally intensive approach to the problem. Approximations to the inferential model based on stochastic differential equations (SDEs) are considered, as well as improvements to the inference scheme that exploit the SDE structure. We apply the methodology to a Lotka–Volterra system and a prokaryotic auto-regulatory network. PMID:23226583

Liquid Metal Engineering by Application of Intensive Melt Shearing

NASA Astrophysics Data System (ADS)

Patel, Jayesh; Zuo, Yubo; Fan, Zhongyun

In all casting processes, liquid metal treatment is an essential step in order to produce high quality cast products. A new liquid metal treatment technology has been developed which comprises of a rotor/stator set-up that delivers high shear rate to the liquid melt. It generates macro-flow in a volume of melt for distributive mixing and intensive shearing for dispersive mixing. The high shear device exhibits significantly enhanced kinetics for phase transformations, uniform dispersion, distribution and size reduction of solid particles and gas bubbles, improved homogenisation of chemical composition and temperature fields and also forced wetting of usually difficult-to-wet solid particles in the liquid metal. Hence, it can benefit various casting processes to produce high quality cast products with refined microstructure and enhanced mechanical properties. Here, we report an overview on the application of the new high shear technology to the processing of light metal alloys.

Process and apparatus for producing ultrafine explosive particles

DOEpatents

McGowan, Michael J.

1992-10-20

A method and an improved eductor apparatus for producing ultrafine explosive particles is disclosed. The explosive particles, which when incorporated into a binder system, have the ability to propagate in thin sheets, and have very low impact sensitivity and very high propagation sensitivity. A stream of a solution of the explosive dissolved in a solvent is thoroughly mixed with a stream of an inert nonsolvent by obtaining nonlaminar flow of the streams by applying pressure against the flow of the nonsolvent stream, to thereby diverge the stream as it contacts the explosive solution, and violently agitating the combined stream to rapidly precipitate the explosive particles from the solution in the form of generally spheroidal, ultrafine particles. The two streams are injected coaxially through continuous, concentric orifices of a nozzle into a mixing chamber. Preferably, the nonsolvent stream is injected centrally of the explosive solution stream. The explosive solution stream is injected downstream of and surrounds the nonsolvent solution stream for a substantial distance prior to being ejected into the mixing chamber.

Simultaneous Modeling of Gradual SEP Events at the Earth and the Mars

NASA Astrophysics Data System (ADS)

Hu, J.; Li, G.

2017-12-01

Solar Energetic Particles (SEP) event is the number one space hazard for spacecraft instruments and astronauts' safety. Recent studies have shown that both longitudinal and radial extent of SEP events can be very significant. In this work, we use the improved Particle Acceleration and Transport in the Heliosphere (iPATH) model to simulate gradual SEP events that have impacts upon both the Earth and the Mars. We follow the propagation of a 2D CME-driven shock. Particles are accelerated at the shock via the diffusive shock acceleration (DSA) mechanism. Transport of the escaped particles to the Earth and the Mars is then followed using a backward stochastic differential equation method. Perpendicular diffusion is considered in both the DSA and the transport process. Model results such as time intensity profile and energetic particle spectrum at the two locations are compared to understand the spatial extent of an SEP event. Observational data at the Earth and the Mars are also studied to validate the model.

Neighbour lists for smoothed particle hydrodynamics on GPUs

NASA Astrophysics Data System (ADS)

Winkler, Daniel; Rezavand, Massoud; Rauch, Wolfgang

2018-04-01

The efficient iteration of neighbouring particles is a performance critical aspect of any high performance smoothed particle hydrodynamics (SPH) solver. SPH solvers that implement a constant smoothing length generally divide the simulation domain into a uniform grid to reduce the computational complexity of the neighbour search. Based on this method, particle neighbours are either stored per grid cell or for each individual particle, denoted as Verlet list. While the latter approach has significantly higher memory requirements, it has the potential for a significant computational speedup. A theoretical comparison is performed to estimate the potential improvements of the method based on unknown hardware dependent factors. Subsequently, the computational performance of both approaches is empirically evaluated on graphics processing units. It is shown that the speedup differs significantly for different hardware, dimensionality and floating point precision. The Verlet list algorithm is implemented as an alternative to the cell linked list approach in the open-source SPH solver DualSPHysics and provided as a standalone software package.

Tailoring MCM-41 mesoporous silica particles through modified sol-gel process for gas separation

NASA Astrophysics Data System (ADS)

Sang, Wong Yean; Ching, Oh Pei

2017-10-01

Mobil Composition of Matter-41 (MCM-41) is recognized as a potential filler to enhance permeability of mixed matrix membrane (MMM). However, the required loading for available micron-sized MCM-41 was considerably high in order to achieve desired separation performance. In this work, reduced-size MCM-41 was synthesized to minimize filler loading, improve surface modification and enhance polymer-filler compatibility during membrane fabrication. The effect of reaction condition, stirring rate and type of post-synthesis washing solution used on particle diameter of resultant MCM-41 were investigated. It was found that MCM-41 produced at room temperature condition yield particles with smaller diameter, higher specific surface area and enhanced mesopore structure. Increase of stirring rate up to 500 rpm during synthesis also reduced the particle diameter. In addition, replacing water with methanol as the post-synthesis washing solution to remove bromide ions from the precipitate was able to further reduce the particle size by inhibiting polycondensation reaction.

Optimisation of powders for pulmonary delivery using supercritical fluid technology.

PubMed

Rehman, Mahboob; Shekunov, Boris Y; York, Peter; Lechuga-Ballesteros, David; Miller, Danforth P; Tan, Trixie; Colthorpe, Paul

2004-05-01

Supercritical fluid technology exploited in this work afforded single-step production of respirable particles of terbutaline sulphate (TBS). Different crystal forms of TBS were produced consistently, including two polymorphs, a stoichiometric monohydrate and amorphous material as well as particles with different degrees of crystallinity, size, and morphology. Different solid-state and surface characterisation techniques were applied in conjunction with measurements of powder flow properties using AeroFlow device and aerosol performance by Andersen Cascade Impactor tests. Improved fine particle fraction (FPF) was demonstrated for some powders produced by the SCF process when compared to the micronised material. Such enhanced flow properties and dispersion correlated well with the reduced surface energy parameters demonstrated by these powders. It is shown that semi-crystalline particles exhibited lower specific surface energy leading to a better performance in the powder flow and aerosol tests than crystalline materials. This difference of the surface and bulk crystal structure for selected powder batches is explained by the mechanism of precipitation in SCF which can lead to surface conditioning of particles produced.

Effect of cuprous oxide with different sizes on thermal and combustion behaviors of unsaturated polyester resin.

PubMed

Hou, Yanbei; Hu, Weizhao; Gui, Zhou; Hu, Yuan

2017-07-15

Cuprous oxide (Cu 2 O) as an effective catalyst has been applied to enhance the fire safety of unsaturated polyester resin (UPR), but the particle size influence on combustion behaviors has not been previously reported. Herein, the UPR/Cu 2 O composites (metal oxide particles with average particle-size of 10, 100, and 200nm) were successfully synthesized by thermosetting process. The effects of Cu 2 O with different sizes on thermostability and combustion behaviors of UPR were characterized by TGA, MCC, TG-IR, FTIR, and SSTF. The results revel that the addition of Cu 2 O contributes to sufficient decomposition of oxygen-containing compounds, which is beneficial to the release of nontoxic compounds. The smallest-sized Cu 2 O performs the excellent catalytic decomposition effect and promotes the complete combustion of UPR, which benefits the enhancement of fire safety. While the other additives retard pyrolysis process and yield more char residue, and thus the flame retardancy of UPR composites was improved. Therefore, catalysis plays a major role for smaller-sized particles during thermal decomposition of matrix, while flame retarded effect became gradual distinctly for the larger-sized additives. Copyright © 2017 Elsevier B.V. All rights reserved.

Rheological of chocolate-flavored, reduced-calories coating as a function of conching process.

PubMed

Medina-Torres, Luis; Sanchez-Olivares, Guadalupe; Nuñez-Ramirez, Diola Marina; Moreno, Leonardo; Calderas, Fausto

2014-07-01

Continuous flow and linear viscoelasticity rheology of chocolate coating is studied in this work using fat substitute gums (xanthan, GX). An alternative conching process, using a Rotor-Estator (RE) type impeller, is proposed. The objective is to obtain a chocolate coating material with improved flow properties. Characterization of the final material through particle size distribution (PSD), differential scanning calorimetry (DSC) and proximal analysis is reported. Particle size distribution of the final material showed less polydispersity and therefore, greater homogeneity; fusion points were also generated at around 20 °C assuming crystal type I (β'2) and II (α). Moreover, the final material exhibited crossover points (higher structure material), whereas the commercial brand chocolate used for comparison did not. The best conditions to produce the coating were maturing of 36 h and 35 °C, showing crossover points around 76 Pa and a 0.505 solids particle dispersion (average particle diameter of 0.364 μm), and a fusion point at 20.04 °C with a ΔHf of 1.40 (J/g). The results indicate that xanthan gum is a good substitute for cocoa butter and provides stability to the final product.

Corticosteroid microparticles produced by supercritical-assisted atomization: process optimization, product characterization, and "in vitro" performance.

PubMed

Della Porta, G; Ercolino, S F; Parente, L; Reverchon, E

2006-09-01

In this work, the production of dexametasone and dexametasone acetate microparticles is proposed using supercritical-assisted atomization (SAA). This process is based on the solubilization of supercritical carbon dioxide in a liquid solution containing the drug; then, the ternary mixture is sprayed through a nozzle and submicroparticles are formed as a consequence of the enhanced atomization. Several process parameters such as different organic solvent (methanol and acetone), solute concentration and flow rate ratio between the liquid solution and carbon dioxide are investigated; their influence is evaluated on the morphology and size of precipitated particles. Spherical corticosteroid particles with mean diameters ranging from 0.5 to 1.2 microm are produced at the optimum operating conditions and narrow particle size distributions (PSDs) have also been obtained. No drug degradation was observed after SAA processing and solvent residues of 300 and 500 ppm for acetone and methanol, respectively, were measured. Drug microparticles produced by SAA can be semi-crystalline or amorphous depending on the process condition; a micronized drug surface area ranging from about 4 to 5 m2/g was also observed. The "in vitro" activity of both untreated and SAA processed glucocorticoids was tested on the release of pro-inflammatory cytokines from stimulated cells. The results shown that SAA-glucocorticoids have retained the activity of the parent untreated compounds and, in the case of dexamethasone, SAA processing improves drug performance. (c) 2006 Wiley-Liss, Inc. and the American Pharmacists Association.

Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging.

PubMed

Pedersen, E B L; Angmo, D; Dam, H F; Thydén, K T S; Andersen, T R; Skjønsfjell, E T B; Krebs, F C; Holler, M; Diaz, A; Guizar-Sicairos, M; Breiby, D W; Andreasen, J W

2015-08-28

Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing industry, which has reduced the use of organic solvents since the 1980s. Through ptychographic X-ray computed tomography (PXCT), we image quantitatively a roll-to-roll coated photovoltaic tandem stack consisting of one bulk heterojunction active layer and one Landfester particle active layer. We extract the layered morphology with structural and density information including the porosity present in the various layers and the silver electrode with high resolution in 3D. The Landfester particle layer is found to have an undesired morphology with negatively correlated top- and bottom interfaces, wide thickness distribution and only partial surface coverage causing electric short circuits through the layer. By top coating a polymer material onto the Landfester nanoparticles we eliminate the structural defects of the layer such as porosity and roughness, and achieve the increased performance larger than 1 V expected for a tandem cell. This study highlights that quantitative imaging of weakly scattering stacked layers of organic materials has become feasible by PXCT, and that this information cannot be obtained by other methods. In the present study, this technique specifically reveals the need to improve the coatability and layer formation of Landfester nanoparticles, thus allowing improved solar cells to be produced.

Optimizing manufacturing and composition of a TLR4 nanosuspension: physicochemical stability and vaccine adjuvant activity

PubMed Central

2013-01-01

Background Nanosuspensions are an important class of delivery system for vaccine adjuvants and drugs. Previously, we developed a nanosuspension consisting of the synthetic TLR4 ligand glucopyranosyl lipid adjuvant (GLA) and dipalmitoyl phosphatidylcholine (DPPC). This nanosuspension is a clinical vaccine adjuvant known as GLA-AF. We examined the effects of DPPC supplier, buffer composition, and manufacturing process on GLA-AF physicochemical and biological activity characteristics. Results DPPC from different suppliers had minimal influence on physicochemical and biological effects. In general, buffered compositions resulted in less particle size stability compared to unbuffered GLA-AF. Microfluidization resulted in rapid particle size reduction after only a few passes, and 20,000 or 30,000 psi processing pressures were more effective at reducing particle size and recovering the active component than 10,000 psi. Sonicated and microfluidized batches maintained good particle size and chemical stability over 6 months, without significantly altering in vitro or in vivo bioactivity of GLA-AF when combined with a recombinant malaria vaccine antigen. Conclusions Microfluidization, compared to water bath sonication, may be an effective manufacturing process to improve the scalability and reproducibility of GLA-AF as it advances further in the clinical development pathway. Various sources of DPPC are suitable to manufacture GLA-AF, but buffered compositions of GLA-AF do not appear to offer stability advantages over the unbuffered composition. PMID:24359024

An evaluation of noise reduction algorithms for particle-based fluid simulations in multi-scale applications

NASA Astrophysics Data System (ADS)

Zimoń, M. J.; Prosser, R.; Emerson, D. R.; Borg, M. K.; Bray, D. J.; Grinberg, L.; Reese, J. M.

2016-11-01

Filtering of particle-based simulation data can lead to reduced computational costs and enable more efficient information transfer in multi-scale modelling. This paper compares the effectiveness of various signal processing methods to reduce numerical noise and capture the structures of nano-flow systems. In addition, a novel combination of these algorithms is introduced, showing the potential of hybrid strategies to improve further the de-noising performance for time-dependent measurements. The methods were tested on velocity and density fields, obtained from simulations performed with molecular dynamics and dissipative particle dynamics. Comparisons between the algorithms are given in terms of performance, quality of the results and sensitivity to the choice of input parameters. The results provide useful insights on strategies for the analysis of particle-based data and the reduction of computational costs in obtaining ensemble solutions.

Genetic particle swarm parallel algorithm analysis of optimization arrangement on mistuned blades

NASA Astrophysics Data System (ADS)

Zhao, Tianyu; Yuan, Huiqun; Yang, Wenjun; Sun, Huagang

2017-12-01

This article introduces a method of mistuned parameter identification which consists of static frequency testing of blades, dichotomy and finite element analysis. A lumped parameter model of an engine bladed-disc system is then set up. A bladed arrangement optimization method, namely the genetic particle swarm optimization algorithm, is presented. It consists of a discrete particle swarm optimization and a genetic algorithm. From this, the local and global search ability is introduced. CUDA-based co-evolution particle swarm optimization, using a graphics processing unit, is presented and its performance is analysed. The results show that using optimization results can reduce the amplitude and localization of the forced vibration response of a bladed-disc system, while optimization based on the CUDA framework can improve the computing speed. This method could provide support for engineering applications in terms of effectiveness and efficiency.

Improvements of the cyclone separator performance by down-comer tubes.

PubMed

Ganegama Bogodage, Sakura; Leung, A Y T

2016-07-05

Enhancement of fine particle (PM2.5) separation is important for cyclone separators to reduce any extra purification process required at the outlet. Therefore, the present experimental research was performed to explore the performance of cyclone separators modified with down-comer tubes at solid loading rates from 0 to 8.0 g/m(3) with a 10 m/s inlet velocity. The study proved the effectiveness of down-comer tubes in reducing the particle re-entrainment and increasing the finer separation with acceptable pressure drops, which was pronounced at low solid loading conditions. The experimental results were compared with theories of Smolik and Muschelknautz. Theories were acceptable for certain ranges, and theory breakdown was mainly due to the neglect of particle agglomeration, re-entrainment and the reduction of swirling energy, as well as the increase of wall friction due to presence of particles. Copyright © 2016. Published by Elsevier B.V.

Particle production at energies available at the CERN Large Hadron Collider within an evolutionary model

NASA Astrophysics Data System (ADS)

Sinyukov, Yu. M.; Shapoval, V. M.

2018-06-01

The particle yields and particle number ratios in Pb+Pb collisions at the CERN Large Hadron Collider (LHC) energy √{sN N}=2.76 TeV are described within the integrated hydrokinetic model (iHKM) at two different equations of state (EoS) for quark-gluon matter and the two corresponding hadronization temperatures T =165 MeV and T =156 MeV. The role of particle interactions at the final afterburner stage of the collision in the particle production is investigated by means of comparison of the results of full iHKM simulations with those where the annihilation and other inelastic processes (except for resonance decays) are switched off after hadronization/particlization, similarly as in the thermal models. An analysis supports the picture of continuous chemical freeze-out in the sense that the corrections to the sudden chemical freeze-out results, which arise because of the inelastic reactions at the subsequent evolution times, are noticeable and improve the description of particle number ratios. An important observation is that, although the particle number ratios with switched-off inelastic reactions are quite different at different particlization temperatures which are adopted for different equations of state to reproduce experimental data, the complete iHKM calculations bring very close results in both cases.

The Effect of Grain Refinement on Solid Particle Erosion of Grade 5 Ti Alloy

NASA Astrophysics Data System (ADS)

Kazarinov, N. A.; Evstifeev, A. D.; Petrov, Y. V.; Atroshenko, S. A.; Valiev, R. R.

2018-04-01

In this work, the results on solid particle erosion of an ultrafine-grained Grade 5 titanium alloy, which was produced using high-pressure torsion (HPT) technique, are presented. In order to assess influence of the HPT treatment on material's behavior in erosive conditions, special experimental procedures were developed. The ultrafine-grained (UFG) alloy was tested alongside with a conventional coarse-grained (CG) Grade 5 titanium alloy in equal conditions. The experiments were conducted in a small-scale wind tunnel with corundum particles as an abrasive material. Both particle dimensions and particle velocities were varied in course of the experiments. Erosion resistance of the samples was evaluated in two ways—mass reduction measurements with subsequent gravimetric erosion rate calculations and investigation of samples' surface roughness after erosion tests. The UFG titanium alloy demonstrated considerable improvement of static mechanical properties (ultimate tensile strength, microhardness), whereas its CG counterpart appeared to be slightly more resistant to solid particle erosion, which might indicate the drop of dynamic strength properties for the HPT-processed material.

A New Approach to Time-Resolved 3D-PTV

NASA Astrophysics Data System (ADS)

Boomsma, Aaron; Troolin, Dan; Bjorkquist, Dan; TSI Inc Team

2017-11-01

Volumetric three-component velocimetry via particle tracking is a powerful alternative to TomoPIV. It has been thoroughly documented that compared to TomoPIV, particle tracking velocimetry (PTV) methods (whether 2D or 3D) better resolve regions of high velocity gradient, identify fewer ghost particles, and are less computationally demanding, which results in shorter processing times. Recently, 3D-PTV has seen renewed interest in the PIV community with the availability of time-resolved data. Of course, advances in hardware are partly to thank for that availability-higher speed cameras, more effective memory management, and higher speed lasers. But in software, algorithms that utilize time resolved data to improve 3D particle reconstruction and particle tracking are also under development and advancing (e.g. shake-the-box, neighbor tracking reconstruction, etc.). .In the current study, we present a new 3D-PTV method that incorporates time-resolved data. We detail the method, its performance in terms of particle identification and reconstruction error and their relation to varying seeding densities, as well as computational performance.

Uncertainty characterization of particle location from refocused plenoptic images.

PubMed

Hall, Elise M; Guildenbecher, Daniel R; Thurow, Brian S

2017-09-04

Plenoptic imaging is a 3D imaging technique that has been applied for quantification of 3D particle locations and sizes. This work experimentally evaluates the accuracy and precision of such measurements by investigating a static particle field translated to known displacements. Measured 3D displacement values are determined from sharpness metrics applied to volumetric representations of the particle field created using refocused plenoptic images, corrected using a recently developed calibration technique. Comparison of measured and known displacements for many thousands of particles allows for evaluation of measurement uncertainty. Mean displacement error, as a measure of accuracy, is shown to agree with predicted spatial resolution over the entire measurement domain, indicating robustness of the calibration methods. On the other hand, variation in the error, as a measure of precision, fluctuates as a function of particle depth in the optical direction. Error shows the smallest variation within the predicted depth of field of the plenoptic camera, with a gradual increase outside this range. The quantitative uncertainty values provided here can guide future measurement optimization and will serve as useful metrics for design of improved processing algorithms.

Aluminum-Scandium: A Material for Semiconductor Packaging

NASA Astrophysics Data System (ADS)

Geissler, Ute; Thomas, Sven; Schneider-Ramelow, Martin; Mukhopadhyay, Biswajit; Lang, Klaus-Dieter

2016-10-01

A well-known aluminum-scandium (Al-Sc) alloy, already used in lightweight sports equipment, is about to be established for use in electronic packaging. One application for Al-Sc alloy is manufacture of bonding wires. The special feature of the alloy is its ability to harden by precipitation. The new bonding wires with electrical conductivity similar to pure Al wires can be processed on common wire bonders for aluminum wedge/wedge (w/w) bonding. The wires exhibit very fine-grained microstructure. Small Al3Sc particles are the main reason for its high strength and prevent recrystallization and grain growth at higher temperatures (>150°C). After the wire-bonding process, the interface is well closed. Reliability investigations by active power cycling demonstrated considerably improved lifetime compared with pure Al heavy wires. Furthermore, the Al-Sc alloy was sputter-deposited onto silicon wafer to test it as chip metallization in copper (Cu) ball/wedge bonding technology. After deposition, the layers exhibited fine-grained columnar structure and small coherent Al3Sc particles with dimensions of a few nanometers. These particles inhibit softening processes such as Al splashing in fine wire bonding processes and increase the thickness of remnant Al under the copper balls to 85% of the initial thickness.

Single-step preparation and deagglomeration of itraconazole microflakes by supercritical antisolvent method for dissolution enhancement.

PubMed

Sathigari, Sateesh Kumar; Ober, Courtney A; Sanganwar, Ganesh P; Gupta, Ram B; Babu, R Jayachandra

2011-07-01

Itraconazole (ITZ) microflakes were produced by supercritical antisolvent (SAS) method and simultaneously mixed with pharmaceutical excipients in a single step to prevent drug agglomeration. Simultaneous ITZ particle formation and mixing with fast-flo lactose (FFL) was performed in a high-pressure stirred vessel at 116 bar and 40 °C by the SAS-drug excipient mixing (SAS-DEM) method. The effects of stabilizers, such as sodium dodecyl sulfate and poloxamer 407 (PLX), on particle formation and drug dissolution were studied. Drug-excipient formulations were characterized for surface morphology, crystallinity, drug-excipient interactions, drug content uniformity, and drug dissolution rate. Mixture of drug microflakes and FFL formed by the SAS-DEM process shows that the process was successful in overcoming drug-drug agglomeration. PLX produced crystalline drug flakes in loose agglomerates with superior dissolution and flow properties even at higher drug loadings. Characterization studies confirmed the crystallinity of the drug and absence of chemical interactions during the SAS process. The dissolution of ITZ was substantially higher due to SAS and SAS-DEM processes; this improvement can be attributed to the microflake particle structures, effective deagglomeration, and wetting of the drug flakes with the excipients. Copyright © 2011 Wiley-Liss, Inc. and the American Pharmacists Association

The effect of microstructure on the performance of Li-ion porous electrodes

NASA Astrophysics Data System (ADS)

Chung, Ding-Wen

By combining X-ray tomography data and computer-generated porous elec- trodes, the impact of microstructure on the energy and power density of lithium-ion batteries is analyzed. Specifically, for commercial LiMn2O4 electrodes, results indi- cate that a broad particle size distribution of active material delivers up to two times higher energy density than monodisperse-sized particles for low discharge rates, and a monodisperse particle size distribution delivers the highest energy and power density for high discharge rates. The limits of traditionally used microstructural properties such as tortuosity, reactive area density, particle surface roughness, morphological anisotropy were tested against degree of particle size polydispersity, thus enabling the identification of improved porous architectures. The effects of critical battery processing parameters, such as layer compaction and carbon black, were also rationalized in the context of electrode performance. While a monodisperse particle size distribution exhibits the lowest possible tortuosity and three times higher surface area per unit volume with respect to an electrode conformed of a polydisperse particle size distribution, a comparable performance can be achieved by polydisperse particle size distributions with degrees of polydispersity less than 0.2 of particle size standard deviation. The use of non-spherical particles raises the tortuosity by as much as three hundred percent, which considerably lowers the power performance. However, favorably aligned particles can maximize power performance, particularly for high discharge rate applications.

Number size distribution of fine and ultrafine fume particles from various welding processes.

PubMed

Brand, Peter; Lenz, Klaus; Reisgen, Uwe; Kraus, Thomas

2013-04-01

Studies in the field of environmental epidemiology indicate that for the adverse effect of inhaled particles not only particle mass is crucial but also particle size is. Ultrafine particles with diameters below 100 nm are of special interest since these particles have high surface area to mass ratio and have properties which differ from those of larger particles. In this paper, particle size distributions of various welding and joining techniques were measured close to the welding process using a fast mobility particle sizer (FMPS). It turned out that welding processes with high mass emission rates (manual metal arc welding, metal active gas welding, metal inert gas welding, metal inert gas soldering, and laser welding) show mainly agglomerated particles with diameters above 100 nm and only few particles in the size range below 50 nm (10 to 15%). Welding processes with low mass emission rates (tungsten inert gas welding and resistance spot welding) emit predominantly ultrafine particles with diameters well below 100 nm. This finding can be explained by considerably faster agglomeration processes in welding processes with high mass emission rates. Although mass emission is low for tungsten inert gas welding and resistance spot welding, due to the low particle size of the fume, these processes cannot be labeled as toxicologically irrelevant and should be further investigated.

Fabrication and characterization of a biodegradable Mg-2Zn-0.5Ca/1β-TCP composite.

PubMed

Huang, Yan; Liu, Debao; Anguilano, Lorna; You, Chen; Chen, Minfang

2015-09-01

A biodegradable magnesium matrix and beta-tricalcium phosphate (β-TCP) particles reinforced composite Mg-2Zn-0.5Ca/1beta-TCP (wt.%) was fabricated for biomedical applications by the novel route of combined high shear solidification (HSS) and equal channel angular extrusion (ECAE). The as-cast composite obtained by HSS showed a fine and equiaxed grain structure with globally uniformly distributed β-TCP particles in aggregates of 2-25 μm in size. The ECAE processing at 300 °C resulted in further microstructural refinement and the improvement of β-TCP particle distribution. During ECAE, the β-TCP aggregates were broken into smaller ones or individual particles, forming a dispersion in the matrix. Such fabricated composite exhibited enhanced hardness and in vitro corrosion resistance. The enhanced hardness was attributed to both the addition of β-TCP particles and grain refinement while the development of a Ca-P rich surface layer from β-TCP during corrosion was responsible for the improvement in corrosion resistance. The composite was characterized in terms of microstructural evolution during fabrication, mechanical properties and electrochemical performance during polarization and immersion tests in a simulated body fluid. Discussions are made on the benefits of both HSS and ECAE and the mechanisms responsible for the enhanced corrosion resistance. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of drug physico-chemical properties on the efficiency of top-down process and characterization of nanosuspension.

PubMed

Liu, Tao; Müller, Rainer H; Möschwitzer, Jan P

2015-01-01

The top-down approach is frequently used for drug nanocrystal production. A large number of review papers have referred to the top-down approach in terms of process parameters such as stabilizer selection. However, a very important factor, that is, the influence of drug properties, has been not addressed so far. This review will first discuss different nanocrystal technologies in brief. The focus will be on reviewing the different drug properties such as solid state and particle morphology on the efficiency of particle size reduction during top-down processes. Furthermore, the drug properties in the final nanosuspensions are critical for drug dissolution velocity. Therefore, another focus is the characterization of drugs in obtained nanosuspension. Drug physical properties play an important role in the production efficiency. The combinative technologies using modified drugs could significantly improve the performances of top-down processes. However, further understanding of the drug millability and homogenization will still be needed. In addition, a carefully established characterization system for nansuspension is essential.

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.

Influence of surface morphology and UFG on damping and mechanical properties of composite reinforced with spinel MgAl{sub 2}O{sub 4}-SiC core-shell microcomposites

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

Singh, Subhash; Pal, Kaushik, E-mail: pl_kshk@yaho

Interface between ceramic particulate and matrix is known to control the response of the materials and functionality of the composite. Among numerous physical properties, grain structure of the materials has also played a significant role in defining the behaviour of metal matrix composites. Usually, silicon carbide (SiC) particles show poor interfacial wettability in aluminium melt. Herein, we were successfully synthesized magnesium oxide (MgO) and nanocrystalline magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel coated silicon carbide (SiC) core-shell micro-composites through sol-gel technique to improve the wettability of dispersoids. Core-shell structures of submicron size were thoroughly investigated by various characterization techniques. Further, aluminiummore » matrix composites incorporated with pristine SiC, MgO grafted SiC and MgAl{sub 2}O{sub 4} grafted SiC particles were fabricated by stir casting technique, respectively. Additionally, as-cast composites were processed via friction stir processing (FSP) technique to observe the influence of grain refinement on mechanical and damping properties. Electron back scattered diffraction (EBSD), Field emission scanning electron microscopy (FE-SEM) and X-ray energy dispersion spectroscopy (EDX) analysis were conducted for investigating grain size refinement, adequate dispersion, stability and de-agglomeration of encapsulated SiC particles in aluminium matrix. The mechanical as well as thermal cyclic (from − 100 to 400 °C) damping performance of the as-cast and friction stir processed composites were studied, respectively. Finally, the enhanced properties were attributable to reduced agglomeration, stabilization and proper dispersion of the tailored SiC particles Al matrix. - Highlights: •Synthesizing a novel coating layer of MgO and MgAl{sub 2}O{sub 4} spinel onto SiC particles •Significant improvement in UTS and hardness by reinforcing tailored SiC in Al •Significant grain refinements were obtained through FSP •SiC/MgAl{sub 2}O{sub 4}/Al exhibits ~ 61% higher storage modulus as compare to pure Al after FSP.« less

Modeling reactive transport with particle tracking and kernel estimators

NASA Astrophysics Data System (ADS)

Rahbaralam, Maryam; Fernandez-Garcia, Daniel; Sanchez-Vila, Xavier

2015-04-01

Groundwater reactive transport models are useful to assess and quantify the fate and transport of contaminants in subsurface media and are an essential tool for the analysis of coupled physical, chemical, and biological processes in Earth Systems. Particle Tracking Method (PTM) provides a computationally efficient and adaptable approach to solve the solute transport partial differential equation. On a molecular level, chemical reactions are the result of collisions, combinations, and/or decay of different species. For a well-mixed system, the chem- ical reactions are controlled by the classical thermodynamic rate coefficient. Each of these actions occurs with some probability that is a function of solute concentrations. PTM is based on considering that each particle actually represents a group of molecules. To properly simulate this system, an infinite number of particles is required, which is computationally unfeasible. On the other hand, a finite number of particles lead to a poor-mixed system which is limited by diffusion. Recent works have used this effect to actually model incomplete mix- ing in naturally occurring porous media. In this work, we demonstrate that this effect in most cases should be attributed to a defficient estimation of the concentrations and not to the occurrence of true incomplete mixing processes in porous media. To illustrate this, we show that a Kernel Density Estimation (KDE) of the concentrations can approach the well-mixed solution with a limited number of particles. KDEs provide weighting functions of each particle mass that expands its region of influence, hence providing a wider region for chemical reactions with time. Simulation results show that KDEs are powerful tools to improve state-of-the-art simulations of chemical reactions and indicates that incomplete mixing in diluted systems should be modeled based on alternative conceptual models and not on a limited number of particles.

Particle damage sources for fused silica optics and their mitigation on high energy laser systems.

PubMed

Bude, J; Carr, C W; Miller, P E; Parham, T; Whitman, P; Monticelli, M; Raman, R; Cross, D; Welday, B; Ravizza, F; Suratwala, T; Davis, J; Fischer, M; Hawley, R; Lee, H; Matthews, M; Norton, M; Nostrand, M; VanBlarcom, D; Sommer, S

2017-05-15

High energy laser systems are ultimately limited by laser-induced damage to their critical components. This is especially true of damage to critical fused silica optics, which grows rapidly upon exposure to additional laser pulses. Much progress has been made in eliminating damage precursors in as-processed fused silica optics (the advanced mitigation process, AMP3), and very high damage resistance has been demonstrated in laboratory studies. However, the full potential of these improvements has not yet been realized in actual laser systems. In this work, we explore the importance of additional damage sources-in particular, particle contamination-for fused silica optics fielded in a high-performance laser environment, the National Ignition Facility (NIF) laser system. We demonstrate that the most dangerous sources of particle contamination in a system-level environment are laser-driven particle sources. In the specific case of the NIF laser, we have identified the two important particle sources which account for nearly all the damage observed on AMP3 optics during full laser operation and present mitigations for these particle sources. Finally, with the elimination of these laser-driven particle sources, we demonstrate essentially damage free operation of AMP3 fused silica for ten large optics (a total of 12,000 cm 2 of beam area) for shots from 8.6 J/cm 2 to 9.5 J/cm 2 of 351 nm light (3 ns Gaussian pulse shapes). Potentially many other pulsed high energy laser systems have similar particle sources, and given the insight provided by this study, their identification and elimination should be possible. The mitigations demonstrated here are currently being employed for all large UV silica optics on the National Ignition Facility.

The role of aluminum in slow sand filtration.

PubMed

Weber-Shirk, Monroe L; Chan, Kwok Loon

2007-03-01

Engineering enhancement of slow sand filtration has been an enigma in large part because the mechanisms responsible for particle removal have not been well characterized. The presumed role of biological processes in the filter ripening process nearly precluded the possibility of enhancing filter performance since interventions to enhance biological activity would have required decreasing the quality of the influent water. In previous work, we documented that an acid soluble polymer controls filter performance. The new understanding that particle removal is controlled in large part by physical chemical mechanisms has expanded the possibilities of engineering slow sand filter performance. Herein, we explore the role of naturally occurring aluminum as a ripening agent for slow sand filters and the possibility of using a low dose of alum to improve filter performance or to ripen slow sand filters.

Aerosol modelling and validation during ESCOMPTE 2001

NASA Astrophysics Data System (ADS)

Cousin, F.; Liousse, C.; Cachier, H.; Bessagnet, B.; Guillaume, B.; Rosset, R.

The ESCOMPTE 2001 programme (Atmospheric Research. 69(3-4) (2004) 241) has resulted in an exhaustive set of dynamical, radiative, gas and aerosol observations (surface and aircraft measurements). A previous paper (Atmospheric Research. (2004) in press) has dealt with dynamics and gas-phase chemistry. The present paper is an extension to aerosol formation, transport and evolution. To account for important loadings of primary and secondary aerosols and their transformation processes in the ESCOMPTE domain, the ORISAM aerosol module (Atmospheric Environment. 35 (2001) 4751) was implemented on-line in the air-quality Meso-NH-C model. Additional developments have been introduced in ORganic and Inorganic Spectral Aerosol Module (ORISAM) to improve the comparison between simulations and experimental surface and aircraft field data. This paper discusses this comparison for a simulation performed during one selected day, 24 June 2001, during the Intensive Observation Period IOP2b. Our work relies on BC and OCp emission inventories specifically developed for ESCOMPTE. This study confirms the need for a fine resolution aerosol inventory with spectral chemical speciation. BC levels are satisfactorily reproduced, thus validating our emission inventory and its processing through Meso-NH-C. However, comparisons for reactive species generally denote an underestimation of concentrations. Organic aerosol levels are rather well simulated though with a trend to underestimation in the afternoon. Inorganic aerosol species are underestimated for several reasons, some of them have been identified. For sulphates, primary emissions were introduced. Improvement was obtained too for modelled nitrate and ammonium levels after introducing heterogeneous chemistry. However, no modelling of terrigeneous particles is probably a major cause for nitrates and ammonium underestimations. Particle numbers and size distributions are well reproduced, but only in the submicrometer range. Our work points out to the need of introducing coarse dust particles to further improve the simulation of PM-10 concentrations and more accurate modelling of gas-particle interactions.

Modelling the influence of total suspended solids on E. coli removal in river water.

PubMed

Qian, Jueying; Walters, Evelyn; Rutschmann, Peter; Wagner, Michael; Horn, Harald

2016-01-01

Following sewer overflows, fecal indicator bacteria enter surface waters and may experience different lysis or growth processes. A 1D mathematical model was developed to predict total suspended solids (TSS) and Escherichia coli concentrations based on field measurements in a large-scale flume system simulating a combined sewer overflow. The removal mechanisms of natural inactivation, UV inactivation, and sedimentation were modelled. For the sedimentation process, one, two or three particle size classes were incorporated separately into the model. Moreover, the UV sensitivity coefficient α and natural inactivation coefficient kd were both formulated as functions of TSS concentration. It was observed that the E. coli removal was predicted more accurately by incorporating two particle size classes. However, addition of a third particle size class only improved the model slightly. When α and kd were allowed to vary with the TSS concentration, the model was able to predict E. coli fate and transport at different TSS concentrations accurately and flexibly. A sensitivity analysis revealed that the mechanisms of UV and natural inactivation were more influential at low TSS concentrations, whereas the sedimentation process became more important at elevated TSS concentrations.

Monitoring of antisolvent crystallization of sodium scutellarein by combined FBRM-PVM-NIR.

PubMed

Liu, Xuesong; Sun, Di; Wang, Feng; Wu, Yongjiang; Chen, Yong; Wang, Longhu

2011-06-01

Antisolvent crystallization can be used as an alternative to cooling or evaporation for the separation and purification of solid product in the pharmaceutical industry. To improve the process understanding of antisolvent crystallization, the use of in-line tools is vital. In this study, the process analytical technology (PAT) tools including focused beam reflectance measurement (FBRM), particle video microscope (PVM), and near-infrared spectroscopy (NIRS) were utilized to monitor antisolvent crystallization of sodium scutellarein. FBRM was used to monitor chord count and chord length distribution of sodium scutellarein particles in the crystallizer, and PVM, as an in-line video camera, provided pictures imaging particle shape and dimension. In addition, a quantitative model of PLS was established by in-line NIRS to detect the concentration of sodium scutellarein in the solvent and good calibration statistics were obtained (r(2) = 0.976) with the residual predictive deviation value of 11.3. The discussion over sensitivities, strengths, and weaknesses of the PAT tools may be helpful in selection of suitable PAT techniques. These in-line techniques eliminate the need for sample preparation and offer a time-saving approach to understand and monitor antisolvent crystallization process. Copyright © 2011 Wiley-Liss, Inc.

A new airborne sampler for interstitial particles in ice and liquid clouds

NASA Astrophysics Data System (ADS)

Moharreri, A.; Craig, L.; Rogers, D. C.; Brown, M.; Dhaniyala, S.

2011-12-01

In-situ measurements of cloud droplets and aerosols using aircraft platforms are required for understanding aerosol-cloud processes and aiding development of improved aerosol-cloud models. A variety of clouds with different temperature ranges and cloud particle sizes/phases must be studied for comprehensive knowledge about the role of aerosols in the formation and evolution of cloud systems under different atmospheric conditions. While representative aerosol measurements are regularly made from aircrafts under clear air conditions, aerosol measurements in clouds are often contaminated by the generation of secondary particles from the high speed impaction of ice particles and liquid droplets on the surfaces of the aircraft probes/inlets. A new interstitial particle sampler, called the blunt-body aerosol sampler (BASE) has been designed and used for aerosol sampling during two recent airborne campaigns using NCAR/NSF C-130 aircraft: PLOWS (2009-2010) and ICE-T (2011). Central to the design of the new interstitial inlet is an upstream blunt body housing that acts to shield/deflect large cloud droplets and ice particles from an aft sampling region. The blunt-body design also ensures that small shatter particles created from the impaction of cloud-droplets on the blunt-body are not present in the aft region where the interstitial inlet is located. Computational fluid dynamics (CFD) simulations along with particle transport modeling and wind tunnel studies have been utilized in different stages of design and development of this inlet. The initial flights tests during the PLOWS campaign showed that the inlet had satisfactory performance only in warm clouds and when large precipitation droplets were absent. In the presence of large droplets and ice, the inlet samples were contaminated with significant shatter artifacts. These initial results were reanalyzed in conjunction with a computational droplet shatter model and the numerical results were used to arrive at an improved sampler design. Analysis of the data from the recent ICE-T campaign with the improved sampler design shows that the modified version of BASE can provide shatter-artifact free sampling of aerosol particles in the presence of ice particles and significantly reduced shatter artifacts in warm clouds. Detailed design and modeling aspects of the sampler will be discussed and the sampler performance in warm and cold clouds will be presented and compared with measurements made using other aerosol inlets flown on the NCAR/NSF C-130 aircraft.

Image pre-processing method for near-wall PIV measurements over moving curved interfaces

NASA Astrophysics Data System (ADS)

Jia, L. C.; Zhu, Y. D.; Jia, Y. X.; Yuan, H. J.; Lee, C. B.

2017-03-01

PIV measurements near a moving interface are always difficult. This paper presents a PIV image pre-processing method that returns high spatial resolution velocity profiles near the interface. Instead of re-shaping or re-orientating the interrogation windows, interface tracking and an image transformation are used to stretch the particle image strips near a curved interface into rectangles. Then the adaptive structured interrogation windows can be arranged at specified distances from the interface. Synthetic particles are also added into the solid region to minimize interfacial effects and to restrict particles on both sides of the interface. Since a high spatial resolution is only required in high velocity gradient region, adaptive meshing and stretching of the image strips in the normal direction is used to improve the cross-correlation signal-to-noise ratio (SN) by reducing the velocity difference and the particle image distortion within the interrogation window. A two dimensional Gaussian fit is used to compensate for the effects of stretching particle images. The working hypothesis is that fluid motion near the interface is ‘quasi-tangential flow’, which is reasonable in most fluid-structure interaction scenarios. The method was validated against the window deformation iterative multi-grid scheme (WIDIM) using synthetic image pairs with different velocity profiles. The method was tested for boundary layer measurements of a supersonic turbulent boundary layer on a flat plate, near a rotating blade and near a flexible flapping flag. This image pre-processing method provides higher spatial resolution than conventional WIDIM and good robustness for measuring velocity profiles near moving interfaces.

Process for making silver metal filaments

DOEpatents

Bamberger, Carlos E.

1997-01-01

A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

A fast multi-resolution approach to tomographic PIV

NASA Astrophysics Data System (ADS)

Discetti, Stefano; Astarita, Tommaso

2012-03-01

Tomographic particle image velocimetry (Tomo-PIV) is a recently developed three-component, three-dimensional anemometric non-intrusive measurement technique, based on an optical tomographic reconstruction applied to simultaneously recorded images of the distribution of light intensity scattered by seeding particles immersed into the flow. Nowadays, the reconstruction process is carried out mainly by iterative algebraic reconstruction techniques, well suited to handle the problem of limited number of views, but computationally intensive and memory demanding. The adoption of the multiplicative algebraic reconstruction technique (MART) has become more and more accepted. In the present work, a novel multi-resolution approach is proposed, relying on the adoption of a coarser grid in the first step of the reconstruction to obtain a fast estimation of a reliable and accurate first guess. A performance assessment, carried out on three-dimensional computer-generated distributions of particles, shows a substantial acceleration of the reconstruction process for all the tested seeding densities with respect to the standard method based on 5 MART iterations; a relevant reduction in the memory storage is also achieved. Furthermore, a slight accuracy improvement is noticed. A modified version, improved by a multiplicative line of sight estimation of the first guess on the compressed configuration, is also tested, exhibiting a further remarkable decrease in both memory storage and computational effort, mostly at the lowest tested seeding densities, while retaining the same performances in terms of accuracy.

Plasma Synthesis and Sintering of Advanced Ceramics

DTIC Science & Technology

1990-09-15

CONTENTS Page LIST OF TABLES iv OBJECTIVES 1 COLLOIDAL PLASMA PROCESSING: CONCEPTS 1 BACKGROUND 2 Ultrafine Particles 2 Colloidal Plasma 3 Particle...colloidal plasma processing of ceramics. COLLOIDAL PLASMA PROCESSING: CONCEPTS It is well known that ultrafine particles prepared in gas plasmas agglomerate...BACKGROUND Ultrafine Particles . There are well recognized advantages to using small particles in ceramic processing. The instantaneous densification

Particle morphology characterization and manipulation in biomass slurries and the effect on rheological properties and enzymatic conversion.

PubMed

Dibble, Clare J; Shatova, Tatyana A; Jorgenson, Jennie L; Stickel, Jonathan J

2011-01-01

An improved understanding of how particle size distribution relates to enzymatic hydrolysis performance and rheological properties could enable enhanced biochemical conversion of lignocellulosic feedstocks. Particle size distribution can change as a result of either physical or chemical manipulation of a biomass sample. In this study, we employed image processing techniques to measure slurry particle size distribution and validated the results by showing that they are comparable to those from laser diffraction and sieving. Particle size and chemical changes of biomass slurries were manipulated independently and the resulting yield stress and enzymatic digestibility of slurries with different size distributions were measured. Interestingly, reducing particle size by mechanical means from about 1 mm to 100 μm did not reduce the yield stress of the slurries over a broad range of concentrations or increase the digestibility of the biomass over the range of size reduction studied here. This is in stark contrast to the increase in digestibility and decrease in yield stress when particle size is reduced by dilute-acid pretreatment over similar size ranges. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

Compressed Air Quality, A Case Study In Paiton Coal Fired Power Plant Unit 1 And 2

NASA Astrophysics Data System (ADS)

Indah, Nur; Kusuma, Yuriadi; Mardani

2018-03-01

The compressed air system becomes part of a very important utility system in a Plant, including the Steam Power Plant. In PLN’S coal fired power plant, Paiton units 1 and 2, there are four Centrifugal air compressor types, which produce compressed air as much as 5.652 cfm and with electric power capacity of 1200 kW. Electricity consumption to operate centrifugal compressor is 7.104.117 kWh per year. Compressed air generation is not only sufficient in quantity (flow rate) but also meets the required air quality standards. compressed air at Steam Power Plant is used for; service air, Instrument air, and for fly Ash. This study aims to measure some important parameters related to air quality, followed by potential disturbance analysis, equipment breakdown or reduction of energy consumption from existing compressed air conditions. These measurements include counting the number of dust particles, moisture content, relative humidity, and also compressed air pressure. From the measurements, the compressed air pressure generated by the compressor is about 8.4 barg and decreased to 7.7 barg at the furthest point, so the pressure drop is 0.63 barg, this number satisfies the needs in the end user. The measurement of the number of particles contained in compressed air, for particle of 0.3 micron reaches 170,752 particles, while for the particle size 0.5 micron reaches 45,245 particles. Measurements of particles conducted at several points of measurement. For some point measurements the number of dust particle exceeds the standard set by ISO 8573.1-2010 and also NACE Code, so it needs to be improved on the air treatment process. To see the amount of moisture content in compressed air, it is done by measuring pressure dew point temperature (PDP). Measurements were made at several points with results ranging from -28.4 to 30.9 °C. The recommendation of improving compressed air quality in steam power plant, Paiton unit 1 and 2 has the potential to extend the life of instrumentation equipment, improve the reliability of equipment, and reduce the amount of energy consumption up to 502,579 kWh per year.

Effect of diet processing method and ingredient substitution on feed characteristics and survival of larval walleye, Sander vitreus

USGS Publications Warehouse

Barrows, F.T.; Lellis, W.A.

2006-01-01

Two methods were developed for the production of larval fish diets. The first method, microextrusion marumerization (MEM), has been tested in laboratory feeding trials for many years and produces particles that are palatable and water stable. The second method, particle-assisted rotational agglomeration (PARA), produced diets that have lower density than diets produced by MEM. Each method was used to produce diets in the 250- to 400- and 400- to 700-??m range and compared with a reference diet (Fry Feed Kyowa* [FFK]) for feeding larval walleye in two experiments. The effect of substituting 4% of the fish meal with freeze-dried artemia fines was also investigated. In the first experiment, 30-d survival was greater (P < 0.05) for fish fed a diet produced by PARA without Artemia (49.1.0%) than for fish fed the same diet produced by MEM (27.6%). The addition of Artemia to a diet produced by MEM did not increase survival of larval walleye. Fish fed the reference diet had 24.4% survival. In the second experiment, there was an effect of both processing method and Artemia supplementation, and an interaction of these effects, on survival. Fish fed a diet produced by PARA without Artemia supplementation had 48.4% survival, and fish fed the same diet produced by MEM had only 19.6% survival. Inclusion of 4% freeze-dried Artemia improved (P < 0.04) survival of fish fed MEM particles but not those fed PARA particles. Fish fed FFK had greater weight gain than fish fed other diets in both experiments. Data indicate that the PARA method of diet processing produces smaller, lower density particles than the MEM process and that diets produced by the PARA process support higher survival of larval walleye with low capital and operating costs. ?? Copyright by the World Aquaculture Society 2006.

Red mud flocculation process in alumina production

NASA Astrophysics Data System (ADS)

Fedorova, E. R.; Firsov, A. Yu

2018-05-01

The process of thickening and washing red mud is a gooseneck of alumina production. The existing automated systems of the thickening process control involve stabilizing the parameters of the primary technological circuits of the thickener. The actual direction of scientific research is the creation and improvement of models and systems of the thickening process control by model. But the known models do not fully consider the presence of perturbing effects, in particular the particle size distribution in the feed process, distribution of floccules by size after the aggregation process in the feed barrel. The article is devoted to the basic concepts and terms used in writing the population balance algorithm. The population balance model is implemented in the MatLab environment. The result of the simulation is the particle size distribution after the flocculation process. This model allows one to foreseen the distribution range of floccules after the process of aggregation of red mud in the feed barrel. The mud of Jamaican bauxite was acting as an industrial sample of red mud; Cytec Industries of HX-3000 series with a concentration of 0.5% was acting as a flocculant. When simulating, model constants obtained in a tubular tank in the laboratories of CSIRO (Australia) were used.

Novel Binders and Methods for Agglomeration of Ore

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

S. K. Kawatra; T. C. Eisele; K. A. Lewandowski

2006-12-31

Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that willmore » work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process, and advanced ironmaking processes, where binders must function satisfactorily over an extraordinarily large range of temperatures (from room temperature up to over 1200 C). As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching and advanced primary ironmaking. This project has identified several acid-resistant binders and agglomeration procedures that can be used for improving the energy efficiency of heap leaching, by preventing the ''ponding'' and ''channeling'' effects that currently cause reduced recovery and extended leaching cycle times. Methods have also been developed for iron ore processing which are intended to improve the performance of pellet binders, and have directly saved energy by increasing filtration rates of the pelletization feed by as much as 23%.« less

Improvements in Production of Single-Walled Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Balzano, Leandro; Resasco, Daniel E.

2009-01-01

A continuing program of research and development has been directed toward improvement of a prior batch process in which single-walled carbon nanotubes are formed by catalytic disproportionation of carbon monoxide in a fluidized-bed reactor. The overall effect of the improvements has been to make progress toward converting the process from a batch mode to a continuous mode and to scaling of production to larger quantities. Efforts have also been made to optimize associated purification and dispersion post processes to make them effective at large scales and to investigate means of incorporating the purified products into composite materials. The ultimate purpose of the program is to enable the production of high-quality single-walled carbon nanotubes in quantities large enough and at costs low enough to foster the further development of practical applications. The fluidized bed used in this process contains mixed-metal catalyst particles. The choice of the catalyst and the operating conditions is such that the yield of single-walled carbon nanotubes, relative to all forms of carbon (including carbon fibers, multi-walled carbon nanotubes, and graphite) produced in the disproportionation reaction is more than 90 weight percent. After the reaction, the nanotubes are dispersed in various solvents in preparation for end use, which typically involves blending into a plastic, ceramic, or other matrix to form a composite material. Notwithstanding the batch nature of the unmodified prior fluidized-bed process, the fluidized-bed reactor operates in a continuous mode during the process. The operation is almost entirely automated, utilizing mass flow controllers, a control computer running software specific to the process, and other equipment. Moreover, an important inherent advantage of fluidized- bed reactors in general is that solid particles can be added to and removed from fluidized beds during operation. For these reasons, the process and equipment were amenable to modification for conversion from batch to continuous production.

Effects of processing, particle size and moisturizing of sorghum-based feeds on pellet quality and broiler production.

PubMed

da Silva, Patrícia Garcia; Oliveira, Luana Martins Schaly; de Oliveira, Nayanne Rodrigues; de Moura Júnior, Fábio Ataides; Silva, Maura Regina Sousa; Cordeiro, Deibity Alves; Minafra, Cibele Silva; Dos Santos, Fabiana Ramos

2018-01-01

This study aimed to assess the effect of pelleted and expanded sorghum-based feeds prepared with different moisture levels and particle size of ingredients on metabolizable energy, ileal digestibility of amino acids and broiler performance. The experiment was performed with 720 male broiler chicks of the Cobb strain, with treatments of six replications, with 15 birds each; they were arranged in a completely randomized design and 2×2×2 factorial scheme (pelleted or expanded feed processing, 0.8% or 1.6% moisture addition in the mixer, and particle size of 650 or 850 microns). Higher pellet quality (pellets, % and pellet durability index [PDI]) was obtained in expanded diets and inclusion of 1.6% moisture. The particle size of 850 microns increased the PDI of final diet. All studied treatments had no significant effect on weight gain and broiler carcass and cut yields. Lower feed conversion occurred for birds fed pelleted feed at 42 d. The highest apparent metabolizable energy (AME) and apparent metabolizable energy corrected to zero nitrogen balance (AMEn) values of feed in the initial rearing phase (10 to 13 days) were observed in birds fed pelleted feed or for feed prepared with 1.6% moisture. The highest ileal digestibility coefficients of amino acids were obtained with the consumption of pelleted feed prepared with a particle size of 650 microns and 1.6% moisture. Pelleted feed prepared with a milling particle size of 650 microns and 1.6% moisture provided increased ileal digestibility of amino acids and AMEn in the starter period. However, the expanded feed improved pellet quality and feed conversion of broilers at 42 days of age. We conclude that factors such as moisture, particle size and processing affect the pellet quality, and therefore should be considered when attempting to optimize broiler performance.

The Effect of Suspended Sediment Transport and Deposition on Streambed Clogging Under Losing and Gaining Flow Conditions

NASA Astrophysics Data System (ADS)

Fox, A.; Packman, A. I.; Preziosi-Ribero, A.; Li, A.; Arnon, S.

2017-12-01

Sediment transport and deposition in streams can affect streambed hydraulic characteristics due to clogging, reduce water fluxes through the hyporheic zone, and thus expected to affect biogeochemical processes. Processes affecting deposition of suspended particles were systematically studied under various overlying velocities but without taking into account the interactions with groundwater. This is despite the fact that the interaction with groundwater were shown to play an important role in deposition patterns of fine sediments in field studies. The objective of this study was to evaluate the effect of losing and gaining fluxes on suspended sediment depositional patterns and on hyporheic exchange fluxes. Experiments were conducted in a laboratory flume system (640 cm long and 30 cm wide) that has a capacity to enforce losing or gaining flow conditions. The flume was packed with homogenous sand, while suspended sediment deposition was evaluated by adding kaolinite particles to the water and following the deposition rate by particle disappearance from the bulk water. Consecutive additions of kaolinite were done, while hyporheic exchange fluxes were evaluated by conducting NaCl tracer experiments between each kaolinite additions. Furthermore, dye injections were used to visualize the flow patterns in the streambed using time-lapse photography through the transparent sidewalls of the flume. Hyporheic exchange and particle tracking simulations were done to assess the results of particle deposition and feedbacks between hyporheic flow, particle transport, and streambed clogging. Experimental results showed that the deposition of clay decreases with increasing amount of clay concentration in the sediment. Hyporheic exchange flux decreases linearly with increasing amount of clay added to the system and the region of active hyporheic exchange was confined to the upper part of the sediment. Understanding the particle deposition mechanisms under losing and gaining flow condition are expected to improve our predictive ability to capture the dynamics of streambed characteristics, which has implications to sediment transport, biogeochemical processes and hyporheic ecology.

Effects of processing, particle size and moisturizing of sorghum-based feeds on pellet quality and broiler production

PubMed Central

2018-01-01

Objective This study aimed to assess the effect of pelleted and expanded sorghum-based feeds prepared with different moisture levels and particle size of ingredients on metabolizable energy, ileal digestibility of amino acids and broiler performance. Methods The experiment was performed with 720 male broiler chicks of the Cobb strain, with treatments of six replications, with 15 birds each; they were arranged in a completely randomized design and 2×2×2 factorial scheme (pelleted or expanded feed processing, 0.8% or 1.6% moisture addition in the mixer, and particle size of 650 or 850 microns). Results Higher pellet quality (pellets, % and pellet durability index [PDI]) was obtained in expanded diets and inclusion of 1.6% moisture. The particle size of 850 microns increased the PDI of final diet. All studied treatments had no significant effect on weight gain and broiler carcass and cut yields. Lower feed conversion occurred for birds fed pelleted feed at 42 d. The highest apparent metabolizable energy (AME) and apparent metabolizable energy corrected to zero nitrogen balance (AMEn) values of feed in the initial rearing phase (10 to 13 days) were observed in birds fed pelleted feed or for feed prepared with 1.6% moisture. The highest ileal digestibility coefficients of amino acids were obtained with the consumption of pelleted feed prepared with a particle size of 650 microns and 1.6% moisture. Conclusion Pelleted feed prepared with a milling particle size of 650 microns and 1.6% moisture provided increased ileal digestibility of amino acids and AMEn in the starter period. However, the expanded feed improved pellet quality and feed conversion of broilers at 42 days of age. We conclude that factors such as moisture, particle size and processing affect the pellet quality, and therefore should be considered when attempting to optimize broiler performance. PMID:28920405

Efficient Photocatalytic H2 Evolution: Controlled Dewetting-Dealloying to Fabricate Site-Selective High-Activity Nanoporous Au Particles on Highly Ordered TiO2 Nanotube Arrays.

PubMed

Nguyen, Nhat Truong; Altomare, Marco; Yoo, JeongEun; Schmuki, Patrik

2015-05-27

Anodic self-organized TiO2 nanostumps are formed and exploited for self-ordering dewetting of Au-Ag sputtered films. This forms ordered particle configurations at the tube top (crown position) or bottom (ground position). By dealloying from a minimal amount of noble metal, porous Au nanoparticles are then formed, which, when in the crown position, allow for a drastically improved photocatalytic H2 production compared with nanoparticles produced by conventional dewetting processes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A discussion on improving hydration activity of steel slag by altering its mineral compositions.

PubMed

Wang, Qiang; Yan, Peiyu; Feng, Jianwen

2011-02-28

This study aims to investigate the ways to improve the cementitious properties of steel slag. The results show that the cementitious phase of steel slag is composed of silicate and aluminate, but the large particles of these phases make a very small contribution to the cementitious properties of steel slag. RO phase (CaO-FeO-MnO-MgO solid solution), Fe(3)O(4), C(2)F and f-CaO make no contribution to the cementitious properties of steel slag. A new kind of steel slag with more cementitious phase and less RO phase can be obtained by removing some large particles. This new steel slag possesses better cementitious properties than the original steel slag. The large particles can be used as fine aggregates for concrete. Adding regulating agent high in CaO and SiO(2) during manufacturing process of steel slag to increase the cementitious phase to inert phase ratio is another way to improve its cementitious properties. The regulating agent should be selected to adapt to the specific steel slag and the alkalinity should be increased as high as possible on the premise that the f-CaO content does not increase. The cooling rate should be enhanced to improve the hydration activity of the cementitious phase at the early ages and the grindability of steel slag. Copyright © 2010 Elsevier B.V. All rights reserved.

Application of the combinative particle size reduction technology H 42 to produce fast dissolving glibenclamide tablets.

PubMed

Salazar, Jaime; Müller, Rainer H; Möschwitzer, Jan P

2013-07-16

Standard particle size reduction techniques such as high pressure homogenization or wet bead milling are frequently used in the production of nanosuspensions. The need for micronized starting material and long process times are their evident disadvantages. Combinative particle size reduction technologies have been developed to overcome the drawbacks of the standard techniques. The H 42 combinative technology consists of a drug pre-treatment by means of spray-drying followed by standard high pressure homogenization. In the present paper, spray-drying process parameters influencing the diminution effectiveness, such as drug and surfactant concentration, were systematically analyzed. Subsequently, the untreated and pre-treated drug powders were homogenized for 20 cycles at 1500 bar. For untreated, micronized glibenclamide, the particle size analysis revealed a mean particle size of 772 nm and volume-based size distribution values of 2.686 μm (d50%) and 14.423 μm (d90%). The use of pre-treated material (10:1 glibenclamide/docusate sodium salt ratio spray-dried as ethanolic solution) resulted in a mean particle size of 236 nm and volume-based size distribution values of 0.131 μm (d50%) and 0.285 μm (d90%). These results were markedly improved compared to the standard process. The nanosuspensions were further transferred into tablet formulations. Wet granulation, freeze-drying and spray-drying were investigated as downstream methods to produce dry intermediates. Regarding the dissolution rate, the rank order of the downstream processes was as follows: Spray-drying>freeze-drying>wet granulation. The best drug release (90% within 10 min) was obtained for tablets produced with spray-dried nanosuspension containing 2% mannitol as matrix former. In comparison, the tablets processed with micronized glibenclamide showed a drug release of only 26% after 10 min. The H 42 combinative technology could be successfully applied in the production of small drug nanocrystals. A nanosuspension transfer to tablets that maintained the fast dissolution properties of the drug nanocrystals was successfully achieved. Copyright © 2013 Elsevier B.V. All rights reserved.

The Effect of Microgravity on the Growth of Silica Nanostructures

NASA Technical Reports Server (NTRS)

Smith, D. D.; Sibille, L.; Cronise, R.; Oldenburg, S. J.; Wolfe, D.; Halas, N. J.

2001-01-01

The process of the formation of structures from coagulating ensembles is fundamentally important since the collective behavior of the constituents often results in dramatically improved or unusual mechanical, thermal, chemical, and optical properties. In this study we examine the effect of microgravity on the formation of silica structures, specifically particles and gels.

Crystal and Particle Engineering Strategies for Improving Powder Compression and Flow Properties to Enable Continuous Tablet Manufacturing by Direct Compression.

PubMed

Chattoraj, Sayantan; Sun, Changquan Calvin

2018-04-01

Continuous manufacturing of tablets has many advantages, including batch size flexibility, demand-adaptive scale up or scale down, consistent product quality, small operational foot print, and increased manufacturing efficiency. Simplicity makes direct compression the most suitable process for continuous tablet manufacturing. However, deficiencies in powder flow and compression of active pharmaceutical ingredients (APIs) limit the range of drug loading that can routinely be considered for direct compression. For the widespread adoption of continuous direct compression, effective API engineering strategies to address power flow and compression problems are needed. Appropriate implementation of these strategies would facilitate the design of high-quality robust drug products, as stipulated by the Quality-by-Design framework. Here, several crystal and particle engineering strategies for improving powder flow and compression properties are summarized. The focus is on the underlying materials science, which is the foundation for effective API engineering to enable successful continuous manufacturing by the direct compression process. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Panorama parking assistant system with improved particle swarm optimization method

NASA Astrophysics Data System (ADS)

Cheng, Ruzhong; Zhao, Yong; Li, Zhichao; Jiang, Weigang; Wang, Xin'an; Xu, Yong

2013-10-01

A panorama parking assistant system (PPAS) for the automotive aftermarket together with a practical improved particle swarm optimization method (IPSO) are proposed in this paper. In the PPAS system, four fisheye cameras are installed in the vehicle with different views, and four channels of video frames captured by the cameras are processed as a 360-deg top-view image around the vehicle. Besides the embedded design of PPAS, the key problem for image distortion correction and mosaicking is the efficiency of parameter optimization in the process of camera calibration. In order to address this problem, an IPSO method is proposed. Compared with other parameter optimization methods, the proposed method allows a certain range of dynamic change for the intrinsic and extrinsic parameters, and can exploit only one reference image to complete all of the optimization; therefore, the efficiency of the whole camera calibration is increased. The PPAS is commercially available, and the IPSO method is a highly practical way to increase the efficiency of the installation and the calibration of PPAS in automobile 4S shops.

Research on particle swarm optimization algorithm based on optimal movement probability

NASA Astrophysics Data System (ADS)

Ma, Jianhong; Zhang, Han; He, Baofeng

2017-01-01

The particle swarm optimization algorithm to improve the control precision, and has great application value training neural network and fuzzy system control fields etc.The traditional particle swarm algorithm is used for the training of feed forward neural networks,the search efficiency is low, and easy to fall into local convergence.An improved particle swarm optimization algorithm is proposed based on error back propagation gradient descent. Particle swarm optimization for Solving Least Squares Problems to meme group, the particles in the fitness ranking, optimization problem of the overall consideration, the error back propagation gradient descent training BP neural network, particle to update the velocity and position according to their individual optimal and global optimization, make the particles more to the social optimal learning and less to its optimal learning, it can avoid the particles fall into local optimum, by using gradient information can accelerate the PSO local search ability, improve the multi beam particle swarm depth zero less trajectory information search efficiency, the realization of improved particle swarm optimization algorithm. Simulation results show that the algorithm in the initial stage of rapid convergence to the global optimal solution can be near to the global optimal solution and keep close to the trend, the algorithm has faster convergence speed and search performance in the same running time, it can improve the convergence speed of the algorithm, especially the later search efficiency.

Low Temperature Regolith Bricks for In-Situ Structural Material

NASA Technical Reports Server (NTRS)

Grossman, Kevin; Sakthivel, Tamil S.; Mantovani, James; Seal, Sudipta

2016-01-01

Current technology for producing in-situ structural materials on future missions to Mars or the moon relies heavily on energy-intensive sintering processes to produce solid bricks from regolith. This process requires heating the material up to temperatures in excess of 1000 C and results in solid regolith pieces with compressive strengths in the range of 14000 to 28000 psi, but are heavily dependent on the porosity of the final material and are brittle. This method is currently preferred over a low temperature cementation process to prevent consumption of precious water and other non-renewable materials. A high strength structural material with low energy requirements is still needed for future colonization of other planets. To fulfill these requirements, a nano-functionalization process has been developed to produce structural bricks from regolith simulant and shows promising mechanical strength results. Functionalization of granular silicate particles into alkoxides using a simple low temperature chemical process produces a high surface area zeolite particles that are held together via inter-particle oxygen bonding. Addition of water in the resulting zeolite particles produces a sol-gel reaction called "inorganic polymerization" which gives a strong solid material after a curing process at 60 C. The aqueous solution by-product of the reaction is currently being investigated for its reusability; an essential component of any ISRU technology. For this study, two batches of regolith bricks are synthesized from JSC-1A; the first batch from fresh solvents and chemicals, the second batch made from the water solution by-product of the first batch. This is done to determine the feasibility of recycling necessary components of the synthesis process, mainly water. Characterization including BET surface area, SEM, and EDS has been done on the regolith bricks as well as the constituent particles,. The specific surface area of 17.53 sq m/g (average) of the granular regolith material was obtained from nitrogen adsorption isotherm measurement. The size, shape and textures of regolith from SEM shows that the particles are 25-50 micrometers in size and mostly irregular in shape (Figure 1a). The elemental composition of regolith was identified from EDS analysis showed the presence of Si, Al, Fe, Na, Mg, Ca, Ti, O and C (see figure 1b). Each set of cylindrical brick samples were prepared by low energy process, and cured for 21 and 28 days, respectively to compare their compressive strength. Figure 1c, and d shows the JSC-1A brick and the compressive strength measurements. The results from the 21 day cured bricks (2 bricks) have been done and yielded an aver-age strength of 3050 psi, considerably higher than Portland cement mortars (Type IV and V). This promising technology provides the benefits of construction material similar to concrete, with a low complexity, low energy synthesis process and the likelihood of complete reusability of precious resources. Compressive strength using this method can be improved by increasing the surface area of the particles, using bi-modal particle size distribution, and adding certain additives to increase inter-particle forces.

Influence of process parameters on content uniformity of a low dose active pharmaceutical ingredient in a tablet formulation according to GMP.

PubMed

Muselík, Jan; Franc, Aleš; Doležel, Petr; Goněc, Roman; Krondlová, Anna; Lukášová, Ivana

2014-09-01

The article describes the development and production of tablets using direct compression of powder mixtures. The aim was to describe the impact of filler particle size and the time of lubricant addition during mixing on content uniformity according to the Good Manufacturing Practice (GMP) process validation requirements. Processes are regulated by complex directives, forcing the producers to validate, using sophisticated methods, the content uniformity of intermediates as well as final products. Cutting down of production time and material, shortening of analyses, and fast and reliable statistic evaluation of results can reduce the final price without affecting product quality. The manufacturing process of directly compressed tablets containing the low dose active pharmaceutical ingredient (API) warfarin, with content uniformity passing validation criteria, is used as a model example. Statistic methods have proved that the manufacturing process is reproducible. Methods suitable for elucidation of various properties of the final blend, e.g., measurement of electrostatic charge by Faraday pail and evaluation of mutual influences of researched variables by partial least square (PLS) regression, were used. Using these methods, it was proved that the filler with higher particle size increased the content uniformity of both blends and the ensuing tablets. Addition of the lubricant, magnesium stearate, during the blending process improved the content uniformity of blends containing the filler with larger particles. This seems to be caused by reduced sampling error due to the suppression of electrostatic charge.

Application of close-packed structures in dental resin composites.

PubMed

Wang, Ruili; Habib, Eric; Zhu, X X

2017-03-01

The inorganic filler particles in dental resin composites serve to improve their mechanical properties and reduce polymerization shrinkage during their use. Efforts have been made in academia and industry to increase the filler particle content, but, few studies examine the theoretical basis for the maximum particle loading. This work evaluates the packing of spherical particles in a close-packed state for highly loaded composites. Calculations show that for low dispersity particles, the maximum amount of particles is 74.05vol%, regardless of the particle size. This can be further improved by using a mix of large and small particles or by the use of non-spherical particles. For representative spherical particles with a diameter of 1000nm, two types of secondary particles with respective sizes of 414nm (d I ) and 225nm (d II ) are selected. The results show that after embedding secondary particles I & II into primary spherical particles, the packing factor is increased to 81.19% for the close-packed structures, which shows an improvement of 9.64%, compared to the 74.05% obtained only with primary spherical particles. This packing factor is also higher than either structure with the embedded secondary particles I or II. Examples of these mixtures with different spherical particle sizes are shown as a theoretical estimation, serving as a guideline for the design and formulation of new dental resin composites with better properties and improved performance. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Particle Physics in High School: A Diagnose Study

PubMed Central

Solbes, Jordi

2016-01-01

The science learning process improves when the contents are connected to students’ lives. Particle physics has had a great impact in our society in the last years and has changed the theoretical picture about matter fundamental dynamics. Thus, we think that academic contents about matter components and interactions should be updated. With this study we aim to characterize the level of knowledge of high school students about this topic. We built a test with questions about classical atomic models, particle physics, recent discoveries, social implications and students opinions about it. Contrary to our first suspicion, students’ answers show a high variability. They have new physics ideas and show a great interest towards modern concepts. We suggest including an updated view of this topic as part of the curriculum. PMID:27253377

Particle Physics in High School: A Diagnose Study.

PubMed

Tuzón, Paula; Solbes, Jordi

2016-01-01

The science learning process improves when the contents are connected to students' lives. Particle physics has had a great impact in our society in the last years and has changed the theoretical picture about matter fundamental dynamics. Thus, we think that academic contents about matter components and interactions should be updated. With this study we aim to characterize the level of knowledge of high school students about this topic. We built a test with questions about classical atomic models, particle physics, recent discoveries, social implications and students opinions about it. Contrary to our first suspicion, students' answers show a high variability. They have new physics ideas and show a great interest towards modern concepts. We suggest including an updated view of this topic as part of the curriculum.

Representation of Arctic mixed-phase clouds and the Wegener-Bergeron-Findeisen process in climate models: Perspectives from a cloud-resolving study

NASA Astrophysics Data System (ADS)

Fan, Jiwen; Ghan, Steven; Ovchinnikov, Mikhail; Liu, Xiaohong; Rasch, Philip J.; Korolev, Alexei

2011-01-01

Two types of Arctic mixed-phase clouds observed during the ISDAC and M-PACE field campaigns are simulated using a 3-dimensional cloud-resolving model (CRM) with size-resolved cloud microphysics. The modeled cloud properties agree reasonably well with aircraft measurements and surface-based retrievals. Cloud properties such as the probability density function (PDF) of vertical velocity (w), cloud liquid and ice, regimes of cloud particle growth, including the Wegener-Bergeron-Findeisen (WBF) process, and the relationships among properties/processes in mixed-phase clouds are examined to gain insights for improving their representation in General Circulation Models (GCMs). The PDF of the simulated w is well represented by a Gaussian function, validating, at least for arctic clouds, the subgrid treatment used in GCMs. The PDFs of liquid and ice water contents can be approximated by Gamma functions, and a Gaussian function can describe the total water distribution, but a fixed variance assumption should be avoided in both cases. The CRM results support the assumption frequently used in GCMs that mixed phase clouds maintain water vapor near liquid saturation. Thus, ice continues to grow throughout the stratiform cloud but the WBF process occurs in about 50% of cloud volume where liquid and ice co-exist, predominantly in downdrafts. In updrafts, liquid and ice particles grow simultaneously. The relationship between the ice depositional growth rate and cloud ice strongly depends on the capacitance of ice particles. The simplified size-independent capacitance of ice particles used in GCMs could lead to large deviations in ice depositional growth.

High throughput screening of particle conditioning operations: I. System design and method development.

PubMed

Noyes, Aaron; Huffman, Ben; Godavarti, Ranga; Titchener-Hooker, Nigel; Coffman, Jonathan; Sunasara, Khurram; Mukhopadhyay, Tarit

2015-08-01

The biotech industry is under increasing pressure to decrease both time to market and development costs. Simultaneously, regulators are expecting increased process understanding. High throughput process development (HTPD) employs small volumes, parallel processing, and high throughput analytics to reduce development costs and speed the development of novel therapeutics. As such, HTPD is increasingly viewed as integral to improving developmental productivity and deepening process understanding. Particle conditioning steps such as precipitation and flocculation may be used to aid the recovery and purification of biological products. In this first part of two articles, we describe an ultra scale-down system (USD) for high throughput particle conditioning (HTPC) composed of off-the-shelf components. The apparatus is comprised of a temperature-controlled microplate with magnetically driven stirrers and integrated with a Tecan liquid handling robot. With this system, 96 individual reaction conditions can be evaluated in parallel, including downstream centrifugal clarification. A comprehensive suite of high throughput analytics enables measurement of product titer, product quality, impurity clearance, clarification efficiency, and particle characterization. HTPC at the 1 mL scale was evaluated with fermentation broth containing a vaccine polysaccharide. The response profile was compared with the Pilot-scale performance of a non-geometrically similar, 3 L reactor. An engineering characterization of the reactors and scale-up context examines theoretical considerations for comparing this USD system with larger scale stirred reactors. In the second paper, we will explore application of this system to industrially relevant vaccines and test different scale-up heuristics. © 2015 Wiley Periodicals, Inc.

Development of Metallic Sensory Alloys

NASA Technical Reports Server (NTRS)

Wallace Terryl A.; Newman, John A.; Horne, Michael R.; Messick, Peter L.

2010-01-01

Existing nondestructive evaluation (NDE) technologies are inherently limited by the physical response of the structural material being inspected and are therefore not generally effective at the identification of small discontinuities, making the detection of incipient damage extremely difficult. One innovative solution to this problem is to enhance or complement the NDE signature of structural materials to dramatically improve the ability of existing NDE tools to detect damage. To address this need, a multifunctional metallic material has been developed that can be used in structural applications. The material is processed to contain second phase sensory particles that significantly improve the NDE response, enhancing the ability of conventional NDE techniques to detect incipient damage both during and after flight. Ferromagnetic shape-memory alloys (FSMAs) are an ideal material for these sensory particles as they undergo a uniform and repeatable change in both magnetic properties and crystallographic structure (martensitic transformation) when subjected to strain and/or temperature changes which can be detected using conventional NDE techniques. In this study, the use of a ferromagnetic shape memory alloy (FSMA) as the sensory particles was investigated.

Radio frequency shielding behaviour of silane treated Fe2O3/E-glass fibre reinforced epoxy hybrid composite

NASA Astrophysics Data System (ADS)

Arun prakash, V. R.; Rajadurai, A.

2016-10-01

In this work, radio frequency shielding behaviour of polymer (epoxy) matrixes composed of E-glass fibres and Fe2O3 fillers have been studied. The principal aim of this project is to prepare suitable shielding material for RFID application. When RFID unit is pasted on a metal plate without shielding material, the sensing distance is reduced, resulting in a less than useful RFID system. To improve RF shielding of epoxy, fibres and fillers were utilized. Magnetic behaviour of epoxy polymer composites was measured by hysteresis graphs (B-H) followed by radio frequency identifier setup. Fe2O3 particles of sizes 800, 200 and 100 nm and E-glass fibre woven mat of 600 g/m2 were used to make composites. Particle sizes of 800 nm and 200 nm were prepared by high-energy ball milling, whereas particles of 100 nm were prepared by sol-gel method. To enhance better dispersion of particles within the epoxy matrix, a surface modification process was carried out on fillers by an amino functional coupling agent called 3-Aminopropyltrimethoxysilane (APTMS). Crystalline and functional groups of siliconized Fe2O3 particles were characterized by XRD and FTIR spectroscopy analysis. Variable quantity of E-glass fibre (25, 35, and 45 vol%) was laid down along with 0.5 and 1.0 vol% of 800, 200, and 100 nm size Fe2O3 particles into the matrix, to fabricate the hybrid composites. Scanning electron microscopy and transmission electron microscopy images reveal the shape and size of Fe2O3 particles for different milling times and particle dispersion in the epoxy matrix. The maximum improved sensing distance of 45.2, 39.4 and 43.5 % was observed for low-, high-, and ultra-high radio frequency identifier setup along with shielding composite consist of epoxy, 1 vol% 200 nm Fe2O3 particles and 45 vol% of E-glass fibre.

Pairwise-interaction extended point-particle model for particle-laden flows

NASA Astrophysics Data System (ADS)

Akiki, G.; Moore, W. C.; Balachandar, S.

2017-12-01

In this work we consider the pairwise interaction extended point-particle (PIEP) model for Euler-Lagrange simulations of particle-laden flows. By accounting for the precise location of neighbors the PIEP model goes beyond local particle volume fraction, and distinguishes the influence of upstream, downstream and laterally located neighbors. The two main ingredients of the PIEP model are (i) the undisturbed flow at any particle is evaluated as a superposition of the macroscale flow and a microscale flow that is approximated as a pairwise superposition of perturbation fields induced by each of the neighboring particles, and (ii) the forces and torque on the particle are then calculated from the undisturbed flow using the Faxén form of the force relation. The computational efficiency of the standard Euler-Lagrange approach is retained, since the microscale perturbation fields induced by a neighbor are pre-computed and stored as PIEP maps. Here we extend the PIEP force model of Akiki et al. [3] with a corresponding torque model to systematically include the effect of perturbation fields induced by the neighbors in evaluating the net torque. Also, we use DNS results from a uniform flow over two stationary spheres to further improve the PIEP force and torque models. We then test the PIEP model in three different sedimentation problems and compare the results against corresponding DNS to assess the accuracy of the PIEP model and improvement over the standard point-particle approach. In the case of two sedimenting spheres in a quiescent ambient the PIEP model is shown to capture the drafting-kissing-tumbling process. In cases of 5 and 80 sedimenting spheres a good agreement is obtained between the PIEP simulation and the DNS. For all three simulations, the DEM-PIEP was able to recreate, to a good extent, the results from the DNS, while requiring only a negligible fraction of the numerical resources required by the fully-resolved DNS.

Development of droplet microfluidic platforms for the synthesis of monodisperse lipid vesicles and polymer particles

NASA Astrophysics Data System (ADS)

Teh, Shia-Yen

This body of work presents my approaches to the design and development of microfluidic platforms for synthesizing monodisperse polymer particles and phospholipid vesicles. There is interest in both of these particles for use in a variety of biomedical applications. Poly(D,L-lactide-co-glycolic acid) (PLGA) particles in particular have been sought out as vehicles for drug delivery due to their biocompatibility and because the rate of degradation -- hence cargo release - can be controlled. On the other hand, liposomes possess membrane structures resembling that of cells, an ability to adopt both hydrophilic and hydrophobic molecules, and are easily functionalized, which make lipid vesicles the ideal candidate for applications ranging from targeted therapeutic delivery to formation of artificial cells. However, current methods of production for both of these particles result in a wide range of sizes and poor cargo uptake efficiency. We address these challenges by utilizing a flow focusing droplet generation design, which allows for fine control over droplet size and improves encapsulation efficiencies. The size of these droplets can be determined by channel geometry and the ratio of fluid flow rates. I will discuss the work I have done to improve upon current technologies to form nano- to micrometer sized PLGA particles and cell-sized lipid vesicles. Solvent evaporation and solvent extraction methods were implemented and tested in several device designs to optimize the formation process. The particles produced were characterized for their stability, size variation, and ability to encapsulate a model drug. The release profiles of PLGA particles were also measured to determine the length of delivery. In addition, I worked on the generation of monodisperse lipid vesicles to investigate the application of liposomes as an artificial cell. As a proof of principle, expression of green fluorescent protein (GFP) was successfully carried out in the lipid vesicles. This demonstrates the versatility of the microfluidic device for generating a range of particles of controlled size for therapeutic agent delivery and artificial cell applications.

Parallel Visualization Co-Processing of Overnight CFD Propulsion Applications

NASA Technical Reports Server (NTRS)

Edwards, David E.; Haimes, Robert

1999-01-01

An interactive visualization system pV3 is being developed for the investigation of advanced computational methodologies employing visualization and parallel processing for the extraction of information contained in large-scale transient engineering simulations. Visual techniques for extracting information from the data in terms of cutting planes, iso-surfaces, particle tracing and vector fields are included in this system. This paper discusses improvements to the pV3 system developed under NASA's Affordable High Performance Computing project.

Effects of preparation process on performance of rubber modified asphalt

NASA Astrophysics Data System (ADS)

Liu, Hanbing; Luo, Guobao; Wang, Xianqiang; Jiao, Yubo

2015-06-01

The rational utilization of waste rubber tire is essential for the environmental protection. Utilizing rubber particles to modify asphalt can not only improve asphalt performance, but also help the recycling of waste materials. Considering the effect of different preparation process parameters on the performance of rubber modified asphalt, this paper analyzes the effects of the shear temperature, shear time and shear rate on the performance of rubber modified asphalt, and provided a reference for its preparation.

Microstructure, Mechanical and Corrosion Properties of Friction Stir-Processed AISI D2 Tool Steel

NASA Astrophysics Data System (ADS)

Yasavol, Noushin; Jafari, Hassan

2015-05-01

In this study, AISI D2 tool steel underwent friction stir processing (FSP). The microstructure, mechanical properties, and corrosion resistance of the FSPed materials were then evaluated. A flat WC-Co tool was used; the rotation rate of the tool varied from 400 to 800 rpm, and the travel speed was maintained constant at 385 mm/s during the process. FSP improved mechanical properties and produced ultrafine-grained surface layers in the tool steel. Mechanical properties improvement is attributed to the homogenous distribution of two types of fine (0.2-0.3 μm) and coarse (1.6 μm) carbides in duplex ferrite-martensite matrix. In addition to the refinement of the carbides, the homogenous dispersion of the particles was found to be more effective in enhancing mechanical properties at 500 rpm tool rotation rate. The improved corrosion resistance was observed and is attributed to the volume fraction of low-angle grain boundaries produced after friction stir process of the AISI D2 steel.

An Improved Elastic and Nonelastic Neutron Transport Algorithm for Space Radiation

NASA Technical Reports Server (NTRS)

Clowdsley, Martha S.; Wilson, John W.; Heinbockel, John H.; Tripathi, R. K.; Singleterry, Robert C., Jr.; Shinn, Judy L.

2000-01-01

A neutron transport algorithm including both elastic and nonelastic particle interaction processes for use in space radiation protection for arbitrary shield material is developed. The algorithm is based upon a multiple energy grouping and analysis of the straight-ahead Boltzmann equation by using a mean value theorem for integrals. The algorithm is then coupled to the Langley HZETRN code through a bidirectional neutron evaporation source term. Evaluation of the neutron fluence generated by the solar particle event of February 23, 1956, for an aluminum water shield-target configuration is then compared with MCNPX and LAHET Monte Carlo calculations for the same shield-target configuration. With the Monte Carlo calculation as a benchmark, the algorithm developed in this paper showed a great improvement in results over the unmodified HZETRN solution. In addition, a high-energy bidirectional neutron source based on a formula by Ranft showed even further improvement of the fluence results over previous results near the front of the water target where diffusion out the front surface is important. Effects of improved interaction cross sections are modest compared with the addition of the high-energy bidirectional source terms.

A thin porous substrate using bonded particles for reverse-emulsion electrophoretic displays

NASA Astrophysics Data System (ADS)

Ahumada, M.; Bryning, M.; Cromer, R.; Hartono, M.; Lee, S. J.

2012-03-01

A thin porous layer of bonded ceramic microparticles has been developed to provide structural integrity and a stationary matrix for use in reflective-mode reverse-emulsion electrophoretic displays (REED), based on self-assembled nanodroplets dispersed in a non-polar liquid. REED ink uses low-cost materials and manufacturing processes, yet is capable of video speed and low voltage operation below 10 V. Porous layers of titanium dioxide (TiO2) are prepared as thin as 10 microns by fluidizing the particles in a water-based slurry with polymeric adhesive. The slurry is distributed between glass shear plates, one of which serves as the substrate for the working device. Particle morphology is examined using scanning electron microscopy and layer uniformity is characterized by opacity measurements using a throughbeam fiber optic sensor. Performance of the bonded matrix with REED ink is compared to baseline performance of a paste mixture, comprised of the same ink and unbonded TiO2 particles. Results show that at 25% volume fraction, the bonded substrate improves image bistability and is better able to maintain both light and dark intensity after extensive switching. The same bonded substrate also improves image bistability when power is disconnected, even compared to a paste with 40% volume fraction of TiO2.

Gene transfer of Hodgkin cell lines via multivalent anti-CD30 scFv displaying bacteriophage.

PubMed

Chung, Yoon-Suk A; Sabel, Katja; Krönke, Martin; Klimka, Alexander

2008-04-16

The display of binding ligands, such as recombinant antibody fragments, on the surface of filamentous phage makes it possible to specifically attach these phage particles to target cells. After uptake of the phage, their internal single-stranded DNA is processed by the host cell, which allows transient expression of an encoded eukaryotic gene cassette. This opens the possibility to use bacteriophage as vectors for targeted gene therapy, although the transduction efficiency is very low. Here we demonstrate the display of an anti-CD30 single chain variable fragment fused to the major coat protein pVIII on the surface of bacteriophage. These phage particles showed an improved binding and transduction efficiency of CD30 positive Hodgkin-lymphoma cells, compared to bacteriophage with the anti-CD30 single chain variable fragment fused to the minor coat protein pIII. We can conclude from the results that the postulated multivalency of the anti-CD30-pVIII displaying bacteriophage combined with disseminated display of the anti-CD30 scFv on the whole particle surface is responsible for the improved gene transfer rate. These results mark an important step towards the use of phage particles as a cheap and safe gene transfer vehicle for the gene delivery of the desired target cells via their specific surface receptors.

Knowledge, as the Result of the Processed Information by Human's Sub-particles (substrings)/Mind in our Brain

NASA Astrophysics Data System (ADS)

Gholibeigian, Hassan

In my vision, there are four animated sub-particles (mater, plant, animal and human sub-particles) as the origin of the life and creator of momentum in each fundamental particle (string). They communicate with dimension of information which is nested with space-time for getting a package of information in each Planck time. They are link-point between dimension of information and space-time. Sub-particle which identifies its fundamental particle, processes the package of information for finding its next step. Processed information carry always by fundamental particles as the history of the universe and enhance its entropy. My proposed formula for calculating number of packages is I =tP- 1 . τ , Planck time tP, and τ is fundamental particle's lifetime. For example a photon needs processes 1 . 8 ×1043 packages of information for finding its path in a second. Duration of each process is faster than light speed. In our bodies, human's sub-particles (substrings) communicate with dimension of information and get packages of information including standard ethics for process and finding their next step. The processed information transforms to knowledge in our mind. This knowledge is always carried by us. Knowledge, as the Result of the Processed Information by Human's Sub-particles (sub-strings)/Mind in our Brain.

Experimental Study of the Microstructure and Micromechanical Properties of Laser Cladded Ni-based Amorphous Composite Coatings

NASA Astrophysics Data System (ADS)

Li, Ruifeng; Zheng, Qichi; Zhu, Yanyan; Li, Zhuguo; Feng, Kai; Liu, Chuan

2018-01-01

(Ni0.6Fe0.4)65B18Si10Nb4C3 amorphous composite coating was successfully fabricated on AISI 1045 steel substrate by using laser cladding process with coaxial powder feeding equipment. The microstructure and phase distribution of the coating were investigated by using x-ray diffraction, scanning electron microscopy and transmission electron microscope. The mechanical properties of the coating were examined by using microhardness testing and nanoindentation. The experimental results indicated that the volume fraction of amorphous phase increased with the decrease in laser cladding heat input, leading to an improvement of mean microhardness and nanohardness. NbC particles in a size ranging between 150 and 1650 nm were found embedding in the amorphous composite coatings in all situations. The presence of the NbC particles can contribute to an improvement of 96.7 HV in hardness on the basis of experimental results, while theoretical prediction suggests an improvement of 92.5 HV by using Orowan-Ashby equation.

Process tool monitoring and matching using interferometry technique

NASA Astrophysics Data System (ADS)

Anberg, Doug; Owen, David M.; Mileham, Jeffrey; Lee, Byoung-Ho; Bouche, Eric

2016-03-01

The semiconductor industry makes dramatic device technology changes over short time periods. As the semiconductor industry advances towards to the 10 nm device node, more precise management and control of processing tools has become a significant manufacturing challenge. Some processes require multiple tool sets and some tools have multiple chambers for mass production. Tool and chamber matching has become a critical consideration for meeting today's manufacturing requirements. Additionally, process tools and chamber conditions have to be monitored to ensure uniform process performance across the tool and chamber fleet. There are many parameters for managing and monitoring tools and chambers. Particle defect monitoring is a well-known and established example where defect inspection tools can directly detect particles on the wafer surface. However, leading edge processes are driving the need to also monitor invisible defects, i.e. stress, contamination, etc., because some device failures cannot be directly correlated with traditional visualized defect maps or other known sources. Some failure maps show the same signatures as stress or contamination maps, which implies correlation to device performance or yield. In this paper we present process tool monitoring and matching using an interferometry technique. There are many types of interferometry techniques used for various process monitoring applications. We use a Coherent Gradient Sensing (CGS) interferometer which is self-referencing and enables high throughput measurements. Using this technique, we can quickly measure the topography of an entire wafer surface and obtain stress and displacement data from the topography measurement. For improved tool and chamber matching and reduced device failure, wafer stress measurements can be implemented as a regular tool or chamber monitoring test for either unpatterned or patterned wafers as a good criteria for improved process stability.

Particle monitoring and control in vacuum processing equipment

NASA Astrophysics Data System (ADS)

Borden, Peter G., Dr.; Gregg, John

1989-10-01

Particle contamination during vacuum processes has emerged as the largest single source of yield loss in VLSI manufacturing. While a number of tools have been available to help understand the sources and nature of this contamination, only recently has it been possible to monitor free particle levels within vacuum equipment in real-time. As a result, a better picture is available of how particle contamination can affect a variety of processes. This paper reviews some of the work that has been done to monitor particles in vacuum loadlocks and in processes such as etching, sputtering and ion implantation. The aim has been to make free particles in vacuum equipment a measurable process parameter. Achieving this allows particles to be controlled using statistical process control. It will be shown that free particle levels in load locks correlate to wafer surface counts, device yield and process conditions, but that these levels are considerable higher during production than when dummy wafers are run to qualify a system. It will also be shown how real-time free particle monitoring can be used to monitor and control cleaning cycles, how major episodic events can be detected, and how data can be gathered in a format suitable for statistical process control.

Interfacial Phenomena in Fe/Stainless Steel-TiC Systems and the Effect of Mo

NASA Astrophysics Data System (ADS)

Kiviö, Miia; Holappa, Lauri; Yoshikawa, Takeshi; Tanaka, Toshihiro

2014-12-01

Titanium carbide is used as reinforcement particles in composites due to its hardness, wear resistance and stability. This work is a part of the study in which titanium carbides are formed in stainless steel castings in the mold to improve the wear resistance of a certain surface of the casting. Such local reinforcement is a very potential method but it is a quite demanding task requiring profound knowledge of interfacial phenomena in the system, wettability, stability, dissolution and precipitation of new phases in production of these materials. Good wetting between different constituents in the material is a key factor to attain maximal positive effects. Mo is used with TiC or Ti(C,N) reinforcement in composites to improve wettability. In this work the effect of Mo on the phenomena in Fe/stainless steel-TiC systems was examined by wetting experiments between the substrate and the alloy. Wetting was not significantly improved by adding Mo to the systems. Core-rim type carbides as well as more homogenous carbide particles were observed. Overall the carbide particles are very complex regarding to their chemistry, size and shape which aspects have to be taken into account in the development of these materials and manufacturing processes.

Chemical Processing and Characterization of Fiber Reinforced Nanocomposite Silica Materials

NASA Astrophysics Data System (ADS)

Burnett, Steven Shannon

Ultrasound techniques, acoustic and electroacoustic spectroscopy, are used to investigate and characterize concentrated fluid phase nanocomposites. In particular, the data obtained from ultrasound methods are used as tools to improve the understanding of the fundamental process chemistry of concentrated, multicomponent, nanomaterial dispersions. Silicon nitride nanofibers embedded in silica are particularly interesting for lightweight nanocomposites, because silicon nitride is isostructural to carbon nitride, a super hard material. However, the major challenge with processing these composites is retarding particle-particle aggregation, to maintain highly dispersed systems. Therefore, a systematic approach was developed to evaluate the affect of process parameters on particle-particle aggregation, and improving the chemical kinetics for gelation. From the acoustic analysis of the nanofibers, this thesis was able to deduce that changes in aspect ratio affects the ultrasound propagation. In particular, higher aspect ratio fibers attenuate the ultrasound wave greater than lower aspect fibers of the same material. Furthermore, our results confirm that changes in attenuation depend on the hydrodynamical interactions between particles, the aspect ratio, and the morphology of the dispersant. The results indicate that the attenuation is greater for fumed silica due to its elastic nature and its size, when compared to silica Ludox. Namely, the larger the size, the greater the attenuation. This attenuation is mostly the result of scattering loss in the higher frequency range. In addition, the silica nanofibers exhibit greater attenuation than their nanoparticle counterparts because of their aspect ratio influences their interaction with the ultrasound wave. In addition, this study observed how 3M NH 4 Cl's acoustic properties changes during the gelation process, and during that change, the frequency dependency deviates from the expected squared of the frequency, until the system becomes fully dense and turns into a pure gel. Moreover, our results demonstrated the use of ultrasound to determine the critical coagulation concentration, and a double logarithm plot of the CVI indicated a possible power law dependency for NH4 Cl concentrations. Lastly, the mechanism of the gelation reaction of colloidal silica, Si(OH) 4(aq) + Si(OH)3(O) --(aq) → Si2O8H5--( aq) + H2O, by an anionic pathway was investigated using density functional theory (DFT). Using transition state theory, the rate constants were obtained by analyzing the potential energy surface at the reactants, saddle point, and the products. In addition, reaction rate constants were investigated in the presence of ammonium chloride (NH 4 Cl) and sodium chloride (NaCl). These salts act as catalysis to induce gelation due to their ability to destabilize the double layer of the colloid. Furthermore, it was observed that ammonium chloride plays an important role by initiating a hydride transfer allowing the reaction to proceed from the second transition state to the final product, and was predicted to be spontaneous for all temperatures. In summary, this thesis provides a comprehensive approach on examining the parameters required for the chemical processing of nanofiber dispersions, thus improving the understanding of the physio-chemical interactions, the gelation mechanism, and their influence on obtaining highly dispersed fluid phase composite systems.

Preparation of brookite TiO2 nanoparticles with small sizes and the improved photovoltaic performance of brookite-based dye-sensitized solar cells.

PubMed

Xu, Jinlei; Wu, Shufang; Jin, Jingpeng; Peng, Tianyou

2016-11-10

Brookite TiO 2 nanoparticles with small sizes (hereafter denoted as BTP particles) were synthesized through the hydrothermal treatment of TiCl 4 solution with Pb(NO 3 ) 2 as an additive. The obtained BTP particles have a large specific surface area (∼122.2 m 2 g -1 ) and relatively uniform particle sizes (∼10 nm) with the coexistence of a small quantity of nanorods with a length of ∼100 nm. When used as a photoanode material for dye-sensitized solar cells (DSSCs), the BTP particles show a much higher dye-loading content than the brookite TiO 2 quasi nanocubes (denoted as BTN particles) with a mean size of ∼50 nm and a specific surface area of ∼34.2 m 2 g -1 that were prepared through a similar hydrothermal process but without the addition of Pb(NO 3 ) 2 . The fabricated BTP film-based solar cell with an optimized film thickness gives a conversion efficiency up to 6.36% with a 74% improvement when compared to the BTN film-based one (3.65%) under AM 1.5G one sun irradiation, while the corresponding bilayer brookite-based solar cell by using brookite TiO 2 submicrometer particles as an overlayer of the BTP film displays a significantly enhanced efficiency of 7.64%. Both of them exceed the current record (5.97%) for the conversion efficiency of pure brookite-based DSSCs reported in the literature. The present results not only demonstrate a really simple synthesis of brookite TiO 2 nanoparticles with both high phase purity and a large surface area, but also offer an efficient approach to improve the photovoltaic performance of brookite-based solar cells by offsetting brookite's inherent shortages such as lower dye-loading and poor conductivity as compared to anatase.

Improved signal recovery for flow cytometry based on ‘spatially modulated emission’

NASA Astrophysics Data System (ADS)

Quint, S.; Wittek, J.; Spang, P.; Levanon, N.; Walther, T.; Baßler, M.

2017-09-01

Recently, the technique of ‘spatially modulated emission’ has been introduced (Baßler et al 2008 US Patent 0080181827A1; Kiesel et al 2009 Appl. Phys. Lett. 94 041107; Kiesel et al 2011 Cytometry A 79A 317-24) improving the signal-to-noise ratio (SNR) for detecting bio-particles in the field of flow cytometry. Based on this concept, we developed two advanced signal processing methods which further enhance the SNR and selectivity for cell detection. The improvements are achieved by adapting digital filtering methods from RADAR technology and mainly address inherent offset elimination, increased signal dynamics and moreover reduction of erroneous detections due to processing artifacts. We present a comprehensive theory on SNR gain and provide experimental results of our concepts.

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.

Modification of Structure and Tribological Properties of the Surface Layer of Metal-Ceramic Composite under Electron Irradiation in the Plasmas of Inert Gases

NASA Astrophysics Data System (ADS)

Ovcharenko, V. E.; Ivanov, K. V.; Mohovikov, A. A.; Yu, B.; Xu, Yu; Zhong, L.

2018-01-01

Metal-ceramic composites are the main materials for high-load parts in tribomechanical systems. Modern approaches to extend the operation life of tribomechanical systems are based on increasing the strength and tribological properties of the surface layer having 100 to 200 microns in depth. The essential improvement of the properties occurs when high dispersed structure is formed in the surface layer using high-energy processing. As a result of the dispersed structure formation the more uniform distribution of elastic stresses takes place under mechanical or thermal action, the energy of stress concentrators emergence significantly increases and the probability of internal defects formation reduces. The promising method to form the dispersed structure in the surface layer is pulse electron irradiation in the plasmas of inert gases combining electron irradiation and ion bombardment in one process. The present work reports upon the effect of pulse electron irradiation in plasmas of different inert gases with different atomic mass and ionization energy on the structure and tribological properties of the surface layer of TiC/(Ni-Cr) metal-ceramic composite with the volume ratio of the component being 50:50. It is experimentally shown that high-dispersed heterophase structure with a fraction of nanosized particles is formed during the irradiation. Electron microscopy study reveals that refining of the initial coarse TiC particles occurs via their dissolution in the molten metal binder followed by the precipitation of secondary fine particles in the interparticle layers of the binder. The depth of modified layer and the fraction of nanosized particles increase when the atomic number of the plasma gas increases and ionization energy decreases. The wear resistance of metal-ceramic composite improves in accordance to the formation of nanocrystalline structure in the surface layer.

Numerical analysis of single and multiple particles of Belchatow lignite dried in superheated steam

NASA Astrophysics Data System (ADS)

Zakrzewski, Marcin; Sciazko, Anna; Komatsu, Yosuke; Akiyama, Taro; Hashimoto, Akira; Kaneko, Shozo; Kimijima, Shinji; Szmyd, Janusz S.; Kobayashi, Yoshinori

2018-03-01

Low production costs have contributed to the important role of lignite in the energy mixes of numerous countries worldwide. High moisture content, though, diminishes the applicability of lignite in power generation. Superheated steam drying is a prospective method of raising the calorific value of this fuel. This study describes the numerical model of superheated steam drying of lignite from the Belchatow mine in Poland in two aspects: single and multi-particle. The experimental investigation preceded the numerical analysis and provided the necessary data for the preparation and verification of the model. Spheres of 2.5 to 30 mm in diameter were exposed to the drying medium at the temperature range of 110 to 170 °C. The drying kinetics were described in the form of moisture content, drying rate and temperature profile curves against time. Basic coal properties, such as density or specific heat, as well as the mechanisms of heat and mass transfer in the particular stages of the process laid the foundations for the model construction. The model illustrated the drying behavior of a single particle in the entire range of steam temperature as well as the sample diameter. Furthermore, the numerical analyses of coal batches containing particles of various sizes were conducted to reflect the operating conditions of the dryer. They were followed by deliberation on the calorific value improvement achieved by drying, in terms of coal ingredients, power plant efficiency and dryer input composition. The initial period of drying was found crucial for upgrading the quality of coal. The accuracy of the model is capable of further improvement regarding the process parameters.

Silicon as anode for high-energy lithium ion batteries: From molten ingot to nanoparticles

NASA Astrophysics Data System (ADS)

Leblanc, Dominic; Hovington, Pierre; Kim, Chisu; Guerfi, Abdelbast; Bélanger, Daniel; Zaghib, Karim

2015-12-01

In this work, we demonstrate that a new mechanical attrition process can be used to prepare nanosilicon powder from metallurgical grade silicon lumps. Composite Li-ion anode made from this nanometer-size powder was found to have a high reversible capacity of 2400 mAh g-1 and an improved cycling stability compared to micrometer-sized powder. It is proposed that improved battery cycling performance is ascribed to the nanoscale silicon particles which supresses the volume expansion owing to its superplasticity.

Centrifugal casting of ZA8 zinc alloy and composite A356/silicon carbide: Study and modeling of phases' and particles' segregation

NASA Astrophysics Data System (ADS)

Balout, Bahaa

Centrifugation is a casting technology that allows the production of cylindrical and graduated parts with different mechanical properties through the section. The need for materials with good quality and specific mechanical properties has been driven this technology in order to produce different types of materials such as zinc alloys and graduated metal matrix composites reinforced by hard and wear resistant particles. The goal of this research project is to study and model the eutectic macrosegregation, the solidification speed, and the speeds of solidification fronts during centrifugal casting of ZA8 zinc-aluminum alloy in order to improve the part quality and increase its strength and field reliability. Moreover, the segregation of the particles during centrifugal casting of an aluminum matrix composite reinforced by silicon carbide particles (A356/SiC) is also studied to improve and control the graduation of the parts. The cooling rate, the speed, acceleration/deceleration, displacement, and segregation of the particles across the section will be modeled by discretization of Stokes' law in time in order to take into consideration the change in the centrifugal radius and melt viscosity during cooling process. This study will allow the control of the graduation degree of particles across the section in order to improve the properties and wear resistance of the composite. This composite can be used in systems where friction is critical and load is high (reinforcements of parts for the cylinders of pneumatic systems). The results show that the maximum macrosegregation zone of the eutectic across the casting section corresponds to the last point of solidification. The eutectic macrosegregation produced during centrifugal casting of thin walled part is a normal segregation which varies depending on the solidification speed and the ratio between the speeds of solidification fronts. On the other hand, it was found that the position and volume fraction of the particles on the outer/inner casting surface and across the section varies whether the viscosity of the liquid metal used and the centrifugal radius are considered constant or variable during the modeling. Modeling the particles' segregation while discretizing, in time, the particles' velocities gives more consistent results compared to those obtained experimentally. Key-words: centrifugal casting, composite, macrosegregation, solidification.

Concept for individualized patient allocation: ReCompare--remote comparison of particle and photon treatment plans.

PubMed

Lühr, Armin; Löck, Steffen; Roth, Klaus; Helmbrecht, Stephan; Jakobi, Annika; Petersen, Jørgen B; Just, Uwe; Krause, Mechthild; Enghardt, Wolfgang; Baumann, Michael

2014-02-18

Identifying those patients who have a higher chance to be cured with fewer side effects by particle beam therapy than by state-of-the-art photon therapy is essential to guarantee a fair and sufficient access to specialized radiotherapy. The individualized identification requires initiatives by particle as well as non-particle radiotherapy centers to form networks, to establish procedures for the decision process, and to implement means for the remote exchange of relevant patient information. In this work, we want to contribute a practical concept that addresses these requirements. We proposed a concept for individualized patient allocation to photon or particle beam therapy at a non-particle radiotherapy institution that bases on remote treatment plan comparison. We translated this concept into the web-based software tool ReCompare (REmote COMparison of PARticlE and photon treatment plans). We substantiated the feasibility of the proposed concept by demonstrating remote exchange of treatment plans between radiotherapy institutions and the direct comparison of photon and particle treatment plans in photon treatment planning systems. ReCompare worked with several tested standard treatment planning systems, ensured patient data protection, and integrated in the clinical workflow. Our concept supports non-particle radiotherapy institutions with the patient-specific treatment decision on the optimal irradiation modality by providing expertise from a particle therapy center. The software tool ReCompare may help to improve and standardize this personalized treatment decision. It will be available from our website when proton therapy is operational at our facility.

Processing and properties of magnesium containing a dense uniform dispersion of nanoparticles.

PubMed

Chen, Lian-Yi; Xu, Jia-Quan; Choi, Hongseok; Pozuelo, Marta; Ma, Xiaolong; Bhowmick, Sanjit; Yang, Jenn-Ming; Mathaudhu, Suveen; Li, Xiao-Chun

2015-12-24

Magnesium is a light metal, with a density two-thirds that of aluminium, is abundant on Earth and is biocompatible; it thus has the potential to improve energy efficiency and system performance in aerospace, automobile, defence, mobile electronics and biomedical applications. However, conventional synthesis and processing methods (alloying and thermomechanical processing) have reached certain limits in further improving the properties of magnesium and other metals. Ceramic particles have been introduced into metal matrices to improve the strength of the metals, but unfortunately, ceramic microparticles severely degrade the plasticity and machinability of metals, and nanoparticles, although they have the potential to improve strength while maintaining or even improving the plasticity of metals, are difficult to disperse uniformly in metal matrices. Here we show that a dense uniform dispersion of silicon carbide nanoparticles (14 per cent by volume) in magnesium can be achieved through a nanoparticle self-stabilization mechanism in molten metal. An enhancement of strength, stiffness, plasticity and high-temperature stability is simultaneously achieved, delivering a higher specific yield strength and higher specific modulus than almost all structural metals.

Physical Investigations of Small Particles: (I) Aerosol Particle Charging and Flux Enhancement and (II) Whispering Gallery Mode Sensing

NASA Astrophysics Data System (ADS)

Lopez-Yglesias, Xerxes

Part I: Particles are a key feature of planetary atmospheres. On Earth they represent the greatest source of uncertainty in the global energy budget. This uncertainty can be addressed by making more measurement, by improving the theoretical analysis of measurements, and by better modeling basic particle nucleation and initial particle growth within an atmosphere. This work will focus on the latter two methods of improvement. Uncertainty in measurements is largely due to particle charging. Accurate descriptions of particle charging are challenging because one deals with particles in a gas as opposed to a vacuum, so different length scales come into play. Previous studies have considered the effects of transition between the continuum and kinetic regime and the effects of two and three body interactions within the kinetic regime. These studies, however, use questionable assumptions about the charging process which resulted in skewed observations, and bias in the proposed dynamics of aerosol particles. These assumptions affect both the ions and particles in the system. Ions are assumed to be point monopoles that have a single characteristic speed rather than follow a distribution. Particles are assumed to be perfect conductors that have up to five elementary charges on them. The effects of three body interaction, ion-molecule-particle, are also overestimated. By revising this theory so that the basic physical attributes of both ions and particles and their interactions are better represented, we are able to make more accurate predictions of particle charging in both the kinetic and continuum regimes. The same revised theory that was used above to model ion charging can also be applied to the flux of neutral vapor phase molecules to a particle or initial cluster. Using these results we can model the vapor flux to a neutral or charged particle due to diffusion and electromagnetic interactions. In many classical theories currently applied to these models, the finite size of the molecule and the electromagnetic interaction between the molecule and particle, especially for the neutral particle case, are completely ignored, or, as is often the case for a permanent dipole vapor species, strongly underestimated. Comparing our model to these classical models we determine an "enhancement factor" to characterize how important the addition of these physical parameters and processes is to the understanding of particle nucleation and growth. Part II: Whispering gallery mode (WGM) optical biosensors are capable of extraordinarily sensitive specific and non-specific detection of species suspended in a gas or fluid. Recent experimental results suggest that these devices may attain single-molecule sensitivity to protein solutions in the form of stepwise shifts in their resonance wavelength, lambdaR, but present sensor models predict much smaller steps than were reported. This study examines the physical interaction between a WGM sensor and a molecule adsorbed to its surface, exploring assumptions made in previous efforts to model WGM sensor behavior, and describing computational schemes that model the experiments for which single protein sensitivity was reported. The resulting model is used to simulate sensor performance, within constraints imposed by the limited material property data. On this basis, we conclude that nonlinear optical effects would be needed to attain the reported sensitivity, and that, in the experiments for which extreme sensitivity was reported, a bound protein experiences optical energy fluxes too high for such effects to be ignored.

Investigating the settling dynamics of cohesive silt particles with particle-resolving simulations

NASA Astrophysics Data System (ADS)

Sun, Rui; Xiao, Heng; Sun, Honglei

2018-01-01

The settling of cohesive sediment is ubiquitous in aquatic environments, and the study of the settling process is important for both engineering and environmental reasons. In the settling process, the silt particles show behaviors that are different from non-cohesive particles due to the influence of inter-particle cohesive force. For instance, the flocs formed in the settling process of cohesive silt can loosen the packing, and thus the structural densities of cohesive silt beds are much smaller than that of non-cohesive sand beds. While there is a consensus that cohesive behaviors depend on the characteristics of sediment particles (e.g., Bond number, particle size distribution), little is known about the exact influence of these characteristics on the cohesive behaviors. In addition, since the cohesive behaviors of the silt are caused by the inter-particle cohesive forces, the motions of and the contacts among silt particles should be resolved to study these cohesive behaviors in the settling process. However, studies of the cohesive behaviors of silt particles in the settling process based on particle-resolving approach are still lacking. In the present work, three-dimensional settling process is investigated numerically by using CFD-DEM (Computational Fluid Dynamics-Discrete Element Method). The inter-particle collision force, the van der Waals force, and the fluid-particle interaction forces are considered. The numerical model is used to simulate the hindered settling process of silt based on the experimental setup in the literature. The results obtained in the simulations, including the structural densities of the beds, the characteristic lines, and the particle terminal velocity, are in good agreement with the experimental observations in the literature. To the authors' knowledge, this is the first time that the influences of non-dimensional Bond number and particle polydispersity on the structural densities of silt beds have been investigated separately. The results demonstrate that the cohesive behavior of silt in the settling process is attributed to both the cohesion among silt particles themselves and the particle polydispersity. To guide to the macro-scale modeling of cohesive silt sedimentation, the collision frequency functions obtained in the numerical simulations are also presented based on the micromechanics of particles. The results obtained by using CFD-DEM indicate that the binary collision theory over-estimated the particle collision frequency in the flocculation process at high solid volume fraction.

Measurement of the aerosol absorption coefficient with the nonequilibrium process

NASA Astrophysics Data System (ADS)

Li, Liang; Li, Jingxuan; Bai, Hailong; Li, Baosheng; Liu, Shanlin; Zhang, Yang

2018-02-01

On the basis of the conventional Jamin interferometer,the improved measuring method is proposed that using a polarization type reentrant Jamin interferometer measures atmospheric aerosol absorption coefficient under the photothermal effect.The paper studies the relationship between the absorption coefficient of atmospheric aerosol particles and the refractive index change of the atmosphere.In Matlab environment, the variation curves of the output voltage of the interferometer with different concentration aerosol samples under stimulated laser irradiation were plotted.Besides, the paper also studies the relationship between aerosol concentration and the time required for the photothermal effect to reach equilibrium.When using the photothermal interferometry the results show that the time required for the photothermal effect to reach equilibrium is also increasing with the increasing concentration of aerosol particles,the absorption coefficient and time of aerosol in the process of nonequilibrium are exponentially changing.

Agricultural runoff pollution control by a grassed swales coupled with wetland detention ponds system: a case study in Taihu Basin, China.

PubMed

Zhao, Jinhui; Zhao, Yaqian; Zhao, Xiaoli; Jiang, Cheng

2016-05-01

The performance of a field grassed swales (GSs) coupled with wetland detention ponds (WDPs) system was monitored under four typical rainfall events to assess its effectiveness on agricultural runoff pollution control in Taihu Basin, China. The results indicated that suspended solids (SS) derived from the flush process has significant influence on pollution loads in agricultural runoff. Determination of first flush effect (FFE) indicated that total suspended solids (TSS) and total phosphorus (TP) exhibited moderate FFE, while chemical oxygen demand (COD) and total nitrogen (TN) showed weak FFE. Average removal efficiencies of 83.5 ± 4.5, 65.3 ± 6.8, 91.6 ± 3.8, and 81.3 ± 5.8 % for TSS, COD, TN, and TP were achieved, respectively. The GSs played an important role in removing TSS and TP and acted as a pre-treatment process to prevent clogging of the subsequent WDPs. Particle size distributions (PSDs) analysis indicated that coarse particles larger than 75 μm accounted for 80 % by weight of the total particles in the runoff. GSs can effectively reduce coarse particles (≥75 μm) in runoff, while its removal efficiency for fine particles (<75 μm) was low, even minus results being recorded, especially for particles smaller than 25 μm. The length of GSs is a key factor in its performance. The WDPs can remove particles of all sizes by sedimentation. In addition, WDPs can improve water quality due to their buffering and dilution capacity during rainfall as well as their water purification ability during dry periods. Overall, the ecological system of GSs coupled with WDPs is an effective system for agricultural runoff pollution control.

Automated Diatom Analysis Applied to Traditional Light Microscopy: A Proof-of-Concept Study

NASA Astrophysics Data System (ADS)

Little, Z. H. L.; Bishop, I.; Spaulding, S. A.; Nelson, H.; Mahoney, C.

2017-12-01

Diatom identification and enumeration by high resolution light microscopy is required for many areas of research and water quality assessment. Such analyses, however, are both expertise and labor-intensive. These challenges motivate the need for an automated process to efficiently and accurately identify and enumerate diatoms. Improvements in particle analysis software have increased the likelihood that diatom enumeration can be automated. VisualSpreadsheet software provides a possible solution for automated particle analysis of high-resolution light microscope diatom images. We applied the software, independent of its complementary FlowCam hardware, to automated analysis of light microscope images containing diatoms. Through numerous trials, we arrived at threshold settings to correctly segment 67% of the total possible diatom valves and fragments from broad fields of view. (183 light microscope images were examined containing 255 diatom particles. Of the 255 diatom particles present, 216 diatoms valves and fragments of valves were processed, with 170 properly analyzed and focused upon by the software). Manual analysis of the images yielded 255 particles in 400 seconds, whereas the software yielded a total of 216 particles in 68 seconds, thus highlighting that the software has an approximate five-fold efficiency advantage in particle analysis time. As in past efforts, incomplete or incorrect recognition was found for images with multiple valves in contact or valves with little contrast. The software has potential to be an effective tool in assisting taxonomists with diatom enumeration by completing a large portion of analyses. Benefits and limitations of the approach are presented to allow for development of future work in image analysis and automated enumeration of traditional light microscope images containing diatoms.

A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films.

PubMed

Revaux, Amelie; Dantelle, Geraldine; George, Nathan; Seshadri, Ram; Gacoin, Thierry; Boilot, Jean-Pierre

2011-05-01

A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 °C), which result in increased particle size and aggregation, and lead to oxidation of Ce(iii) to Ce(iv). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 °C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 °C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 ± 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing. © The Royal Society of Chemistry 2011

Flow chemistry using milli- and microstructured reactors-from conventional to novel process windows.

PubMed

Illg, Tobias; Löb, Patrick; Hessel, Volker

2010-06-01

The terminology Novel Process Window unites different methods to improve existing processes by applying unconventional and harsh process conditions like: process routes at much elevated pressure, much elevated temperature, or processing in a thermal runaway regime to achieve a significant impact on process performance. This paper is a review of parts of IMM's works in particular the applicability of above mentioned Novel Process Windows on selected chemical reactions. First, general characteristics of microreactors are discussed like excellent mass and heat transfer and improved mixing quality. Different types of reactions are presented in which the use of microstructured devices led to an increased process performance by applying Novel Process Windows. These examples were chosen to demonstrate how chemical reactions can benefit from the use of milli- and microstructured devices and how existing protocols can be changed toward process conditions hitherto not applicable in standard laboratory equipment. The used milli- and microstructured reactors can also offer advantages in other areas, for example, high-throughput screening of catalysts and better control of size distribution in a particle synthesis process by improved mixing, etc. The chemical industry is under continuous improvement. So, a lot of research is being done to synthesize high value chemicals, to optimize existing processes in view of process safety and energy consumption and to search for new routes to produce such chemicals. Leitmotifs of such undertakings are often sustainable development(1) and Green Chemistry(2).

A Nonlinear Framework of Delayed Particle Smoothing Method for Vehicle Localization under Non-Gaussian Environment.

PubMed

Xiao, Zhu; Havyarimana, Vincent; Li, Tong; Wang, Dong

2016-05-13

In this paper, a novel nonlinear framework of smoothing method, non-Gaussian delayed particle smoother (nGDPS), is proposed, which enables vehicle state estimation (VSE) with high accuracy taking into account the non-Gaussianity of the measurement and process noises. Within the proposed method, the multivariate Student's t-distribution is adopted in order to compute the probability distribution function (PDF) related to the process and measurement noises, which are assumed to be non-Gaussian distributed. A computation approach based on Ensemble Kalman Filter (EnKF) is designed to cope with the mean and the covariance matrix of the proposal non-Gaussian distribution. A delayed Gibbs sampling algorithm, which incorporates smoothing of the sampled trajectories over a fixed-delay, is proposed to deal with the sample degeneracy of particles. The performance is investigated based on the real-world data, which is collected by low-cost on-board vehicle sensors. The comparison study based on the real-world experiments and the statistical analysis demonstrates that the proposed nGDPS has significant improvement on the vehicle state accuracy and outperforms the existing filtering and smoothing methods.

PSO-tuned PID controller for coupled tank system via priority-based fitness scheme

NASA Astrophysics Data System (ADS)

Jaafar, Hazriq Izzuan; Hussien, Sharifah Yuslinda Syed; Selamat, Nur Asmiza; Abidin, Amar Faiz Zainal; Aras, Mohd Shahrieel Mohd; Nasir, Mohamad Na'im Mohd; Bohari, Zul Hasrizal

2015-05-01

The industrial applications of Coupled Tank System (CTS) are widely used especially in chemical process industries. The overall process is require liquids to be pumped, stored in the tank and pumped again to another tank. Nevertheless, the level of liquid in tank need to be controlled and flow between two tanks must be regulated. This paper presents development of an optimal PID controller for controlling the desired liquid level of the CTS. Two method of Particle Swarm Optimization (PSO) algorithm will be tested in optimizing the PID controller parameters. These two methods of PSO are standard Particle Swarm Optimization (PSO) and Priority-based Fitness Scheme in Particle Swarm Optimization (PFPSO). Simulation is conducted within Matlab environment to verify the performance of the system in terms of settling time (Ts), steady state error (SSE) and overshoot (OS). It has been demonstrated that implementation of PSO via Priority-based Fitness Scheme (PFPSO) for this system is potential technique to control the desired liquid level and improve the system performances compared with standard PSO.

A study of bauxite tailing quality improvement by reverse flotation

NASA Astrophysics Data System (ADS)

Wulandari, W.; Purwasasmita, M.; Sanwani, E.; Malatsih, W.; Fadilla, F.

2018-01-01

The pre-treatment of bauxite ore from Tayan, West Kalimantan includes washing and screening fine bauxite particles (-2mm) prior as the feed to the Bayer process for producing alumina. These fine particles are believed to have high content of silica which is detrimental to the process. This washed bauxite tailing still has a significant amount of alumina content. Previous research has indicated that bauxite ore can be upgraded by applying reverse flotation method to reduce its silica content in the ore. Therefore, this study is aimed to utilize reverse flotation method to recover alumina content from washed bauxite tailing. The reverse flotation experiments were carried out at pH of 6 and 8; while the particle sizes were varied at - 140+270 mesh and -270 mesh, using a batch and circuit configuration. The result of this study shows that the batch reverse flotation can recover alumina in the tailing up to 81.4%, however the silica content is still significant. The complexity of silica-alumina minerals in the tailing prevents a complete separation of the ores by only using reverse flotation.

Synthesis and orientation of barium hexaferrite ceramics by magnetic alignment

NASA Astrophysics Data System (ADS)

Autissier, Denis

1990-01-01

Particles of Ba 2Mn xZn 2- xFe 12O 22 with planar structure were prepared by chemical precipitation. They were processed by sleep casting in presence of a magnetic field. The degree of alignment was improved by a special sintering treatment. By this procedure an alignment as high as 99.9% is obtained.

FLUID PURIFIER AND SEALING VALVE

DOEpatents

Swanton, W.F.

1962-04-24

An improved cold trap designed to condense vapors and collect foreign particles in a flowing fluid is described. In the arrangement, a valve is provided to prevent flow reversal in case of pump failure and to act as a sealing valve. Provision is made for reducing the temperature of the fluid being processed, including a pre-cooling stage. (AEC)

Virus Characterization by FFF-MALS Assay

NASA Astrophysics Data System (ADS)

Razinkov, Vladimer

2009-03-01

Adequate biophysical characterization of influenza virions is important for vaccine development. The influenza virus vaccines are produced from the allantoic fluid of developing chicken embryos. The process of viral replication produces a heterogeneous mixture of infectious and non-infectious viral particles with varying states of aggregation. The study of the relative distribution and behavior of different subpopulations and their inter-correlation can assist in the development of a robust process for a live virus vaccine. This report describes a field flow fractionation and multiangle light scattering (FFF-MALS) method optimized for the analysis of size distribution and total particle counts. A method using a combination of asymmetric flow field-flow fractionation (AFFFF) and multiangle light scattering (MALS) techniques has been shown to improve the estimation of virus particle counts and the amount of aggregated virus in laboratory samples. The FFF-MALS method was compared with several other methods such as transmission electron microscopy (TEM), atomic force microscopy (AFM), size exclusion chromatography followed by MALS (SEC-MALS), quantitative reverse transcription polymerase chain reaction (RT Q-PCR), median tissue culture dose (TCID(50)), and the fluorescent focus assay (FFA). The correlation between the various methods for determining total particle counts, infectivity and size distribution is reported. The pros and cons of each of the analytical methods are discussed.

The Sectional Stratospheric Sulfate Aerosol module (S3A-v1) within the LMDZ general circulation model: description and evaluation against stratospheric aerosol observations

NASA Astrophysics Data System (ADS)

Kleinschmitt, Christoph; Boucher, Olivier; Bekki, Slimane; Lott, François; Platt, Ulrich

2017-09-01

Stratospheric aerosols play an important role in the climate system by affecting the Earth's radiative budget as well as atmospheric chemistry, and the capabilities to simulate them interactively within global models are continuously improving. It is important to represent accurately both aerosol microphysical and atmospheric dynamical processes because together they affect the size distribution and the residence time of the aerosol particles in the stratosphere. The newly developed LMDZ-S3A model presented in this article uses a sectional approach for sulfate particles in the stratosphere and includes the relevant microphysical processes. It allows full interaction between aerosol radiative effects (e.g. radiative heating) and atmospheric dynamics, including e.g. an internally generated quasi-biennial oscillation (QBO) in the stratosphere. Sulfur chemistry is semi-prescribed via climatological lifetimes. LMDZ-S3A reasonably reproduces aerosol observations in periods of low (background) and high (volcanic) stratospheric sulfate loading, but tends to overestimate the number of small particles and to underestimate the number of large particles. Thus, it may serve as a tool to study the climate impacts of volcanic eruptions, as well as the deliberate anthropogenic injection of aerosols into the stratosphere, which has been proposed as a method of geoengineering to abate global warming.

Improved Mo-Re VPS Alloys for High-Temperature Uses

NASA Technical Reports Server (NTRS)

Hickman, Robert; Martin, James; McKechnie, Timothy; O'Dell, John Scott

2011-01-01

Dispersion-strengthened molybdenum- rhenium alloys for vacuum plasma spraying (VPS) fabrication of high-temperature-resistant components are undergoing development. In comparison with otherwise equivalent non-dispersion-strengthened Mo-Re alloys, these alloys have improved high-temperature properties. Examples of VPS-fabricated high-temperature-resistant components for which these alloys are expected to be suitable include parts of aircraft and spacecraft engines, furnaces, and nuclear power plants; wear coatings; sputtering targets; x-ray targets; heat pipes in which liquid metals are used as working fluids; and heat exchangers in general. These alloys could also be useful as coating materials in some biomedical applications. The alloys consist of 60 weight percent Mo with 40 weight percent Re made from (1) blends of elemental Mo and Re powders or (2) Re-coated Mo particles that have been subjected to a proprietary powder-alloying-and-spheroidization process. For most of the dispersion- strengthening experiments performed thus far in this development effort, 0.4 volume percent of transition-metal ceramic dispersoids were mixed into the feedstock powders. For one experiment, the proportion of dispersoid was 1 volume percent. In each case, the dispersoid consisted of either ZrN particles having sizes <45 m, ZrO2 particles having sizes of about 1 m, HfO2 particles having sizes <45 m, or HfN particles having sizes <1 m. These materials were chosen for evaluation on the basis of previously published thermodynamic stability data. For comparison, Mo-Re feedstock powders without dispersoids were also prepared.

Micronization of Taxifolin by Supercritical Antisolvent Process and Evaluation of Radical Scavenging Activity

PubMed Central

Zu, Shuchong; Yang, Lei; Huang, Jinming; Ma, Chunhui; Wang, Wenjie; Zhao, Chunjian; Zu, Yuangang

2012-01-01

The aim of this study was to prepare micronized taxifolin powder using the supercritical antisolvent precipitation process to improve the dissolution rate of taxifolin. Ethanol was used as solvent and carbon dioxide was used as an antisolvent. The effects of process parameters, such as temperature (35–65 °C), pressure (10–25 MPa), solution flow rate (3–6 mL/min) and concentration of the liquid solution (5–20 mg/mL) on the precipitate crystals were investigated. With a lower temperature, a stronger pressure and a lower concentration of the liquid solution, the size of crystals decreased. The precipitation temperature, pressure and concentration of taxifolin solution had a significant effect. However, the solution flow rate had a negligible effect. It was concluded that the physicochemical properties and dissolution rate of crystalline taxifolin could be improved by physical modification such as particle size reduction using the supercritical antisolvent (SAS) process. Further, the SAS process was a powerful methodology for improving the physicochemical properties and radical scavenging activity of taxifolin. PMID:22942740

Improved Vemurafenib Dissolution and Pharmacokinetics as an Amorphous Solid Dispersion Produced by KinetiSol® Processing.

PubMed

Ellenberger, Daniel J; Miller, Dave A; Kucera, Sandra U; Williams, Robert O

2018-03-14

Vemurafenib is a poorly soluble, low permeability drug that has a demonstrated need for a solubility-enhanced formulation. However, conventional approaches for amorphous solid dispersion production are challenging due to the physiochemical properties of the compound. A suitable and novel method for creating an amorphous solid dispersion, known as solvent-controlled coprecipitation, was developed to make a material known as microprecipitated bulk powder (MBP). However, this approach has limitations in its processing and formulation space. In this study, it was hypothesized that vemurafenib can be processed by KinetiSol into the same amorphous formulation as MBP. The KinetiSol process utilizes high shear to rapidly process amorphous solid dispersions containing vemurafenib. Analysis of the material demonstrated that KinetiSol produced amorphous, single-phase material with acceptable chemical purity and stability. Values obtained were congruent to analysis conducted on the comparator material. However, the materials differed in particle morphology as the KinetiSol material was dense, smooth, and uniform while the MBP comparator was porous in structure and exhibited high surface area. The particles produced by KinetiSol had improved in-vitro dissolution and pharmacokinetic performance for vemurafenib compared to MBP due to slower drug nucleation and recrystallization which resulted in superior supersaturation maintenance during drug release. In the in-vivo rat pharmacokinetic study, both amorphous solid dispersions produced by KinetiSol exhibited mean AUC values at least two-fold that of MBP when dosed as a suspension. It was concluded that the KinetiSol process produced superior dosage forms containing vemurafenib with the potential for substantial reduction in patient pill burden.

Tribological Analysis of Copper-Coated Graphite Particle-Reinforced A359 Al/5 wt.% SiC Composites

NASA Astrophysics Data System (ADS)

Lin, C. B.; Wang, T. C.; Chang, Z. C.; Chu, H. Y.

2013-01-01

Copper-coated graphite particles can be mass-produced by the cementation process using simple equipment. Graphite particulates that were coated with electroless copper and 5 wt.% SiC particulates were introduced into an aluminum alloy by compocasting to make A359 Al/5 wt.% SiC(p) composite that contained 2, 4, 6, and 8 wt.% graphite particulate composite. The effects of SiC particles, quantity of graphite particles, normal loading, sliding speed and wear debris on the coefficient of friction, and the wear rate were investigated. The results thus obtained indicate that the wear properties were improved by adding small amounts of SiC and graphite particles into the A359 Al alloy. The coefficient of friction of the A359 Al/5 wt.% SiC(p) composite that contained 6.0 wt.% graphite particulates was reduced to 0.246 and the amount of graphite film that was released on the worn surface increased with the graphite particulate content. The coefficient of friction and the wear rate were insensitive to the variation in the sliding speed and normal loading.

Modeling the Hydrological Cycle in the Atmosphere of Mars: Influence of a Bimodal Size Distribution of Aerosol Nucleation Particles

NASA Astrophysics Data System (ADS)

Shaposhnikov, Dmitry S.; Rodin, Alexander V.; Medvedev, Alexander S.; Fedorova, Anna A.; Kuroda, Takeshi; Hartogh, Paul

2018-02-01

We present a new implementation of the hydrological cycle scheme into a general circulation model of the Martian atmosphere. The model includes a semi-Lagrangian transport scheme for water vapor and ice and accounts for microphysics of phase transitions between them. The hydrological scheme includes processes of saturation, nucleation, particle growth, sublimation, and sedimentation under the assumption of a variable size distribution. The scheme has been implemented into the Max Planck Institute Martian general circulation model and tested assuming monomodal and bimodal lognormal distributions of ice condensation nuclei. We present a comparison of the simulated annual variations, horizontal and vertical distributions of water vapor, and ice clouds with the available observations from instruments on board Mars orbiters. The accounting for bimodality of aerosol particle distribution improves the simulations of the annual hydrological cycle, including predicted ice clouds mass, opacity, number density, and particle radii. The increased number density and lower nucleation rates bring the simulated cloud opacities closer to observations. Simulations show a weak effect of the excess of small aerosol particles on the simulated water vapor distributions.

Particle tracing modeling of ion fluxes at geosynchronous orbit

DOE PAGES

Brito, Thiago V.; Woodroffe, Jesse; Jordanova, Vania K.; ...

2017-10-31

The initial results of a coupled MHD/particle tracing method to evaluate particle fluxes in the inner magnetosphere are presented. This setup is capable of capturing the earthward particle acceleration process resulting from dipolarization events in the tail region of the magnetosphere. On the period of study, the MHD code was able to capture a dipolarization event and the particle tracing algorithm was able to capture our results of these disturbances and calculate proton fluxes in the night side geosynchronous orbit region. The simulation captured dispersionless injections as well as the energy dispersion signatures that are frequently observed by satellites atmore » geosynchronous orbit. Currently, ring current models rely on Maxwellian-type distributions based on either empirical flux values or sparse satellite data for their boundary conditions close to geosynchronous orbit. In spite of some differences in intensity and timing, the setup presented here is able to capture substorm injections, which represents an improvement regarding a reverse way of coupling these ring current models with MHD codes through the use of boundary conditions.« less

Particle tracing modeling of ion fluxes at geosynchronous orbit

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

Brito, Thiago V.; Woodroffe, Jesse; Jordanova, Vania K.

The initial results of a coupled MHD/particle tracing method to evaluate particle fluxes in the inner magnetosphere are presented. This setup is capable of capturing the earthward particle acceleration process resulting from dipolarization events in the tail region of the magnetosphere. On the period of study, the MHD code was able to capture a dipolarization event and the particle tracing algorithm was able to capture our results of these disturbances and calculate proton fluxes in the night side geosynchronous orbit region. The simulation captured dispersionless injections as well as the energy dispersion signatures that are frequently observed by satellites atmore » geosynchronous orbit. Currently, ring current models rely on Maxwellian-type distributions based on either empirical flux values or sparse satellite data for their boundary conditions close to geosynchronous orbit. In spite of some differences in intensity and timing, the setup presented here is able to capture substorm injections, which represents an improvement regarding a reverse way of coupling these ring current models with MHD codes through the use of boundary conditions.« less

A Novel Multi-Sensor Environmental Perception Method Using Low-Rank Representation and a Particle Filter for Vehicle Reversing Safety

PubMed Central

Zhang, Zutao; Li, Yanjun; Wang, Fubing; Meng, Guanjun; Salman, Waleed; Saleem, Layth; Zhang, Xiaoliang; Wang, Chunbai; Hu, Guangdi; Liu, Yugang

2016-01-01

Environmental perception and information processing are two key steps of active safety for vehicle reversing. Single-sensor environmental perception cannot meet the need for vehicle reversing safety due to its low reliability. In this paper, we present a novel multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. The proposed system consists of four main steps, namely multi-sensor environmental perception, information fusion, target recognition and tracking using low-rank representation and a particle filter, and vehicle reversing speed control modules. First of all, the multi-sensor environmental perception module, based on a binocular-camera system and ultrasonic range finders, obtains the distance data for obstacles behind the vehicle when the vehicle is reversing. Secondly, the information fusion algorithm using an adaptive Kalman filter is used to process the data obtained with the multi-sensor environmental perception module, which greatly improves the robustness of the sensors. Then the framework of a particle filter and low-rank representation is used to track the main obstacles. The low-rank representation is used to optimize an objective particle template that has the smallest L-1 norm. Finally, the electronic throttle opening and automatic braking is under control of the proposed vehicle reversing control strategy prior to any potential collisions, making the reversing control safer and more reliable. The final system simulation and practical testing results demonstrate the validity of the proposed multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. PMID:27294931

A Novel Multi-Sensor Environmental Perception Method Using Low-Rank Representation and a Particle Filter for Vehicle Reversing Safety.

PubMed

Zhang, Zutao; Li, Yanjun; Wang, Fubing; Meng, Guanjun; Salman, Waleed; Saleem, Layth; Zhang, Xiaoliang; Wang, Chunbai; Hu, Guangdi; Liu, Yugang

2016-06-09

Environmental perception and information processing are two key steps of active safety for vehicle reversing. Single-sensor environmental perception cannot meet the need for vehicle reversing safety due to its low reliability. In this paper, we present a novel multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. The proposed system consists of four main steps, namely multi-sensor environmental perception, information fusion, target recognition and tracking using low-rank representation and a particle filter, and vehicle reversing speed control modules. First of all, the multi-sensor environmental perception module, based on a binocular-camera system and ultrasonic range finders, obtains the distance data for obstacles behind the vehicle when the vehicle is reversing. Secondly, the information fusion algorithm using an adaptive Kalman filter is used to process the data obtained with the multi-sensor environmental perception module, which greatly improves the robustness of the sensors. Then the framework of a particle filter and low-rank representation is used to track the main obstacles. The low-rank representation is used to optimize an objective particle template that has the smallest L-1 norm. Finally, the electronic throttle opening and automatic braking is under control of the proposed vehicle reversing control strategy prior to any potential collisions, making the reversing control safer and more reliable. The final system simulation and practical testing results demonstrate the validity of the proposed multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety.

Structural and Functional Properties of Soy Protein Isolates Modified by Soy Soluble Polysaccharides.

PubMed

Xu, Yan-Teng; Liu, Ling-Ling

2016-09-28

Aiming to achieve the modification to soy protein isolate (SPI) by soy soluble polysaccharides (SSPS), electrically driven complex systems were first established in the environment of pH 3.0, and then reconstituted SPI particles with different SPI-SSPS ratios were obtained under freeze-drying process. Through this treatment, the structures of SPI particles were partly unfolded and adsorbed SSPS mainly via hydrophobic interactions and hydrogen bonding with larger particle sizes. The adherence of SSPS decreased the surface hydrophobicity of reconstituted SPI particles, but exerted not much influence on the emulsifying and foaming activities and increased the corresponding stabilities due to enhancing the unfolded extent of structure and improving the conformation flexibility. Reconstituted SPI-SSPS particles might rearrange and link each other due to the presence of SSPS on the air-water interface to better stabilize these systems. At SPI-SSPS ratio of 10:1, lower temperature was required to form gels with lower gel intensity and porous structure. The findings provide a further comprehension to the relationship between structures and functional properties of SPI modified by SSPS and the feasibility of applying these reconstituted particles to needed areas.

Tracking Debris Shed by a Space-Shuttle Launch Vehicle

NASA Technical Reports Server (NTRS)

Stuart, Phillip C.; Rogers, Stuart E.

2009-01-01

The DEBRIS software predicts the trajectories of debris particles shed by a space-shuttle launch vehicle during ascent, to aid in assessing potential harm to the space-shuttle orbiter and crew. The user specifies the location of release and other initial conditions for a debris particle. DEBRIS tracks the particle within an overset grid system by means of a computational fluid dynamics (CFD) simulation of the local flow field and a ballistic simulation that takes account of the mass of the particle and its aerodynamic properties in the flow field. The computed particle trajectory is stored in a file to be post-processed by other software for viewing and analyzing the trajectory. DEBRIS supplants a prior debris tracking code that took .15 minutes to calculate a single particle trajectory: DEBRIS can calculate 1,000 trajectories in .20 seconds on a desktop computer. Other improvements over the prior code include adaptive time-stepping to ensure accuracy, forcing at least one step per grid cell to ensure resolution of all CFD-resolved flow features, ability to simulate rebound of debris from surfaces, extensive error checking, a builtin suite of test cases, and dynamic allocation of memory.

Inertial particles in a shearless mixing layer: direct numerical simulations

NASA Astrophysics Data System (ADS)

Ireland, Peter; Collins, Lance

2010-11-01

Entrainment, the drawing in of external fluid by a turbulent flow, is present in nearly all turbulent processes, from exhaust plumes to oceanic thermoclines to cumulus clouds. While the entrainment of fluid and of passive scalars in turbulent flows has been studied extensively, comparatively little research has been undertaken on inertial particle entrainment. We explore entrainment of inertial particles in a shearless mixing layer across a turbulent-non-turbulent interface (TNI) and a turbulent-turbulent interface (TTI) through direct numerical simulation (DNS). Particles are initially placed on one side of the interface and are advanced in time in decaying turbulence. Our results show that the TTI is more efficient in mixing droplets than the TNI. We also find that without the influence of gravity, over the range of Stokes numbers present in cumulus clouds, particle concentration statistics are essentially independent of the dissipation scale Stokes number. The DNS data agrees with results from experiments performed in a wind tunnel with close parametric overlap. We anticipate that a better understanding of the role of gravity and turbulence in inertial particle entrainment will lead to improved cloud evolution predictions and more accurate climate models. Sponsored by the U.S. NSF.

Aging of Secondary Organic Aerosol from β-Pinene: Changes in Chemical Composition, Density and Morphology

NASA Astrophysics Data System (ADS)

Sarrafzadeh, M.; Hastie, D. R.

2013-12-01

Biogenic volatile organic compounds (VOC) are emitted in large quantities into the atmosphere. These VOC, which includes β-pinene, can react to produce secondary organic aerosols (SOA), which contribute to a substantial fraction of ambient organic aerosols and are known to adversely affect visibility, climate and health. Despite this, the current knowledge regarding the SOA composition, their physical properties and the chemical aging processes they undergo in the atmosphere is limited. In this study, chemical aging of SOA generated from the photooxidation of β-pinene was investigated in the York University smog chamber. The formation and aging of both gas and particle phase products were analyzed using an atmospheric pressure chemical ionization triple quadrupole mass spectrometer. The density of secondary organic matter was also simultaneously measured over the course of the aging experiments, allowing us to improve our understanding in changes in particle composition that may occur. In addition, particle phase and shape was investigated for generated particles from β-pinene oxidation by scanning electron microscope (SEM). Results of this work, including particle density and morphology will be presented as well as comparisons of gas and particle phase products time profiles during aging.