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Size Analysis (size + analysis)
Kinds of Size Analysis Selected AbstractsA Novel Device for Single Particle Light Scattering Size Analysis and Concentration Measurement at High Pressures and TemperaturesPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 2 2008Heinz Umhauer Abstract Based on the findings of previous work, a novel instrument was developed for the size analysis and concentration measurement of particles dispersed in gases at high temperatures (600,°C) and pressures (16 bar). The main motivation for the construction of this device was a measurement requirement at the conditions of a pressurized pulverized coal combustion (PPCC) test installation in Dorsten, Germany. The development of a high efficiency (>,50,%), coal based, combined cycle process, and specifically, the development of efficient gas cleaning technology for gas combustion under demanding conditions (1400,°C and 16 bar) was the main target. A suitable measurement technique was required for the determination of particle size and concentration downstream of the gas cleaning equipment, which is able to operate close to the given conditions. The performance of the novel device was tested in several measurement series with various monodisperse aerosols at ambient conditions as well as in high pressure, high temperature situations with very satisfactory results, i.e., the lower detection limit (50,% counting efficiency at ca. 0.3 ,m) and resolution of the novel device are comparable to state of the art instruments (of the same principle) intended for room temperature operation. [source] Single Particle Detection and Size Analysis with Statistical Methods from Particle Imaging DataPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 2 2006Benno Wessely Abstract The application of imaging techniques for particle characterization in the micrometer range is often advantageous under process conditions. Particle imaging analysis of disperse systems not only allows the evaluation of the particle size, but also the concentration of particles and particle shape. Under process conditions online imaging techniques have to deal with high particle concentrations and sometimes with high velocities. Two general principles for the evaluation of particle images are discussed in this paper: particle analysis by means of object identification and a statistical method to analyze overlapping clusters of particles. [source] Variations in Grain Size Analysis with a Time-of-Transition Laser Sizer (Galai CIS-50) using a Gravitational Flow SystemPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 6 2004Björn Bohling Abstract This study deals with grain size analysis with a Laser Sizer Galai CIS-50. This device utilizes the time-of-transition method and is equipped with a module for measurements in the range 0.5 to 150,,m along with a gravitational flow system. Experiments were conducted using natural marine sediments. The aim was to determine possible explanations for discrepancies in the measured results that occurred between different operators of the Galai CIS-50. These discrepancies may be due to differences in the technique of inserting a sub-sample into the measurement system. Furthermore, the influence of the sample concentration and the flow velocity in the device's liquid flow cell is considered, since these factors can act as potential sources of inaccuracies and errors in the experimental setup. Strong variations in the results occurred, which were mainly due to problems in the detection of particles >20,,m. In the range>20,,m gaps appeared in the registration of the size distribution. An improvement in reproducibility was achieved by using a pipette instead of a beaker for the insertion step. Nevertheless, the standard deviation for mean grain sizes of natural marine sediments obtained with the Galai CIS-50 is still about 20%. [source] Impact of Grain Size on the Cerchar Abrasiveness TestGEOMECHANICS AND TUNNELLING, Issue 1 2008Klaus Lassnig Mag. The Cerchar abrasiveness test is a common testing procedure for the prediction of tool wear but consistent and detailed recommendations of the testing procedure are inexistent until now. One point of disagreement is the required number of scratch tests per sample to obtain reliable results depending on the grain size of the samples. The focus of this work was to verify the influence of grain size on the number of required single examinations per sample. Grain size analyses were performed to get sum-curves of each tested rock sample. From the grain size data the median and the interquartile range of the grain sizes were calculated. CAI values after 5 and after 10 scratch tests were compared with the median and the interquartile-range of the grain size. No grain size dependency of the CAI deviation between 5 and 10 tests in the analysed range was observed. Einfluss der Korngröße auf den Cerchar Abrasivitätstest Der Cerchar-Abrasivitätstest ist ein häufig verwendeter Indextest zur Ermittlung der Abrasivität von Gesteinen gegenüber Bohrwerkzeugen. Bis jetzt existieren keine einheitlichen und detaillierten Empfehlungen für die Durchführung des Tests. Insbesondere gilt das für die Anzahl der durchzuführenden Tests in Abhängigkeit von der Korngröße der Gesteine. Es existiert lediglich ein Empfehlung, wonach bei grobkörnigen Gesteinen zehn anstatt der sonst üblichen fünf Tests durchzuführen seien. In dieser Arbeit wird der Einfluss der Korngröße auf das Testergebnis in Abhängigkeit von der Anzahl der Tests untersucht. Dazu wurden an den getesteten Proben die Korngrößen bestimmt. Von den Korngrößendaten wurden die statistische Parameter Median und Interquartile-range, berechnet. Die CAI Ergebnisse nach fünf Ritztests und nach zehn Ritztest wurden dann mit dem Median und dem Interquartile-range der Korngrößen verglichen. Im untersuchten Korngrößenbereich wurde kein Einfluss der Korngröße auf die Differenzwerte von fünf und zehn Tests beobachtet. Daraus kann abgeleitet werden, dass im untersuchten Korngrößenbereich die Korngröße , entgegen den bisherigen Annahmen , keinen messbaren Einfluss auf das Ergebnis des CAI-Tests hat. [source] Synthesis of Dense TiB2 -TiN Nanocrystalline Composites through Mechanical and Field ActivationJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2001Jae Won Lee The synthesis of dense nanometric composites of TiN-TiB2 by mechanical and field activation was investigated. Powder mixtures of Ti, BN, and B were mechanically activated through ball milling. Some powders were milled to reduce crystallite size but to avoid initiating a reaction. In other cases powders were milled and allowed to partially react. All these were subsequently reacted in a spark plasma synthesis (SPS) apparatus. The products were composites with equimolar nitride and boride components with relative densities ranging from 90.1% to 97.2%. Crystallite size analyses using the XRD treatments of Williamson-Hall and Halder-Wagner gave crystallite sizes for the TiN and TiB2 components in the range 38.5,62.5 and 31.2,58.8 nm, respectively. Vickers microhardness measurements (at 2 N force) on the dense samples gave values ranging from 14.8 to 21.8 GPa and fracture toughness determinations (at 20 N) resulted in values ranging from 3.32 to 6.50 MPa·m1/2. [source] Long-term effective population size of three endangered Colorado River fishesANIMAL CONSERVATION, Issue 2 2002Daniel Garrigan The extant genetic variation of a population is the legacy of both long-term and recent population dynamics. Most practical methods for estimating effective population size are only able to detect recent effects on genetic variation and do not account for long-term fluctuations in species abundance. The utility of a maximum likelihood estimator of long-term effective population size based upon the coalescent theory of gene genealogies is examined for three endangered Colorado River fishes: humpback chub (Gila cypha), bonytail chub (Gila elegans) and razorback sucker (Xyrauchen texanus). Extant mitochondrial DNA (mtDNA) variation in humpback chub suggests this species has retained its historical equilibrium genetic variation despite recent declines in abundance. The mtDNA variation in razorback suckers indicates the population was quite large and expanding prior to recent declines and that rare alleles still survive in the remnant populations. The remaining mtDNA variation in bonytail chub indicates that dramatic, recent declines may have already obliterated a substantial portion of any historical variation. The results from long-term effective population size analyses are consistent with known natural history and illustrate the utility of the analysis for endangered species management. [source] Transformation behaviors of excluded pyrite during O2/CO2 combustion of pulverized coalASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010Changdong Sheng Abstract The article was addressed to the transformation of excluded pyrite during O2/CO2 combustion of pulverized coal. Raw pyrite mineral was added to a pulverized coal sample, which was density fractionated to remove the excluded minerals, to simulate the excluded pyrite present in coal. The mixed sample was burned in a drop tube furnace in O2/CO2 and O2/N2 conditions to generate the residue ash, which was characterized by Mössbauer spectroscopic and size analyses. It was found that, in comparison with O2/N2 combustion at the same oxygen concentration, slightly less iron glass silicate was formed from excluded pyrite and silicates although the transformation of pyrite to oxides was slowed in O2/CO2 combustion, different from the behaviors of included pyrite in pulverized coal those were observed in previous study. Additionally, less fragmentation of excluded pyrite particles was also observed in O2/CO2 combustion. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] NGF and GDNF ameliorate the increase in ATF3 expression which occurs in dorsal root ganglion cells in response to peripheral nerve injuryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004Sharon Averill Abstract Activating transcription factor-3 (ATF3) is a member of the ATF/CREB transcription factor superfamily and is induced in dorsal root ganglion (DRG) cells after nerve injury. In order to study the regulation of ATF3, we have examined the effect of nerve growth factor (NGF) and glial cell line-derived neurotrophic factor (GDNF) on ATF3 expression. In untreated rats, sciatic nerve transection induced ATF3 immunoreactivity in 82% of L4 DRG cells at 14 days after axotomy. Intrathecal delivery of NGF or GDNF for 2 weeks commencing immediately after injury reduced the ATF3 expression to 35 and 23% of DRG cells, respectively. Cell size analysis indicated that NGF had protected a population of mainly small- to medium-sized cells, but that the GDNF had protected a population of both small and large cells. This effect was confirmed by double labelling for P2X3, CGRP and 200 kDa neurofilament, markers for small peptide-poor cells, peptide-rich cells and large cells, respectively. Thus GDNF reduced the percentage of ATF3-immunoreactive P2X3 cells from 70 to 4%, and the percentage of ATF3-immunoreactive neurofilament cells from 63 to 24%. NGF was less effective than GDNF in reducing ATF3 expression in these cell types, but reduced the percentage of ATF3-immunoreactive CGRP cells from 10% to <,1%. These results show that ATF3 expression in specific populations of DRG cells can be modulated by exogenous supplementation of specific trophic factors, and suggest that ATF3 expression may normally be induced by the loss of target-derived NGF and GDNF. [source] Variations of magnetic susceptibility and fine quartz accumulation rate in Daisen loam over the past 200 000 years: Interaction between winter and summer monsoons in south-west JapanISLAND ARC, Issue 2 2001Jun-Ichi Kimura Abstract A loam section near Daisen volcano, South-west Japan, has been examined for low-field magnetic susceptibility (MS) and fine quartz accumulation rate. Fission track dating of tephra layers interbedded in the deposit shows that the loam age ranges from about 200 ka to the Present. The MS was measured for both bulk sample and the < 63 ,m fine fraction. Fine quartz contents in the < 63 ,m fraction were also determined using acid-alkali digestions and recalculated to derive fine quartz accumulation rate (Rqz). Grain size analysis was then carried out on the separated fine quartz. Low-field MS varies from low frequency magnetic suspectibility (,(LF)) 5 to 100 (× 10,6 m3/kg) for bulk samples and from 1 to 30 for fine fractions. The fine fraction ,(LF) variation correlated with Chinese loess MS stratigraphy, which indicated changes in pedogenic enhancement of the MS and is reflected by summer monsoon intensity. The Rqz are high in cool climate stages, with volumes between 0.2 and 0.4 (× 10,2 kg/m2 per yr), whereas in warm stages the rate falls to about 0.1. These values compare well with those reported from the Hokkaido and Kanto areas, suggesting the fine quartz originates from tropospheric dust. The strong winter monsoons during glacial stages alternated with weak summer monsoons as a result of a southward shift of the jet stream. In interglacials, summer monsoons were stronger. Seasonal alternating monsoons appear to have operated in South-west Japan through the past 200 000 years. [source] Synthesis and characterization of uniform-sized hollow chitosan microspheresADVANCES IN POLYMER TECHNOLOGY, Issue 1 2009Shan Wang Abstract Hollow chitosan (CS) microspheres were obtained using an inverse-emulsion crosslinking method. The temperature and viscosity of the CS emulsion affected the characteristics of the derived microspheres. The microspheres were characterized by differential scanning calorimetry, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy, optical microscopy, scanning electron microscopy (SEM), and laser particle size analysis. FT-IR indicated the sequence of transformations taking place before, during, and after the crosslinking of CS. Optical microscopy and SEM confirmed the spherical morphology of the gel. The formation of hollow microspheres with a single cavity was identified by SEM. The CS microspheres exhibited a narrow particle size distribution. Furthermore, particle size could be controlled by changing the stirring speed. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:40,47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20145 [source] Crystal structure of cobalt-substituted calcium hydroxyapatite nanopowders prepared by hydrothermal processingJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2010Ljiljana Veselinovi A series of cobalt-exchanged hydroxyapatite (CoHAp) powders with different Ca/Co ratios and nominal unit-cell contents Ca10,xCox(PO4)6(OH)2, x = 0, 0.5, 1.0, 1.5 and 2.0, were synthesized by hydrothermal treatment of a precipitate at 473,K for 8,h. Based on ICP (inductively coupled plasma) emission spectroscopy analysis, it was established that the maximum amount of cobalt incorporation saturated at ,12,at.% under these conditions. The effects of cobalt content on the CoHAp powders were investigated using ICP emission spectroscopy, particle size analysis, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) analyses as well as X-ray powder diffraction (XRPD) including Rietveld analysis. According to XRPD, all the materials are single-phase HAp and CoHAp of low crystallinity. Rietveld analysis shows that Co enrichment causes the c cell parameter to decrease at a faster rate than the a cell parameter. A microstructural analysis showed anisotropic X-ray line broadening due to crystallite size reduction. In CoHAp there is significant crystal elongation in [001], and the average size decreases with increasing cobalt content. The crystallite morphology transforms from rod-like for the pure HAp to lamellae at the highest degree of Co substitution. The results of Rietveld refinement (symmetry, size and morphology of the crystallites) were confirmed by TEM and HRTEM analysis. [source] Association of interleukin-1 receptor antagonist gene polymorphisms with early onset periodontitis in JapaneseJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2002Hideaki Tai Abstract Background/Aims: Early onset periodontitis (EOP), newly ,aggressive periodontitis', is considered to have genetic basis, which have not been clearly defined. The interleukin-1 (IL-1) gene cluster polymorphism as one of genetic factors may influence the expression of several chronic inflammatory diseases. The aim of this study is to investigate the frequency of single nucleotide polymorphisms (SNPs) in the genes encoding IL-1,, IL-1, and a variable number of tandem repeat (VNTR) polymorphisms in the IL-1 receptor antagonist gene (IL-1RN) in 47 generalized EOP (G-EOP) patients and 97 periodontally healthy controls. Material and methods: All subjects were of Japanese descent and systemically healthy. They were identified according to established clinical criteria. SNPs in the IL-1, (+ 4845) and IL-1, (, 511, + 3954) genes were analyzed by amplifying the polymorphic region using polymerase chain reaction (PCR), followed by restriction-enzyme digestion and agarose gel electrophoresis. IL-1RN (VNTR) polymorphisms were then detected by PCR amplification and fragment size analysis. Results: There was no significant difference in the IL-, (+ 4845) and IL-1, (, 511, +,3954) genotypes and allele frequencies between G-EOP patients and healthy controls. However, the frequency of IL-1RN (VNTR) polymorphic alleles was found to be significantly increased in G-EOP patients (,2 test, P = 0.007; odds ratio = 3.40). Additionally, the carriage rate of IL-1RN (VNTR) polymorphisms was significantly higher in G-EOP patients than in healthy controls (,2 test, P = 0.005; odds ratio = 3.81). Conclusion: These findings suggest that IL-1RN (VNTR) polymorphisms are associated with G-EOP in Japanese. [source] Reactivation of spent Pd/AC catalyst by supercritical CO2 fluid extractionAICHE JOURNAL, Issue 9 2009Xiaoxin Zhang Abstract In this article, we reported a nondestructive and environmentally friendly method for the reactivation of a spent Pd/AC catalyst for the hydrogenation of benzoic acid by using supercritical CO2 (scCO2) fluid extraction. The effects of reactivation conditions, such as extraction temperature, pressure, CO2 flow rate, and time, on the activity of the reactivated Pd/AC catalyst, were presented. The catalyst was characterized by N2 physisorption, laser particle size analysis, and transmission electron spectroscopy, and the liquid extract was analyzed by GC-MS. It is found that scCO2 fluid extraction was very efficient in eliminating organic substances blocking the pores of the catalyst, while did not affect noticeably the granule size of the catalyst and the particle size of Pd. The reactivated Pd/AC catalyst regained more than 70% of the activity of the fresh 5.0 wt % Pd/AC catalyst, and has been successfully used in an industrial unit for the hydrogenation of benzoic acid. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Gaining fluid bed process understanding by in-line particle size analysisJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2009Tero Närvänen Abstract Different process phenomena and process failure modes could be monitored using the in-line particle size data measured by spatial filtering technique (SFT). In addition to the real-time granule growth monitoring, other events, such as the blocking of filter bags and the distributor plate, could be observed. SFT was used off-line, at-line and in-line in 14 differently manufactured granulation batches. No significant fouling occurred during the manufacturing due to the appropriate positioning of the probe. The off-line SFT results correlated well (R2,=,0.97) with the sieve analysis results. It was also found that size segregation influenced both the in-line and at-line particle size results during the fluidization: in-line method underestimated and at-line method overestimated the final particle size. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1110,1117, 2009 [source] Stabilization of alum-adjuvanted vaccine dry powder formulations: Mechanism and applicationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2003Yuh-Fun Maa Abstract Studies were performed to elucidate the mechanism of alum gel coagulation upon freezing and drying and its relationship to vaccine potency loss and to develop a novel freeze-drying process for the production of stable alum-adjuvanted vaccine formulations suitable for conventional needle injection and epidermal powder immunization (EPI). The alum hydroxide-adjuvanted hepatitis-B surface antigen (Alum-HBsAg) and the alum phosphate-adjuvanted diphtheria and tetanus toxoids (Alum-DT) were dehydrated by freeze drying (FD), spray drying (SD), air drying (AD), or spray freeze drying (SFD). After drying by FD, SD, or AD, alum gels coagulated when examined by optical microscopy and particle size analysis. In addition, desorption of antigen molecules from the coagulated when examined by optical microscopy and particle size analysis. In addition, desorption of antigen molecules from the coagulated alum gel upon reconstitution appeared to be difficult, as indicated by attenuated band intensity on SDS-PAGE. In contrast, SFD alum gels turned a homogenous suspension upon reconstitution, suggesting minimal alum coagulation. In the mouse model, the in vivo immunogenicity of SFD Alum-HBsAg was preserved, whereas the FD Alum-HBsAg suffered significant immunogenicity loss. Grinding of coagulated FD Alum-HBsAg into smaller particles could partially recover the immunogenicity. In a guinea pig study using EPI, the SD Alum-DT formulation was not immunogenic, but the SFD Alum-DT formulations had a vaccine potency comparable to that of the untreated DT administered by I.M. injection. Overall, the relationship of coagulation of alum gel upon reconstitution and the loss of vaccine potency was established in this study. Alum gels became highly coagulated after dehydration by spray drying and traditional freeze-drying processes. However, freezing rate played a critical role in preserving the adjuvant effect of alum and fast freezing decreased the tendency of alum coagulation. Spraying the alum gel into liquid nitrogen represents the fastest freezing rate achievable and resulted in no discernible alum coagulation. Therefore, SFD presents a novel and effective drying process for alum-adjuvanted vaccine formulations and is particularly valuable for dry powder applications such as EPI. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:319,332, 2003 [source] Sedimentation field-flow fractionation and granulometric analysis of PLGA microspheresJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2003Nathalie Faisant Abstract Sedimentation field flow fractionation operated in the steric hyperlayer mode was used to obtain fractions of defined characteristics from crude samples of poly(D,L-lactic-co-glycolic acid) microspheres which were polydisperse in size. In less than ten minutes, Sedimentation Field Flow Fractionation (SdFFF) separation yielded three analytical fractions of very different size and particle size distribution (PSD) characteristics, as determined by granulometric analyses (Coulter Counter® and image analysis of SEM). A crude sample (average size = 45 ,m, 105% size polydispersity index) was separated into fractions of 73 ,m, 56 ,m, 8 ,m average diameters which showed a PSD of 39%, 33%, 30%, respectively. Our results demonstrated that SdFFF used in conjunction with particle size analysis offers a new approach to laboratory scale production of drug vectors of a specified average size and reduced size dispersity. In the future, this could be used to select the most convenient particles for drug loading and release. [source] Barium Holmium Zirconate, A New Perovskite Oxide: II, Synthesis as Nanoparticles through a Modified Combustion ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2002Rajan Jose Nanoparticles of barium holmium zirconate, a new complex perovskite ceramic oxide, has been synthesized using a modified self-propagating combustion process. The solid combustion products obtained were characterized by X-ray diffraction (XRD), electron diffraction, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, particle size analysis, surface area determination, and high-resolution transmission electron microscopy. The XRD and electron diffraction studies have shown that the as-prepared powder is phase pure Ba2HoZrO5.5 and has a complex cubic perovskite (A2BB,O6) structure with a lattice constant a= 8.428 Å. The transmission electron microscopic investigation has shown that the particle size of the as-prepared powder was in the range 4,16 nm with a mean grain size of 8.2 nm. The nanoparticles of Ba2HoZrO5.5 obtained by the present method could be sintered to 98% theoretical density at 1500°C. [source] Enzymatic modification as a tool to improve the functional properties of heat-processed soy flourJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2008Cheruppanpullil Radha Abstract BACKGROUND: There are a number of antinutritional factors present in soybeans that exert a negative impact on the nutritional quality of the protein. Among those factors that are destroyed by heat treatment are protease inhibitors and lectins. Protease inhibitors show antinutritional effect and moreover the digestibility of the protein is limited by the presence of these antinutrients. The aims of the present study are (1) to study the effect of autoclaving on the trypsin inhibitor inactivation, nitrogen solubility and protein digestibility of defatted soy flour and (2) to study the effect of enzymatic modification on the functional properties of autoclaved soy flour. RESULTS: The solubility of the soy flour decreased with increase in autoclaving time. Partial hydrolysis of the autoclaved soy flour increased its acid solubility (pH 4.5) from 17% to 56% over a control value of 24% without affecting its functional properties. Inactivation of trypsin inhibitors improved the protein digestibility of soy flour from 25% to 95%. Particle size analysis of the autoclaved flour indicated the formation of soy protein aggregates, which resulted in poor solubility. The enzymatic modification of autoclaved soy flour resulted in its property as a good emulsifying agent with an emulsion capacity of 118 ± 4 mL. CONCLUSION: Enzymatic modification of the heat-processed soy flour increased its solubility and other functional attributes. The increased acid solubility would be advantageous in the utilization of soy proteins in acidic foods. Thus the autoclaved and partially modified soy flour is a potential source for specific functional foods. Copyright © 2007 Society of Chemical Industry [source] A Novel Device for Single Particle Light Scattering Size Analysis and Concentration Measurement at High Pressures and TemperaturesPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 2 2008Heinz Umhauer Abstract Based on the findings of previous work, a novel instrument was developed for the size analysis and concentration measurement of particles dispersed in gases at high temperatures (600,°C) and pressures (16 bar). The main motivation for the construction of this device was a measurement requirement at the conditions of a pressurized pulverized coal combustion (PPCC) test installation in Dorsten, Germany. The development of a high efficiency (>,50,%), coal based, combined cycle process, and specifically, the development of efficient gas cleaning technology for gas combustion under demanding conditions (1400,°C and 16 bar) was the main target. A suitable measurement technique was required for the determination of particle size and concentration downstream of the gas cleaning equipment, which is able to operate close to the given conditions. The performance of the novel device was tested in several measurement series with various monodisperse aerosols at ambient conditions as well as in high pressure, high temperature situations with very satisfactory results, i.e., the lower detection limit (50,% counting efficiency at ca. 0.3 ,m) and resolution of the novel device are comparable to state of the art instruments (of the same principle) intended for room temperature operation. [source] Transmission Fluctuation Spectrometry in Concentrated Suspensions.PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 1 2005Part Three: Measurements Abstract The theory of transmission fluctuation spectrometry (TFS) was developed for particle size analysis in flowing particle suspensions, whereby the statistical transmission fluctuations are used to extract the particle size distribution (PSD) and particle concentration. In the previous parts of this publication high concentration effects on TFS were investigated theoretically and by simulation. This work presents a study on TFS measurements in concentrated suspensions. By introducing an empirical correction to include the high concentration effects from both the monolayer structure and particle overlapping in the inversion algorithm, it is possible to obtain the particle size distribution and particle concentration over broad ranges of particle sizes and concentrations. [source] Variations in Grain Size Analysis with a Time-of-Transition Laser Sizer (Galai CIS-50) using a Gravitational Flow SystemPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 6 2004Björn Bohling Abstract This study deals with grain size analysis with a Laser Sizer Galai CIS-50. This device utilizes the time-of-transition method and is equipped with a module for measurements in the range 0.5 to 150,,m along with a gravitational flow system. Experiments were conducted using natural marine sediments. The aim was to determine possible explanations for discrepancies in the measured results that occurred between different operators of the Galai CIS-50. These discrepancies may be due to differences in the technique of inserting a sub-sample into the measurement system. Furthermore, the influence of the sample concentration and the flow velocity in the device's liquid flow cell is considered, since these factors can act as potential sources of inaccuracies and errors in the experimental setup. Strong variations in the results occurred, which were mainly due to problems in the detection of particles >20,,m. In the range>20,,m gaps appeared in the registration of the size distribution. An improvement in reproducibility was achieved by using a pipette instead of a beaker for the insertion step. Nevertheless, the standard deviation for mean grain sizes of natural marine sediments obtained with the Galai CIS-50 is still about 20%. [source] Effects of synthesis conditions on crystal morphological structures and thermal degradation behavior of hydrotalcites and flame retardant and mechanical properties of EVA/hydrotalcite blendsPOLYMER COMPOSITES, Issue 2 2007Longchao Du The effects of synthesis methods and reaction conditions on the crystal morphological structures and thermal degradation behavior of hydrotalcites have been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), particle size analysis (PSA), and differential thermal analysis (DTA). The flame retardant and mechanical properties of ethylene,vinyl acetate (EVA) blends with the corresponding hydrotalcites have been estimated by limiting oxygen index (LOI), UL-94, and mechanical measurements. The results from the XRD, TEM, and PSA demonstrate that the hydrotalcites synthesized by ultrasound method have larger crystal sizes and particle size distribution than those by mechanical stirring method. Higher reaction temperature, longer dripping time, and lower solution concentration can increase the crystal and particle sizes of ultrasound-synthesized hydrotalcites, whereas the longer ultrasound aging time can increase the crystal sizes and decrease the particle sizes of hydrotalcites because of the smashing conglomeration. The DTA data give a positive evidence that the hydrotalcite samples prepared by mechanical stirring method with longer alkaline dripping time have higher thermal degradation temperature than those by ultrasound method, since the ultrasound-synthesized hydrotalcites have more lattice defects than stirring-prepared hydrotalcites. The data from LOI, UL-94, and mechanical tests show that the ultrasonic-synthesized hydrotalcites have better flame retardant properties, whereas the stirring-synthesized hydrotalcites have better tensile strength in the EVA/hydrotalcite blends. POLYM. COMPOS., 28:131,138, 2007. © 2007 Society of Plastics Engineers [source] Effect of fabrication temperature on strain-sensing capacity of polypyrrole-coated conductive fabricsPOLYMER INTERNATIONAL, Issue 7 2007Joanna Tsang Abstract Textile strain sensors were made from polypyrrole-coated stretchable fabrics by a method of screen printing with chemical vapor deposition. The effect of polymerization temperature on the sensing performances was studied. It was found that polymerization at low temperature significantly improved the electrical conductivity, strain sensitivity and environmental stability of the fabric sensors. The conductive fabrics were characterized using X-ray diffraction, thermogravimetry, contact angle measurements, particle size analysis, scanning electron microscopy and scanning probe microscopy. Powders of pure polypyrrole prepared by the same fabrication method were characterized for a better understanding of the polypyrrole coating. Copyright © 2007 Society of Chemical Industry [source] Glass bead grafting with poly(carboxylic acid) polymers and maleic anhydride copolymersPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2008H. Zengin Abstract Glass beads were etched with acids and bases to increase the surface porosity and the number of silanol groups that could be used for grafting materials to the surfaces. The pretreated glass beads were functionalized using 3-aminopropyltriethoxysilane (APS) coupling agent and then further chemically modified by reacting the carboxyl groups of carboxylic acid polymers with the amino groups of the pregrafted APS. Several carboxylic acid polymers and poly(maleic anhydride) copolymers, such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), poly(styrene-alt-maleic anhydride) (PSMA), and poly(ethylene-alt-maleic anhydride) (PEMA) were grafted onto the bead surface. The chemical modifications were investigated and characterized by FT-IR spectroscopy, particle size analysis, and tensiometry for contact angle and porosity changes. The amount of APS and the different polymer grafted on the surface was determined from thermal gravimetric analysis and elemental analysis data. Spectroscopic studies and elemental analysis data showed that carboxylic acid polymers and maleic anhydride copolymers were chemically attached to the glass bead surface. The improved surface properties of surface modified glass beads were determined by measuring water and hexane penetration rates and contact angle. Contact angles increased and porosity decreased as the molecular weights of the polymer increased. The contact angles increased with the hydrophobicity of the attached polymer. The surface morphology was examined by scanning electron microscopy (SEM) and showed an increase in roughness for etched glass beads. Copyright © 2007 John Wiley & Sons, Ltd. [source] Correlating the surface area and synthesis conditions of block co-polymer templated mesoporous silicaASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010A. T. Harris Abstract In this work we investigate the influence of (1) temperature, (2) curing (post reaction ageing) technique, (3) curing time, (4) surfactant (block co-polymer) concentration, and (5) the addition of secondary (pore swelling) reagents on the surface area and structure of ordered hexagonal mesoporous silica (SBA-15). We also investigate the use of microwave preparation and curing techniques, as a precursor to the development of large-scale synthesis processes for mesoporous silica. Samples were analyzed using transmission electron microscopy and nitrogen pore size analysis. The results of the study show that it is possible to optimize the surface area of the final material in a reproducible way, by using higher hydrolysis temperatures or lower surfactant concentrations. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Synthesis and modification of zeolite NaA adsorbents for separation of hydrogen and methaneASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Yanna Liu Abstract To improve the adsorption capacity of zeolite A, two kinds of zeolite NaA with submicron and hierarchical structure were prepared. The XRD patterns indicated that both synthesized products were pure zeolite with LTA-type framework. The SEM images and laser particle size analysis showed that the particle size of submicron zeolite NaA was about 240 nm. The TEM and N2 adsorption/desorption isotherms proved the existence of mesopores in the hierarchical zeolite NaA. The adsorption capacities of single component CH4 or H2 on zeolite SrA adsorbents, obtained by Sr2+ ion-exchange of submicron and hierarchical zeolite NaA, and commercial zeolite 5A adsorbent were measured by the static volume method at 25 °C and pressures up to 1 MPa. The results show that both prepared zeolite SrA adsorbents have higher adsorption capacities of CH4 and ideal separation factors of CH4/H2 than commercial zeolite 5A, and the submicron zeolite SrA has the largest adsorption capacity of CH4 and ideal separation factor of CH4/H2. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Electrical transport properties of aliovalent cation-doped CeO2ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Mark C. Pearce Abstract We report the comparative electrical properties of monovalent (Na+), divalent (Ca2+, Sr2+), trivalent (In3+, La3+) and coupled substitution of divalent and trivalent (Ca2+ + Sm3+) cation-doped CeO2. The investigated samples were prepared by solid-state reaction (ceramic) using the corresponding metal oxides and salts in the temperature range 1000,1600 °C in air. Powder X-ray diffraction (PXRD), laser particle size analysis (LPSA), scanning electron microscopy (SEM), and ac impedance spectroscopy measurements were employed for structural, morphology, and electrical characterization. PXRD studies reveal the formation of single-phase cubic fluorite-type structures for all investigated samples except those doped with In3+. The variation of lattice parameters is consistent with ionic radii (IR) of the dopant metal ions, with the exception of Na+ -doped CeO2. Our attempt to substitute In3+ for Ce4+ in CeO2 using both ceramic and wet chemical methods was unsuccessful. Furthermore, diffraction peaks attributed to CeO2 and In2O3 were observed up to sintering conditions of 1600 °C. Among the single-phase compounds investigated, Ce0.85Ca0.05Sm0.1O1.9 exhibits the highest bulk conductivity of 1.3 × 10,3 S/cm at 500 °C with activation energy of 0.64 eV in air. The electrical conductivity data obtained for Ce0.85Ca0.05Sm0.1O1.9 in air and Ar were found to be very similar over the investigated temperature range, indicating the absence of p-electronic conduction in the high oxygen partial pressure (pO2) range which is consistent with literature reported on Sm-doped CeO2. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Understanding the key factors for enzymatic conversion of pretreated lignocellulose by partial least square analysisBIOTECHNOLOGY PROGRESS, Issue 2 2010Renliang Huang Abstract The relationship between the physicochemical properties of lignocellulosic substrates and enzyme digestion is still not well known. After different pretreatments, cellulase hydrolysis and measurements of physicochemical characteristics by column solute exclusion, particle size analysis, X-ray diffraction, Fourier transform infrared spectroscopy and solid state 13C nuclear magnetic resonance were performed in this study. Partial least squares was then applied to seek the key factors limiting the rate and extent of cellulose digestion. According to the PLS results, the most important factor for cellulose digestion was accessible interior surface area, followed by delignification and the destruction of the hydrogen bonds. The cellulose digestion at 2 and 24 hr were improved with the increased accessibility of interior surface area to the reporter molecules of 5.1-nm diameter. Removal of lignin and breaking of hydrogen bonds were also found to significantly promote cellulose conversion. Other properties, including the breakdown of intramolecular hydrogen bonds, cellulose crystallinity, and hemicellulose content, had less effect on the efficiency of enzymatic hydrolysis. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Ultra scale-down approaches for clarification of mammalian cell culture broths in disc-stack centrifugesBIOTECHNOLOGY PROGRESS, Issue 6 2009Ferhana Zaman Abstract Ultra-scale down (USD) methodology developed by University College London for cell broth clarification with industrial centrifuges was applied to two common cell lines (NS0 and GS-CHO) expressing various therapeutic monoclonal antibodies. A number of centrifuges at various scales were used with shear devices operating either by high speed rotation or flow-through narrow channels. The USD methodology was found effective in accounting for both gravitational and shear effects on clarification performance with three continuous centrifuges at pilot and manufacturing scales. Different shear responses were observed with the two different cell lines and even with the same cell line expressing different products. Separate particle size analysis of the treated broths seems consistent with the shear results. Filterability of the centrifuged solutions was also evaluated to assess the utility of the USD approach for this part of the clarification operation. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] The presence of dominant T-cell clones in peripheral blood of patients with collagen vascular disorders: a prospective study of 97 casesBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2006O. Dereure Summary Background, T-lymphocyte dysfunction has been seldom investigated in collagen vascular disorders. The search for dominant T-cell clones has been scarcely reported, although the presence of such clones might be expected in disorders showing immune responses directed against a variety of autoantigens. Objectives, We conducted a systematic search for dominant T-cell clones in peripheral blood in patients with collagen vascular disorders. Patients and methods, Ninety-seven patients with collagen vascular disorders were studied (7 cutaneous and 38 systemic lupus erythematosus; 8 multiple morphea; 12 regional scleroderma; 32 systemic sclerosis of the CREST type). A dominant T-cell clone was searched for in peripheral blood by polymerase chain reaction targeting the T-cell receptor , chain followed by a size analysis of amplified fragments. Peripheral blood from patients with nonlymphocyte-dependent disorders and matched by age and sex was assessed in the same conditions. Results in both groups were compared using nonparametric statistical tests. Results, Overall, a circulating dominant T-cell clone was found in 52% of patients compared with 16·9% in controls. More precisely, such a dominant clone was present in 43% and 37% of cutaneous and systemic lupus erythematosus, respectively, in 75% of multiple morphea, 75% of regional scleroderma and 60% of CREST syndrome patients. The percentages in all subsets of patients were significantly higher than in the control group. Conclusions, The presence of a dominant T-cell clone in peripheral blood is significantly more frequent in collagen vascular disorders than in controls, especially in patients with scleroderma, whatever the clinical subset, which suggests T-cell involvement in the immune response dysfunction in these diseases classically characterized by disturbances of B lymphocytes. The relevance of such a dominant clone regarding diagnosis, pathomechanisms, long-term outcome and visceral prognosis of these diseases as well as therapeutic decisions remains to be evaluated. [source] | ||||||||||||||||||||||