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Specific Volume (specific + volume)
Selected AbstractsInfluence of a novel castor-oil-derived additive on the mechanical properties and oxygen diffusivity of polystyreneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Markus Klinger Abstract Mechanical properties, densities, and oxygen diffusion coefficients have been measured in polystyrene samples (PS) as a function of additive loading. The additive employed is based on castor oil, and is a desirable alternative to phthalates. Tensile strength measurements indicate the additive renders PS stronger at low loadings, i.e. it antiplasticizes the material. In contrast, the additive plasticizes PS at high loadings. Specific volumes and oxygen diffusion coefficients do not show this dual behavior. Rather, one observes a monotonic decrease in density and oxygen diffusivity with an increase in additive loading. This suggests that the larger segmental motions responsible for the macroscopic properties of the polymer are influenced by the additive in a different manner than the local motions and confined changes in free volume that govern the mobility of oxygen. These data indicate that antiplasticization cannot be predicted solely from diffusivity and density measurements and, vice versa, trends in diffusivity cannot be deduced from mechanical measurements alone. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] On the use of pressure-volume-temperature data of polyethylene liquids for the determination of their solubility and interaction parametersPOLYMER ENGINEERING & SCIENCE, Issue 5 2004L. Zhao Specific volumes of high-density and low-density polyethylene liquids at several elevated temperatures and pressures were measured. The measured specific volumes were then used to estimate the thermal expansion coefficients and isothermal compressibility of the polymers. Two different approaches were used in which one was simply to fit the raw data by second order polynomials to obtain (,v/,T)P and (,v/,P)T, while the other by the Sanchez-Lacombe (S-L) equation of state. It was found that the resultant , and , obtained from the above methods differ significantly, indicating that the S-L equation of state may not be suitable for determining , and , at elevated temperatures. When these two sets of , and , were used to calculate the corresponding solubility parameters and then the Flory-Huggins interaction parameters (,) of the polymers, the results also differ considerably. Nonetheless, , obtained from the first method agrees well with the results obtained from small angle neutron scattering measurements while the S-L equation of state method does not. The current results suggest that solubility and interaction parameters obtained from pressure-volume-temperature experiments depend critically on the manner by which the data analysis is performed. Polym. Eng. Sci. 44:853,860, 2004. © 2004 Society of Plastics Engineers. [source] Java applet on computation of thermodynamic properties of steam and R134a refrigerantCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2003F. L. Tan Abstract This paper describes the application of Java programming on the computation of thermodynamic properties of steam and the HFC-134a, 1,1,1,2-tetrafluoroethane (R134a) refrigerant through the Java applets. The Java applets can compute thermodynamic properties of steam and R134a refrigerant, such as specific volume, internal energy, enthalpy, and entropy in the phases of saturated mixture, compressed liquid, and superheated vapor. The calculated values are accurate compared to the standard reference properties tables for steam and refrigerant. © 2004 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 211,225, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10049 [source] Polymeric alkenoxy amino acid surfactants: I. Highly selective class of molecular micelles for chiral separation of ,-blockersELECTROPHORESIS, Issue 15 2003Syed A. A. Rizvi Abstract Two amino acid-based alkenoxy micelle polymers were synthesized for this study. These include polysodium N -undecenoxy carbonyl- L -leucinate (poly- L -SUCL) and polysodium N -undecenoxy carbonyl- L -isoleucinate (poly- L -SUCIL). The polymerization time and concentration of the synthesized micelle polymers were optimized by 1H-nuclear magnetic resonance (NMR) and capillary electrophoresis (CE) experiments. Detailed physicochemical properties (1H NMR, critical micelle concentration (CMC), optical rotation, partial specific volume, aggregation number, and polarity) were determined, and these molecular micelles were introduced as a pseudostationary phase in micellar electrokinetic chromatography to study the molecular recognition and to develop a method for simultaneous separation of eight chiral ,-blockers. It is found that poly- L -SUCL gives overall better chiral resolution and wider chiral window than poly- L -SUCIL. After optimizing the type of micelle polymer, injection size and temperature, simultaneous separation and enantioseparation of eight ,-blockers were achieved in less than 35 min. A comparison with the amide-type surfactants of the same polar head group and alkyl chain length showed that carbamate-type surfactants always work better than the corresponding amide-type surfactant. [source] Analytical solutions for a three-invariant Cam clay model subjected to drained loading historiesINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2006Dunja Peri Abstract Analytical solutions are derived for a three-invariant Cam clay model subjected to proportional and circular drained loading histories. The solutions are presented for a specific volume, and volumetric and generalized shear strains. In the case of a proportional loading only straight effective stress paths are considered while in the case of a circular loading the maximum possible change in Lode's angle is ,/3 due to plastic isotropy. Additionally, a concept of deviatoric stiffness is devised and an analytical expression for the generalized hardening modulus is derived. Qualitative and quantitative analyses are carried out in the form of direct comparisons between analytical solutions for drained and undrained loading histories thus offering an improved understanding of the three-invariant model. Copyright © 2006 John Wiley & Sons, Ltd. [source] Prediction of the non-ideal detonation performance of commercial explosives using the DeNE and JWL++ codesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005S. Esen Abstract The non-ideal detonation performance of two commercial explosives is determined using the DeNE and JWL++ codes. These two codes differ in that DeNE is based on a pseudo-one-dimensional theory which is valid on the central stream-tube and capable of predicting the non-ideal detonation characteristics of commercial explosives as a function of the explosive type, rock properties and blasthole diameter. On the other hand, JWL++ is a hydrocode running in a 2-D arbitrary Lagrangian,Eulerian code with CALE-like properties and can determine the flow properties in all stream lines within the reaction zone. The key flow properties (detonation velocity, pressure, specific volume, extent of reaction and reaction zone length) at the sonic locus on the charge axis have been compared. In general, it is shown that the flow parameters determined using both codes agree well. The pressure contours determined using the JWL++ are analysed in detail for two explosives at 165 mm blastholes confined in limestone and kimberlite with a view to further investigate the explosive/rock interface. The DeNE and JWL++ codes have been validated using the measured in-hole detonation velocity data. Copyright © 2005 John Wiley & Sons, Ltd. [source] Cooling load density characteristics of an endoreversible variable-temperature heat reservoir air refrigeratorINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2002Shengbing Zhou Abstract The performance optimization of an endoreversible air refrigerator with variable-temperature heat reservoirs is carried out by taking the cooling load density, i.e. the ratio of cooling load density to the maximum specific volume in the cycle, as the optimization objective in this paper. The analytical relations of cooling load, cooling load density and coefficient of performance are derived with the heat resistance losses in the hot- and cold-side heat exchangers. The maximum cooling load density optimization is performed by searching the optimum pressure ratio of the compressor, the optimum distribution of heat conductance of the hot- and cold-side heat exchangers for the fixed total heat exchanger inventory, and the heat capacity rate matching between the working fluid and the heat reservoirs. The influences of some design parameters, including the heat capacitance rate of the working fluid, the inlet temperature ratio of heat reservoirs and the total heat exchanger inventory on the maximum cooling load density, the optimum heat conductance distribution, the optimum pressure ratio and the heat capacity rate matching between the working fluid and the heat reservoirs are provided by numerical examples. The refrigeration plant design with optimization leads to a smaller size including the compressor, expander and the hot- and cold-side heat exchangers. Copyright © 2002 John Wiley & Sons, Ltd. [source] Wheat dough rheology and bread quality effected by Lactobacillus brevis preferment, dry sourdough and lactic acid additionINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2010Daliborka Koceva Komleni Summary The influence of chemical and biological acidification on dough rheological properties and bread quality has been investigated. Two different flour types were used. Dough was chemically acidified with lactic acid. Two types of biologically acidified dough were prepared: dough with dry sourdough and with a Lactobacillus brevis preferment. Wheat dough rheological properties were investigated using the Farinograph, Extensograph and Amylograph. The baking response was also determined using standard baking tests. Addition of acidifiers resulted in firmer doughs with less stability, decreased extensibility and decreased gelatinisation maximum. The biological acidifiers increased the bread specific volume. Lactic acid addition had no influence on bread specific volume. In general, biological and chemical acidification decreased bread hardness. The addition of dry sourdough significantly decreased the lightness and increased the yellowness and redness of the bread crumb. The crust chroma, hue angle and brownness index were significantly changed by addition of acidifiers. [source] Effects of extrusion conditions on quality of cassava bran/cassava starch extrudatesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2003Jorge Minoru Hashimoto Summary Blends of cassava bran and cassava starch were processed in a single-screw extruder. Response surface methodology was used to determine the effect of the concentration of cassava bran (10,50%), barrel temperature (150,210 °C), feed moisture (16,20%) and screw speed (120,180 r.p.m.) on the characteristics of the dried extrudates. All the independent variables were significant (P < 0.05) for radial expansion. The water absorption index (WAI) and water solubility index (WSI) were affected by bran level, screw speed and temperature, while only moisture and temperature influenced specific volume. The maximum radial expansion was found when all the independent variables were at their lowest levels. Lowest-density extrudates (highest specific volume) were obtained at 16,18% moisture and 180,200 °C. An increase in bran level increased the WAI but decreased the WSI when the temperature was higher than 170 °C . Screw speed had a slight effect on those responses, decreasing water absorption and increasing water solubility when changed from 120 to 180 r.p.m. [source] Effects of Size of Cellulose Granules on Dough Rheology, Microscopy, and Breadmaking PropertiesJOURNAL OF FOOD SCIENCE, Issue 2 2007M. Seguchi ABSTRACT:, Breadmaking was performed with cellulose-blended wheat flour. Cellulose granules (7 types) of various sizes (diameter) were prepared by kneading. With increase of the blend percent of the cellulose samples from 10% to 20%, breadmaking properties such as bread height and specific volume (SV) gradually decreased in every sample; however, the decreasing levels of the properties in 7 types of various sizes varied. The decrease of bread height and SV was associated with the size of the cellulose granule. It was observed at both 10% and 20% blends that the same bread height and SV as for bread baked with only wheat flour could be obtained when the diameter of cellulose granule was above 154 ,m in cellulose/wheat flour breadmaking, while they gradually decreased with granules below 154 ,m. When the largest cellulose granules were mechanically ground to make smaller ones, the bread height and SV decreased with increasing grinding time. It was ascertained that the size of the cellulose granule was important for breadmaking properties. Cellulose-blended wheat flour was subjected to mixograph tests. When cellulose granules above 154-,m dia were blended with wheat flour, the profile of the mixogram was almost the same as that for wheat flour; that is, the profile had a short mixing requirement and showed a viscous gluten matrix. However, when cellulose granules below 81-,m dia were blended, a different curve showing a nonviscous dough due to breakdown of the gluten protein was observed, as ascertained by microscopy. Farmograph test showed that the amount of the released gas from cellulose-blended bread dough increased with decrease of the size of the cellulose granule due to breakdown of the gluten protein. [source] Effect of Maitake (Grifola frondosa) Mushroom Powder on Bread PropertiesJOURNAL OF FOOD SCIENCE, Issue 2 2001M. Seguchi ABSTRACT: Maitake mushroom powder drastically decreased dough strength in Brabender farinography and was also effective in deteriorating bread-making properties (bread height and specific volume). These effects of maitake on farinograph values and bread-making properties were lost by boiling maitake/water suspensions or by adding EDTA, suggesting that the deteriorative effects by maitake may be caused by a metal protease. Flour dough that contained maitake was treated with 1% sodium dodecyl sulfate (SDS), and extracted proteins were subjected to SE-HPLC and SDS-PAGE. The range of high-molecular-weight (HMW) protein in those profiles gradually decreased with an increase of maitake, and HMW protein/total protein correlated well with bread height but did not have a clear effect on specific volume. [source] EFFECT OF NaCl AND WATER CONTENT ON EXPANSION AND COLOR OF CASSAVA AND POTATO STARCHES ON BAKINGJOURNAL OF TEXTURE STUDIES, Issue 6 2009A. FARAHNAKY ABSTRACT Due to the importance of the role of NaCl in starch-based systems, the effect of NaCl and water content on specific volume, color parameters and moisture loss of cassava and potato starches was studied and response surface methodology was used to find and estimate any nonlinearity between the parameters under study. Glass transition (Tg) is one of the main factors determining the quality parameters of toasted and baked samples. Therefore, Tg of two starch systems (cassava and potato) at low water levels (<20%) as affected by NaCl and water content was investigated. Using experimental modeling, equations were obtained to relate expansion, color change and moisture loss of baked samples to salt level and water content. Differential scanning calorimetry-measured Tg showed that NaCl had negative impact on glass/rubber transition temperature of starch,salt mixtures compared with the samples without NaCl. This could have practical implications in baking, toasting and extrusion processing of starch-based systems. PRACTICAL APPLICATION Due to concerns over health-related issues of high intake of salt by the consumers, recently, the reduction of salt in different food products has become the focus of many industrial projects, conferences and workshops. In breakfast cereals, other than starch type, other added ingredients such as sugar and salt can have profound effects on the physical characteristics of final products. The inclusion of salt in breakfast cereals has some important technological roles, e.g., structure formation and flavor and color generation. Salt plays a key role in the expansion of low-moisture extruded starch-based products. Using the findings of this paper, one may quantify the effects of salt level on expansion and color of baked, toasted or extruded starch-based cereal products and relate the changes to the glass rubber transition of the system. [source] Effects of green tea extract on the quality of bread made from unfrozen and frozen dough processesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2006Rong Wang Abstract Two different green tea extracts (GTE-A and -B) as a rich source of tea catechins were incorporated into a no-time bread-making process, where bread made from the unfrozen and frozen dough processes was compared by specific volume and texture profile. GTE-A and -B both exhibited significant effects on bread volume and firmness, but to a different extent. GTE-A with higher content of tea catechins (73%) at a level of 1.5 g kg,1 flour was found to lead to a significant reduction in bread volume in unfrozen dough process and an increment in firmness during storage for 4 days at ambient temperature (22 °C). GTE-B, with a lower content of catechins (60%), had relatively mild effects on the bread quality. Significantly negative effects were evident starting at a higher level of 5.0 g kg,1 flour in unfrozen dough process. Frozen storage showed more predominant deteriorating effects than the GTEs over a period of 9 weeks frozen storage at ,20 °C. Copyright © 2006 Society of Chemical Industry [source] On the Interrelationship of Transreactions with Thermal Properties and Dynamic Mechanical Analysis of PTT/PEN BlendsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2009Seyed-Hassan Jafari Abstract An attempt was made to explore the effects of interchange reactions on the crystallization, melting, and dynamic mechanical behavior of binary blends based on poly(trimethylene terephthalate) (PTT)/poly(ethylene 2,6-naphthalate) (PEN). 1H NMR spectroscopy is used to verify the occurrence of interchange reactions at the interface, which are increased upon an increase in the melt processing time and temperature. The crystallinity of PTT was reduced while that of PEN was increased on blending. In addition, the crystallization temperatures of both phases showed depression. A single composition-dependent glass transition temperature (Tg) was detected in the second and subsequent heating thermograms of the blends, which is indicative of miscibility. The cold crystallization of the PTT phase was observed to increase while that of PEN was suppressed on blending. Each phase crystallized individually and a melting point depression was evident, which suggests a certain level of miscibility. Dynamic mechanical thermal analysis corroborated differential scanning calorimetry results. A constructive synergism was observed in the glassy state storage moduli of the blends, which is suggestive of a reduced specific volume of the system because of enhanced interactions and crystallinity. [source] Polystyrene/CaCO3 composites with different CaCO3 radius and different nano-CaCO3 content,structure and propertiesPOLYMER COMPOSITES, Issue 7 2010Linlin Zha The Archimedes' principle and physical theory are attempted to analysis the densification and structure of the polystyrene (PS) composites by melt compounding with CaCO3 having different particle size. The difference between the measured specific volume (,) andthe theoretically calculated specific volume (,mix), ,, = ,,,mix, can reflect the densification of the composites. It is clearly demonstrated that the PS composites become more condensed with the reduction of the CaCO3 particle size. Especially, when the content for nano-CaCO3 achieves 2 wt%, the ,, value of the composites reaches the least, which shows the best densification. Meanwhile, the glass transition temperature (Tg) reaches the maximum value of about 100°C by differential scanning calorimetry (DSC) and thermal mechanical analysis (TMA), which indirectly reveals the composites microstructure more condensed. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal that 2 wt% nano-CaCO3 uniformly disperses in PS composites. The CaCO3 selected in this experiment has certain toughening effect on PS. The impact and tensile strength increase with addition of nano-CaCO3, but the elongation at break decreases. When nano-CaCO3 content achieved 2 wt%, the impact and tensile strength present the maximum value of 1.63 KJ/m2 and 44.5 MPa, which is higher than the pure PS and the composites filled with the same content of micro-CaCO3. POLYM. COMPOS., 31:1258,1264, 2010. © 2009 Society of Plastics Engineers [source] Microautosamplers for discrete sample injection and dispensationELECTROPHORESIS, Issue 9 2005Chun-Wei Huang Abstract Microfluidic systems show considerable potential for use in the continuous reaction and analysis of biosamples for various applications, such as drug screening and chemical synthesis. Typically, microfluidic chips are externally connected with large-scale autosamplers to inject specific volumes of discrete samples in the continuous monitoring and analysis of multiple samples. This paper presents a novel microelectromechanical system (MEMS)-based autosampler capable of performing the discrete injection and dispensation of variable-volume samples. This microdevice can be integrated with other microfluidic devices to facilitate the continuous monitoring and analysis of multiple biosamples. By means of electroosmotic focusing and switching controlled by the direct application of electric sources on specific fluid reservoirs, a precise sample volume can be injected into the specified outlet port. Fluorescence dye images verify the performance of the developed device. An injection-and-washing scheme is developed to prevent cross-contamination during the continuous injection of different samples. This approach renders feasible the injection of several discrete samples using a single microchip. Compared to its large-scale counterparts, the developed microautosampler is compact in size, has low fabrication costs, is straightforward to control, and most importantly, is readily integrated with other microfluidic devices (e.g., microcapillary electrophoresis chips) to form a microfluidic system capable of the continuous monitoring and analysis of bioreactions. The proposed microautosampler could be promising towards realizing the micrototal analysis system (,-TAS) concept. [source] Anticipating bipedalism: trabecular organization in the newborn iliumJOURNAL OF ANATOMY, Issue 6 2009Craig A. Cunningham Abstract Trabecular bone structural organization is considered to be predominantly influenced by localized temporal forces which act to maintain and remodel the trabecular architecture into a biomechanically optimal configuration. In the adult pelvis, the most significant remodelling forces are believed to be those generated during bipedal locomotion. However, during the fetal and neonatal period the pelvic complex is non-weight bearing and, as such, structural organization of iliac trabecular bone cannot reflect direct stance-related forces. In this study, micro-computed tomography scans from 28 neonatal ilia were analysed, using a whole bone approach, to investigate the trabecular characteristics present within specific volumes of interest relevant to density gradients highlighted in a previous radiographic study. Analysis of the structural indices bone volume fraction, trabecular thickness, trabecular spacing and trabecular number was carried out to quantitatively investigate structural composition. Quantification of the neonatal trabecular structure reinforced radiographic observations by highlighting regions of significant architectural form which grossly parallel architectural differences in the adult pattern but which have previously been attributed to stance-related forces. It is suggested that the seemingly organized rudimentary scaffold observed in the neonatal ilium may be attributable to other non-weight bearing anatomical interactions or even to a predetermined genetic blueprint. It must also be postulated that whilst the observed patterning may be indicative of a predetermined inherent template, early non-weight bearing and late stance-related locomotive influences may subsequently be superimposed upon this scaffolding and perhaps reinforced and likely remodelled at a later age. Ultimately, the analysis of this fundamental primary pattern has core implications for understanding the earliest changes in pelvic trabecular architecture and provides a baseline insight into future ontogenetic development and bipedal capabilities. [source] Use of affinity capillary electrophoresis for characterizing pharmaceutical colloidal vehicle systems thermodynamicallyBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7-8 2001Neubert Reinhard Abstract This review offers a detailed discussion of the interaction between pharmaceutical compounds and vehicles using the affinity capillary electrophoresis and the microemulsion electrokinetic chromatography. Partition coefficients of drugs were calculated between a micelle and an aqueous phases from the measurement of the migration time, provided the critical micelle concentration and the phase ratio are known. Thermodynamic quantities such as enthalpy and entropy changes of micellar solubilization were calculated from the temperature dependence of the partition coefficients. Partial specific volumes were measured using dynamic light scattering. The logarithm of the partition coefficients and the capacity factor in the micellar system were correlated with the logarithm of the n-octanol/water partition coefficients. Copyright © 2001 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||