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Concentration
Kinds of Concentration Terms modified by Concentration Selected AbstractsFILM FORMING MECHANISM AND MECHANICAL AND THERMAL PROPERTIES OF WHEY PROTEIN ISOLATE-BASED EDIBLE FILMS AS AFFECTED BY PROTEIN CONCENTRATION, GLYCEROL RATIO AND PULLULAN CONTENTJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2010MAHAMADOU ELHADJI GOUNGA ABSTRACT Tensile strength (TS), elongation at break (EAB) and elastic modulus (EM) of edible films prepared from 5, 7 and 9% whey protein isolate (WPI) plasticized with different levels of glycerol (Gly) (WPI : Gly = 3.6:1, 3:1 and 2:1) were investigated in order to completely characterize WPI-Gly films. On increasing protein concentration an increase in TS and EAB was observed. On the other hand, increasing Gly led to a decrease in TS and EM, while EAB increased. The addition of pullulan (Pul) into the film forming solution (FFS) increased EAB while TS, EM and thermal properties were reduced. This suggested that Pul had a similar effect as plasticizers. Films with higher Pul content showed lighter protein bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Fourier transform infrared spectroscopy showed that hydrogen bonding was high in WPI : Pul films as compared with the control. This is attributed to the protein-polysaccharide interactions brought about by the dominance of Pul in the FFS. PRACTICAL APPLICATIONS This work describes some physical properties of films based on blends of whey protein isolate (WPI) and pullulan (Pul), made after a previous study on some characteristics of films based on pure WPI plasticized by glycerol. The most studied proteins in the edible films technology being gluten and WPI, the use of Pul in mixture with WPI is considered as a new investigation to explore the utilization of WPI-Pul in edible film and coating materials applied to food products. Furthermore, the use of WPI-Pul films and coatings could potentially extend the shelf life and improve the stability of the coated products as shown by the resultant properties in this investigation and previous works. [source] RHEOLOGICAL PROPERTIES OF NONCOHESIVE APPLE DISPERSION WITH HELICAL AND VANE IMPELLERS: EFFECT OF CONCENTRATION AND PARTICLE SIZEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2000DENIS CANTÚ-LOZANO ABSTRACT The proportionality constant, ks, between shear rate, ,, and agitation velocity, N, for a helical ribbon-screw (HRS) agitator was 17.8. Using the HRS agitator, values of consistency index K and the flow behavior index n of 14 apple pulp suspensions at seven different solids concentrations and two average particle diameters 0.71 mm and 1.21 mm were determined; in addition, values of the Casson viscosity ,c and yield stress ,OC were also calculated. The magnitudes of K increased and of n decreased with increase in pulp concentration. Experimental values of the vane yield stress, ,O,, measured with a six-blade vane increased with increase in pulp content. The values of ,OC obtained using the Casson model were close to the experimental values ,O,. The effect of particle size on the relative viscosity, ,r, was correlated with Peclet number. [source] OPTIMAL COAGULANT CONCENTRATION, SOYMILK AND TOFU QUALITY AS AFFECTED BY A SHORT-TERM MODEL STORAGE OF PROTO SOYBEANSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2008ZHI-SHENG LIU ABSTRACT Soybeans were adjusted to water activities (Aw) from 0.60 to 0.81, and stored at 30C for up to 3 months. At 1-month intervals, soybeans were retrieved from the storage and processed into 10.5 Brix soymilk. The optimal coagulant concentration (OCC) for making filled tofu was determined using a titration method. Other soymilk characteristics, including total solids, protein, 11 S/7 S protein ratio, phytate, titratable acidity, pH and color, were also determined. Filled tofu was prepared from each stored soybeans with the respective OCC using MgCl2 or CaCl2. With increasing Aw or storage time, the OCC decreased significantly. The decrease in OCC was significantly correlated to the difference in soymilk titratable acidity and the change in soymilk pH. Soybean storage time slightly decreased the breaking stress and apparent Young's modulus of the filled tofu, particularly the MgCl2 coagulated tofu. With increasing Aw or storage time, the lightness and yellowness intensity of both soymilk and tofu decreased, whereas their redness intensity increased. PRACTICAL APPLICATIONS Tofu and soymilk are popular soybean foods. Using optimal concentration of coagulant in soymilk is the most critical step among many steps of unit operations during tofu manufacturing for achieving high quality tofu. Improper use of coagulant can lead to product failure and therefore significant economic loss for the manufacturers. The optimal coagulant concentration varies not only with processing condition, but also with soybean materials which are affected by variety and storage conditions. Acidity, pH and food color are important quality factors to influence taste and consumer acceptance. Soybeans are subject to storage and transportation before processing. Storage length and environmental humidity are two of important factors which affect soybean quality and processing property. This study provides very important information that is useful for the soymilk and tofu manufacturers in controlling product quality through the understanding of the chemistry and processing characteristics of stored soybeans. Manufacturers can utilize the methods presented in this article to calculate the optimal coagulant concentrations to avoid product failure and to produce the best quality products. [source] OSMOTIC DEHYDRATION OF MUSKMELON (CUCUMIS MELO): INFLUENCE OF BLANCHING AND SYRUP CONCENTRATIONJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 4 2007RENZO M. FERNANDEZ ABSTRACT The influence of blanching and syrup concentration on the quality parameters of osmo-air-dried muskmelon product was investigated. Fruit samples were dehydrated with sucrose solutions at 40, 50 and 60°Brix and the resulting products were analyzed for browning degree, ascorbic acid (AA) concentration and water activity. The values for all three parameters decreased as the syrup concentration increased. Blanching treatment before the osmotic processing had no effect on browning but caused a decrease in AA concentration. Osmotically dehydrated fruits showed no browning increase for at least 4 weeks at 2C. A decrease of about 60% in AA concentration was observed within the first 2 weeks at 10C. In contrast, AA loss was only observed after 2 weeks at 2C. The influence of storage time and temperature on AA retention was investigated by 22 factorial design. Statistical analysis of results showed that the two factors have a significant effect on AA retention. Osmotic dehydration may be an interesting alternative for processing of muskmelon as a pretreatment followed by cold storage or drying. [source] FLAVOR AND AROMA ATTRIBUTES OF RIESLING WINES PRODUCED BY FREEZE CONCENTRATION AND MICROWAVE VACUUM DEHYDRATIONJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 4 2006C. CLARY ABSTRACT This article describes the production of sweet dessert wines produced using late-harvest freeze concentration, wine produced from fresh grapes frozen using refrigeration and wine produced from grapes partially dried using microwave vacuum dehydration. The objective was to compare the aroma and flavor attributes of the wines to determine the effect of each method of juice concentration. The replicated wine samples were evaluated by 12 experienced judges, and the wines were analyzed using solid-phase microextraction. The microextraction detected 28 compounds; however, levels of concentration of these compounds were below published aroma thresholds. Although all the wines were judged as acceptable sweet dessert wines, the judges detected significant differences. The wine made from the dehydrated grapes exhibited lower fresh fruit aroma, higher fusel oils and oxidation, and flavor notes including citrus/grapefruit and acidity were lower. [source] EFFECT OF OXYGEN CONCENTRATION ON THE BIOCHEMICAL AND CHEMICAL CHANGES OF STORED LONGAN FRUITJOURNAL OF FOOD QUALITY, Issue 1 2009G. CHENG ABSTRACT Longan fruits were stored for 6 days in atmosphere of 5, 21 (air) or 60% O2 (balance N2) at 28C and 90,95% relative humidity to examine effects of low and high O2 concentration on enzymatic browning and quality attributes of the fruit. Changes in pericarp browning, pulp breakdown, disease development, total phenol content, activities of phenol metabolism-associated enzymes, relative leakage rate, ,,, -diphenyl- , -picrylhydrazy (DPPH) radical scavenging activity, and contents of total soluble solids, titratable acidity and ascorbic acid were evaluated. Storage of fruit in a 5% O2 atmosphere markedly delayed pericarp browning in association with maintenance of high total phenolic content and reduced activities of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia lyase. Moreover, the fruit stored in a 5% O2 atmosphere exhibited a lower relative leakage rate and higher DPPH radical scavenging activity than fruit stored in air. This presumably was beneficial in maintaining compartmentation of enzymes and substrates, and thus, reducing pericarp browning. Pulp breakdown and disease development were also reduced by exposure to a 5% oxygenatmosphere. On the contrary, exposure of longan fruit to a 60% O2 atmosphere accelerated pericarp browning, pulp breakdown and decay development. PPO and POD activities and relative leakage rate were similar for control and 60% O2 -treated fruit after 4 and 6 days of storage. Furthermore, treatment with 60% O2 significantly decreased the phenolic content and DPPH scavenging activity of fruit. In addition, exposure to 5 or 60% O2 resulted in a higher level of total soluble solids, but a lower level of ascorbic acid of longan fruit flesh. In conclusion, exposure to a 5% O2 atmosphere showed great potential to reduce pericarp browning and extend shelf life of longan fruit. PRACTICAL APPLICATIONS Pericarp browning and pulp breakdown are the major causes of deterioration in postharvest longan. Conventional controlled atmosphere with low O2 and high CO2 is effective in maintaining quality and extending shelf life of fruits and vegetables, including inhibition of tissue browning. In this study, 5%-controlled atmosphere reduced significantly pericarp browning, pulp breakdown and rot development. It could potentially be useful as a postharvest technology of longan fruit for reducing or replacing the use of chemicals such as SO2 and fungicides, but it requires further investigation. [source] ODOR PERCEPTION OVER LIQUID EMULSIONS CONTAINING SINGLE AROMA COMPOUNDS: EFFECTS OF AROMA CONCENTRATION AND OIL VOLUME FRACTIONJOURNAL OF SENSORY STUDIES, Issue 6 2002CHANTAL BROSSARD ABSTRACT This study aimed to check the hypothesis that aroma concentration in the aqueous phase of an oil-in-water emulsion controlled the odor intensity of single aroma compounds. A set of flavored oil-in-water emulsions, prepared according to a 22 experimental design (aroma concentration, oil volume fraction) with two central points, was assessed for odor intensity by a 24-member panel during four sessions. In each session, three of the four-studied aroma molecules (benzaldehyde, ethyl butyrate, linalool and acetophenone) were investigated. Whatever the aroma, the experimental data showed that the oil volume fraction of the emulsion (from 0.12 to 0.48) did not influence the odor intensity. For each emulsion composition, aroma concentrations at equilibrium in both phases were calculated using the oil-water partition coefficient of the compound. Odor intensities, estimated from aroma concentration in the aqueous phase using previously reported modeling of odor intensity above water solutions, were then compared to experimental data. It is confirmed that the perceived odor intensity is governed by the aroma concentration in the aqueous phase at the time of the trial and not by the averaged apparent concentration in the emulsion. [source] BANK COMPETITION, CONCENTRATION AND EFFICIENCY IN THE SINGLE EUROPEAN MARKET,THE MANCHESTER SCHOOL, Issue 4 2006BARBARA CASU The deregulation of financial services in the European Union (EU), together with the establishment of the Economic and Monetary Union, aimed at the creation of a level playing-field in the provision of banking services across the EU. The plan was to remove entry barriers and to foster both competition and efficiency in national banking markets. However, one of the effects of the regulatory changes was to spur a trend towards consolidation, resulting in the recent wave of mergers and acquisitions. To investigate the impact of increased consolidation on the competitive conditions of the EU banking markets, we employ both structural (concentration ratios) and non-structural (Panzar,Rosse statistic) concentration measures. Using bank-level balance sheet data for the major EU banking markets, in a period following the introduction of the Single Banking Licence (1997,2003), this paper also investigates the factors that may influence the competitive conditions. Specifically, we control for differences in efficiency estimates, structural conditions and institutional characteristics. The results seem to suggest that the degree of concentration is not necessarily related to the degree of competition. We also find little evidence that more efficient banking systems are also more competitive. The relationship between competition and efficiency is not a straightforward one: increased competition has forced banks to become more efficient but increased efficiency does not seem to be fostering more competitive EU banking systems. [source] DESENSITIZATION OF GUINEA-PIG TAENIA CAECI SMOOTH MUSCLE INDUCED BY A LOW CONCENTRATION OF CARBACHOLCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2007Shigeru Hishinuma SUMMARY 1In guinea-pig taenia caeci smooth muscle we have found that 10,4 mol/L carbachol-induced desensitization to muscarinic agonists develops within 15,30 s, followed by transient resensitization at 1 min, whereas the desensitization to depolarizing high K+ develops with maximal desensitization at 1 min followed by sustained resensitization up to 30 min. In both cases, Ca2+ -dependent processes play a crucial role in determining the development of desensitization. 2To elucidate whether these peculiar processes of desensitization/resensitization may be induced by a lower concentration of carbachol, we examined the development of desensitization induced by 10,6 mol/L carbachol, because at this concentration carbachol is known to induce biphasic changes in intracellular Ca2+ concentrations, with a smaller transient increase followed by a larger sustained increase than seen with 10,4 mol/L carbachol. 3Contractile responses to muscarinic agonists (carbachol or AHR-602) and high K+ were desensitized by pretreatment with 10,6 mol/L carbachol for 30 min in a manner dependent on the presence of extracellular Ca2+. 4The development of 10,6 mol/L carbachol-induced desensitization to these muscarinic agonists in the presence of extracellular Ca2+ showed three successive phases: fast desensitization within 30 s, followed by transient resensitization at 1 min and the subsequent development of desensitization up to 30 min. In contrast, desensitization to high K+ did not develop up to 10 min and significant desensitization occurred at 30 min, with no apparent resensitization phase. 5These results suggest that the characteristics of the Ca2+ -dependent development of desensitization to muscarinic agonists, but not to high K+, are well maintained in desensitization induced by a lower concentration of carbachol. [source] EFFECTS OF PHYSICAL EXERCISE ON PLASMA CONCENTRATIONS OF SEX HORMONES IN ELDERLY WOMEN WITH DEMENTIAJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 6 2005Masahiro Akishita MD No abstract is available for this article. [source] IMPACTS OF SOLAR UV RADIATION ON THE PHOTOSYNTHESIS, GROWTH, AND UV-ABSORBING COMPOUNDS IN GRACILARIA LEMANEIFORMIS (RHODOPHYTA) GROWN AT DIFFERENT NITRATE CONCENTRATIONS,JOURNAL OF PHYCOLOGY, Issue 2 2009Yangqiao Zheng Solar ultraviolet radiation (UVR, 280,400 nm) is known to affect macroalgal physiology negatively, while nutrient availability may affect UV-absorbing compounds (UVACs) and sensitivity to UVR. However, little is known about the interactive effects of UVR and nitrate availability on macroalgal growth and photosynthesis. We investigated the growth and photosynthesis of the red alga Gracilaria lemaneiformis (Bory) Grev. at different levels of nitrate (natural or enriched nitrate levels of 41 or 300 and 600 ,M) under different solar radiation treatments with or without UVR. Nitrate-enrichment enhanced the growth, resulted in higher concentrations of UVACs, and led to negligible photoinhibition of photosynthesis even at noon in the presence of UVR. Net photosynthesis during the noon period was severely inhibited by both ultraviolet-A radiation (UVA) and ultraviolet-B radiation (UVB) in the thalli grown in seawater without enriched nitrate. The absorptivity of UVACs changed in response to changes in the PAR dose when the thalli were shifted back and forth from solar radiation to indoor low light, and exposure to UVR significantly induced the synthesis of UVACs. The thalli exposed to PAR alone exhibited higher growth rates than those that received PAR + UVA or PAR + UVA + UVB at the ambient or enriched nitrate concentrations. UVR inhibited growth approximately five times as much as it inhibited photosynthesis within a range of 60,120 ,g UVACs · g,1 (fwt) when the thalli were grown under nitrate-enriched conditions. Such differential inhibition implies that other metabolic processes are more sensitive to solar UVR than photosynthesis. [source] SCANNING ELECTRON MICROSCOPY OBSERVATIONS OF DEFORMITIES IN SMALL PENNATE DIATOMS EXPOSED TO HIGH CADMIUM CONCENTRATIONS,JOURNAL OF PHYCOLOGY, Issue 6 2008Soizic Morin Different types of malformations are likely to affect the morphology of diatoms when exposed to particularly unstable environmental conditions, the most easily identifiable being distortion of the whole frustule. In the present study, we investigated, by means of SEM, valve abnormalities induced by high cadmium contamination (100 ,g · L,1) in small pennate diatoms. Changes in the shape of Amphora pediculus (Kütz.) Grunow and anomalous sculpturing of the cell wall of many species, such as Encyonema minutum (Hilse) D. G. Mann, Mayamaea agrestris (Hust.) Lange-Bert., Gomphonema parvulum (Kütz.) Kütz., or Eolimna minima (Grunow) Lange-Bert., were observed, which were not, or almost not, noticeable in the LM. With consideration to current knowledge of diatom morphogenesis, metal uptake by the cell would induce, directly or indirectly, damage to many cytoplasmic components (e.g., microtubules, cytoskeleton, Golgi-derived vesicles) involved in the precisely organized silica deposition. This study confirms that many species, whatever their size, are likely to exhibit morphological abnormalities under cadmium stress, and that this indicator may be valuable for the biomonitoring of metal contamination, even if SEM observations are not necessary for routine studies. [source] METABOLIC AND ECOLOGICAL CONSTRAINTS IMPOSED BY SIMILAR RATES OF AMMONIUM AND NITRATE UPTAKE PER UNIT SURFACE AREA AT LOW SUBSTRATE CONCENTRATIONS IN MARINE PHYTOPLANKTON AND MACROALGAE,JOURNAL OF PHYCOLOGY, Issue 2 2007T. Alwyn Marine phytoplankton and macroalgae acquire important resources, such as inorganic nitrogen, from the surrounding seawater by uptake across their entire surface area. Rates of ammonium and nitrate uptake per unit surface area were remarkably similar for both marine phytoplankton and macroalgae at low external concentrations. At an external concentration of 1 ,M, the mean rate of nitrogen uptake was 10±2 nmol·cm,2·h,1 (n=36). There was a strong negative relationship between log surface area:volume (SA:V) quotient and log nitrogen content per cm2 of surface (slope=,0.77), but a positive relationship between log SA:V and log maximum specific growth rate (,max; slope=0.46). There was a strong negative relationship between log SA:V and log measured rate of ammonium assimilation per cm2 of surface, but the slope (,0.49) was steeper than that required to sustain ,max (,0.31). Calculated rates of ammonium assimilation required to sustain growth rates measured in natural populations were similar for both marine phytoplankton and macroalgae with an overall mean of 6.2±1.4 nmol·cm,2·h,1 (n=15). These values were similar to maximum rates of ammonium assimilation in phytoplankton with high SA:V, but the values for algae with low SA:V were substantially less than the maximum rate of ammonium assimilation. This suggests that the growth rates of both marine phytoplankton and macroalgae in nature are often constrained by rates of uptake and assimilation of nutrients per cm2 surface area. [source] GELLING BEHAVIOR OF RICE FLOUR DISPERSIONS AT DIFFERENT CONCENTRATIONS OF SOLIDS AND TIME OF HEATINGJOURNAL OF TEXTURE STUDIES, Issue 3 2008ALKA KAPRI ABSTRACT Rice flour dispersions, under suitable conditions of processing, can form a gel. The effect of concentration of solids (10,18%) and time (0,75 min) of processing on textural attributes, and viscoelasticity were investigated along with sensory attributes. The textural attribute determined is gel strength, while viscoelasticity was determined in terms of mechanical spectra like storage modulus (G,), loss modulus (G,), complex viscosity (,*) and loss factor (tan ,) during a frequency sweep varying from 0.01 to 40 Hz at a constant stress of 25 Pa. Microstructural observation indicates the swelling of starch granules in the beginning of heating, while damaged granule and leached-out materials are visible at the end of the gelling process. Desirability function analysis has been applied to obtain a rice gel with acceptable textural attributes; a solid concentration of 15.2% and a heating time of 75 min can lead to the development of a gel with a satisfaction level of 0.6. PRACTICAL APPLICATIONS Rice flour gels in the form of hard-set gels, porridges and spreads are popular in several parts of the world particularly for feeding of infants and children. The application of the present study lies in understanding the role of major processing variables on the quality attributes and viscoelasticity of a product, characterization of cooked gels and for developing rice flour-based food gels. The findings may also be extended for the development of other cereal-based gels. [source] FOREST-RIVER INTERACTIONS: INFLUENCE ON HYPORHEIC DISSOLVED ORGANIC CARBON CONCENTRATIONS IN A FLOODPLAIN TERRACE,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2002Sandra M. Clinton ABSTRACT: In large floodplain rivers, hyporheic (subsurface) flow-paths transfer nutrients from productive riparian terraces to oligotrophic off-channel habitats. Because dissolved organic carbon (DOC) fuels microbial processes and hyporheic microorganisms represent the first stage of retention and transformation of these nutrients, understanding DOC flux can provide information on the constraints of microbial metabolism in the hyporheic zone of rivers. We monitored hydrology, physicochemical indicators, and dissolved organic carbon (DOC) dynamics during low and high discharge periods in the hyporheic zone of a riparian terrace on the Queets River, Washington, to understand what processes control the supply of carbon to subsurface microbial communities. As discharge increased, terrace hyporheic flowpaths changed from parallel to focused, and the location of surface water inputs to the terrace shifted from the terrace edge to head. Overall, DOC concentrations decreased along hyporheic flowpaths; however, concentrations at points along the flowpaths varied with position along the head gradient and age of the overlying vegetation. We estimated that there is insufficient DOC in adverting surface water to support hyporheic microbial metabolism in this riparian terrace. These trends indicate that there are additional carbon sources to the subsurface water, and we conclude that DOC is leaching from overlying riparian soils within the forest patches. Thus, subsurface DOC concentrations reflect a balance between surface water inputs, metabolic uptake, and allochthonous inputs from forest soils. [source] STORM DISCHARGE, LOADS, AND AVERAGE CONCENTRATIONS IN NORTHWEST OHIO RIVERS, 1975,1995,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2001R. Peter Richards ABSTRACT: A computerized technique was developed to identify storm runoff episodes and calculate storm discharges, storm loads, and storm average concentrations for each event in datasets with up to 10,000 records. This technique was applied to four watersheds within the Lake Erie drainage basin and identified between 160 and 250 runoff events in each. Storm event loads and storm event mean concentrations were calculated for each runoff event for suspended solids, total phosphorus, soluble reactive phosphorus, nitrate, and total Kjeldahl nitrogen. The basic characteristics of the resulting data are described, as are systematic differences as a function of watershed size, seasonal differences, and trends over time. Many of the results of this study reflect the importance of nonpoint processes and improvements in agricultural best management practices in these watersheds. [source] ELECTROPHYSIOLOGICAL EFFECTS OF KETAMINE ON HUMAN ATRIAL MYOCYTES AT THERAPEUTICALLY RELEVANT CONCENTRATIONSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2008Chun-Yu Deng SUMMARY 1Ketamine is widely used for the induction of anaesthesia in high-risk patients with cardiovascular instability or severe hypovolaemia. However, the ionic mechanisms involved in the effects of ketamine at therapeutically relevant concentrations in human cardiac myocytes are unclear. The present study was designed to investigate the effects of ketamine on L-type Ca2+ (ICa), transient outward K+ (Ito), ultra-rapid delayed rectifier K+ (IKur) and inward rectifier potassium (IK1) currents, as well as on action potentials, in human isolated atrial myocytes. 2Atrial myocytes were isolated enzymatically from specimens of human atrial appendage obtained from patients undergoing coronary artery bypass grafting. The action potential and membrane currents were recorded in both current- and voltage-clamp modes using the patch-clamp technique. 3Ketamine inhibited ICa with an IC50 of 1.8 µmol/L. In addition, 10 µmol/L ketamine decreased the ICa peak current at +10 mV from 5.1 ± 0.3 to 2.1 ± 0.4 pA/pF (P < 0.01), but did not change the threshold potential, peak current potential and reverse potential. 4Ketamine had no effect on Ito, IKur or IK1, but it reversibly shortened the duration of the action potential in human atrial myocytes. 5In conclusion, ketamine, at a clinically relevant concentration, shortens the action potential duration of the human atrial myocytes, probably by inhibiting ICa. [source] Ownership Concentration and Corporate Performance on the Budapest Stock Exchange: do too many cooks spoil the goulash?CORPORATE GOVERNANCE, Issue 2 2005John S. Earle We examine the impact of ownership concentration on firm performance using panel data for firms listed on the Budapest Stock Exchange, where ownership tends to be highly concentrated and frequently involves multiple blocks. Fixed-effects estimates imply that the size of the largest block increases profitability and efficiency strongly and monotonically, but the effects of total blockholdings are much smaller and statistically insignificant. Controlling for the size of the largest block, point estimates of the marginal effects of additional blocks are negative. The results suggest that the marginal costs of concentration may outweigh the benefits when the increased concentration involves "too many cooks". [source] Histometric and Histochemical Analysis of the Effect of Trichloroacetic Acid Concentration in the Chemical Reconstruction of Skin Scars MethodDERMATOLOGIC SURGERY, Issue 10 2006SUNG BIN CHO MD BACKGROUND Atrophic scars can be induced by various causes, including severely inflamed acne, chicken pox, and trauma. Many treatment modalities are used for reconstructing and improving the appearance of scars with various treatment results. OBJECTIVE A recent report shows the clinical efficacy of the chemical reconstruction of skin scars (CROSS) method, which consists of the focal application of trichloroacetic acid (TCA) in a higher concentration. Histometric analysis of the CROSS method, however, has not yet been established. METHODS In this study, five hairless mice were used to evaluate the effect of the CROSS method and to analyze the difference between the CROSS method and simple TCA application. RESULTS Similar histologic changes were observed in the two methods, including epidermal and dermal rejuvenation with new collagen deposition. These changes, however, were more prominent in the CROSS method,treated areas, particularly when 100% TCA was used. CONCLUSION The results of this study suggest that treatment of atrophic scars using the CROSS method is more effective than simple application of TCA in activating fibroblasts in the dermis and increasing the amount of collagen. [source] Trade Liberalization and the Geography of Production: Agglomeration, Concentration, and Dispersal in Indonesia's Manufacturing IndustryECONOMIC GEOGRAPHY, Issue 3 2004Örjan Sjöberg Abstract: The effect of the liberalization of trade on the spatial concentration of economic activities is not straightforward. It has been widely argued that protectionism increases spatial concentration as firms locate close to the main domestic markets. However, it has also been argued that an expansion of international trade primarily favors existing industrial centers and therefore leads to increased regional inequalities. Against the background of ongoing debates in both mainstream economics and in geography, we examine the spatial concentration of manufacturing in Indonesia between 1980 and 1996, a period when Indonesia substantially liberalized its trade regime. The high concentration did not decrease during this period, and establishments that engaged in international trade were actually comparably concentrated. We discuss some possible explanations for the spatial concentration in Indonesia and conclude that a host of factors may affect the outcome of trade liberalizations. In particular, the spatial configuration of the national settlement system is a potentially important factor in this regard. [source] Detection of Explosives Using Field-Effect TransistorsELECTROANALYSIS, Issue 20 2009Etery Sharon Abstract The gate surfaces of ion-sensitive field-effect transistor (ISFET) devices were functionalized with the ,-donor units, 6-hydroxydopamine (1) or 4-aminothiophenol (2). Concentration of trinitrotoluene, TNT, on the gate via ,-donor-acceptor interactions yields charge-transfer complexes that alter the gate potential. This enables the label-free analysis of TNT with a detection limit corresponding to 1×10,7,M. [source] Cover Picture: Electrophoresis 16'2010ELECTROPHORESIS, Issue 17 2010Article first published online: 7 SEP 2010 Issue no. 17 is a regular issue comprising 18 manuscripts distributed over 5 separate parts. Part I has 7 research articles on some aspects of proteins and cell separations. Part II has 3 research articles on nucleic acid research including cloning/amplification, gene regulation and STR analysis. Part III offers ways of measuring diffusion and binding constants in two separate articles. Concentration and detection approaches are treated in 4 research articles making up Part IV. The last two articles in this issue (Part V) are on CEC and EKC describing a mixed mode monolithic stationary phase and a cyclodextrin-modified MEEKC. Featured articles include: Lamp-based wavelength-resolved fluorescence detection for protein capillary electrophoresis: Set-up and detector performance ((doi: 10.1002/elps.201000246)) Electromigration diffusivity spectrometry: A way for simultaneous determination of diffusion coefficients from mixed samples ((doi: 10.1002/elps.201000252)) Sample stacking capillary electrophoretic microdevice for highly sensitive mini Y short tandem repeat genotyping ((doi: 10.1002/elps.201000270)) [source] Long-term stability of biological denitrification process for high strength nitrate removal from wastewater of uranium industryENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2008Prashant M. Biradar Abstract The aim of the present study was to biologically denitrify uranium nitrate raffinate (UNR) from nuclear industry, which is a principle source of high strength nitrate waste. To denitrify the high nitrate waste, a pilot-scale continuous stirred tank reactor was designed with two inbuilt settlers. Acclimatization of mixed culture with synthetic waste was carried out prior to the inoculation of the acclimatized sludge into the reactor. Initial concentration of nitrate in uranium raffinate was 77,000 mg/L NO3. It was diluted and used as a feed to the reactor. Concentration of nitrate in feed was increased gradually from 10,000 mg/L NO3 to 40,000 mg/L NO3 with hydraulic retention time (HRT) maintained at 34.4 h. Complete denitrification of 40,000 mg/L NO3 was achieved in a specified HRT. To facilitate understanding of the treatablity and long-term stability of biological denitrification of UNR, study was carried out for 211 days by periodical perturbation of the system. Furthermore, to find the volume ratio of reactor to settler required for the full-scale design of the denitrification plant, settling of acclimatized sludge was carried out. © 2008 American Institute of Chemical Engineers Environ Prog, 2008 [source] Response of the freshwater alga Chlorella vulgaris to trichloroisocyanuric acid and ciprofloxacin,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2008Xiangping Nie Abstract The effects of trichloroisocyanuric acid (TCCA) and ciprofloxacin (CPFX) on the freshwater alga Chlorella vulgaris were assessed by toxicity bioassays and by the values of biomarkers in phase I and phase II. The biomarkers included growth rate, concentration of chlorophyll a, activities of 7-ethoxyresorufin- O -dealkylases (EROD), glutathione S -transferase (GST), catalase (CAT), and total glutathione (GSH). Ciprofloxacin was a weaker growth inhibitor than TCCA but, at a concentration of greater than 12.5 mg/L, decreased the growth of C. vulgaris. Concentration of chlorophyll a showed a similar trend. The 96-h median effective concentration (EC50; i.e., 50% reduction in growth relative to the control) of CPFX was 20.6 mg/L. Trichloroisocyanuric acid was a strong growth inhibitor and, at concentrations of greater than 0.80 mg/L, caused 100% inhibition on 24-h exposure. The 96-h EC50 of TCCA was 0.313 mg/L. Ciprofloxacin and TCCA affected the phase I and phase II enzyme activities differently. On exposure to CPFX, both EROD and GSH decreased at low CPFX concentrations (<5.0 mg/L) and increased at high CPFX concentrations (>12.5 mg/L), and CAT and GST exhibited induction at low concentrations and inhibition at high concentrations. In TCCA exposure, GST activity was significantly stimulated, and GSH concentration was increased. Catalase activity increased only at TCCA concentrations of greater than 0.12 mg/L, and no change in EROD activity was observed. [source] Uptake and accumulation of sediment-associated 4-nonylphenol in a benthic invertebrate (Lumbriculus variegatus, freshwater oligochaete)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2005Valeria Croce Abstract In the present work, the oligochaete Lumbriculus variegatus was exposed for 56 d to lake sediment spiked with 4-nonylphenol (4-NP), which is a breakdown product of alkylphenol polyethoxylates, an important class of nonionic surfactants. During the exposure period, the content of 4-NP was determined in the oligochaetes, sediment, overlying water, and pore water in order to monitor the distribution of the 4-NP in the compartments of the test system. Concentration of 4-NP in L. variegatus increased linearly over the course of the test, with an uptake rate coefficient of 1.9 × 10,2 (± 0.2 × 10,2; [g carbon/(g lipid-h)]). No steady state was reached at the end of the exposure period, suggesting that the elimination of 4-NP by the organism was negligible. Ingested sediments played an important role in the accumulation of 4-NP in L. variegatus, which may achieve very high 4-NP body concentrations. The 56-d biota sediment accumulation factor (BSAF) was 24 ± 7 g carbon/g lipid. L. variegatus also was exposed to 4-NP-contaminated field sediment, and field oligochaetes and sediments were collected for 4-NP pollution assessment in aquatic ecosystem. The 4-NP uptake with natural sediment was in accordance with that measured with spiked sediments, suggesting that the bioavailability of sediment-associated 4-NP for L. variegatus was not affected by 4-NP sediment concentration and abiotic sediment characteristics. The BSAFs measured in field oligochaetes, ranging from 39 to 55 g carbon/g lipid, was relatively higher than the bioaccumulation factor measured in laboratory tests. The results suggest that 4-NP concentration can reach high levels in benthic oligochaetes; this can be an important way of exposure for their pelagic predators. [source] Effects of Potassium Concentration on Firing Patterns of Low-Calcium Epileptiform Activity in Anesthetized Rat Hippocampus: Inducing of Persistent Spike ActivityEPILEPSIA, Issue 4 2006Zhouyan Feng Summary:,Purpose: It has been shown that a low-calcium high-potassium solution can generate ictal-like epileptiform activity in vitro and in vivo. Moreover, during status epileptiform activity, the concentration of [K+]o increases, and the concentration of [Ca2+]o decreases in brain tissue. Therefore we tested the hypothesis that long-lasting persistent spike activity, similar to one of the patterns of status epilepticus, could be generated by a high-potassium, low-calcium solution in the hippocampus in vivo. Methods: Artificial cerebrospinal fluid was perfused over the surface of the exposed left dorsal hippocampus of anesthetized rats. A stimulating electrode and a recording probe were placed in the CA1 region. Results: By elevating K+ concentration from 6 to 12 mM in the perfusate solution, the typical firing pattern of low-calcium ictal bursts was transformed into persistent spike activity in the CA1 region with synaptic transmission being suppressed by calcium chelator EGTA. The activity was characterized by double spikes repeated at a frequency ,4 Hz that could last for >1 h. The analysis of multiple unit activity showed that both elevating [K+]o and lowering [Ca2+]o decreased the inhibition period after the response of paired-pulse stimulation, indicating a suppression of the after-hyperpolarization (AHP) activity. Conclusions: These results suggest that persistent status epilepticus,like spike activity can be induced by nonsynaptic mechanisms when synaptic transmission is blocked. The unique double-spike pattern of this activity is presumably caused by higher K+ concentration augmenting the frequency of typical low-calcium nonsynaptic burst activity. [source] Low Concentration of DL-2-Amino-5-phosphonovalerate Induces Epileptiform Activity in Guinea Pig Hippocampal SlicesEPILEPSIA, Issue 10 2001Ali Gorji Summary: , Purpose: The specific mechanisms by which low concentrations of cyclosporine induce seizures and low concentrations of phencyclidine provoke behavioral excitation remain to be elucidated. Both compounds block N -methyl- d -aspartate (NMDA) receptors. The aim of this study was to determine if low concentrations of the NMDA-receptor blockers increase the seizure susceptibility. Methods: Guinea pig hippocampal slices were exposed to artificial cerebrospinal fluid containing the NMDA blocker dl -2-amino-5-phosphono-valerate (APV; 0.1,10 ,M). Extracellular field potentials were recorded from CA1 and CA3 regions. Results: Low concentrations of APV induced epileptiform burst discharges (0.1,0.25 ,M), whereas higher doses failed to decrease the seizure threshold (1,10 ,M). Conclusions: The results indicate that the excitatory effect of low concentrations NMDA blockers may play a role in the neurotoxicity of aforementioned substances. [source] Concentration of methylprednisolone in the centrodistal joint after administration of methylprednisolone acetate in the tarsometatarsal jointEQUINE VETERINARY JOURNAL, Issue 2 2005A. SERENA Summary Reasons for performing study: The centrodistal (CD) and tarsometatarsal (TMT) joints are often injected individually with a corticosteroid to resolve lameness caused by osteoarthritis (OA). There are no data available regarding diffusion of methylprednisolone (MP) from the TMT joint to the CD joint. Hypothesis: A therapeutic concentration of MP diffuses into the CD joint after methylprednisolone acetate (MPA) is administered into the TMT joint. Objective: To measure the concentration of MP in the CD joint after MPA was administered into the TMT joint. Methods: MPA was administered into a TMT joint of 16 horses. At different times, the ipsilateral CD joint of these horses was injected with a small amount of saline and recovered saline was measured for concentration of MP using high performance liquid chromatography. Results: Six hours after administration of MPA into the TMT joint, a therapeutic concentration of MP was found in all 10 CD joints sampled at this time. Conclusions: Horses with pain arising from the distal 2 joints of the hock can be treated by administering MPA into the TMT joint alone. Potential relevance: Administering MPA into the TMT joint only, to treat OA of the distal 2 hock joints, reduces the difficulties and risks associated with centesis of the CD joint. [source] Effects of Market Segmentation and Bank Concentration on Mutual Fund Expenses and Returns: Evidence from FinlandEUROPEAN FINANCIAL MANAGEMENT, Issue 3 2004Timo P. Korkeamaki G15; G18; G20 Abstract A tremendous amount of research examines US mutual funds, but fund markets also thrive in other countries. However, research about these fast growing markets is lacking. This study addresses Finnish funds. Fast growth of the Finnish fund industry, strong bank dominance in the industry and recent EU membership make it an interesting market to examine. The Finnish fund market is also of particular interest since it had the fastest growth among the EU countries during 1996,2000. We find evidence that bank-managed and older funds charge higher expenses but investors are not compensated for paying higher expenses with higher risk-adjusted returns, suggesting a potential agency problem. Overall, Finnish fund expenses have decreased over time, consistent with EU membership reducing market segmentation and generating competition. [source] Mechanical stretch induces TGF-, synthesis in hepatic stellate cellsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2 2004R. Sakata Abstract Background, It is known that mechanical stress induces extracellular matrix via transforming growth factor-, (TGF-,) synthesis in vascular smooth muscle cells. Activated hepatic stellate cells (HSCs) are an important source of TGF-, in the liver. However, it remains unclear whether mechanical stress induces TGF-, in HSCs. The Rho small GTP-binding protein (Rho) has recently emerged as an important regulator of actin and cytoskeleton. We examined whether TGF-, is expressed in stretched HSCs and whether Rho is involved in stretch-induced TGF-, synthesis. Materials and methods, A cultured human HSC cell line, LI90, was used for this study. Hepatic stellate cells were cyclically stretched using the Flexercell® strain unit. Concentration of TGF-, in the conditioned medium was estimated by a bioassay using mink lung epithelial cells transfected with a plasminogen activator inhibitor-1 promoter-luciferase construct. Transforming growth factor-, mRNA expression of HSCs was estimated by a reverse-transcription polymerase chain reaction. Replication-defective adenoviral vectors expressing a dominant negative type of Rho was utilized to suppress its effect on HSCs. Results, Transforming growth factor-, concentration of the conditioned media of stretched HSCs showed time-dependent increases as compared to nonstretched HSCs from 2 h to 24 h. Transforming growth factor-, mRNA expression in stretched HSCs was increased compared with that in nonstretched HSCs. Transfection of dominant negative Rho inhibited the stretch-induced TGF-, synthesis. Conclusions, Mechanical stretch enhanced TGF-, expression on mRNA and protein level in HSCs. Rho was closely related to stretch-induced TGF-, synthesis in HSCs. [source] | ||||||||||||||||||||||||||||||||||||||||||||||