Home About us Contact
|
Home About us Contact | ||
|
|
||
Small Volume (small + volume)
Selected AbstractsUltra scale-down studies of the effect of shear on cell quality; Processing of a human cell line for cancer vaccine therapyBIOTECHNOLOGY PROGRESS, Issue 5 2009Ryan McCoy Abstract Whole cell therapy is showing potential in the clinic for the treatment of many chronic diseases. The translation of laboratory-scale methods for cell harvesting and formulation to commercial-scale manufacturing offers major bioprocessing challenges. This is especially the case when the cell properties determine the final product effectiveness. This study is focused on developing an ultra scale-down method for assessing the impact of the hydrodynamic environment on human cells that constitute the therapeutic product. Small volumes of a prostate cancer cell line, currently being developed in late phase II clinical trials as an allogeneic whole cell vaccine therapy for prostate cancer, were exposed to hydrodynamic shear rates similar to those present in downstream process, formulation and vial filling operations. A small scale rotating disc shear device (20 mL) was used over a range of disc speeds to expose cells to maximum shear rates ranging from 90 × 103 to 175 × 103 s -1 (equivalent maximum power dissipation rates of 14 × 103 to 52 × 103 W kg -1). These cells were subsequently analyzed for critical cell quality attributes such as the retention of membrane integrity and cell surface marker profile and density. Three cell surface markers (CD9, CD147, and HLAA-C) were studied. The cell markers exhibited different levels of susceptibility to hydrodynamic shear but in all cases this was less than or equal to the loss of membrane integrity. It is evident that the marker, or combination or markers, which might provide the required immunogenic response, will be affected by hydrodynamic shear environment during bioprocessing, if the engineering environment is not controlled to within the limits tolerated by the cell components. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] The organisation of invertebrate brains: cells, synapses and circuitsACTA ZOOLOGICA, Issue 1 2010Ian A. Meinertzhagen Abstract Meinertzhagen, I.A. 2010. The organisation of invertebrate brains: cells, synapses and circuits. ,Acta Zoologica (Stockholm) 91: 64,71 Invertebrate brains are structurally diverse. Neuron numbers range from ,102 to 108 in different groups, compared with larger numbers in vertebrate brains, ,107 to 1014. The underpopulated brains of invertebrates are noted in their extreme cases for having few cells, and neurons that can be identified from animal to animal, many known in great detail. Although few in number, invertebrate neurons nevertheless comprise many classes. Correlated with the paucity of their number they are sparsely connected, many having ,50 synapses or fewer. Synaptic densities, roughly 1 per ,m3 of neuropile, differ little from those for much larger vertebrate neurons. Invertebrate neurons differ from their vertebrate counterparts in the position of their soma, generally in a cortex surrounding the neuropile that consequently occupies a relatively small volume. Their axons typically lack myelin and, supporting a range of conduction velocities, have diameters that differ over a wide range, from 103 to 10,1,m. Nerves with thousands of axons differ from neuropile fascicles, which typically have 20 or less. Unlike most vertebrate synapses, but like those of the vertebrate retina, synapses in many invertebrate groups , probably all ecdysozoans and possibly some lophotrochozoans , have synaptic contacts with multiple postsynaptic elements, dyads, triads and so on. [source] Voltametric and Flow Injection Determination of Oxytetracycline Residues in Food Samples Using Carbon Fiber MicroelectrodesELECTROANALYSIS, Issue 7 2003L. Agüí Abstract A voltammetric method for the determination of the antibiotic oxytetracycline (OTC) in food samples is reported. Carbon fiber microelectrodes (CFMEs), which allow voltammetric measurements to be performed in a small volume (1,mL) of the analyte extract from the samples, are employed. Repeatable electroanalytical responses were obtained with no need of applying cleaning treatments to the CFME. Under the optimized square-wave conditions, a linear calibration plot for OTC was obtained in the 1.0×10,6,1.0×10,4,mol,L,1 range, with a detection limit of 2.9×10,7,mol,L,1 (150,ng,mL,1) OTC. The determination of OTC by a flow-injection method with amperometric detection using a homemade flow cell specially designed to work with CFMEs, was also evaluated using pure acetonitrile as the carrier. The SW voltammetric method was applied to the determination of OTC in spiked milk and eggs samples, at 100,ng,mL,1 and 200,ng g,1 levels, respectively. The procedure involved the extraction of the analyte in ethyl acetate, evaporation of the solvent and reconstitution of the residue in acetonitrile ,5.0×10,4,mol,L,1 tetrabutylammonium perchlorate medium. Recoveries of 96±8 and 91±8% were obtained for milk and eggs, respectively, by applying the standard additions method. [source] Combined use of supported liquid membrane and solid-phase extraction to enhance selectivity and sensitivity in capillary electrophoresis for the determination of ochratoxin A in wineELECTROPHORESIS, Issue 7 2008Sara Almeda Abstract This paper proposes a novel strategy to enhance selectivity and sensitivity in CE, using supported liquid membrane (SLM) and off-line SPE simultaneously. The determination of ochratoxin A (OA) in wine has been used to demonstrate the potential of this methodology. In the SLM step, the donor phase (either a 20,mL volume of a standard solution at pH,1 or a wine sample at pH,8) was placed in a vial, where a micromembrane extraction unit accommodating the acceptor phase (1,mL water, pH,11) in its lumen was immersed. The SLM was constructed by impregnating a porous Fluoropore Teflon (PTFE) membrane with a water-immiscible organic solvent (octanol). In the off-line SPE step, the nonpolar sorbent (C-18, 4,mg) selectively retained the target ochratoxin, enabling small volumes of acceptor phase (1,mL) to be introduced. The captured analytes were eluted in a small volume of methanol (0.1,mL). This procedure resulted in sample cleanup and concentration enhancement. The method was evaluated for accuracy and precision, and its RSD found to be 5%. The LODs for OA in the standard solutions and wine samples were 0.5 and 30,,g/L, respectively. The results obtained demonstrate that SLM combined with off-line is a good alternative to the use of immunoaffinity columns prior to CE analysis. [source] Pregnancy rates in mares after a single fixed time hysteroscopic insemination of low numbers of frozen-thawed spermatozoa onto the uterotubal junctionEQUINE VETERINARY JOURNAL, Issue 2 2003L. H. A. MORRIS Summary Reasons for performing study: To compensate for the wide variation in the freezability of stallion spermatozoa, it has become common veterinary practice to carry out repeated ultrasonography of the ovaries of oestrous mares in order to be able to inseminate them within 6,12 h of ovulation with a minimum of 300,500 × 106 frozen-thawed spermatozoa. Furthermore, in order to achieve satisfactory fertility, this requirement for relatively high numbers of spermatozoa currently limits our ability to exploit recently available artificial breeding technologies, such as sex-sorted semen, for which only 5,20 × 106 spermatozoa are available for insemination. Objectives: This study was designed to evaluate and compare the efficacy of hysteroscopic vs. conventional insemination when low numbers of spermatozoa are used at a single fixed time after administration of an ovulation-inducing agent. Methods: In the present study, pregnancy rates were compared in 86 mares inseminated once only with low numbers of frozen-thawed spermatozoa (3,14 × 106) at 32 h after treatment with human chorionic gonadotrophin (hCG), either conventionally into the body of the uterus or hysteroscopically by depositing a small volume of the inseminate directly onto the uterotubal papilla ipsilateral to the ovary containing the pre-ovulatory follicle. Results: Pregnancy rates were similarly high in mares inseminated conventionally or hysteroscopically with 14 × 106 motile frozen-thawed spermatozoa (67% vs. 64%). However, when the insemination dose was reduced to 3 × 106 spermatozoa, the pregnancy rate was significantly higher in the mares inseminated hysteroscopically onto the uterotubal junction compared to those inseminated into the uterine body (47 vs. 15%, P<0.05). Conclusions: When inseminating mares with <10 × 106 frozen-thawed stallion spermatozoa, hysteroscopic uterotubal junction deposition of the inseminate is the preferred method. Potential clinical relevance: Satisfactory pregnancy rates are achievable after insemination of mares with frozen-thawed semen from fertile stallions 32 h after administration of human chorionic gonadotrophin (Chorulon)1. Furthermore, these results were obtained when mares were inseminated with 14 × 106 progressively motile frozen-thawed spermatozoa from 2 stallions of proven fertility. [source] Pigments and proteins in green bacterial chlorosomes studied by matrix-assisted laser desorption ionization mass spectrometryFEBS JOURNAL, Issue 2 2000Søren Persson We have used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for mass determination of pigments and proteins in chlorosomes, the light-harvesting organelles from the photosynthetic green sulfur bacterium Chlorobium tepidum. By applying a small volume (1 µL) of a concentrated suspension of isolated chlorosomes directly to the target of the mass spectrometer we have been able to detect bacteriochlorophyll a and all the major homologs of bacteriochlorophyll c. The peak heights of the different bacteriochlorophyll c homologs in the MALDI spectra were proportional to peak areas obtained from HPLC analysis of the same sample. The same result was also obtained when whole cells of Chl. tepidum were applied to the target, indicating that MALDI-MS can provide a rapid method for obtaining a semiquantitative determination or finger-print of the bacteriochlorophyll homologs in a small amount of green bacterial cells. In addition to information on pigments, the MALDI spectra also contained peaks from chlorosome proteins. Thus we have been able with high precision to confirm the molecular masses of the chlorosome proteins CsmA and CsmE which have been previously determined by conventional biochemical and genetic methods, and demonstrate the presence of truncated versions of CsmA and CsmB. [source] Nanofibers from Laser Spinning: Laser Spinning of Bioactive Glass Nanofibers (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Mater. This cover image is a graphical representation of the laser spinning process described by Félix Quintero et al. on page 3084. Laser spinning involves the use of a high power laser to melt a very small volume from a plate of the precursor material. A high speed supersonic gas jet causes the rapid elongation and cooling of the melt, yielding a glass nanofiber. The authors also describe the use of this technique in producing Bioglass nanofibers. [source] Conditional gene recombination by adenovirus-driven Cre in the mouse uterusGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 2 2006Haibin Wang Abstract Cre-mediated conditional gene targeting has been shown to be successful in many cell and tissue types. However, gene recombination in the uterus with heterogeneous cell types by Cre activation is not yet well established. Using recombinant adenoviruses expressing a functional Cre (ADV-Cre) and ROSA26 reporter mice, we show here that ADV-Cre infused intraluminally in a small volume (10 ,l) conditionally excises the loxP site, resulting in lacZ expression in uterine luminal epithelial cells without significantly affecting pregnancy. In contrast, a similar intraluminal infusion of ADV-Cre in a larger volume (50 ,l) damages the normal architecture and integrity of the luminal epithelium, inducing gene recombination in the underneath stromal cells, with disruption of pregnancy. Further, decidualizing stromal cells at the implantation sites can be targeted by ADV-Cre after intravenous administration on days 5,6. This route of administration also elicits Cre activity in other tissues, including the liver, spleen, ovary, and, more remarkably, in the adrenal cortex. These findings demonstrate the feasibility of achieving conditional expression or deletion of specific genes in uterine cells at desired times and physiological states. genesis 44:51,56, 2006. © 2006 Wiley-Liss, Inc. [source] Nitrogen-Enriched Nonporous Carbon Electrodes with Extraordinary SupercapacitanceADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Denisa Hulicova-Jurcakova Abstract Nitrogen-enriched nonporous carbon materials derived from melamine,mica composites are subjected to ammonia treatment to further increase the nitrogen content. For samples preoxidized prior to the ammonia treatment, the nitrogen content is doubled and is mainly incorporated in pyrrol-like groups. The materials are tested as electrodes for supercapacitors, and in acidic or basic electrolytes, the gravimetric capacitance of treated samples is three times higher than that of untreated samples. This represents a tenfold increase of the capacitance per surface area (3300,µF,cm,2) in basic electrolyte. Due to the small volume of the carbon materials, high volumetric capacitances are achieved in various electrolytic systems: 280,F,cm,3 in KOH, 152,F,cm,3 in H2SO4, and 92,F,cm,3 in tetraethylammonium tetrafluoroborate/propylene carbonate. [source] A Bayesian approach to estimating tectonic stress from seismological dataGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2007Richard Arnold SUMMARY Earthquakes are conspicuous manifestations of tectonic stress, but the non-linear relationships between the stresses acting on a fault plane, its frictional slip, and the ensuing seismic radiation are such that a single earthquake by itself provides little information about the ambient state of stress. Moreover, observational uncertainties and inherent ambiguities in the nodal planes of earthquake focal mechanisms preclude straightforward inferences about stress being drawn on the basis of individual focal mechanism observations. However, by assuming that each earthquake in a small volume of the crust represents a single, uniform state of stress, the combined constraints imposed on that stress by a suite of focal mechanism observations can be estimated. Here, we outline a probabilistic (Bayesian) technique for estimating tectonic stress directions from primary seismological observations. The Bayesian formulation combines a geologically motivated prior model of the state of stress with an observation model that implements the physical relationship between the stresses acting on a fault and the resultant seismological observation. We show our Bayesian formulation to be equivalent to a well-known analytical solution for a single, errorless focal mechanism observation. The new approach has the distinct advantage, however, of including (1) multiple earthquakes, (2) fault plane ambiguities, (3) observational errors and (4) any prior knowledge of the stress field. Our approach, while computationally demanding in some cases, is intended to yield reliable tectonic stress estimates that can be confidently compared with other tectonic parameters, such as seismic anisotropy and geodetic strain rate observations, and used to investigate spatial and temporal variations in stress associated with major faults and coseismic stress perturbations. [source] Simultaneous estimation of diffusive Volatile Organic Compound (VOC) fluxes and Non-Aqueous Phase Liquid (NAPL) saturation in the vadose zoneGROUND WATER MONITORING & REMEDIATION, Issue 2 2005David Werner Soil-gas monitoring is a widely used tool to observe the migration of volatile organic compounds (VOCs) at contaminated sites. By combining this technique with natural gradient tracer methods, diffusive contaminant fluxes can be measured in situ, and non,aqueous phase liquid (NAPL) can be detected and roughly quantified. This work describes the new approach and its application at a field site in Denmark with an emplaced NAPL contamination. Soil-gas probes with a low dead volume were installed at 1-m depths in the sandy vadose zone, and a small volume of gas containing conservative and partitioning tracers was injected. Soil-gas samples were withdrawn subsequently during 1 to 4 h and analyzed simultaneously for VOCs and tracers. Tracers detected the NAPL reliably, and the combined data allowed for a close delineation of the source zone. The calculated NAPL saturation deviated by up to a factor of 3 from the analyses of soil cores. Better agreement was found by taking the NAPL composition into consideration, which is, however, generally unknown at the actual field sites. In addition, the tracers were also used to estimate effective diffusion coefficients in situ, which varied by a factor of 2 between various locations. From these data, diffusive contaminant vapor fluxes were quantified without additional laboratory experiments or the use of empirical relationships. The new approach yields a better site investigation with a few additional measurements. [source] History of hemodialyzers' designsHEMODIALYSIS INTERNATIONAL, Issue 2 2008Zbylut J. TWARDOWSKI Abstract Accumulation of knowledge requisite for development of hemodialysis started in antiquity and continued through Middle Ages until the 20th century. Firstly, it was determined that the kidneys produce urine containing toxic substances that accumulate in the body if the kidneys fail to function properly; secondly, it was necessary to discover the process of diffusion and dialysis; thirdly, it was necessary to develop a safe method to prevent clotting in the extracorporeal circulation; and fourthly, it was necessary to develop biocompatible dialyzing membranes. Most of the essential knowledge was acquired by the end of the 19th century. Hemodialysis as a practical means of replacing kidney function started and developed in the 20th century. The original hemodialyzers, using celloidin as a dialyzing membrane and hirudin as an anticoagulant, were used in animal experiments at the beginning of the 20th century, and then there were a few attempts in humans in the 1920s. Rapid progress started with the application of cellophane membranes and heparin as an anticoagulant in the late 1930s and 1940s. The explosion of new dialyzer designs continued in the 1950s and 1960s and ended with the development of capillary dialyzers. Cellophane was replaced by other dialyzing membranes in the 1960s, 1970s, and 1980s. Dialysis solution was originally prepared in the tank from water, electrolytes, and glucose. This solution was recirculated through the dialyzer and back to the tank. In the 1960s, a method of single-pass dialysis solution preparation and delivery system was designed. A large quantity of dialysis solution was used for a single dialysis. Sorbent systems, using a small volume of regenerated dialysis solution, were developed in the mid 1960s, and continue to be used for home hemodialysis and acute renal failure. At the end of the 20th century, a new closed system, which prepared and delivered ultrapure dialysis solution preparation, was developed. This system also had automatic reuse of lines and dialyzers and prepared the machine for the next dialysis. This was specifically designed for quotidian home hemodialysis. Another system for frequent home hemodialysis or acute renal failure was developed at the turn of the 21st century. This system used premanufactured dialysis solution, delivered to the home or dialysis unit, as is done for peritoneal dialysis. [source] Injectable Biomaterials for Regenerating Complex Craniofacial Tissues,ADVANCED MATERIALS, Issue 32-33 2009James D. Kretlow Abstract Engineering complex tissues requires a precisely formulated combination of cells, spatiotemporally released bioactive factors, and a specialized scaffold support system. Injectable materials, particularly those delivered in aqueous solution, are considered ideal delivery vehicles for cells and bioactive factors and can also be delivered through minimally invasive methods and fill complex 3D shapes. In this review, we examine injectable materials that form scaffolds or networks capable of both replacing tissue function early after delivery and supporting tissue regeneration over a time period of weeks to months. The use of these materials for tissue engineering within the craniofacial complex is challenging but ideal as many highly specialized and functional tissues reside within a small volume in the craniofacial structures and the need for minimally invasive interventions is desirable due to aesthetic considerations. Current biomaterials and strategies used to treat craniofacial defects are examined, followed by a review of craniofacial tissue engineering, and finally an examination of current technologies used for injectable scaffold development and drug and cell delivery using these materials. [source] Miniaturized planar ferrite junction circulator in the form of substrate-integrated waveguideINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2008Wenquan Che Abstract The theoretical analysis and engineering implementation of the planar substrate-integrated waveguide (SIW) ferrite junction circulator have been proposed in this article. The ferrite junction circulator is implemented in the form of SIW, taking the features of low profile, small volume and easy integration with other planar circuits. The design strategies of the device have been introduced, including the design consideration of the microstrip transition. One C-band prototype of SIW ferrite junction circulator has been fabricated and measured. The experimental results indicate the bandwidth is about 33% at ,15 dB isolation and the maximum isolation is near 40 dB. However, the insertion loss is a little big, owing to the imperfect dielectric material and fabrication inaccuracy. The SIW ferrite junction circulator and the microstrip transition are integrated into a same substrate, resulting in a very compact planar ferrite junction circulator and indicating potential applications in integrated communication and radar systems. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. [source] Acceleration of nitric oxide autoxidation and nitrosation by membranesIUBMB LIFE, Issue 4-5 2007Matias N. Möller Abstract The reaction between nitric oxide (,NO) and oxygen yields reactive species capable of oxidizing and nitrosating proteins, as well as deaminating DNA bases. Although this reaction is considered too slow to be biologically relevant, it has been shown that membranes, lipoproteins, mitochondria and possibly proteins can accelerate this reaction. This effect stems from the higher solubility of both ,NO and O2in the hydrophobic phase of these biological particles, leading to a concentration of both reagents and so a higher rate of reaction. It has been determined that this reaction occurs from 30 to 300 times more rapidly within the membrane, while even higher values have been suggested for proteins. The autoxidation of ,NO in membranes is not the main route for cellular ,NO consumption but an important consequence of this phenomenon is to focus the generation of significant amounts of oxidizing and nitrosating molecules (nitrogen dioxide and dinitrogen trioxide) in the small volume comprised by cellular membranes. Even so, these reactive species are diffusible and their ultimate fate will depend on the reactivity towards available substrates rather than on physical barriers. The acceleration of ,NO autoxidation by biological hydrophobic phases may thus be a general phenomenon that increases in importance in cases of ,NO overproduction. IUBMB Life, 59: 243-248, 2007 [source] Scanning electron microscopy and transmission electron microscopy microstructural investigation of high-speed tool steel after Nd:YAG pulsed laser meltingJOURNAL OF MICROSCOPY, Issue 1 2006S. KAC Summary This article presents the microstructure of a pulsed Nd:YAG laser-melted high-speed steel, namely HS6-5-2. The high chemical homogeneity and fine structure of the melted zone was attributed to high cooling rates due to the short duration of interaction with the Nd:YAG pulsed laser radiation and the relatively small volume of the melted material. The structure obtained in the surface layer after laser melting has a high level of hardness and shows improved wear resistance. [source] The importance of gel properties for mucoadhesion measurements: a multivariate data analysis approachJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2004Helene Hägerström ABSTRACT In this study we used tensile strength measurements and a recently developed interpretation procedure to evaluate the mucoadhesive properties of a large set of gel preparations with diverse rheological properties. Multivariate data analysis in the form of principal component analysis (PCA) and partial least square projection to latent structures (PLS) was applied to extract useful information from the rather large quantities of data obtained. PCA showed that the selected series of gels was heterogeneous. Some groupings could be detected but none of the gels was identified as an outlier. By using PLS we investigated the relations between the rheological properties of a gel and the parameters defining the cohesiveness, as measured with the texture analyser used for the mucoadhesion measurements. The rheological properties proved to be important for the results of both the mucoadhesion and the cohesiveness measurements. Furthermore, by using PLS two different measurement configurations were evaluated and it was concluded that the combination of a relatively small volume of gel and two pieces of mucosa seems to be more appropriate than a large volume of gel in combination with one piece of mucosa. [source] Ultrasound-assisted dispersive liquid,liquid microextraction coupled with capillary gas chromatography for simultaneous analysis of nine pyrethroids in domestic wastewatersJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2010Hongyuan Yan Abstract A simple and rapid ultrasound-assisted dispersive liquid,liquid microextraction method coupled with GC-flame ionization detection was developed for simultaneous determination of nine pyrethroids in domestic wastewater samples. An ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution using small volume of disperser solvent, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters affecting the extraction efficiency were investigated, including the type and volume of extraction solvent and disperser solvent, extraction and ultrasonic time. Good linearity was obtained for all analytes in the range of 0.8,100,,g/L with the correlation coefficient (r2),0.998. The recoveries at three spiking levels ranged from 75.3 to 101.2% with the RSD less than 8.7% (n=5). Under the optimum condition, the enrichment factors for the nine pyrethroids ranged from 728- to 1725-fold. This method offered a good alternative for routine analysis due to its simplicity and reliability. [source] Selective preconcentration of volatile mercaptans in small SPE cartridges: Quantitative determination of trace odor-active polyfunctional mercaptans in wineJOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009Laura Mateo-Vivaracho Abstract A general procedure for the selective preconcentration and purification of mercaptans has been developed. Mercaptans are strongly retained in a small (20,mg) SPE cartridge containing p- hydroxymercurybenzoate. The cartridge can then be rinsed with relatively high volumes of polar (water/methanol mixtures) and non-polar (pentane or pentane/ether mixtures) rinsing solutions to remove nearly all volatile compounds lacking a thiol functionality. Retained analytes are further eluted with a small volume of an organic solvent containing 1,4-dithioerythritol. Some basic aspects of the strategy, such as the retention of p -hydroxymercurybenzoate in the sorbent and its stability versus different rinsing and eluting systems, have been studied in depth. Light sulfur compounds contained in water or wine, including mercaptans such as methanethiol or thioethers, such as diethyl sulfide, can be quantitatively extracted, although only mercaptans can be quantitatively recovered if a polar rinsing is applied. The strategy has been applied to the GC-MS quantitative determination of some trace polyfunctional mercaptans that are key aromas in wine, such as 2-methyl-3-furanthiol, 2-furfurylthiol, 4-mercapto-4-methyl-2-pentanone, 3-mercaptohexyl acetate or 3-mercaptohexanol. The developed method reaches detection limits in the ng/L range and has a satisfactory analytical behavior, being quite simple and fast. [source] Determination of uric acid in plasma and allantoic fluid of chicken embryos by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2007Jana Mat, ková Abstract Capillary electrophoresis with diode array detection (DAD) was used to determine uric acid (UA) in chicken plasma and the allantoic fluid of chicken embryos. Complete separation of uric and ascorbic acids was attained in less than 10 min in the optimized BGE containing 60 mM MES + 30 mM Tris + 0.001% (w/v) polybrene (pH 6.1). The limit of UA detection (0.2 mg/L) was found to be low enough for sensitive analysis of native plasma and allantoic fluid samples. Range of linearity (1,200 mg/L), repeatability for peak area (CV <4.1%) and migration time (CV <2.5%), as well as recovery of UA from biological samples (97,100%), were found to be satisfactory. The method was applied to detect the elevated UA concentrations (hyperuricemia) in chicken embryos with induced unilateral renal agenesis. CE/DAD analysis of the chicken plasma can be carried out with a relatively small volume of samples (1 ,L). [source] Development of cryogenic chromatography using thermoelectric modules for the separation of methyltin compoundsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6-7 2003Liu Jiemin Abstract A nonliquid cryogenic gas chromatograph using thermoelectric modules for the cryogenic separation of low boiling-point compounds was developed. The new system included four thermoelectric modules, a U shape heat exchanger, a cold block, a temperature controller, and three aluminum sheets. The minimum operating temperature of the assembly was ,10°C. This thermoelectric system was used to directly cool the capillary column, without any need for a traditional cryogen and had a small volume. The system was cost-effective and convenient to operate. It was successfully applied to the separation of methyltin species. [source] Ethanol Exposure Enhances Apoptosis Within the TestesALCOHOLISM, Issue 10 2000Qianlong Zhu Background: Chronic ethanol abuse causes testicular atrophy and male infertility in alcoholic men. It is well known that ethanol exposure disrupts the hypothalamic-pituitary-gonadal axis, adversely affects the secretory function of Sertoli cells, and produces oxidative stress within the testes. It is still not clear what cellular mechanisms are responsible for the morphologic alteration of the testes that results in a reduction of testicular mass as a consequence of ethanol exposure. The hypothesis tested was that ethanol enhances apoptosis of testicular germ cells. Methods: In the experiments of chronic ethanol exposure, male Sprague Dawley® rats (Harlan Sprague Dawley, Inc., Indianapolis, IN) were fed Liber-Decarlie liquid diet for 9 weeks. In the experiments of acute ethanol exposure, a small volume of 20% ethanol solution was administered by intratesticular injection. Both 3,-end labeling of isolated testicular deoxyribonucleic acid (DNA) and labeling of apoptotic cells in situ by the terminal deoxynucleotidyl transferase-mediated deoxyuridine 5,-triphosphate nick end-labeling method were used to determine apoptosis rates within the testes. The expression of proteins involved in apoptosis was assessed by reverse transcription-polymerase chain reaction and by Western blotting. Results: The testes of rats that were fed an ethanol-containing liquid diet had more testicular DNA fragmentation than did those of animals that were fed an isocaloric control diet. Ethanol increased the number of apoptotic spermatogonia as well as spermatocytes. Direct intratesticular injections of ethanol solution enhanced testicular DNA fragmentation, suggesting an increase in apoptosis. Moreover, Fas ligand levels were increased within the testes of rats that were chronically fed ethanol. In vitro, ethanol treatment of cultured Sertoli cells enhanced the production of Fas ligand. In addition, testicular levels of p53 messenger ribonucleic acid were increased in rats that were chronically fed ethanol. Conclusions: All of these observations suggest that ethanol enhances testicular germ cell apoptosis. [source] Pharmacokinetics of the injectable formulation of methadone hydrochloride administered orally in horsesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2009R. L. LINARDI Methadone hydrochloride is a synthetic ,-opioid receptor agonist with potent analgesic properties. Oral methadone has been successfully used in human medicine and may overcome some limitations of other analgesics in equine species for producing analgesia with minimal adverse effects. However, there are no studies describing the pharmacokinetics (PK) of oral opioids in horses. The aim of this study was to describe the PK of orally administered methadone (0.1, 0.2 and 0.4 mg/kg) and physical effects in 12 healthy adult horses. Serum methadone concentrations were measured by gas chromatography/mass spectrometry at predetermined time points for 24 h, and PK parameters were estimated using a noncompartmental model. Physical effects were observed and recorded by experienced clinicians. No drug toxicity, behavioural or adverse effects were observed in the horses. The disposition of methadone followed first order elimination and a biphasic serum profile with rapid absorption and elimination phases. The PK profile of methadone was characterized by high clearance (Cl/F), small volume of distribution (Vd/F) and short elimination half-life (t1/2). The mean of the estimated t1/2 (SD) for each dose (0.1, 0.2 and 0.4 mg/kg) was 2.2 (35.6), 1.3 (46.1) and 1.5 (40.8), and the mean for the estimated Cmax (SD) was 33.9 (6.7), 127.9 (36.0) and 193.5 (65.8) respectively. [source] Liquid Chromatography of Synthetic Polymers under Limiting Conditions of Insolubility IIIMACROMOLECULAR SYMPOSIA, Issue 1 2007Application of Monolithic Columns Abstract Summary Performance was evaluated of silica based commercial monolithic rod-like columns in liquid chromatography of synthetic polymers under limiting conditions of enthalpic interactions (LC LC). LC LC employs the barrier effect of the pore permeating and therefore slowly eluting small molecules toward the pore excluded, fast eluting macromolecules. Phase separation (precipitation) barrier action was applied in present study. The barrier was created either by the narrow pulse of an appropriate nonsolvent injected into the column just before the sample solution (LC LC of insolubility , LC LCI) or by the eluent itself. In the latter case, the polymer sample was dissolved and injected in a good solvent (LC LC of solubility , LC LCS). In LC LCI, polymer species cannot break thru the nonsolvent zone while in LC LCS they cannot enter eluent, which is their precipitant. Therefore, polymer species keep moving in the zone of their original solvent. Macromolecules eluting under the LC LC mechanism leave the column in the retention volume (VR) roughly corresponding to VR of the low molar mass substances and can be efficiently separated from the polymer species non-hindered by the barrier action. The known advantages of monoliths were confirmed. From the point of view of LC LCI and LC LCS the most important quality of monolithic columns represents their excellent permeability, which allows both working at high flow rates and injecting very high (in the range of 5%) sample concentrations. Monolithic column tolerate also extremely high molar mass samples (M>10,000 kg,·,mol,1). On the other hand, the mesopores (separation pores) of the tested monoliths exhibited rather small volume and wide size distribution. These shortcomings partially impair the permeability advantage of monoliths because in order to obtain high LC LC separation selectivity a tandem of several monolithic columns must be applied. Presence of large mesopores also reduces applicability of monolithic columns for molar masses below about 50 kg,·,mol,1 because VRs of polymers eluted behind the barrier are similar to that of freely eluting species. The non- negligible break-thru phenomenon was observed for the very high polymer molar masses largely eluting behind the barrier. It is assumed that the fraction of very large mesopores present in the monoliths or association/microphase separation of macromolecules may be responsible for this phenomenon. This is why the presently marketed SiO2 monolithic columns are mainly suitable for the fast purification of the LC LC eluting macromolecules from the polymeric admixtures non-hindered by the barrier-forming liquid. Still, monolithic columns have large potential in the LC LCI and LC LCS procedures provided size (effective diameter) of the mesopores can be reduced and their volume increased. [source] Xenon-129 MR imaging and spectroscopy of rat brain using arterial delivery of hyperpolarized xenon in a lipid emulsionMAGNETIC RESONANCE IN MEDICINE, Issue 2 2001Guillaume Duhamel Abstract Hyperpolarized 129Xe dissolved in a lipid emulsion constitutes an NMR tracer that can be injected into the blood stream, enabling blood-flow measurement and perfusion imaging. A small volume (0.15 ml) of this tracer was injected in 1.5 s in rat carotid and 129Xe MR spectra and images were acquired at 2.35 T to evaluate the potential of this approach for cerebral studies. Xenon spectra consistently showed two resonances, at 194.5 ppm and 199.0 ppm relative to the gas peak. The signal-to-noise ratio (SNR) obtained for the two peaks was sufficient (ranging from 12 to 90) to follow their time courses. 2D transverse-projection xenon images were obtained with an in-plane resolution of 900 ,m per pixel (SNR range 8,15). Histological analysis revealed no brain damage except in two rats that had received three injections. Magn Reson Med 46:208,212, 2001. © 2001 Wiley-Liss, Inc. [source] Heterogeneous agglutinitic glass and the fusion of the finest fraction (F3) modelMETEORITICS & PLANETARY SCIENCE, Issue 12 2002Abhijit Basu They include (1) theoretical expectations that shock pulses should engulf and melt smaller grains more efficiently than larger grains, (2) experimental results of impact shock, albeit at lower than presumed hypervelocity impacts of micrometeorites on the lunar regolith, and (3) new analyses confirming previous results that average compositions of agglutinitic glass are biased towards that of the finest fraction of lunar soils from which they had formed. We add another reason in support of the F3 model. Finer grains of lunar soils are also much more abundant. Hence, electrostatic forces associated with the rotating terminator region bring the finest grains that are obviously much lighter than courser grains to the surface of the Moon. This further contributes to the preferential melting of the finest fraction upon micrometeoritic impacts. New backscattered electron imaging shows that agglutinitic glass is inhomogeneous at submicron scale. Composition ranges of agglutinitic glass are extreme and deviate from that of the finest fraction, even by more than an order of magnitude for some components. Additionally, we show how an ilmenite grain upon impact would produce TiO2 -rich agglutinitic glass in complete disregard to the requirements of fusion of the finest fraction. We propose an addition to the F3 model to accommodate these observations (i.e., that micrometeorite impacts indiscriminately melt the immediate target regardless of grain size or grain composition). We, therefore, suggest that (1) agglutinitic glass is the sum of (a) the melt produced by the fusion of the finest fraction of lunar soils and (b) the microvolume of the indiscriminate target, which melts at high-shock pressures from micrometeoritic impacts, and that (2) because of the small volume of the melt and incorporating cold soil grains, the melt quenched so rapidly that it did not mix and homogenize to represent any preferential composition, for example, that of the finest fraction. [source] A novel miniature monopole tag antenna for passive UHF RFID applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2010Hsien-Wen Liu Abstract A novel miniature monopole tag antenna for passive Ultra-High Frequency (UHF) radio frequency identification (RFID) operation is presented. The antenna possesses a two-sided structure that is printed on an FR4 substrate and fed by a 50-, microstrip line. By properly using helical strips and vias, the antenna size can be reduced to a small volume of 10 (L) × 9.5 (W) × 0.8 (H) mm3 to be easily integrated within various portable devices. A miniaturized quasi-lumped circuit is also designed to attain a good impedance matching between the antenna and the chip. Experimental results demonstrate that the antenna has a suitable operating band about 914,939 MHz and also quite omnidirectional radiation pattern with appreciable gain. Moreover, the proposed compact tag antenna, capable of achieving a maximum readable range of about 5.6 m with an EIRP equal to 4 W, is well suited for RFID applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2770,2772, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25596 [source] Seven-band folded-loop chip antenna for WWAN/WLAN/WiMAX operation in the mobile phoneMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009Ming-Ren Hsu Abstract A chip antenna formed by using an FR4 chip base and a folded-loop metal pattern embedded therein for internal mobile phone antenna application is presented. The folded-loop metal pattern is embedded in two different layers inside the FR4 chip base to achieve a compact structure, and a coupling gap is introduced to successfully excite two wide operating bands at about 900 and 2000 MHz to cover GSM850/900/1800/1900/UMTS, 2.4-GHz WLAN, and 2.5-GHz WiMAX operations; that is, a seven-band internal mobile phone antenna for covering WWAN/WLAN/WiMAX operation is obtained. The proposed chip antenna also occupies a small volume of 4 × 5 × 40 mm3 (0.8 cm3) and shows a low profile of 5 mm when mounted on the system circuit board of the mobile phone, making it suitable for thin mobile phone applications. The proposed chip antenna is studied and tested. The SAR effect of the antenna is also analyzed in the study. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 543,549, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24063 [source] Internal hybrid loop/monopole slot antenna for quad-band operation in the mobile phoneMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2008Chih-Hsien Wu Abstract A novel printed hybrid loop/monopole slot antenna for quad-band operation in the mobile phone is presented. The proposed hybrid antenna is composed of a meandered loop antenna and a monopole slot antenna, and can generate two wide operating bands centered at about 900 and 1900 MHz to cover GSM850/900/DCS/PCS operation. The hybrid antenna is easily fabricated by bending the meandered loop antenna at low cost, which is connected to and centered at the top edge of the system ground plane where a straight monopole slot is embedded. With quad-band operation obtained, the hybrid antenna, however, occupies a small volume of 5.5 × 6 × 60 mm3 or 1.98 cm3 only inside the mobile phone. A 50-, microstrip feedline is used to excite the meandered loop antenna and the monopole slot antenna in series. Detailed results and parametric studies of the proposed hybrid antenna are presented. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 795,801, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23201 [source] Surface-mount loop antenna for AMPS/GSM/DCS/PCS operation in the PDA phoneMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007Wei-Yu Li Abstract A surface-mount loop antenna very suitable for application in the mobile devices such as the PDA (Personal Digital Assistant) phone for quad-band operation is presented. The antenna comprises of a loop metal pattern for generating two wideband resonant modes at about 900 and 1800 MHz to cover the AMPS/GSM/DCS/PCS bands and a central coupling stub as the feed structure. Although quad-band operation is obtained, the antenna occupies a small volume of 7 × 8 × 60 mm3 or about 3.4 cm3 only and is easy to be embedded inside the PDA phone as an internal antenna. Details of the proposed surface-mount loop antenna are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2250,2254, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22700 [source] | ||||||||||||||||||||||||||||||||||||||||