Selectively Swollen Films of Triblock/Diblock Copolymer Blends: Dependence of Swollen Film Structure on Blend Composition

Compositional variation in blends of triblock and diblock copolymer films can be used to adjust the film response to a selective solvent. We investigated the relationship between blend composition and film structure in ordered films containing poly(styrene-b-2-vinylpyridine) (PS-P2VP) diblocks and PS-P2VP-PS triblocks. The study focuses on films possessing a lamellar morphology. Methanol, a strongly selective solvent for P2VP, is used to swell the films. Since methanol solvates P2VP but not PS, periodic multilayer structures result in which solvent-rich P2VP domains are separated by undissolved PS domains. The film structure is characterized in the dry and swollen states with neutron reflectivity. Although the dry state morphology dimensions are practically identical for all samples, in the swollen state films richer in triblock swell less due to higher density of bridges interconnecting the PS domains. Furthermore, in swollen triblock-containing samples, polymer concentration variations in P2VP domains are suppressed and the PS domains are better aligned with respect to the substrate.     

A sample purification method for rugged and high-performance DNA sequencing by capillary electrophoresis using replaceable polymer solutions. A. Development of the cleanup protocol

A method for the cleanup of Sanger DNA sequencing reaction products for capillary electrophoresis analysis with replaceable polymer solutions has been developed. A poly(ether sulfone) ultrafiltration membrane pretreated with linear polyacrylamide was first used to remove template DNA from the sequencing samples. Then, gel filtration in a spin column format (two columns per sample) was employed to decrease the concentration of salts below 10 microM in the sample solution. The method was very reproducible and increased the injected amount of the sequencing fragments 10-50-fold compared to traditional cleanup protocols. Using M13mp18 as template, the resulting cleaned-up single DNA sequencing fragments could routinely be separated to more than 1000 bases with a base-calling accuracy of at least 99% for 800 bases. The method is simple and universal and can be easily automated. In the following paper, a systematic study to determine quantitatively the effects of the sample solution components such as high-mobility ions (e.g., chloride and dideoxynucleotides) and template DNA on the injected amount and separation efficiency of the sequencing fragments is presented.     

Maintenance of the pluripotential phenotype of embryonic stem cells through direct activation of gp130 signalling pathways

Bare alpha track detectors are sensitive to radon progeny as well as to radon gas. This paper reports the test results for two brands of bare alpha track detectors that received several radon exposures at three progeny concentrations. The results show a relationship that is a linear combination of both the radon gas and the radon progeny concentrations. The reported radon concentration depended on the equilibrium factor assumed by the processor. The sensitivity of bare alpha track detectors increases with altitude, but this is a minor, correctable effect compared to the equilibrium factor.     

SURF1, encoding a factor involved in the biogenesis of cytochrome c oxidase, is mutated in Leigh syndrome

A drug with cationic characteristics such as procaine can be conveyed in a Carbomer hydrogel in two different ways: (i) in the form of salt in solution in the aqueous phase, and (ii) in the base form salified with the same polymer. Introduction of the drug into the hydrogel with different concentrations of polymer produced, in both cases, a reduction in viscosity in relation to drug concentration. The gels with procaine salified with the polymer showed greater viscosity. The drug release rate, in general, diminished with the increase in polymer concentration. Nevertheless, when this concentration was maintained, there was no variation in release rate when the viscosity produced as a consequence of drug concentration was changed. Gels with procaine salified with the carboxyvinylic polymer had a faster release rate than those with procaine in the hydrochloride form dissolved in the aqueous phase. These results have also been confirmed by a simulated absorption test.     

Estimating Suspended Sediment Concentration Using Turbidity in an Irrigation-Dominated Southeastern California Watershed

This study investigates the feasibility of using turbidity (T) as a surrogate for suspended sediment concentration (C) in an irrigation-dominated watershed in southeastern California. A nonlinear T–C relationship was developed and evaluated using two independent sets of data obtained by physical sampling and laboratory turbidimeter. The relationship was interpreted in terms of the heterogeneous particle size distribution in the samples. The effects of spatial and temporal variation of particle sizes and water colors on the relationship were examined. Further, possible effects of laboratory procedures on the relationship such as time delay of sample measurement and calibration of T for C using lab-prepared samples were analyzed. The study showed that the variation of particle size distribution is the key factor controlling the T–C relationship. Water color and time delay for sample analysis did not significantly affect the turbidity values, whereas laboratory procedures may mislead the T–C relationship. It is concluded that turbidity may be a surrogate for suspended sediment concentration in such irrigation-dominated watersheds in arid regions, though the T–C relationship has to be established with care.     

Trends in odor intensity for human and electronic noses: relative roles of odorant vapor pressure vs. molecularly specific odorant binding

Response data were collected for a carbon black-polymer composite electronic nose array during exposure to homologous series of alkanes and alcohols. The mean response intensity of the electronic nose detectors and the response intensity of the most strongly driven set of electronic nose detectors were essentially constant for members of a chemically homologous odorant series when the concentration of each odorant in the gas phase was maintained at a constant fraction of the odorant's vapor pressure. A similar trend is observed in human odor detection threshold values for these same homologous series of odorants. Because the thermodynamic activity of an odorant at equilibrium in a sorbent phase is equal to the partial pressure of the odorant in the gas phase divided by the vapor pressure of the odorant and because the activity coefficients are similar within these homologous series of odorants for sorption of the vapors into specific polymer films, the data imply that the trends in detector response can be understood based on the thermodynamic tendency to establish a relatively constant concentration of sorbed odorant into each of the polymeric films of the electronic nose at a constant fraction of the odorant's vapor pressure. Similarly, the data are consistent with the hypothesis that the odor detection thresholds observed in human psychophysical experiments for the odorants studied herein are driven predominantly by the similarity in odorant concentrations sorbed into the olfactory epithelium at a constant fraction of the odorant's vapor pressure.     

Fluorescent determination of chloride in nanoliter samples

BACKGROUND: Measurements of Cl- in nanoliter samples, such as those collected during isolated, perfused tubule experiments, have been difficult, somewhat insensitive, and/or require custom-made equipment. We developed a technique using a fluorescent Cl- indicator, 6-methoxy-N-(3-sulfopropyl) quinolinium (SPQ), to make these measurements simple and reliable. METHODS: This is a simple procedure that relies on the selectivity of the dye and the fact that Cl-quenches its fluorescence. To measure millimolar quantities of Cl- in nanoliter samples, we prepared a solution of 0.25 mm SPQ and loaded it into the reservoir of a continuous-flow ultramicrofluorometer, which can be constructed from commercially available components. Samples were injected with a calibrated pipette via an injection port, and the resultant peak fluorescent deflections were recorded. The deflections represent a decrease in fluorescence caused by the quenching effect of the Cl- injected. RESULTS: The method yielded a linear response with Cl- concentrations from 5 to 200 mm NaCl. The minimum detectable Cl- concentration was approximately 5 mm. The coefficient of variation between 5 and 200 mm was 1.7%. Resolution, defined as two times the standard error divided by the slope, between 10 and 50 mm and between 50 and 200 mm was 1 mm and 2.6 mm, respectively. Furosemide, diisothiocyanostilbene-2,2'-disulfonic acid and other nonchloride anions (HEPES, HCO3, SO4, and PO4) did not interfere with the assay, whereas 150 mm NaBr resulted in a peak height greater than 150 NaCl. In addition, the ability to measure Cl- did not vary with pH within the physiological range. CONCLUSION: We developed an easy, accurate, and sensitive method to measure Cl- concentration in small aqueous solution samples.     

Steady-state concentration distribution of ampholytes in isoelectric focusing in a linear immobilized pH gradient

The equation of balance between electrophoretic and diffusional mass flows in the steady state of isoelectric focusing is analyzed. To create the pH gradient, a model system composed of only one Immobiline is used. The solution is found for the case of a small sample concentration, but without assumptions about linear "focusing force" and constant (linear) conductivity profiles. The effect of sample concentration on the final concentration profile is also evaluated. At high sample concentrations, it is demonstrated that the steady-state distribution is essentially non-Gaussian and results in a considerably lower concentration maximum as compared with low sample levels.     

Preparation of fine needle aspiration biopsy samples for flow cytometric analysis

In order to improve the quality of flow cytometric (FCM) DNA histograms, a new preparatory method was tested on samples obtained by fine needle aspiration biopsy (FNAB) of breast tumors. Twenty-four samples were obtained in vivo (group 1), and 20 were obtained from surgically resected specimens (group 2). Tumors from both groups were aspirated twice each. The first sample was injected directly into 70% ethanol, whereas the second sample was pretreated with a mixture of Tween-20 and citric acid solution (Tween-20 CA) before ethanol fixation. The coefficient of variation (CV) of G0-G1 peaks of Tween 20 CA-pretreated samples varied from 1.85 to 5.10 (mean, 3.3) in group 1 and from 1.87 to 3.72 (mean, 2.77) in group 2. The CV of G0-G1 peaks of ethanol-preserved samples ranged from 2.28 to 7.22 (mean, 5.23) in group 1 and from 1.78 to 4.04 (mean, 3.48) in group 2. The CV values of histograms obtained by the new protocol were significantly lower (group 1, P < .05; group 2, P < .01).     

Trace analysis of proteins by capillary zone electrophoresis with on-column transient isotachophoretic preconcentration

The qualitative and quantitative aspects of transient isotachophoretic (ITP) sample preconcentration in the capillary zone electrophoretic analysis of protein samples have been demonstrated. By the proper selection of components of the background electrolyte and/or additives to the sample solution, two basic electrolyte arrangements have been employed. In the first, a typical isotachophoretic electrolyte system consisting of a leading and terminating electrolyte was used, and after focusing and preconcentration, the terminating electrolyte was replaced by the leading electrolyte, with the separation being continued in the zone electrophoretic mode. In the second, only one background electrolyte was used, containing a co-ion with low electrophoretic mobility, and the sample was supplemented with a salt of a highly mobile co-ion. In this case transient isotachophoretic migration of the sample ions took place at the beginning of the migration and gradually changed to the zone electrophoretic mode. Sample mixtures containing basic (positively charged) or acidic (negatively charged) proteins were examined using surface-coated fused-silica capillaries. For acidic proteins, bare silica was also tested. The isotachophoretic sample stacking permitted injection and preconcentration of sample volumes two to three orders of magnitude higher than usual in capillary zone electrophoresis. For example, up to 1 microL was injected into a 75 microns ID capillary. This approach afforded quantitative analysis of protein samples in the concentration range of 10(-7)-10(-8) M, with detection limits of approximately 10(-9) M. Furthermore, with constant sample volume injected, good reproducibility of migration times was obtained. Finally, the determination of trace components in the presence of a major sample component using transient ITP preconcentration has been demonstrated.     

Extraction of zinc chloride with dibutyl butylphosphonate

The reaction of zinc in chloride solution with dibutyl butylphosphonate (DBBP) in Escaid 110 has been investigated. The extraction coefficient of zinc was independent of equilibrium pH. This independence indicates that the mechanism of the extraction is a solvation. Slope analysis for the system of dilute zinc chloride solution reveals that two moles of DBBP react with one mole of zinc. A series of tests was conducted to bring DBBP to its full loading capacity, and the analysis of the results confirms this stoichiometric factor of 2 for concentrated solutions. The stoichiometric factor of water in the extraction reaction is found to be 4 by determining the activities of water and free chloride ions at various CaCl₂ concentrations. The experimental data also indicate that two chloride ions are involved for each extracted zinc species.     

Interstitial Solution Carbon Concentration and Defects of Ti+Nb ULC-BH Steel by Internal Friction and Positron Annihilation Methods

The interstitial solution carbon concentration and defects in continuously annealed Ti+Nb bearing ULCBH(ultra-low carbon bake hardening)steel samples are investigated by multi-functional internal friction apparatus, positron annihilation lifetime spectroscopy(PALS)and coincidence Doppler broadening spectroscopy(CDBS).The relationship of internal friction peaks,interstitial solution carbon concentrations and movable dislocations in the samples under different conditions is analyzed.A correlation of lifetime componentτ1 values with interstitial solution carbon concentrations in the samples for different continuous annealing processes is established,while a correlation of lifetime componentτ2 values with multi-vacancies,vacancy clusters,microvoids and other types of defects for various continuous annealing processes is also demonstrated.Furthermore,the average lifetime results illustrate the overall defect densities for various continuous annealing processes.The CDBS analysis reflects the chemical surroundings of the defects at the annihilation sites and reveals that the peak heights of the ratio curves relate to the total number of defects such as interstitial carbon atoms,dislocations,vacancies and other types of defects.The results show that internal friction,PALS and CDBS are effective techniques to identify and characterize the interstitial solution carbon concentration,multi-vacancies,vacancy clusters,microvoids and other types of microscopic defects in annealed Ti+ Nb bearing ULC-BH steel.     

A search for extraterrestrial amino acids in carbonaceous Antarctic micrometeorites

Antarctic micrometeorites (AMMs) in the 100-400 microns size range are the dominant mass fraction of extraterrestrial material accreted by the Earth today. A high performance liquid chromatography (HPLC) based technique exploited at the limits of sensitivity has been used to search for the extraterrestrial amino acids alpha-aminoisobutyric acid (AIB) and isovaline in AMMs. Five samples, each containing about 30 to 35 grains, were analyzed. All the samples possess a terrestrial amino acid component, indicated by the excess of the L-enantiomers of common protein amino acids. In only one sample (A91) was AIB found to be present at a level significantly above the background blanks. The concentration of AIB (approximately 280 ppm), and the AIB/isovaline ratio (> or = 10), in this sample are both much higher than in CM chondrites. The apparently large variation in the AIB concentrations of the samples suggests that AIB may be concentrated in rare subset of micrometeorites. Because the AIB/isovaline ratio in sample A91 is much larger than in CM chondrites, the synthesis of amino acids in the micrometeorite parent bodies might have involved a different process requiring an HCN-rich environment, such as that found in comets. If the present day characteristics of the meteorite and micrometeorite fluxes can be extrapolated back in time, then the flux of large carbonaceous micrometeorites could have contributed to the inventory of prebiotic molecules on the early Earth.     

Use of ultra-thin window detectors for biological microanalysis

Films and bulk samples of Nylon, gelatin, Makrofol, epoxy resin, aminoplastic resin and sodium acetate have been used as models of biological samples. It is shown that the use of ultrathin window (UTW) detectors in scanning transmission and scanning electron microsopes permits the quantitative analysis of light elements, yielding a total element analysis with hydrogen estimated by difference or "guesstimated". Comparison with known concentrations of concentrations obtained by chemical analysis shows that X-ray microanalysis of selections by the peak to continuum ratio model and bulk samples by the phi(pz) model gives sufficiently accurate results for biological purposes. It is also shown that sections may be analysed by the standardless ratio model. The application of UTW detectors to total element analysis by quantitative elemental imaging is demonstrated of bulk biological samples. which have been freeze-substituted, embedded in epoxy resin and surface polished. The possibility of imaging the oxygen content of frozen-hydrated bulk tissue samples which have been surface polished is also demonstrated. This may lead to the imaging of water distribution in frozen-hydrated bulk samples of biological tissues. UTW detectors are also useful for detecting mass loss in organic samples by monitoring the decrease in oxygen counts and for detecting contamination by monitoring the increase in carbon counts. It is also shown that changes in carbon counts are good indicators of folds in sections.     

Children''s rights and the biological bias in biological parent versus third-party custody disputes

Hydrophobically modified carboxymethylpullulan (HMCMP) samples were obtained by reaction of small amounts of C16 alkylamine on carboxylic groups of the corresponding polyacid. The molar contents of alkyl chains ranged from 1.3 to 6.8% with respect to the anhydroglucose units (AGU) and the degree of substitution (DS) of carboxylic groups varied from 0.76 to 0.84. Solution properties of the sodium salt of HMCMPs were studied mainly by viscometric and size-exclusion chromatography/light-scattering methods. The low-shear viscosity of modified pullulans in 0.1 M NaCl solutions drastically increases with the hydrophobic content and polymer concentrations and the 6.8% modified sample has a quite pseudoplastic behaviour. These data showed that the polymers aggregated intermolecularly and displayed a compact globular structure in dilute solution. Furthermore, addition of NaCl or ethanol induced a decrease in viscosity although the molecular weights remained approximately constant. These results are consistent with a collapse of the polysaccharide aggregates.     

Leaching of CuFeS2 by aqueous FeCl3, HCl,and NaCl: Effects of solution composition and limited oxidant

Batch leaching experiments were performed in which the initial amounts of chalcopyrite and ferric chloride were selected to ensure that the oxidant was significantly depleted over the course of an experiment. Solution samples were analyzed for Cu(II) and Fe(III) by visible spectrophotometry and for total copper and total iron by atomic absorption, making it possible to measure changes in the solution component concentrations as leaching progressed. For selected samples, the solution potential was also measured. In all experiments, the Cu(II) concentration passed through a maximum and, simultaneously, the Cu(I) concentration increased very sharply. An acceleration in the total rate of leaching was normally observed at the same time. Early in a leach, the solution potential was too high for the reduction of Cu(II) to Cu(I) to take place at the time of the increase in the overall leaching rate, however, the solution potential dropped sharply during a span of a few hours, reaching a value low enough that reduction of cupric ion became possible. The amount of Cu(I) present at the completion of a leach was dependent on the total chloride concentration of the system. The highest Cu(I)/Cu ratios were observed in systems with the highest chloride concentrations. The ultimate extent of CuFeS₂ leaching was dependent on the initial FeCl₃ and total chloride concentrations; the FeCl₃ was virtually completely consumed and the total chloride concentration controlled the extent to which Cu(II) was reduced by reaction with chalcopyrite.     

A test of the measurement equivalence of the revised Job Diagnostic Survey: Past problems and current solutions.

Studied the measurement equivalence of the revised Job Diagnostic Survey (JDS) across samples from 5 worker populations: workers at a printing plant, engineers, nurses and nurses' aides, dairy employees, and part-time workers. Data were analyzed according to J?reskog's model for simultaneous factor analysis in several populations ({sifasp}), revealing the 5 factors contained in Hackman and Oldham's theory of job characteristics. A 6th factor appeared that apparently resulted from the 2 different formats used. When data from each group were analyzed separately by principal axes factor analysis, 3-, 4-, and 5-factor solutions appeared. A Monte Carlo simulation was conducted. Matrices representing the a priori JDS factor loadings and a hypothetical, lengthened JDS with twice the number of items/factor were used with 3 sample sizes (Ns?=?75, 150, and 900). Results suggest that for scales like the JDS, sample sizes larger than those typically recommended are needed to consistently recover the true underlying structure. Simulation results indicate that the {sifasp} solution is preferable to the principal axes solution and that the JDS provides measurement equivalence across worker populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variations in the composition of spinal anesthetic solutions: the effects of drug addition order and preparation methods

Adjuvants such as opioids or epinephrine are commonly added in small volumes to multicomponent spinal anesthetic solutions. In this study, we tested the hypothesis that final adjuvant concentrations vary depending on the devices and techniques used to prepare the anesthetic solution. We compared two aspiration devices, the filter needle and the filter straw, in a laboratory study. Two techniques for drawing up and estimating adjuvant volumes were assessed, as was variation in the composition of a model spinal anesthetic solution resulting from intra- and interindividual variability. A model hyperbaric anesthetic solution consisting of tetracaine, dextrose, and methylene blue (MB) as a small-volume tracer solution was studied. The components were drawn up into a syringe through one of two commercially supplied aspiration devices, a filter straw or a filter needle. The effect of the order of aspiration of the components into the syringe was measured by determining the MB concentration in the final solution by optical absorbance. Ten experienced anesthesiologists then prepared samples of the test solution using one of two different techniques to estimate tracer volume in the aspiration syringe. In comparison studies, the MB tracer was added to the hyperbaric solution with a tuberculin syringe. The order of aspiration of the solution components had a large effect on the final concentration of the MB tracer in the ultimate mixture. Variation in the MB concentration was on the order of four- to fivefold. Effects were larger for the filter straw compared with the filter needle. A comparison of 10 anesthesiologists revealed large intra- and interindividual variations in the final composition of the model anesthetic solution. The concentration of tracer added to the mixture with a tuberculin syringe approximated the planned yield. We conclude that the devices and techniques used to prepare mixtures of drugs for delivery to the cerebrospinal fluid may influence the concentrations of drugs in the anesthetic and, thus, the dose supplied to the patient receiving spinal anesthesia. Variation in clinical effects of spinal anesthetics may be attributable, in part, to variation in the composition of the anesthetic. IMPLICATIONS: This laboratory study demonstrates the potential for large variation in the composition of spinal anesthetic mixtures.     

Passively acquired anti-tetanus and anti-Haemophilus antibodies and the response to Haemophilus influenzae type b-tetanus toxoid conjugate vaccine in infancy

OBJECTIVE: To study the influence of maternally inherited tetanus antitoxin (anti-TT) antibodies on the response to the Haemophilus influenzae type b (Hib) capsular polysaccharide (PS)-tetanus toxoid conjugate (PRP-T) vaccine. DESIGN: One hundred thirty healthy infants received their first dose of PRP-T in the same syringe with diphtheria-tetanus-pertussis vaccine (DTP) at 1 to 2 months, and 66 of them received a second dose at 3 to 4 months of age. RESULTS: Maternal anti-TT antibodies did not interfere with the anti-Hib PS response to the first PRP-T vaccination; the geometric mean concentration (GMC) of anti-Hib PS was 0.14 microgram/ml in those with the lowest preimmunization anti-TT (< 0.3 IU/ml, n = 15) and 0.13 microgram/ml in those with the highest anti-TT (> or = 3 IU/ml, n = 25). After the second dose of PRP-T there was a positive correlation (r = 0.37, P = 0.004) between the anti-Hib PS response and the preimmunization anti-TT; those with the lowest preimmunization anti-TT (< 0.3 IU/ml, n = 9) achieved GMC of anti-Hib PS of 1.22 micrograms/ml and those with anti-TT > or = IU/ml (n = 22) anti-Hib PS GMC of 2.67 micrograms/ml. High preimmunization anti-Hib PS antibodies did not interfere with the final antibody concentrations; the GMC of anti-Hib PS after the second dose of PRP-T was 1.60 micrograms/ml in those with a preimmunization titer > or = 1.0 microgram/ml (n = 12) and 1.57 micrograms/ml in those with a titer of < 1.0 microgram/ml (n = 53). CONCLUSION: The data suggest that infants can be safely vaccinated with PRP-T even though they have received high concentrations of anti-TT from their mother.     

Effect of prostaglandins on macromolecular transport from blood to lymph in the dog

The effect of various prostaglandins on hindlimb lymph flow and macromolecular transport was studied in dogs anesthetized with pentobarbital sodium. Lymph obtained by cannulating the popliteal lymphatics was collected at 30-min intervals and analyzed for protein and exogenously administered dextran (Dextran 110). Arterial blood was obtained at the midpoint of each collection period and similarly analyzed. Prostaglandins (E1, E2, F2alpha, and A2), the vehicle and histamine were injected subcutaneously into the paw of the dog. Prostaglandins slightly increased lymph flow (L') but the lymph-to-plasma concentration ratios (R) for total protein (T) and Dextran 110 (D) decreased. Permeability surface area products (PS) were not altered. The sieving ratios (RD/RT) were substantially less than 1 and were not altered by prostaglandins. These results indicate that selective permeability of the capillary is not impaired by prostaglandins. Timing sequences and dose-response relations were also completed for prostaglandins by subcutaneous testing in dogs injected with Evans blue (T-1824). Leakage of the T-1824-albumin complex occurred when large amounts (migrogram) of prostaglandins were administered, and the response appeared to be short lived (less than 30 min). While the prostaglandins possess vasoactive properties, as demonstrated by an increased lymph flow, they do not alter the restrictive transport of large molecules.