PDMS encasing system for integrated lab-on-chip Ag/AgCl reference electrodes

Poly(dimethylsiloxane) (PDMS) is an organosilicon polymer widely used in the fabrication of microfluidic systems to integrate biochips. In this study, we propose the use of an adapted PDMS mould for the creation of a miniaturized, reusable, reference electrode for in-chip electrochemical measurements. Through its integrated microfluidic system it is possible to replenish internal buffer solutions, unclog critical junctions and treat the electrode’s surface, assuring a long term reuse of the same device. Planar Ag/AgCl reference electrodes were microfabricated over a passivated p-type Silicon Wafer. The PDMS mould, containing an integrated microfluidic system, was fabricated based on patterned SU-8 mould, which includes a lateral horizontal inlet access point. Surface oxidation was used for irreversible permanent bondage between flat surfaces. The final result was planar Ag/AgCl reference electrode with integrated microfluidic that allows for electrochemical analysis in biochips

Micro- and mesoporous structures as drug delivery carriers for salicylic acid

The potential of salicylic acid (SA) encapsulated in porous materials as drug delivery carriers for cancer treatment was studied. Different porous structures, the microporous zeolite NaY, and the mesoporous SBA-15 and MCM-41 were used as hosts for the anti-inflammatory drug. Characterization with different techniques (FTIR, UV/vis, TGA, 1H NMR, and 13C CPMAS NMR) demonstrated the successful loading of SA into the porous hosts. The mesoporous structures showed to be very efficient to encapsulate the SA molecule. The obtained drug delivery systems (DDS) accommodated 0.74 mmol (341 mg/gZEO) in NaY and 1.07 mmol (493 mg/gZEO) to 1.23 mmol (566 mg/gZEO) for SBA-15 and MCM-41, respectively. Interactions between SA molecules and pore structures were identified. A fast and unrestricted liberation of SA at 10 min of the dissolution assay was achieved with 29.3, 46.6, and 50.1 µg/mL of SA from NaY, SBA-15, and MCM-41, respectively, in the in vitro drug release studies (PBS buffer pH 7.4, 37 °C). Kinetic modeling was used to determine the release patterns of the DDS. The porous structures and DDS were evaluated on Hs578T and MDA-MB-468 breast cancer cell lines viability. The porous structures are nontoxic to cancer cells. Cell viability reduction was only observed after the release of SA from MCM- 41 followed by SBA-15 in both breast cancer cell lines.

Enzymatic treatments to improve mechanical properties and surface hydrophobicity of jute fiber membranes

Fiber membranes prepared from jute fragments can be valuable, low cost, and renewable. They have broad application prospects in packing bags, geotextiles, filters, and composite reinforcements. Traditionally, chemical adhesives have been used to improve the properties of jute fiber membranes. A series of new laccase, laccase/mediator systems, and multi-enzyme synergisms were attempted. After the laccase treatment of jute fragments, the mechanical properties and surface hydrophobicity of the produced fiber membranes increased because of the cross-coupling of lignins with ether bonds mediated by laccase. The optimum conditions were a buffer pH of 4.5 and an incubation temperature of 60 °C with 0.92 U/mL laccase for 3 h. Laccase/guaiacol and laccase/alkali lignin treatments resulted in remarkable increases in the mechanical properties; in contrast, the laccase/2,2-azino-bis-(3-ethylthiazoline-6-sulfonate) (ABTS) and laccase/2,6-dimethoxyphenol treatments led to a decrease. The laccase/ guaiacol system was favorable to the surface hydrophobicity of jute fiber membranes. However, the laccase/alkali lignin system had the opposite effect. Xylanase/laccase and cellulase/laccase combined treatments were able to enhance both the mechanical properties and the surface hydrophobicity of jute fiber membranes. Among these, cellulase/laccase treatment performed better; compared to mechanical properties, the surface hydrophobicity of the jute fiber membranes showed only a slight increase after the enzymatic multi-step processes.

Effect of sodium chloride on solutesolvent interactions in aqueous polyethylene glycolsodium sulfate two-phase systems

Partition behavior of eight small organic compounds and six proteins was examined in poly(ethylene glycol)-8000sodium sulfate aqueous two-phase systems containing 0.215 M NaCl and 0.5 M osmolyte (sorbitol, sucrose, TMAO) and poly(ethylene glycol)-10000sodium sulfate0.215 M NaCl system, all in 0.01 M sodium phosphate buffer, pH 6.8. The differences between the solvent properties of the coexisting phases (solvent dipolarity/polarizability, hydrogen bond donor acidity, and hydrogen bond acceptor basicity) were characterized with solvatochromic dyes using the solvatochromic comparison method. Differences between the electrostatic properties of the phases were determined by analysis of partitioning of sodium salts of dinitrophenylated (DNP-) amino acids with aliphatic alkyl side-chain. The partition coefficients of all compounds examined (including proteins) were described in terms of solutesolvent interactions. The results obtained in the study show that solutesolvent interactions of nonionic organic compounds and proteins in polyethylene glycolsodium sulfate aqueous two-phase system change in the presence of NaCl additive.

Interrelationship between partition behavior of organic compounds and proteins in aqueous dextran-Polyethylene glycol and Polyethylene glycol-sodium sulfate two-phase systems

Partition behavior of adenosine and guanine mononucleotides was examined in aqueous dextran-polyethylene glycol (PEG) and PEG-sodium sulfate two-phase systems. The partition coefficients for each series of mononucleotides were analyzed as a functions of the number of phosphate groups and found to be dependent on the nature of nucleic base and on the type of \ATPS\ utilized. It was concluded that an average contribution of a phosphate group into logarithm of partition coefficient of a mononucleotide cannot be used to estimate the difference between the electrostatic properties of the coexisting phases of ATPS. The data obtained in this study were considered together with those for other organic compounds and proteins reported previously, and the linear interrelationship between logarithms of partition coefficients in dextran-PEG, PEG-Na2SO4 and PEG-Na2SO4-0.215 M NaCl (all in 0.01 M Na- or K/Na-phosphate buffer, pH 7.4 or 6.8) was established. Similar relationship was found for the previously reported data for proteins in Dex-PEG, PEG-600-Na2SO4, and PEG-8000-Na2SO4 ATPS. It is suggested that the linear relationships of the kind established in \ATPS\ may be observed for biological properties of compounds as well.

Sensitive label-free electron chemical capacitive transducer signal for D-dimer electroanalyses

Supplementary data associated with this article can be found, in the online version, at: http://dx.doi.org/10.1016/j.electacta.2015.09.169.

Spéciation of chromium in a chromium enriched yeast.

The sample under investigation in this project is an experimental chromium enriched yeast used as a possible additive in animal foodstuff, which was produced by growing yeast in the presence of chromium (III) chloride. Chromium on its own in not biologically active but chromium in the form of chromium enriched yeast is biologically active. The objective of this project was to show the complete absence of chromium(VI) from the sample. A literature survey describing previous work carried out on the speciation of Cr(VI) has been carried out. The principal methods of detection of Cr(VI) used in this project are Polarography, G.F.A.A. Spectroscopy, U.V. Spectroscopy and H.P.L.C. For each of the above methods a calibration curve was obtained and each method was applied to the yeast extract. The H.P.L.C. and U.V. spectroscopic method are specific for Cr(VI) but polarography and G.F.A.A. spectroscopy measure total chromium. Tris-NaOH buffer has been investigated for the extraction of chromium(VT). Problems associated with air oxidation of Cr(III) in alkaline solution have identified and procedures described for the suppression of air oxidation. Procedures are described for the application of the extraction procedure to the yeast extract and for the determination of Cr(VI) in the extract. Procedures are also described for the preconcentration of Cr(VI) on a HPLC column and for the application to the yeast extract. The rate of reduction of Cr(VI) by ascorbic acid is investigated and found to be first order with respect to ascorbic acid concentration. The reduction capacity of the yeast is also investigated and it was found that in acid solution the yeast will reduce Cr(VI) but in neutral or basic solution the reduction capacity is diminished. Conclusions regarding the objectives of the project are drawn and suggestions for further work are given.

Determinação fotométrica do ácido ascórbico

The photometric determination of ascorbic acid with the "E. E. L. portable colorimeter" can be carried" out rapid and conveniently using either 3% HPO3 or 0,4% (COOH) 2 as protective agent. The standards would contain from 2 to 20 micrograms of ascorbic acid per ml of metaphosphoric or oxalic acid solutions. We mix 10 ml of these solutions with 3 ml of the adequate citrate buffer solutions, and we pipet 5 ml of the resulting mixture to a matched test tube containing 5 ml of sodium - 2,6 - dichlorobenzenoneindophenol (80 mg per liter); then we shake well and after 15 seconds the extintion is read using green filter. The readings are subtracted from the blank one. Designating the differences by x and the concentrations of ascorbic acid/ml in the standards by y, we get, with the acid of the method of least squares, the following regression equations: for the metaphosphoric acid Y = 0,543x + 0,629 for the oxalic acid Y = 0,516x + 0,422, which permit, by interpolating, the determination of the ascorbic acid content in plant materials.

Sobre o preparo dos parasitas da malária em distensões espessas, especialmente em amostras supersecas

I) the A. presents a method developed for the preparation of thick blood films, specially old desiccated smears. The observations are based on the experience of more than 53000 blood samples collected in the laboratory of the “Serviço de Malaria do Nordeste” as well as in the research department of the “Serviço de Malaria da Baixada Fluminenese”. II) As in introductory matter, he emphasizes the value of the obstacles presented by overdrying of the thick blood films occurring systematically in great malaria control organizations in which the laboratory receives materials from more or less remote localities, particularly in the Brazilian northeast, in regions invaded by Anopheles gambiae. III) An analysis of the causes of failure of the methods of Chorine and Knowles recorded in the literature for such purposes is given, as well as its adaptability for the simultaneous preparation of large numbers of samples. IV) The method is based the protective action of a previous fixation by a dilute solution of formalin, which, without preventing further dehemoglobinization, prevents morphological alterations in the parasites by the action of Knowles solution which is retained in this metod without modification. V) For washing out the acids of the dehemoglobinizating solution as well as for diluting the Giemsa stain, the A. proposes a very simple technique, extremely convenient for such purpose, which consists in adding acetic acid to the distilled water in the proportion of 1 drop for each 10cc of water, and then increasing the hydrogeni-on concentration to pH 7.2 with a 2% sol. of sodium carbonate. As indicator a 0.02% solution purple-bromcresol prepared in accordante to Medalia, is used. In this reaction there is the formation of the acetic acid ↔ sodium acetate, buffer system very suitable for giving a convenient pH and for preventing the precipitation of the dye, which can be used for two or three batches of 700 or 800 slides each, without changing the staining solution. VI) – The method can be summarized as follow: For a small number of samples, Coplin’s or any other staining jar can be used. Large number of slides must be placed in groups of 10 or 15 units each, the slides being separated by a piece of cardboard, according to Barber & Komp. A) Fix in dilute formalin (2%), during 5 minutes. b) Without washing, put in Knowles solution (see the formula in the text), no more than 20 minutes. c)Two successive washings in distilled water, buffered as explained above (which can be used several times). d) Dry and stain with Giemsa solution, prepared by using 1 drop of the stain for each c. c. of buffered distilled water. Time: 1 hour. E) Was in distilled water and dry.

Considerações sôbre a técnica de determinação do "Índice Lipásico Seabra"

A detailed study of Seabra's lipasic reagent for the diagnostic of tuberculosis has been made. Substrate. The oily emulsion of cotton seed oil containing gum as dispersing agent, presented a pH variation to the ampoulles examined. In these belonging to the same cartoon as well as in those from different cartoons the values obtained electrometrically ranged from pH 5.8-6.4 (Table I). These variations lead us to presuppose: 1) instability of the oily emulsion in gum; 2) spontaneous hydrolysis of the oil; 3) different batches or technique of the oil extraction, or different sources. Buffer: The same variability observed with substrate was found for the buffer. In CHERRY & CRANDALL's method the buffer is pH 7.0. The saline solution from Seabra's oscillated from pH6.25-6.9 (table II). Titration - end point. A colorimetric comparison between the sample and the blank as suggested by Seabra becomes very difficult. The end point in the presence of serum, when phenolphtalein is used as indicator, is very difficult to compare with the blank containing water. Conclusion. The differences observed in the results when the same serum was used, must be due to the variations observed with Seabra's reagents.

Quantitative method of viral pollution determination for large volume of water using ferric hydroxide gel impregnated on the surface of glassfibre cartridge

Quantitative method of viral pollution determination for large volume of water using ferric hydroxide gel impregnated on the surface of glassfibre cartridge filter. The use of ferric hydroxide gel, impregnated on the surface of glassfibre cartridge filter enable us to recover 62.5% of virus (Poliomylitis type I, Lsc strain) exsogeneously added to 400 liters of tap-water. The virus concentrator system consists of four cartridge filters, in which the three first one are clarifiers, where the contaminants are removed physically, without significant virus loss at this stage. The last cartridge filter is impregnated with ferric hydroxide gel, where the virus is adsorbed. After the required volume of water has been processed, the last filter is removed from the system and the viruses are recovered from the gel, using 1 liter of glycine/NaOH buffer, at pH 11. Immediately the eluate is clarified through series of cellulose acetate membranes mounted in a 142mm Millipore filter. For the second step of virus concentration, HC1 1N is added slowly to the eluate to achieve pH 3.5-4. MgC1, is added to give a final concentration of 0.05M and the viruses are readsorbed on a 0.45 , porosity (HA) cellulose acetate membrane, mounted in a 90 mm Millipore filter. The viruses are recovered using the same eluent plus 10% of fetal calf serum, to a final volume of 3 ml. In this way, it was possible to concentrate virus from 400 liters of tap-water, into 1 liter in the first stage of virus concentration and just to 3 ml of final volume in a second step. The efficiency, simplicity and low operational cost, provded by the method, make it feasible to study viral pollution of recreational and tap-water sources.

Study of some parameters affecting the in vitro cultivation of Plasmodium falciparum within saimiri sciureus red blood cells

The in vitro growth and multiplication of the erythrocytic stages of Plasmodium falciparum within Saimiri sciureus (squirrel monkey) red blood cells have been studied. Various parameters, such as the origin of the red blood cells and serum supplement, nature of the buffer, influence of the final pH of the medium, role of proteose peptone and glucose addition, were investigated. The selection of the best culture conditions led to the obtention of a reproducible in vitro growth of two parasite cycles in Saimiri erythrocytes, which is an useful achievement for in vitro studies. Our failure to establish a continuous culture line for longer than 19 days, could be explained by a dramatic increasing of osmotic fragility of the Saimiri red blood cells related to their small size.

High-resolution magnetic resonance imaging quantitatively detects individual pancreatic islets.

OBJECTIVE-We studied whether manganese-enhanced high-field magnetic resonance (MR) imaging (MEHFMRI) could quantitatively detect individual islets in situ and in vivo and evaluate changes in a model of experimental diabetes.RESEARCH DESIGN AND METHODS-Whole pancreata from untreated (n = 3), MnCl(2) and glucose-injected mice (n = 6), and mice injected with either streptozotocin (STZ; n = 4) or citrate buffer (n = 4) were imaged ex vivo for unambiguous evaluation of islets. Exteriorized pancreata of MnCl(2) and glucose-injected mice (n = 6) were imaged in vivo to directly visualize the gland and minimize movements. In all cases, MR images were acquired in a 14.1 Testa scanner and correlated with the corresponding (immuno)histological sections.RESULTS-In ex vivo experiments, MEHFMRI distinguished different pancreatic tissues and evaluated the relative abundance of islets in the pancreata of normoglycemic mice. MEHFMRI also detected a significant decrease in the numerical and volume density of islets in STZ-injected mice. However, in the latter measurements the loss of beta-cells was undervalued under the conditions tested. The experiments on the externalized pancreata confirmed that MEHFMRI could visualize native individual islets in living, anesthetized mice.CONCLUSIONS-Data show that MEHFMRI quantitatively visualizes individual islets in the intact mouse pancreas, both ex vivo and in vivo. Diabetes 60:2853-2860, 2011

New Sorex araneus karyotypes from Germany and the postglacial recolonization of central Europe

New G-banded karyotypes from populations of the common shrew Sorex araneus Linnaeus, 1758 provide a clearer picture of the distribution of chromosome races in central Europe. As expected according to their occurrence in neighbouring countries, the Jutland (kq, no), Laska (k/o) and Drnholec (ko, nr) races are also found in Germany. A new chromosome race "Rugen" (kq) is described from this Baltic Island. Together with the previously recorded races Ulm and Mooswald (kr), six chromosome races are now known from Germany. The resulting distribution pattern is characterized by high frequencies of different race-specific metacentrics at the periphery of the country and clines with decreasing frequencies towards the centre which is occupied by the Ulm race. This race is acrocentric for all chromosome arms involved in the observed race-specific fusions and represents a buffer between the surrounding, more metacentric races. According to the present distribution of these metacentrics, a scenario for the postglacial recolonization of central Europe by S. araneus populations on three different routes is proposed: from the east along the northern slopes of the Carpathian Arc, from the south-east along the Danube Valley and from the south-west through the Upper Rhine Valley.

Family relationships and learning experiences in anxious vs. non-anxious families: Are there differences ?

L'objectif principal de ce travail était d'explorer les relations parent-enfant et les processus d'apprentissage familiaux associés aux troubles anxieux. A cet effet, des familles ayant un membre anxieux (la mère ou l'enfant) ont été comparées avec des familles n'ayant aucun membre anxieux. Dans une première étude, l'observation de l'interaction mère-enfant, pendant une situation standardisée de jeu, a révélé que les mères présentant un trouble panique étaient plus susceptibles de se montrer verbalement contrôlantes, critiques et moins sensibles aux besoins de l'enfant, que les mères qui ne présentaient pas de trouble panique. Une deuxième étude a examiné les perceptions des différents membres de la famille quant aux relations au sein de la famille et a indiqué que, par comparaison aux adolescents non-anxieux, les adolescents anxieux étaient plus enclins à éprouver un sentiment d'autonomie individuelle diminué par rapport à leurs parents. Finalement, une troisième étude s'est intéressée à déterminer l'impact d'expériences d'apprentissage moins directes dans l'étiologie de l'anxiété. Les résultats ont indiqué que les mères présentant un trouble panique étaient plus enclines à s'engager dans des comportements qui maintiennent la panique et à impliquer leurs enfants dans ces comportements, que les mères ne présentant pas de trouble panique. En se basant sur des recherches antérieures qui ont établi une relation entre le contrôle parental, la perception de contrôle chez l'enfant et les troubles anxieux, le présent travail non seulement confirme ce lien mais propose également un modèle pour résumer l'état actuel des connaissances concernant les processus familiaux et le développement des troubles anxieux. Deux routes ont été suggérées par lesquelles l'anxiété pourrait être transmise de manière intergénérationnelle. Chacune de ces routes attribue un rôle important à la perception de contrôle chez l'enfant. L'idée est que lorsque les enfants présentent une prédisposition à interpréter le comportement de leurs parents comme hors de leur contrôle, ils seraient plus enclins à développer de l'anxiété. A ce titre, la perception du contrôle représenterait un tampon entre le comportement de contrôle/surprotection des parents et le trouble anxieux chez l'enfant. - The principal objective of the present work was to explore parent-child relationships and family learning processes associated with anxiety disorders. To this purpose, families with and without an anxious family member (mother or child) were compared. In a first study, observation of mother-child interaction, during a standard play situation, revealed that mothers with panic disorder were more likely to display verbal control and criticism, and less likely to display sensitivity toward their children than mothers without panic disorder. A second study examined family members' perceptions of family relationships and indicated that compared to non-anxious adolescents, anxious adolescents were more prone to experience a diminished sense of individual autonomy in relation to their parents. Finally a third study was interested in determining the effect of less direct learning experiences in the aetiology of anxiety. Results indicated that mothers with panic disorder were more likely to engage in panic-maintaining behaviour and to involve their children in this behaviour than mothers without panic disorder. Based on previous research showing a relationship between parental control, children's perception of control, and anxiety disorders, the present work not only further adds evidence to support this link but also proposes a model summarizing the current knowledge concerning family processes and the development of anxiety disorders. Two pathways have been suggested through which anxiety may be intergenerationally transmitted. Both pathways assign an important role to children's perception of control. The idea is that whenever children have a predisposition towards interpreting their parents' behaviour as beyond of their control, they may be more prone to develop anxiety. As such, perceived control may represent a buffer between parental overcontrolling/overprotective behaviours and childhood anxiety disorder.