Chemical Precipitation Research Papers - Academia.edu (original) (raw)

The purpose of the study was to evaluate the hemostatic effectiveness of brin glue (FG) prepared by a modi cation of cryoprecipitation technique in experimental rat liver surgery. FG component 1 was prepared by triple or 'recycled' cryoprecipitationmethod from single-donor plasma. Rats subjected to liver incision, partial and total lobectomy were treated with FG on the surgical cut surface or underwent standard surgical technique. The ef cacy of FG-treatment was evaluated on the basis of the 24-hour survival ratio and peripheral blood hematological parameters. The mean values of brinogen, FXIII, bronectin and horizontal tensile strength of FG were 54:2 § 19:9 g/ l, 13:5 § 3:6 IU/ ml, 3103:1 § 148:9 mg / l, and 1:076 § 0:18 N / cm 2 , respectively. The survival of FG-treated rats subjected to partial and total lobectomy was signi cantly higher in comparison to the FG-nontreated animals, accompanied with higher values of red blood cell counts, hemoglobin concentration and hematocrit. When liver incision was performed, although there were no differences in survival rate, FG-treated animals had signi cantly higher values of the tested hematological parameters. The presented results demonstrated that by using 'recycled' cryoprecipitation it is possible to obtain high quality single-donor FG with successful hemostatic therapeutical effects, as con rmed in the experimental rat model of liver surgery.

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- Liver, Chemical Precipitation, Rats, Rat

It is well known that boric acid exhibits various toxic effects on plant, animal and human beings even at very low concentrations. Thus, the development of boron-removal technique from wastewater has been intensively investigated. In this study, a new hydrothermal treatment technique was developed to recover boron as recyclable precipitate Ca(2)B(2)O(5).H(2)O from aqueous solutions. As a result, it was found that the hydrothermal treatment using calcium hydroxide as a mineralizer converted boron in the aqueous media effectively into calcium borate, Ca(2)B(2)O(5).H(2)O. In the optimal hydrothermal condition, more than 99% of boron was collected from the synthetic wastewater of 500 ppm. Thus, the present hydrothermal treatment in the presence of calcium hydroxide is recommended as one of the effective techniques to recover boron from aqueous media.

- by Hideaki Itoh
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- Water, Minerals, Scanning Electron Microscopy, Multidisciplinary

This paper presents the results of the preparation and characterization of dysprosium-doped calcium sulfate (CaSO 4 :Dy) phosphor, which was obtained by homogeneous precipitation from calcium acetate Ca(CH 3 COO À) 2. Structural and morphological characteristics were studied using a scanning electronic microscope (SEM). The structure of all compounds was determined by X-ray diffraction method too. Thermoluminescence (TL) emission properties of CaSO 4 :Dy under gamma radiation effects were studied. This phosphor powder presented a TL glow curve with two peaks (Tmax) centered at around of 180 and 300 1C, respectively. The TL response of CaSO 4 :Dy as a function of gamma absorbed dose was linear in a wide range. Both emission and excitation spectra were also obtained. Results showed that this new preparation method of CaSO 4 :Dy TL phosphor is less expensive, cleaner and safer than the conventional preparation method.

- by Juan Azorin
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- Gamma Rays, Clinical Sciences, Chemical Precipitation, X ray diffraction

A central challenge in the development of drug-encapsulated polymeric nanoparticles is the inability to control the mixing processes required for their synthesis resulting in variable nanoparticle physicochemical properties. Nanoparticles may be developed by mixing and nanoprecipitation of polymers and drugs dissolved in organic solvents with nonsolvents. We used rapid and tunable mixing through hydrodynamic flow focusing in microfluidic channels to control nanoprecipitation of poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) diblock copolymers as a model polymeric biomaterial for drug delivery. We demonstrate that by varying (1) flow rates, (2) polymer composition, and (3) polymer concentration we can optimize the size, improve polydispersity, and control drug loading and release of the resulting nanoparticles. This work suggests that microfluidics may find applications for the development and optimization of polymeric nanoparticles in the newly emerging field of nanomedicine.

- by Pamela Basto
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- Microfluidics, Nanoparticles, Polymers, Multidisciplinary

In this work, a brewer’s yeast strain was used to remove heavy metals from a synthetic effluent. The solid–liquid separation process was carried out using the flocculation ability of the strain. The yeast strain was able to sediment in the presence of Cu2+, Ni2+, Zn2+, Cd2+ and Cr3+, which evidences that the flocculation can be used as a cheap and natural separation process for an enlarged range of industrial effluents. For a biomass concentration higher than 0.5 g/l, more than 95% of the cells were settled after 5 min; this fact shows that the auto-aggregation of yeast biomass is a rapid and efficient separation process. Cells inactivated at 45 °C maintain the sedimentation characteristics, while cells inactivated at 80 °C lose partially (40%) the flocculation.The passage of metal-loaded effluent through a series of sequential batches allowed, after the second batch, the reduction of the Ni2+concentration in solution for values below the legal limit of discharge of wastewater in natural waters (2 mg/l); this procedure corresponds to a removal of 91%. A subsequent batch had a marginal effect on Ni2+ removal (96%).Together, the results obtained suggest that the use of brewing flocculent biomass looks a promising alternative in the bioremediation of metal-loaded industrial effluents since the removal of the heavy metals and cell separation are simultaneously achieved.

- by Manuela Machado
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- Engineering, Speciation, Kinetics, Biomass

G. ROJAS, J. M. JIM~NEZ and J. M. GUTII~RREZ. Caprylic acid fractionation of hyperimmune horse plasma: description of a simple procedure for antivenom production. Toxicon 32, 351-363, 1994.--A simple methodology for hyperimmune horse plasma fractionation, based on caprylic acid precipitation, is described. Optimal conditions for fractionation were studied; the method gives best results when concentrated caprylic acid was added to plasma, whose pH had been adjusted to 5.8, until a final caprylic acid concentration of 5% was reached. The mixture was vigorously stirred during caprylic acid addition and then for 60 min; afterwards the mixture was filtered. Non-immunoglobulin proteins precipitated in these conditions, whereas a highly enriched immunoglobulin preparation was obtained in the filtrate, which was then dialysed to remove caprylic acid before the addition of NaC1 and phenol. Thus, antivenom was produced after a single precipitation step followed by dialysis. In order to compare this methodology with that based on ammonium sulfate fractionation, a sample of hyperimmune plasma was divided into two aliquots which were fractionated in parallel by both methods. It was found that caprylic acid-fractionated antivenom was superior in terms of yield, production time, albumin/globulin ratio, turbidity, protein aggregates, electrophoretic pattern and neutralizing potency against several activities of Bothrops asper venom. Owing to its efficacy and simplicity, this method could be of great value in antivenom and antitoxin production laboratories.

- by Gustavo Rojas
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- Snake venoms, Mice, Horses, Chemical Precipitation

Aqueous contaminant removal in the presence of metallic iron (e.g. in Fe 0 /H 2 O systems) is characterized by the large diversity of removing agents. This paper analyses the synergistic effect of adsorption, co-precipitation and reduction on the process contaminant removal in Fe 0 /H 2 O systems on the basis of simple theoretical calculations. The system evolution is characterized by the percent Fe 0 consumption. The results showed that contaminant reduction by Fe 0 is likely to significantly contribute to the removal process only in the earliest stage of Fe 0 immersion. With increasing reaction time, contaminant removal is a complex interplay of adsorption onto iron corrosion products, co-precipitation or sequestration in the matrix of iron corrosion products and reduction by Fe 0 , Fe II or H 2 /H. The results also suggested that in real world Fe 0 /H 2 O systems, any inflowing contaminant can be regarded as foreign species in a domain of precipitating iron hydroxides. Therefore, current experimental protocols with high contaminant to Fe 0 ratios should be revisited. Possible optimising of experimental conditions is suggested.

- by Chicgoua Noubactep
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- Engineering, Water, Adsorption, Optimization

Bone alkaline phosphatase was evaluated by wheat-germ lectin precipitation in several clinical conditions. The study included 33 premenopausal healthy women, 46 postmenopausal apparently healthy women, 19 growing children, 24 patients... more

- by N. Zamberlan and +1
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- Cognitive Science, Aging, Calcium, Adolescent
- by Noemi Zaritzky
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- Engineering, Kinetics, Biomass, Modeling

These studies describe the role of transition metal ions in the liposomal encapsulation of topotecan. Liposomes (1,2-distearoyl-sn-glycero-3phosphocholine (DSPC) and cholesterol (CH) (55:45, mole ratio)) were prepared with manganese (Mn), copper (Cu), zinc (Zn) or cobalt (Co) ion gradients (metal inside). Subsequently, topotecan was added to the liposome exterior (final drug-to-lipid ratio (mol/mol) of 0.2) and drug encapsulation was measured as a function of time and temperature. No drug loading was achieved with liposomes containing Co or Zn. Topotecan could be encapsulated into Mn-containing liposomes only in the presence of the ionophore, A23187 suggesting that a transmembrane pH gradient was necessary. However, Cu-containing liposomes, in the presence or absence of an imposed pH gradient, efficiently encapsulated topotecan. It has been reported that Cu(II) can form transition metal complexes with camptothecin; therefore, the Cu-topotecan interaction was characterized in solution as a function of pH. These investigations demonstrated that topotecan inhibited formation of an insoluble Cu hydroxide precipitate. Cryo-TEM analysis of the topotecan-loaded Cu liposomes showed electron-dense intravesicular precipitates. Further studies demonstrated that only the active lactone form of the drug was encapsulated and this form predominated in Cu-containing liposomes. Copper complexation reactions define a viable methodology to prepare liposomal camptothecin formulations.

- by Aman Taggar
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- Biomedical Engineering, Controlled release, Copper, Cholesterol

present in human urine. Further evidence was not obtained for the presence of this conjugate in human urine. However, Wienert and Gahlen (3) reported the presence of only one drug-related spot on the thin-layer chromatogram when they... more

- by carlos Serna
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- Chemistry, Carbonates, Aluminum, Pharmaceutical Sciences

T . H . A L -S AM A RR AI A ND J. S CH MI D . 2000. We have developed a new, simple and effective method for extraction of fungal genomic DNA. The initial steps involved suspension of freeze-dried mycelium in buffer containing sodium dodecyl sulphate, detachment of DNA from polysaccharides by mild shearing, NaCl precipitation of polysaccharides and protein, chloroform extraction and ethanol precipitation. The ethanol precipitate was then subjected to a second round of mild shearing, NaCl precipitation, chloroform extraction and ethanol precipitation. The procedure required approximately 1 h to perform. The method yielded 8-32 mg of high molecular weight DNA per 30 mg of freeze-dried mycelium when tested on six fungal species: Aspergillus niger, A. flavus, Fusarium graminarum, Neotyphodium lolii, Penicillium citrinum and Rhizopus nigricanes. The DNA was digestible with EcoRI, HindIII, SalI and BamHI. For the slow-growing N. lolii, a modification of the method was developed that removed the agar residue from colonies grown on agar plates by centrifugation at 13 000 rev min −1 in the presence of CsCl. The modified method yielded 1·5-2 mg of high molecular weight DNA per colony.

- by Jan Schmid
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- Fungi, Multidisciplinary, Fusarium, Ethanol

Serum samples and immunoglobulin fraciions of eight mammalian species were applied to a Sepharose-protein A column. As with the human immunoglobulin subclasses IgGl, lgG2 and IgG4, all examined animal IgG classes and subclasses were bound to a greater or lesser extent lo protein A. However, the binding of IgGl of ruminants was very poor. Polyclonal IgM and IgA of the pig, the dog and the cat may be separated in protein A reactive and protein A non-reaciive fractions. In addition, monoclonal canine IgM and IgA partially reacted with protein A. In combination with methods such as ammonium sulphate precipitation, ion exchange chromatography and gel-filtration, affinity chromatography with protein A is recommended for the rapid purification of certain Ig (sub)classes of a number of mammalian species.

- by A. Noordzij
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- Immunology, Cats, Dogs, Sheep

A simple method is described which combines a sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in the first dimension with a second electrophoresis, at right angles to the first, into an agarose matrix. The proteins, separated by SDS-PAGE, are exposed to appropriate antisera after the second stage electrophoresis and immunoprecipitates form in the agarose corresponding to the relative electrophoretic mobilities of proteins in the first stage SDS-PAGE separation. The method thus provides a simple, reproducible means for correlating antigenicity with apparent molecular weight of proteins. The technique is qualitative, but requires smaller quantities of antisera than more conventional immunoelectrophoretic methods such as rocket electrophoresis.

NiS-P zeolite was prepared by ion exchange and precipitation procedures and it was characterized by FT-IR, SEM and thermal methods. The prepared composite was used as a catalyst in the photodecolorization process of Eriochrome Black T (E.B.T.) dye in aqueous solution under UV irradiation. The effect of key operating parameters such as catalyst dosage, temperature, initial concentration of the dye and initial pH of the solutions were studied on the decolorization process of dye. The primary objective was to determine the optimal conditions for each of the parameters. UV-vis spectrophotometric measurements were performed for the determination of decolorization and mineralization extents. The optimal operation parameters were found as follows: pH 9.1, 0.8 g L −1 of catalyst loading and 40 ppm of dye concentration. The NiS particles out of zeolite framework did not show significant decolorization efficiency. The decolorization process obeyed first-order kinetics.

- by Alireza Nezamzadeh Ejhieh
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- Engineering, Catalysis, Kinetics, Scanning Electron Microscopy

Land spreading of dairy soiled water (DSW) may result in pollution of ground and surface waters. Treatment of DSW through sludge-supernatant separation using chemical coagulants is a potential option to reduce the negative environmental impacts of DSW. The aims of this study were to (1) assess the effectiveness of three chemical coagulants-poly-aluminium chloride (PACl), ferric chloride (FeCl 3) and alum-in improving effluent quality, and (2) assess the properties of the sludge that is generated as by-product from the process for its suitability for land application. Taking into consideration optimum doses to minimize pollutants (turbidity, chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), and E. coli), optimum mixing times and cost, FeCl 3 was the best performing coagulant. Generated sludges had higher nutrient content and fewer E. coli than raw DSW, and did not display any evidence of phytotoxicity to the growth of Lolium perenne L. using germination tests. The study discussed the results in a sustainable farm management context, and suggested that the effluent (supernatant) from the treatments may be recycled to wash farm yards, saving water. In parallel, the sludge portion can be applied to amend soil properties with no adverse impacts on the grass growth, providing an agronomic value as an organic fertilizer, and reducing the risk of nutrient losses. This management approach could minimize the overall net cost compared to land application of raw DSW.

A new sample treatment for liquid chromatographic analysis of ochratoxin A (OTA) in beer is proposed. Degassed beer is mixed with lead hydroxyacetate, which precipitates some bulk components but does not remove OTA. The precipitate is separated and the acidified liquid is extracted with chloroform. The solvent is evaporated and the residue is dissolved in mobile phase (acetonitrile-water, 40:60, v/v; acidified at pH 3.0 with phosphoric acid) and separated by liquid chromatography using fluorescence detection. The limit of detection was 0.005 ng/ml. The average recovery rate and the average RSD of recovery in the spiking level range 0.01-0.5 ng/ml were 95.5% and about 5%, respectively. The method is cheaper that other alternative ones using immunoaffinity columns or other solid-phase extraction cleanup. The separation was optimised with regard to composition and flow of the mobile phase and no interference from the matrix was found. The method was applied to 88 samples of beer (domestic and imported) marketed in Spain. OTA was detected in 82.9% of them. The range for positive samples was 0.007-0.204 ng of OTA/ml.

- by Angel Medina
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- Engineering, Technology, Spain, Beer

Binary blend films from lactide-rich poly (D-lactide-co-glycolide) (PDLG) and poly ( Llactide-co-glycolide) (PLLG ) were obtained by casting methylene chloride solutions of the two mixed copolymers with different D-and L-lactide contents... more

- by Hideto Tsuji
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- Structure, Kinetics, Morphology, Poly (lactic acid)
- by Bruce E Herbert
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- Engineering, Civil Engineering, Geochemistry, Thermodynamics

Batch laboratory scale experiments were conducted to investigate the removal of phosphate from aqueous and municipal wastewater samples by addition of FeCls.6HsO. The effect of pH, Fe-dose and initial phosphate concentration were assessed. Optimum phosphate removal, 63% for 1:l molar addition of Fe(II1) was observed at pH 4.5. However, a 155% excess of Fe-dose was necessary for complete phosphorus removal. Phosphorus removal from municipal wastewater was slightly higher than that observed for the aqueous solutions. A chemical precipitation mathematical model was developed and tested with the available experimental data. The model included a total of 15 chemical reactions and 4 solid phases with the option of single-phase precipitation or two-phase co-precipitation. The resulting system of non-linear algebraic equations was solved numerically, using the Wijngaarden-Dekker-Brent method.

- by N. Raikos
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- Modeling, Performance, Mathematical Modelling, Environmental Pollution
- by Frank Frantzen
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- Copper, Zinc, Cobalt, Hemoglobin

In spite of the present advances in the scaffolds fabrication and bioreactor systems, the ability to create functional thick tissue masses in vitro is still a great tissue engineering challenge. To overcome this problem, the fabrication of a capillary bed, for nutrient supply to and waste product removal from the tissue engineering construct as it grows, is essential. However, the technical construction of a capillary-like architecture is complex and challenging. This study reports, for the very first time, a simple method to design and fabricate a porous hollow membrane sheet (PHMsh) to provide both a capillary bed and a scaffold to support tissue growth. The PHMsh composed of a flexible porous sheet involving parallel porous channels and can be used as flat-, rolled-, or sandwiched-shape scaffold. The PHMsh was fabricated from poly(ϵ-caprolactone) polymer solution using solvent casting methods (i.e., immersion precipitation and air casting). Optical microscopy and scanning electron microscopy were used for the morphological analyses. The PHMsh was surface treated using n-hepthylamine plasma polymer (HApp) and X-ray photoelectron spectroscopy confirmed successful surface coating. Human umbilical vein endothelial cells (HUVECs) and fibroblast cells were used to evaluate the capability of PHMsh toward cell adhesion. The HApp coating enhanced both HUVEC and fibroblast cells adhesion. The obtained preliminary results demonstrated the successful fabrication of the PHMsh, with potential application for tissue engineering scaffolds, particularly in large tissue mass generation under perfusion systems in vitro, which is our future research direction. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010

Mycorrhizal fungi are among the most common symbioses found in terrestrial ecosystems, both natural and managed. They are important for many reasons, but most notably because of their positive effects on plant growth, which are mediated by their uptake of nutrients from the soil and transport of these to the roots. Moreover, many edible fungi are mycorrhizal. The study of mycorrhizal fungi has been hampered by the inability to identify species and individuals in the soil. This has been greatly aided by DNA-based methods, which first require the extraction of DNA. Herein, I discuss some general concerns that must be considered when extracting and purifying DNA from ecological samples and offer specific methods for soil, mycorrhizal roots, and fruiting bodies. These methods are rapid, safe, effective, relatively inexpensive, and convenient because they are based on commercially available kits. 58 comparing macromolecules [5]

- by Terje Traavik
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- Symbiosis, Fungi, Microflora of the Gut, DNA

This work aimed to compare methods for the formation of complexes of bixin and curcumin with β-cyclodextrin (β-CD) and to evaluate the stability of the complexes formed by these methods and their food applications. The stoichiometric relationship between curcumin and β-CD was 1:2 and that between bixin and β-CD was 1:1. Curcumin-β-CD and bixin-β-CD complexes formed by kneading, coprecipitation, and simple mixing were evaluated by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), or nuclear magnetic resonance (NMR-H). For both curcumin and bixin, the best method of complexation was coprecipitation. Complexation of colorants with β-CD promoted an intensification of color and increased water solubility; however, stabilization in the presence of light occurred only for bixin. Application of curcumin-β-CD in cheese and yogurt and bixin-β-CD in the curd did not alter the initial characteristics of the products, which were sensorialy well accepted. Therefore, the complexation of these natural colorants with β-CD favors their use in low-fat foods, broadening the field of industrial application.

- by Lucia Durrant
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- Engineering, Carotenoids, Food Technology, Yogurt

In this paper are reported experimental results on the effect of a magnetic field on the precipitation process of calcium carbonate scale from a hard water. Carbonically pure water was circulated at a constant flow rate in a magnetic field. After this treatment, calcium carbonate precipitation was induced by degassing dissolved carbonic gas. The nucleation time was identified from the variations of the pH and the Ca 2+ concentration. The ratio between homogeneous and heterogeneous nucleation was determined from the measurement of the mass of precipitated calcium carbonate. It is shown that the magnetic treatment increases the total amount of precipitate. This effect depends on the solution pH, the flow rate and the duration of the treatment. In addition, the magnetic treatment modifies the ratio between homogeneous/heterogeneous nucleation. Homogeneous nucleation is promoted by an increasing the pH of water, the flow rate as well as the residence time. The magnetic treatment enhances these effects with a maximum for a 15 min treatment time. It is shown that the presence of calcium carbonate colloid particles is not necessary. It is advanced that the main magnetic effects concern the associations of ionic species which are present in the solution and which are involved in the nucleation process of calcium carbonate precipitation

- by gabrielli claude
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- Chemistry, Water, Carbon Dioxide, Water Purification

Large-scale processes used to manufacture grams of plasmid DNA (pDNA) should be cGMP compliant, economically feasible, and environmentally friendly. Alcohol and salt precipitation techniques are frequently used in plasmid DNA (pDNA) downstream processing, as concentration and prepurification steps, respectively. This work describes a study of a standard 2-propanol (IsopOH; 0.7 v/v) and ammonium sulfate (AS; 2.5 M) precipitation. When inserted in a full process, this tandem precipitation scheme represents a high economic and environmental impact due to the large amounts of the two precipitant agents and their environmental relevance. Thus, major goals of the study were the minimization of precipitants and the selection of the best operating conditions for high pDNA recovery and purity. The pDNA concentration in the starting Escherichia coli alkaline lysate strongly affected the efficiency of IsopOH precipitation as a concentration step. The results showed that although an IsopOH concentration of at least 0.6 (v/v) was required to maximize recovery when using lysates with less than 80 µg pDNA/mL, concentrations as low as 0.4 v/v could be used with more concentrated lysates (170 µg pDNA/ mL). Following resuspension of pDNA pellets generated by 0.6 v/v IsopOH, precipitation at 4°C with 2.4 M AS consistently resulted in recoveries higher than 80% and in removal of more than 90% of the impurities (essentially RNA). An experimental design further indicated that AS concentrations could be reduced down to 2.0 M, resulting in an acceptable purity (21-23%) without compromising recovery (84-86%). Plasmid recovery and purity after the sequential IsopOH/AS precipitation could be further improved by increasing the concentration factor (CF) upon IsopOH precipitation from 2 up to 25. Under these conditions, IsopOH and AS concentrations of 0.60 v/v and 1.6 M resulted in high recovery (≈100%) and purity (32%). In conclusion, it is possible to reduce substantially the mass of precipitation agents used without affecting recovery, if a small concession is made regarding purity. This directly translates into an improvement of the process economics and in a reduction of the environmental impact of the process.

- by Duarte Miguel Prazeres
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- Engineering, Technology, Optimization, Biological Sciences

Under natural conditions, arsenic is often associated with iron oxides and iron(III) oxidative capacity towards As(III) is well known. In this study, As(III) and As(V) removal was performed using synthesised iron(III) phosphate, either amorphous or crystalline. This solid can combine (i) As(III) oxidation by iron(III) and (ii) phosphate substitution by As(V) due to their similar properties. Results showed that adsorption capacities were higher towards As(III), leading to Fe 2+ and HAsO 4 2− leaching. Solid dissolution and phosphate/arsenate exchange led to the presence of Fe 3+ and PO 4 3− in solution, therefore various precipitates involving As(V) can be produced: with Fe 2+ as Fe 3 (AsO 4 ) 2 ·8H 2 O (s) and with Fe 3+ as FeAsO 4 ·2H 2 O (s) . Such formations have been assessed by thermodynamic calculations. This sorbent can be a potential candidate for industrial waste treatment, although the high release of phosphate and iron will exclude its application in drinking water plants.

- by DELUCHAT Véronique and +1
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- Engineering, Thermodynamics, Arsenic, Hazardous Waste

The potassium pyroantimonate (KPA) Ca 2þ precipitation technique, X-ray microanalysis and Electron Energy Loss Spectroscopy carried out by transmission electron microscopy were used to analyze the Ca 2þ distribution in Catharanthus roseus L. leaves infected with phytoplasmas belonging to different taxonomic groups, and in phytoplasma cells. The analysis revealed that the distribution of Ca 2þ was different in healthy and diseased plants (where the KPA deposits were numerous) and no differences were observed in the tissues of the three types of infected C. roseus L. Since no KPA precipitates were visible in the phloem and on phytoplasma cells, it is likely that Ca 2þ ions are not directly involved in phytoplasma replication, but, in infected cells is a response to the pathogen indicative of a higher Ca 2þ in the plasmalemma. q

- by Maria Favali and +1
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- Materials Engineering, Condensed Matter Physics, Electron Microscopy, Calcium
- by Muniba Faiza
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- Chemical Engineering, Chemistry, Biochemical Engineering, Fluorescence Microscopy

There is an increasing interest in the microbial communities resident in the gastrointestinal tracts of verte-brates due to the recognition that these microbiomes play critical roles in the nutrition and health of their hosts (1). To... more

- by Zhongtang Yu
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- Technology, Community, Biological Sciences, DNA

The effectiveness of elemental iron (Fe 0 ) to remove uranium (U) from the aqueous phase has been demonstrated. While the mitigation effect is sure, discrepancies in the removal mechanism have been reported. The objective of this study was to investigate the mechanism of U(VI) removal from aqueous phases by Fe 0 . For this purpose a systematic sequence of bulk experiments was conducted to characterize the effects of the availability and the abundance of corrosion products on U(VI) removal. Results indicated that U(VI) removal reactions did not primary occur at the surface of the metallic iron. It is determined that U(VI) co-precipitation with aging corrosion products is a plausible explanation for the irreversible fixation under experimental conditions. Results of XRD analyses did no show any U phases, whereas SEM-EDX analyses showed that U tended to associate with rusted areas on the surface of Fe 0 .

- by Chicgoua Noubactep
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- Engineering, Water Purification, Titanium, Corrosion
- by Shafiqul Islam
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- Water, Carbon, Arsenic, Science
- by J. Lemaître and +2
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- Mechanical Engineering, Chemical Engineering, Chemical, Chemical Precipitation

The purification of a thermostable Caldocellum saccharolyticum B-glucosidase expressed in Escherichia coli was investigated using heat precipitation of unclarified cell homogenates. Heat treatment at 70°C was capable of purification with respect to cell debris, small particulates and the majority of cell protein, although E. coli proteins were even more efficiently removed at 80°C and above. For thermostable proteins expressed in E. coli, a precipitation temperature of 80°C or greater is recommended for optimal removal of contaminant proteins. In small-scale heating trials, heating rate was found to influence enzyme yield significantly. Losses were minimised when 'flash-heating' was employed. The successful single-step removal of particulates, labile protein and nucleic acids was achieved by simultaneous heat-treatment and polyethyleneimine addition, although the purification achieved was additive rather than synergistic.

- by Don A Cowan
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- Engineering, Technology, RNA, Biotechnology

Many studies of calcium phosphate precipitation have been made using relaxation techniques in which the concentrations of the lattice ions are allowed to decrease as equilibrium is approached. Since the nature of the phases that form depend markedly on the solution composition, this decrease can lead to concomitant phase transformations during the crystallization experiments. The results of the present constant composition (CC) studies show that defect apatites may be formed under conditions of sustained supersaturation with a non-stoichiometric coefficient dependent on the pH of the growth medium. An important factor in analyzing these experiments is the initial surface modification and ion-exchange processes involving H+ and Ca2+ ions after inoculation of the supersaturated solutions. Thereafter, active growth sites may be eliminated as the crystals undergo lattice perfection. Transformation of dicalcium phosphate dihydrate to octacalcium phosphate, involving dissolution and subsequent nucleation and growth of the new phase, is also influenced by surface roughening of the initial phase. Typical inhibitors that reduce the rate of growth of seed crystals in supersaturated solutions may actually induce the nucleation of calcium phosphate phases when immobilized on inert surfaces. This may be a factor in the modulation of crystal growth in many biological systems.

- by lore perez
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- Kinetics, Minerals, Crystallization, Biological Sciences

Xylitol was produced by Candida guilliermondii by fermentation of sugarcane bagasse hemicellulosic hydrolysate. Undesirable impurities were extracted from the broth using either ethyl acetate, chloroform or dichloromethane. The best results on clarification of the broth without xylitol loss were obtained with ethyl acetate. When ethanol, acetone or tetrahydrofuran were used for precipitation of impurities, only tetrahydrofuran clarified the fermented broth, but a high xylitol loss (~30%) was observed.

- by Solange I Mussatto
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- Engineering, Biochemistry, Technology, Biotechnology

Purpose: The current study reports on supersaturation, precipitation and excipient mediated precipitation inhibition of five poorly soluble drugs (loviride, glibenclamide, itraconazole, danazol, and etravirine) in human and simulated gastric fluids. Method: Upon induction of supersaturation in human gastric fluids (HGFs), simulated gastric fluid (SGF), and fasted state simulated gastric fluid (FaSSGF) using a solvent shift method, supersaturation and precipitation were assessed as a function of time. In addition, the precipitation inhibitory capacity of three polymers (Eudragit Ò E PO, HPMC-E5, and PVP K25) was investigated. Results: Supersaturation in human gastric fluids was observed for all model compounds, but proved to be relatively unstable (fast precipitation), except for itraconazole. Only modest excipient-mediated stabilizing effects on supersaturation were observed using HPMC-E5 and Eudragit Ò E PO whereas PVP K25 exerted no effect. In contrast to SGF, the observed precipitation behavior in FaSSGF was similar to the behavior in human gastric fluids. Conclusion: The present study demonstrates that supersaturation stability of drugs in human gastric fluids is in general inferior to supersaturation stability in intestinal fluids. As the potential for excipient mediated precipitation inhibition in gastric fluids was only limited, our data suggest that supersaturation should preferably be targeted to the intestine.

- by Bart Hens
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- Polymers, Young Adult, Solubility, European

Sera from mice immunized by repeated anthelmintic-terminated infections (IMS) or by a single primary infection (PMS) of Nematospiroides dubius were assayed for antibodies reactive with N. dubius antigens. The surface proteins of adult worms, the excretory/secretory (ES) proteins of adult worms and soluble extracts from lysates of both adult (AWH) and larval (LWH) N. dubius were used in an immunoprecipitation assay. A 60,000 MW protein was the major radiotabelled surface and ES protein. This antigen was dominant in precipitates by IMS from AWH, ES and surface-labelled worms but was not precipitated by PMS from any antigen source. Minor antigens of 20,000, 33,000, 36,000, 45,000, 50,000 and 66,000 MW were precipitated from AWH by both PMS and IMS but not from ES or surface-labelled worms. The dominant antigen precipitated from LWH by IMS was 20,000 MW. This antigen was not precipitated by PMS but larval antigens of 65,000 and 96,000 MW were precipitated by both PMS and IMS. The major antigens precipitated by IMS were adult (60,000 MW) and larvae (20,000 MW) stage-specific but some minor antigens (33,000, 45,000, 50,000 MW) were common to both stages. Our results show that the dominant antigen precipitated by serum immunoglobulin from mice immunized by repeated anthelmintic-terminated infections are proteins present on both the cuticle surface and in the ES.

- by Iain East
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- Immunology, Mice, Immunization, Immunology & Cell Biology

In this work the extraction of EPSs from culture media of Porphyridium cruentum, by dialysis, solvent-precipitation with 3 polar alcohols (methanol, ethanol and isopropanol) and membrane separation techniques has been studied. Diafiltration (DF) using a membrane with a 300 kDa molecular weight cut off was the most efficient technique compared to solvent-extraction and dialysis methods. After extraction, EPS fraction was characterized in terms of rheological properties and biochemical content. The product exhibited shear thinning behavior and a critical overlap concentration equal to 0.6 g/L. The monosaccharide composition was investigated after acidic hydrolysis. Xylose, galactose, glucose and glucuronic acid were identified as the main constitutive monomers.

- by Sébastien Jubeau and +2
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- Rheology, Dialysis, Filtration, Multidisciplinary

This article describes a modification of the conventional membrane crystallization technique in which a membrane is used to dose the solvent/antisolvent composition to generate supersaturation and induce crystallization in a drug solution. Two operative configurations are proposed: (a) solvent/antisolvent demixing crystallization, where the solvent is removed in at higher flow rate than the antisolvent so that phase inversion promotes supersaturation and (b) antisolvent addition, in which the antisolvent is dosed into the crystallizing drug solution. In both cases, solvent/antisolvent migration occurs in vapor phase and it is controlled by the porous membrane structure, acting on the operative process parameters. This mechanism is different than that observed when forcing the liquid phases through the pores and the more finely controllable supersaturated environment would generate crystals with the desired characteristics. Two organic molecules of relevant industrial implication, like paracetamol and glycine, were used to test the new systems. Experiments demonstrated that, by using antisolvent membrane crystallization in both configurations, accurate control of solution composition at the crystallization point has been achieved with effects on crystals morphology.

- by Antonella Caridi
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- Algorithms, Thermodynamics, Water, Polymorphism

- by Efrem Curcio
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- Algorithms, Thermodynamics, Water, Polymorphism

Background. The prevalence of micronutrient deficiencies in Cambodia is among the highest in Southeast Asia. Fortification of staple foods and condiments is considered to be one of the most cost-effective strategies for addressing micronutrient deficiencies at the population level. The Government of Cambodia has recognized the importance of food fortification as one strategy for improving the nutrition security of its population.

- by Chhea Chhorvann
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- Program Evaluation, Nutrition and Dietetics, Cambodia, Micronutrients

Microcrystals of megestrol acetate (MA), a poorly water-soluble drug, were successfully prepared using an antisolvent precipitation technique for improving the dissolution rate. The effective hydrophilic polymers and surfactants used were screened for their abilities to produce smaller particle sizes. Raw micronized MA and processed MA microcrystals were ranked by the Student-Newman-Keuls test in order of increasing particle size and SPAN values as follows: processed MA microcrystals in the presence of polymer and surfactant (mean diameter 1048 nm) < processed MA microcrystals in the presence of polymer (1654 nm) < processed MA microcrystals in the absence of polymer and surfactant (3491 nm) < raw micronized MA (4352 nm). The order of BET surface area was reversely ranked. Processed MA microcrystals in the presence of polymer and surfactant slightly decreased crystallinity and altered crystal habit and preferred orientation without change in polymorph. In addition, the dissolution properties of the processed MA microcrystals in the presence of polymer and surfactant were significantly enhanced as compared to that of the raw micronized MA. This effect is mainly due to a reduction in particle size resulting in an increased surface area. Therefore, it was concluded that the antisolvent precipitation technique in mild conditions could be a simple and useful technique to prepare poorly water-soluble drug particles with reduction in particle size, a narrow particle size distribution and enhanced dissolution properties.

- by eunbi kim
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- Kinetics, Pharmaceutical Technology, Scanning Electron Microscopy, Powder Diffraction

Mineral precipitation in microbial mats may have been the key to their 18 preservation as fossil stromatolites, potentially documenting evidence of the 19 earliest life on Earth. Two factors that contribute to carbonate mineral 20... more

- by Kimberley Gallagher
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- Geology, Geochemistry, Environmental microbiology, Geobiology

Rossi-Fedele G, Do gramacı EJ, Steier L, de Figueiredo JAP. Interaction between chlorhexidineimpregnated gutta-percha points and several chlorinecontaining endodontic irrigating solutions. International Endodontic Journal, 46, 675-680,... more

- by Giampiero Rossi-fedele and +1
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- Dentistry, Color, Root Canal Irrigants, Hydrogen Peroxide

In this study, we synthesized and characterized two methoxy poly(ethylene glycol)-block-poly(caprolactone) (MePEG-b-PCL) amphiphilic diblock copolymers, both based on MePEG with a molecular weight of 5000 g/mol (114 repeat units) and PCL block lengths of either 19 or 104 repeat units. Nanoparticles were formed from these copolymers by a nanoprecipitation and dialysis technique. The MePEG 114 -b-PCL 19 copolymer was water soluble and formed micelles that had a hydrodynamic diameter of 40 nm at all copolymer concentrations tested, and displayed a relatively low core microviscosity. The practically water insoluble MePEG 114 -b-PCL 104 copolymer formed nanoparticles with a larger hydrodynamic diameter, which was dependent on copolymer concentration, and possessed a higher core microviscosity than the MePEG 114 -b-PCL 19 micelles, characteristic of nanospheres. The micelles solubilized a maximum of 1.6% w/w of the hydrophobic anticancer agent, paclitaxel (PTX), and released 92% of their drug payload over 7 days, as compared to the nanospheres, which solubilized a maximum of 3% w/w of PTX and released 60% over the same period of time. Both types of nanoparticles were found to be hemocompatible, causing only minimal hemolysis and no changes in plasma coagulation times as compared to control. Upon in vitro incubation in human plasma, PTX solubilized by micelles had a plasma distribution similar to free drug. The majority of PTX was associated with the lipoprotein deficient plasma (LPDP) fraction, which primarily consists of albumin and alpha-1glycoprotein. In contrast, nanospheres were capable of retaining more of the encapsulated drug with significantly less PTX partitioning into the LPDP fraction.

- by Richard Liggins
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- Nanoparticle, Dialysis, Pharmacokinetics, Nanoparticles