Home About us Contact
|
Home About us Contact | ||
|
|
||
Ammonium Chloride (ammonium + chloride)
Selected AbstractsEffects of Ammonium Chloride on the Rheological Properties and Sedimentation Behavior of Aqueous Silica SuspensionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000J. Jiyou Guo The influence of ammonium chloride (NH4Cl) on the rheological properties and sedimentation behavior of aqueous silica (SiO2) suspensions of varying solids volume fraction (,s) was studied. SiO2 suspensions with low NH4Cl concentration (,0.05M, pH 5.2) exhibited Newtonian behavior and a constant settling velocity (U). The volume fraction dependence was well described by the Richardson,Zaki form, U=U0(1 ,,s)n, where n= 4.63 and U0= 1.0419 × 10,5 cm/s. At higher NH4Cl concentrations (0.07,2.0M, pH 5.2), suspensions exhibited shear thinning and more complicated sedimentation behavior due to their aggregated nature. For all suspensions studied, however, the apparent suspension viscosity, characteristic cluster size, and initial settling velocity were greatest at ,0.5M NH4Cl and exhibited a similar dependence on salt concentration. Above 0.5M NH4Cl, considerable restabilization was observed. This behavior cannot be explained by traditional DLVO theory. [source] Dead-End Liposomal Electro-Filtration: Phenol Removal by Dioctadecyl Dimethyl Ammonium Chloride as a Case StudyCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2010M. Hakimhashem Abstract Among the important efforts that have been made for the removal of trace organic molecules, sorption by micelles and subsequent membrane filtration is a promising method which, however, still suffers from a number of disadvantages such as low efficiency and high energy consumption. In this article, we present the results of the sorption of phenol (as an important trace organic pollutant in industrial wastewater) to dioctadecyl dimethyl ammonium chloride (DODAC) liposomes, as well as the filtration properties of the resulting dispersion. Whereas the sorption of phenol by a 0.5,wt,% DODAC dispersion at neutral pH and ambient temperature was only 26,35,%, it increased to above 95,% at pH,11. Applying an electric field during the filtration process considerably improved both the filtrate flow rate and the retention. An electric field of 5,V/cm increased the filtrate flow rate at 200,kPa 30-fold. [source] A Simple, Efficient and Regioselective Oxychlorination of Aromatic Compounds Using Ammonium Chloride and Oxone®.CHEMINFORM, Issue 40 2004N. Narender Abstract For Abstract see ChemInform Abstract in Full Text. [source] Reductive Cleavage of Azo Compounds by Zinc and Ammonium Chloride.CHEMINFORM, Issue 38 2004M. B. Sridhara No abstract is available for this article. [source] ChemInform Abstract: The First Zinc-Promoted, Environmentally Friendly, and Highly Efficient Acetoxyallylation of Aldehydes in Aqueous Ammonium Chloride.CHEMINFORM, Issue 9 2002Marco Lombardo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Indium/Ammonium Chloride Mediated Selective Reduction of Aromatic Nitro Compounds: Practical Synthesis of 6-Aminochrysene.CHEMINFORM, Issue 1 2001Bimal K. Banik Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Contact dermatitis in Korean dental techniciansCONTACT DERMATITIS, Issue 1 2001Jun Young Lee The high risk of occupational contact dermatitis in dental personnel are well accepted throughout the world. There are few reports concerning occupational skin disease in dental personnel in Korea. The purposes of this study were to investigate the frequency, characteristics and causative factors of contact dermatitis in Korean dental technicians. Recording of personal history, physical examination and patch tests with the Korean standard series and dental screening series were performed in 49 dental technicians. Most of the subjects were exposed to a variety of compounds, including acrylics, metals, plaster, alginate, etc. 22 (44.9%) subjects had contact dermatitis, present or past, and the site involved was the hand in all 22. The most common clinical feature of hand dermatitis was itching (77.3%); scaling, fissuring and erythema were other common clinical features. Metals, including potassium dichromate (24.5%), nickel sulfate (18.4%), mercury ammonium chloride (16.3%), cobalt chloride (12.2%) and palladium chloride (10.2%), showed high positive rates in patch test results of 49 dental technicians. 7 positive reactions to the various acrylics were found in 3 subjects. In our study, the frequency and clinical features of the contact dermatitis showed a similarity to other reports, though the patch test results were somewhat different; a higher patch-positive reaction to metals and a relatively lower patch-positive reaction to acrylics than the patch test results reported in Europe. [source] Determination of Ytterbium Traces by Cathodic Stripping VoltammetryELECTROANALYSIS, Issue 1 2003Marina Mlakar Abstract The method of ytterbium(III) trace concentration in the presence of 2-thenoyltrifluoroacetone (TTA) and polyethyleneglycol (PEG) in ammonium chloride is described. The adsorption was performed at the HMDE at ,1.0,V using linear scan voltammetry and square-wave voltammetry. The relationship between properties of the SW response of the mixed ligand complex and parameters of a charge transfer were analyzed using theoretical data of SW redox processes. [source] Highly Stereoselective Metal-Mediated Entry to Functionalized Tetrahydrothiophenes by Barbier-Type Carbonyl-Addition ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2008Benito Alcaide Abstract Reactions of tetrahydrothiophene-3-carbaldehydes with stabilized organometallic reagents were investigated in aqueous media. Tetrahydrothiophene-3-carbaldehydes and a variety of stabilized organic halides undergo stereocontrolled coupling under Barbier-type conditions in the presence of different metals (zinc, tin, indium) and additives [ammonium chloride, hydrobromic acid, hafnium(IV) chloride, bismuth(III) chloride]. The regiochemistry of the carbonyl addition processes, when applicable, was excellent.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Two beta-alanyl-CoA:ammonia lyases in Clostridium propionicumFEBS JOURNAL, Issue 3 2005Gloria Herrmann The fermentation of ,-alanine by Clostridium propionicum proceeds via activation to the CoA-thiol ester, followed by deamination to acryloyl-CoA, which is also an intermediate in the fermentation of l -alanine. By shifting the organism from the carbon and energy source ,-alanine to ,-alanine, the enzyme ,-alanyl-CoA:ammonia lyase is induced 300-fold (, 30% of the soluble protein). The low basal lyase activity is encoded by the acl1 gene, whereas the almost identical acl2 gene (six amino acid substitutions) is responsible for the high activity after growth on ,-alanine. The deduced ,-alanyl-CoA:ammonia lyase proteins are related to putative ,-aminobutyryl-CoA ammonia lyases involved in lysine fermentation and found in the genomes of several anaerobic bacteria. ,-Alanyl-CoA:ammonia lyase 2 was purified to homogeneity and characterized as a heteropentamer composed of 16 kDa subunits. The apparent Km value for acryloyl-CoA was measured as 23 ± 4 µm, independent of the concentration of the second substrate ammonia; kcat/Km was calculated as 107 m,1·s,1. The apparent Km for ammonia was much higher, 70 ± 5 mm at 150 µm acryloyl-CoA with a much lower kcat/Km of 4 × 103 m,1·s,1. In the reverse reaction, a Km of 210 ± 30 µM was obtained for ,-alanyl-CoA. The elimination of ammonia was inhibited by 70% at 100 mm ammonium chloride. The content of ,-alanyl-CoA:ammonia lyase in ,-alanine grown cells is about 100 times higher than that required to sustain the growth rate of the organism. It is therefore suggested that the enzyme is needed to bind acryloyl-CoA, in order to keep the toxic free form at a very low level. A formula was derived for the calculation of isomerization equilibra between l -alanine/,-alanine or d -lactate/3-hydroxypropionate. [source] Large aggregating and small leucine-rich proteoglycans are degraded by different pathways and at different rates in tendonFEBS JOURNAL, Issue 17 2004Tom Samiric This work investigated the kinetics of catabolism and the catabolic fate of the newly synthesized 35S-labelled proteoglycans present in explant cultures of tendon. Tissue from the proximal region of bovine deep flexor tendon was incubated with [35S]sulfate for 6 h and then placed in explant cultures for periods of up to 15 days. The amount of radiolabel associated with proteoglycans and free [35S]sulfate lost to the medium and retained in the matrix was determined for each day in culture. It was shown that the rate of catabolism of radiolabelled small proteoglycans (decorin and biglycan) was significantly slower (T½ > 20 days) compared with the radiolabelled large proteoglycans (aggrecan and versican) that were rapidly lost from the tissue (T½ , 2 days). Both the small and large newly synthesized proteoglycans were lost from the matrix with either intact or proteolytically modified core proteins. When explant cultures of tendon were maintained either at 4 °C or in the presence of the lysosomotrophic agent ammonium chloride, inhibition of the cellular catabolic pathway for small proteoglycans was demonstrated indicating the involvement of cellular activity and lysosomes in the catabolism of small proteoglycans. It was estimated from these studies that approximately 60% of the radiolabelled small proteoglycans that were lost from the tissue were degraded by the intracellular pathway present in tendon cells. This work shows that the pathways of catabolism for large aggregating and small leucine-rich proteoglycans are different in tendon and this may reflect the roles that these two populations of proteoglycans play in the maintenance of the extracellular matrix of tendon. [source] A Mild, One-Pot Synthesis of Arylamines via Palladium- Catalyzed Addition of Aryl Aldehydes with Amines and Arylboronic Acids in WaterADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009Ajuan Yu Abstract A mild, one-pot synthesis of diarylmethylamines via the palladium-catalyzed addition of aryl aldehydes with amines and arylboronic acids is reported. Best results were obtained in neat water with ammonium chloride as additive, affording diarylmethylamine derivatives as the main products. [source] Properties of a poly(acrylamide- co -diallyl dimethyl ammonium chloride) hydrogel synthesized in a water,ionic liquid binary systemJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Qian Zhao Abstract A novel copolymer hydrogel, poly(acrylamide- co -diallyl dimethyl ammonium chloride), was prepared by the radical copolymerization of acrylamide and diallyl dimethyl ammonium chloride in an ionic liquid (IL),water binary system in the presence of the crosslinker N,N,-methylene bisacrylamide. The equilibrium swelling ratios of the hydrogels synthesized in the IL,water binary system increased with the content of IL and were remarkably higher than that of the gel synthesized in water. Differential scanning calorimetry measurements showed that the glass-transition temperatures of the dry hydrogels that were synthesized in the IL,water binary system were remarkably lower than that of the gel synthesized in pure water. The mechanical properties of the gels synthesized in both water and the IL,water binary system were characterized with a universal material-testing machine. The results show that fracture toughness of the hydrogels was improved when they were synthesized in the IL,water binary system. The gel shrank under a direct-current electric field. The response rates of the gels that were synthesized with the IL,water binary system were faster than that of the gel synthesized in water. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Antimicrobial finishing of regular and modified nylon-6 fabricsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008S. E. Shalaby Abstract A simple, efficient, and practically applicable functional approach for improvement antimicrobial properties of nylon-6 fabrics and increase the washing durability of biofunctions was developed. This finishing approach is based on grafting of the fabrics with methacrylic acid (MAA) to create additional carboxylic groups in nylon-6 macromolecules, followed by subsequent reaction with dimethylalklbenzyl ammonium chloride (DMABAC) solution under alkaline conditions. The carboxylic groups react with cationic agent through ionic interaction, which led to the immobilization of QAS on nylon-6 fabrics. This immobilization was proofed through determination of nitrogen content, applying scanning electron microscopy (SEM), and FTIR microscopy. The effect of treatment conditions on salt uptake (SUT) on nylon-6 fabrics and reaction efficiency (RE) was investigated. The antimicrobial assessment of regular and grafted with PMAA nylon-6 fabrics treated with DMABAC revealed that both types of fabrics are characterized before washing, by quite strong biocide effect on Bacillus mycoides, Escherichia coli and Candida albicans. The role of grafting nylon-6 fabrics before treatment with salt on durability of antimicrobial functions seems to be more significant as the samples were repeatedly washed. Even after Laundring 10 times the grafted samples could still provide 80%, 100%, and 87.5% microbial reduction against B. mycoides, E. coli and C. albicans, respectively, in contrast with 42.6%, 65.6%, and 42.5% in case of regular nylon-6 fabrics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008. [source] Precipitation polymerization of acrylamide with quaternary ammonium cationic monomer in potassium carbonate solution initiated by plasmaJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Yangang He Abstract Precipitation polymerization of 2-(methacryloyloxyethyl) trimethyl ammonium chloride (DMC)- co -acrylamide (AM) [poly(AM-DMC)] has been successfully performed in potassium carbonate (K2CO3)-water media by plasma initiation. K2CO3 solution was selected because not only the higher solubility of AM and DMC comparing with that of poly(AM-DMC), but the higher intrinsic viscosity of poly(AM-DMC) could be obtained. A set of experiments was performed using different K2CO3 concentration (from 50 down to 10% (w/w)), thus the precipitation architecture was not obtained below 20% (w/w). And particles size, particles size distribution (7,120 ,m), and intrinsic viscosity of poly(AM-DMC) (ranging up to 455 cm3/g) were also summarized in this article. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4060,4067, 2007 [source] Preparation and characterization of UV-grafted ion-exchange textiles in continuous electrodeionizationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2004Kyeong-Ho Yeon Abstract Ion-exchange textiles (IETs) suitable for use in continuous electrodeionization (CEDI) stacks were prepared using the ultraviolet (UV)-induced grafting of acrylic acid and sodium styrene sulfonate for cation-exchange textiles, or 2-hydroxyethyl methacrylate and vinylbenzyl trimethyl ammonium chloride for anion-exchange textiles, onto nonwoven polypropylene fabric using benzophenone as photoinitiator. Although the ion-exchange capacity (2.2 meq g,1) of the prepared strong acid cation-exchange textile was lower than that of IRN77 strong acid cation-exchange resin (4.2 meq g,1), the overall rate constant of IET was very high due to its low crosslinking and high specific surface area. There was no significant difference between the two different media in terms of the Co(II) removal rate. Furthermore, the current efficiency for IETs was higher than that of IRN77 cation-exchange resin during a CEDI operation, with efficiencies of 60% and 20%, respectively. The IET also showed the faster exchange kinetics. Therefore, IETs prepared in this study proved to have desirable ion-conducting characteristics within the CEDI systems. Also this study revealed that the primary removal mechanism in CEDI is the transport of ions through a medium and not the ionic capacity of a medium. Copyright © 2004 Society of Chemical Industry [source] Novel method for clearing red blood cell debris from BacT/ALERT® blood culture medium for improved microscopic and antimycobacterial drug susceptibility test resultsJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2007Krishnamoorthy Gopinath Abstract Even though automation in mycobacterial culture has immensely improved the detection of organisms, identification of species and antimycobacterial susceptibility testing from blood culture bottles remain cumbersome and error-prone due to the presence of intact red blood cells (RBCs). The removal or lysis of these RBCs and excessive protein from the blood components could theoretically help improve this process. The present study reports an effective method that uses ammonium chloride (NH4Cl) and Triton X-100 to lyse the RBCs in blood culture medium. The method was optimized by preparing various concentrations of NH4Cl and Triton X-100, and incubation conditions, leading to eight protocols. The lysis protocol with a concentration of 150,mM of NH4Cl, 0.5% Triton X-100, and 1% potassium bicarbonate, pH 7.0, and incubation at 37°C for 15,min was found to be optimal. This method not only made the culture medium clear, the protein concentration decreased from 753.5±39.4 to 53.2±4.2,mg/mL in the M. tuberculosis -spiked culture medium and in the blood culture medium inoculated with the blood from tuberculosis patients. The method had no adverse effect on mycobacteria, and no depletion of M. tuberculosis colony-forming units was found. The lysate could be used for antimycobacterial susceptibility testing with no difficulty in setting the mycobacterial concentration of inoculum to 0.5 McFarland standards. Furthermore, this method had the added advantage in the microscopy and molecular methods for the speciation of Mycobacterium sp. J. Clin. Lab. Anal. 21:220,226, 2007. © 2007 Wiley-Liss, Inc. [source] PORCINE PLASMA PROTEINS AS GEL ENHANCER IN BIGEYE SNAPPER (PRIACANTHUS TAYENUS) SURIMIJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2001SOOTTAWAT BENJAKUL ABSTRACT Cohn's fraction I-S from porcine plasma showed the highest transglutaminase activity, compared to fractions I. 11+III, IV, IV-l. The optimum temperature for incorporating monodancylcadaverine into dimethylated casein was 45C. Plasma transglutaminase in fraction I-S was activated by calcium chloride but was inhibited by N-ethylmaleimide, ethylenediaminetetraacetic acid, and ammonium chloride. The addition of fraction I-S into bigeye snapper surimi resulted in a substantial increase in gel breaking force and deformation, particularly in the presence of calcium chloride and thrombin. No changes in whiteness and water holding capacity were observed in surimi gel with the addition of 0,0.5% of fraction I-S. Fraction I-S was found to catalyze nondisulfide covalent cross-linking of myosin heavy chain. The combination of endogenous and plasma transglutaminase enhanced surimi gelation. [source] CONTRASTING EFFECTS OF METHIONINE SULFOXIMINE ON UPTAKE AND ASSIMILATION OF AMMONIUM IN ULVA INTESTINALIS (CHLOROPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 4 2004Neill G. Barr Ammonium is assimilated in algae by the glutamine synthetase (GS),glutamine:2-oxoglutarate aminotransferase pathway. In addition to the assimilation of external ammonium taken up across the cell membrane, an alga may have to reassimilate ammonium derived from endogenous sources (i.e. nitrate reduction, photorespiration, and amino acid degradation). Methionine sulfoximine (MSX), an irreversible inhibitor of GS, completely inhibited GS activity in Ulva intestinalis L. after 12 h. However, assimilation of externally derived ammonium was completely inhibited after only 1,2 h in the presence of MSX and was followed by production of endogenous ammonium. However, endogenous ammonium production in U. intestinalis represented only a mean of 4% of total assimilation attributable to GS. The internally controlled rate of ammonium uptake (Vi) was almost completely inhibited in the presence of MSX, suggesting that Vi is a measure of the maximum rate of ammonium assimilation. After complete inhibition of ammonium assimilation in the presence of MSX, the initial or surge (Vs) rate of ammonium uptake in the presence of 400 ,M ammonium chloride decreased by only 17%. However, the amount that the rate of ammonium uptake decreased by was very similar to the uninhibited rate of ammonium assimilation. In addition, the decrease in the rate of ammonium uptake in darkness (in the absence of MSX) in the presence of 400 ,M ammonium chloride matched the decrease in the rate of ammonium assimilation. However, in the presence of 10 ,M ammonium chloride, MSX completely inhibited ammonium assimilation but had no effect on the rate of uptake. [source] Extraction of mobile element fractions in forest soils using ammonium nitrate and ammonium chlorideJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2008Alexander Schöning Abstract The extraction of earth alkaline and alkali metals (Ca, Mg, K, Na), heavy metals (Mn, Fe, Cu, Zn, Cd, Pb) and Al by 1 M NH4NO3 and 0.5 M NH4Cl was compared for soil samples (texture: silt loam, clay loam) with a wide range of pH(CaCl2) and organic carbon (OC) from a forest area in W Germany. For each of these elements, close and highly significant correlations could be observed between the results from both methods in organic and mineral soil horizons. The contents of the base cations were almost convertible one-to-one. However, for all heavy metals NH4Cl extracted clearly larger amounts, which was mainly due to their tendency to form soluble chloro complexes with chloride ions from the NH4Cl solution. This tendency is very distinct in the case of Cd, Pb, and Fe, but also influences the results of Mn and Zn. In the case of Cd and Mn, and to a lower degree also in the case of Pb, Fe, and Zn, the effect of the chloro complexes shows a significant pH dependency. Especially for Cd, but also for Pb, Fe, Mn, Zn, the agreement between both methods increased, when pH(CaCl2) values and/or contents of OC were taken into account. In comparison to NH4Cl, NH4NO3 proved to be chemically less reactive and, thus, more suitable for the extraction of comparable fractions of mobile heavy metals. Since both methods lead to similar and closely correlated results with regard to base cations and Al, the use of NH4NO3 is also recommended for the extraction of mobile/exchangeable alkali, earth alkaline, and Al ions in soils and for the estimation of their contribution to the effective cation-exchange capacity (CEC). Consequently, we suggest to determine the mobile/exchangeable fraction of all elements using the NH4NO3 method. However, the applicability of the NH4NO3 method to other soils still needs to be investigated. [source] Syntheses of cyclic polycarbonates by the direct phosgenation of bisphenol M,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2005Hans R. Kricheldorf Abstract Bisphenol M was subjected to interfacial polycondensations in an NaOH/CH2Cl2 system with triethylamine as a catalyst. Regardless of the catalyst concentration, similar molecular weights were obtained, and matrix-assisted laser desorption/ionization time-of-flight mass spectra exclusively displayed mass peaks of cycles (detectable up to 15,000 Da). With triethyl benzyl ammonium chloride as a catalyst, linear chains became the main products, but the contents of the cycles and the molecular weights strongly increased with higher catalyst/bisphenol ratios. When the pseudo-high-dilution method was applied, both diphosgene and triphosgene yielded cyclic polycarbonates of low or moderate molecular weights. Size exclusion chromatography measurements, evaluated with the triple-detection method, yielded bimodal mass distribution curves with polydispersities of 5,12. Furthermore, a Mark,Houwink equation was elaborated, and it indicated that the hydrodynamic volume of poly(bisphenol M carbonate) was quite similar to that of poly(bisphenol A carbonate)s with similar concentrations of cyclic species. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1248,1254, 2005 [source] Effects of Ammonium Chloride on the Rheological Properties and Sedimentation Behavior of Aqueous Silica SuspensionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000J. Jiyou Guo The influence of ammonium chloride (NH4Cl) on the rheological properties and sedimentation behavior of aqueous silica (SiO2) suspensions of varying solids volume fraction (,s) was studied. SiO2 suspensions with low NH4Cl concentration (,0.05M, pH 5.2) exhibited Newtonian behavior and a constant settling velocity (U). The volume fraction dependence was well described by the Richardson,Zaki form, U=U0(1 ,,s)n, where n= 4.63 and U0= 1.0419 × 10,5 cm/s. At higher NH4Cl concentrations (0.07,2.0M, pH 5.2), suspensions exhibited shear thinning and more complicated sedimentation behavior due to their aggregated nature. For all suspensions studied, however, the apparent suspension viscosity, characteristic cluster size, and initial settling velocity were greatest at ,0.5M NH4Cl and exhibited a similar dependence on salt concentration. Above 0.5M NH4Cl, considerable restabilization was observed. This behavior cannot be explained by traditional DLVO theory. [source] Chemo-Enzymatic Synthesis of Raffinose-Branched Polyelectrolytes and Self-Assembly Application in Microcapsules,MACROMOLECULAR BIOSCIENCE, Issue 1 2006Qi Wu Abstract Summary: A novel biocompatible polyelectrolyte poly(vinyl raffinose- co -acrylic acid) (PRCA) containing a raffinose branch was prepared via redox polymerization using Fe2+/K2S2O8/H2O2 starting from enzymatically-synthesized monomer: 1- O -vinyldecanedioyl raffinose. Copolymers with different monomer feed ratios were prepared and characterized with IR, NMR, and GPC. PRCA can be alternated with polycation to form microcapsules on a crystals template by electrostatic layer-by-layer technique. The multilayers of PRCA/poly(methacryloyloxyethyl dimethylbenzyl ammonium chloride) (PMBA) on quartz slides and PRCA/poly(dimethyldiallyl ammonium chloride) (PDDA) on acyclovir crystals template were fabricated and characterized with UV-Vis spectra, the microelectrophoretic measurement, and TEM. Hollow capsules can be formed after the removal of acyclovir crystals template in a buffer solution. The nano-capsule-carrying galactose residue is a potential targeting drug-controlled delivery systems. Synthesis of PRCA and TEM image of a hollow (PRCA/PDDA)10 capsule. [source] Prophylaxis effect of Trigonella foenum graecum L. seeds on renal stone formation in ratsPHYTOTHERAPY RESEARCH, Issue 10 2007Amine Laroubi Abstract Despite considerable progress in medical therapy, there is no satisfactory drug to treat kidney stones. Therefore, the current study aimed to look for an alternative by using Trigonella foenum graecum (Tfg) on nephrolithiasic rats as a preventive agent against the development of kidney stones, which is commonly used in Morocco as a phytotherapeutic agent. The inhibitory effect of the aqueous extract of Tfg seeds was examined on the formation of calcium oxalate renal stones induced by ethylene glycol (EG) with ammonium chloride. At the end of the experiment all kidneys were removed and examined microscopically for possible crystal/stone locations and the total calcium amount in the renal tissue was evaluated. The blood was recovered to determine the levels of calcium, phosphorus, creatinine and urea. The results showed that the amount of calcification in the kidneys and the total calcium amount of the renal tissue in rats treated with Tfg were significantly reduced compared with the untreated group. Consequently, Tfg may be a useful agent in the treatment of patients with calcic urolithiasis. Copyright © 2007 John Wiley & Sons, Ltd. [source] Combination Nonviral Interleukin-2 Gene Immunotherapy For Head and Neck Cancer: From Bench Top to BedsideTHE LARYNGOSCOPE, Issue 3 2005Bert W. O'Malley Jr MD Abstract Objective/Hypothesis: Intralesional delivery of cytokine genes has emerged as a promising therapeutic strategy for the treatment of cancer. In addition to the therapeutic effect of the delivered cytokine gene, the components of the gene delivery system also have been shown to induce beneficial immune responses. On the basis of these principles, we hypothesized that a molecular therapy could be developed that would provide synergistic antitumor activity by way of intralesional expression of interleukin (IL)-2 from a recombinant plasmid combined with induction of endogenous interferon (IFN)-, and IL-12 cytokines by immunostimulatory DNA. Our objective in these studies was to create and optimize a novel formulation of cationic lipid and DNA that generates local production of IL-2 protein within a targeted tumor environment with concomitant induction of the antitumor cytokines IFN-, and IL-12. Study Design: Prospective laboratory drug development plan that would produce human clinical trials. Materials and Methods: Engineered bacterial plasmids containing a cytomegalovirus promoter (CMV)-IL-2 expression cassette were specifically formulated with cationic lipids and optimized for antitumor effect in a floor of mouth murine tumor model. The treated tumors were assayed for local expression of IL-2 and concurrent expression of secondary cytokines IFN-, and IL-12. Established tumors in C3H/HeJ mice were treated with various IL-2 gene formulations, and clinical and immunologic responses were evaluated. Immunologic studies were performed and included cytolytic T-cell assays and cytokine expression profiles. For human clinical trials, a phase I 10 patient formulated IL-2 gene therapy study was completed. Subsequently, two large scale, phase II multi-institutional and multi-international studies were initiated comparing non-viral IL-2 gene therapy to palliative methotrexate chemotherapy or in combination with cisplatin. Results: In the preclinical stage, maximum tumor inhibition in animal models was obtained using IL-2 plasmid formulated with 1,2-dioleyloxypropyl-3-trimethyl ammonium chloride (DOTMA):cholesterol (1:1 mol:mol) at a plasmid:lipid charge ratio of 1:0.5 (,/+). Cationic lipid formulated IL-2 plasmid significantly inhibited tumor growth compared with formulated control plasmid (P < .01) or vehicle (lactose; P < .01). Consistent with previously reported studies of the immunostimulatory activity of DNA of bacterial origin, treatment of tumors with control plasmid in cationic lipid formulation induced production of endogenous IFN-, and IL-12 but not IL-2. Treatment of tumors with formulated IL-2 plasmid produced IL-2 protein levels that were 5-fold over background and increased IFN-, by 32-fold (P < .001) and IL-12 by 5.5-fold (P < .001) compared with control plasmid formulations. The phase I human trial demonstrated dose escalation safety, which was its primary objective, and there was one anecdotal reduction in tumor size. The phase II studies have been initiated and focus on either comparing the novel nonviral IL-2 gene immunotherapy formulation alone to methotrexate or comparing IL-2 gene therapy in combination with cisplatin in recurrent or unresectable patients with head and neck squamous cell carcinoma. Conclusions: The preclinical data provided proof of principle for matching a delivered IL-2 transgene with an immunostimulatory nonviral formulation to enhance intralesional production of therapeutic cytokines for the maximization of antitumor response. Human clinical trials have demonstrated this novel therapy to be safe in the human clinical setting. Phase II trials have been initiated to assess efficacy and feasibility as a single or combination therapy for head and neck cancer. [source] Initial influence of fertilizer nitrogen types on water qualityAQUACULTURE RESEARCH, Issue 7 2010Charles C Mischke Abstract Using different sources of nitrogen as fertilizers in nursery ponds may affect water quality and plankton responses. We evaluated water quality variables and plankton population responses when using different nitrogen sources for catfish nursery pond fertilization. We compared calcium nitrate (12% N), sodium nitrite (20% N), ammonium chloride (26% N), ammonium nitrate (34% N) and urea (45% N) in 190-L microcosms at equimolar nitrogen application rates. Sodium nitrite-fertilized microcosms had higher nitrite and nitrate levels during the first week; no other differences in the water quality were detected among fertilizer types (P>0.05). No differences in green algae, diatoms or cyanobacteria were detected among treatments; desirable zooplankton for catfish culture was increased in urea-fertilized microcosms. Based on these results, any form of nitrogen used for pond fertilization should perform similarly without causing substantial water quality deterioration. Ammonium nitrate and urea contain a higher percentage of nitrogen, requiring less volume to achieve dosing levels. If both urea and ammonium nitrate are available, we recommend using the one with the least cost per unit of nitrogen. If both types of fertilizer have an equal cost per unit of nitrogen, we recommend using urea because of the potential advantage of increasing desirable zooplankton concentrations. [source] Polymorphism of microcrystalline urate oxidase from Aspergillus flavusACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2010Ines Collings Different polymorphs of rasburicase, a recombinant urate oxidase enzyme (Uox) from Aspergillus flavus, were obtained as a series of polycrystalline precipitates. Different crystallization protocols were followed in which the salt type, pH and polyethylene glycol 8000 (PEG 8000) concentration were varied. The related crystalline phases were characterized by means of high-resolution synchrotron X-ray powder diffraction. In all cases, Uox complexed with the inhibitor 8-azaxanthine (AZA) was not altered from its robust orthorhombic I222 phase by variation of any of the factors listed above. However, in the absence of AZA during crystallization ligand-free Uox was significantly affected by the type of salt, resulting in different crystal forms for the four salts tested: sodium chloride, potassium chloride, ammonium chloride and ammonium sulfate. Remarkable alterations of some of these phases were observed upon gradual increase of the exposure time of the sample to the synchrotron beam in addition to variation of the PEG 8000 concentration. When Uox was crystallized in Tris buffer or pure water in the absence of salt, a distinct polymorph of orthorhombic symmetry (P21212) was obtained that was associated with significantly altered lattice dimensions in comparison to a previously reported isosymmetrical structure. The latter form of Uox exhibits enhanced stability to variation of pH and PEG 8000 concentration accompanied by minor modifications of the unit-cell dimensions in the ranges under study. Accurate lattice parameters were extracted for all crystalline phases. This study reveals the rich phase diagram of Uox, a protein of high pharmaceutical importance, which is associated with an enhanced degree of polymorphism. The outcome of our analysis verifies previously reported results as well as demonstrating polymorphs that have altered unit-cell dimensions with respect to known structural models. [source] Site, vine state and responsiveness to the application of growth regulator fruitsetting agentsAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2009J.A. CONSIDINE Abstract Background and Aims:, This study was initiated to investigate local problems in obtaining consistent fruit-setting responses to a recommended treatment combination of gibberellic acid (GA3) and (2-chloroethyl)-trimethyl ammonium chloride (CCC), with vineyard managers returning to more traditional methods of either cincturing or applying 4-chlorophenoxy acetic acid (4-CPA). Methods and Results:, Five vineyard study sites located in the Chittering,Bindoon region of Western Australia were characterised by multivariate analysis using measures of vegetative and reproductive biomass. Two experiments were carried out in the vineyard to compare responses to combinations of GA3 and CCC. 4-CPA was used as an industry control. Bunch number was used as a novel covariate to adjust responses to individual vine and site factors. Berry volume increased in all vines and sites treated with GA3, irrespective of timing, but dry matter yield increased only in the youngest vineyards. The only site to show a significant response to CCC application was that with the highest vegetative biomass. Conclusions:, We conclude that site and management factors rather than growth regulator type, concentration or timing determined yield responsiveness (sugar production). Significance of the Study:, This study demonstrates a strong physiological and environmental effect on response to growth regulator application, reinforcing the importance of developing site-specific management practices. It shows how multivariate techniques may be used to characterise and compare vineyards, and also, how analysis of covariance using a new parameter, bunch number, may be used to enhance statistical of analysis of field experiments. [source] Grapevine productivity and yield components: A case study using field vines of Zante currantAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2 2004JOHN A. CONSIDINE Abstract Yield components of the parthenocarpic cultivar Zante were analysed for five vineyards of diverse age and management. The data was obtained as part of an experiment to improve fruit set and yield by applying combinations of gibberellin and 2-chloroethyltrimethyl ammonium chloride or 4-chlorophenoxyacetic acid. Four of the vineyards were located in the Brockman valley north of Perth, Western Australia, two of these were irrigated, one was rain fed and one received supplementary flood irrigation. The fifth lay in an adjacent area of coastal sand plain, at the foot of the Darling scarp, and was irrigated. The vines were aged from 6 to 50 years. Principal component analysis showed that vine age was negatively correlated with vigour (pruning weight) and with berry number per bunch. Vine age however was not strongly related to either yield or yield components (bunch number and berry volume). Sugar concentration was negatively correlated with all yield components but imprecisely modelled based on any combination of the measured variables. Berry number per vine appeared to be the underlying factor determining ,sink' strength though this was inextricably confounded with bunch number per vine. Interpretation of the data leads to the conclusion that increased berry volume is an inefficient means of increasing dried yield. This conclusion argues for caution in the application of plant growth regulators that act primarily to increase berry volume. Yield of sugar per vine was accurately modelled based on second order relationships with bunch number per vine, berry number per bunch, berry volume and pruning weight. Vine age also showed a second order relationship to yield although the range was relatively small. The observations are considered in terms of developing strategies for maximising dried yield and devising mathematical models to account for photoassimilate (dry matter) partitioning in Vitis. [source] Crystallization and preliminary crystallographic analysis of nosiheptide-resistance methyltransferase from Streptomyces actuosus in complex with SAMACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2010Huirong Yang Nosiheptide-resistance methyltransferase (NSR) methylates 23S rRNA at the nucleotide adenosine 1067 in Escherichia coli and thus contributes to resistance against nosiheptide, a sulfur-containing peptide antibiotic. Here, the expression, purification and crystallization of NSR from Streptomyces actuosus are reported. Diffracting crystals were grown by the hanging-drop vapour-diffusion method in reservoir solution consisting of 0.35,M ammonium chloride, 24%(w/v) PEG 3350, 0.1,M MES pH 5.7 at 293,K. Native data have been collected from the apo enzyme and a SAM complex, as well as apo SeMet SAD data. The diffraction patterns of the apo form of NSR, of NSR complexed with SAM and of SeMet-labelled NSR crystals extended to 1.90, 1.95 and 2.25,Å resolution, respectively, using synchrotron radiation. All crystals belonged to space group P21, with approximate unit-cell parameters a = 64.6, b = 69.6, c = 64.9,Å, , = 117.8°. [source] | ||||||||||||||||||||||||||||||||||