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Studies on thermal characterization of lignin

Substituted phenol formaldehyde resin as wood adhesives

Journal of Thermal Analysis and Calorimetry
Authors: M. Khan and S. Ashraf

Abstract  

Thermal properties of control phenol formaldehyde (cpf) adhesive and lignin substituted phenol formaldehyde (lpf) adhesives have been investigated in detail. The effect of varying lignin mass percent of phenol and source of lignin like bagasse, eucalyptus bark, coconut coirpith and coffee bean shell on the thermal stability have been studied using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). 50 mass% of lignin loading in cpf adhesive shows better bond strength, whereas lignin incorporation up to 25 mass% yields a resin of thermal stability comparable to cpf. Loading of lignin in cpf delays the first thermal transition event. The mass loss in this event was found to increase with increasing lignin content. Lignin source has significant effect on the thermal stability of lpf resins. Rate of curing is enhanced by incorporation of lignin into cpf.

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Genomics provided biomedical scientists an inventory of all genes and sequences present in a living being. This provides an unique opportunity to the scientists to predict and study biological functions of these genes. The changes in the gene expression regulated by genomic sequences therefore reflect changes in the molecular processes working in a cell or tissue in response to external factors including exposure to toxic compounds and pathogens. Microarray offers a biotechnological revolution with the help of DNA chemistry, silicon chip technology and optics to be used to monitor gene expression for thousands of genes in one single experiment. Briefly, 20,000 to 100,000 unique DNA molecules get applied by a robot to the surface of silicon wafers (approximately the size of a microscope slide). Using a single microarray experiment, the expression level of 20,000 to 100,000 genes will be examined in one single experiment.  Genomics and microarray have a significant role and impact on the design and development of modern detection and diagnostic tools in several different ways. Microarray tools are now used on regular basis for monitoring gene expression of large number of genes and also frequently applied to DNA sequence analysis, immunology, genotyping, and molecular diagnosing. For diagnostics, these tools can be used to distinguish and differentiate between different DNA fragments that differ by as little as a single nucleotide polymorphism (SNP). These microarrays can be divided based on the gene density spots that will be high density (≯10,000 spots) per slide, medium (<1000≯100) and low density (<100). High-density arrays have proven to be very useful in disease diagnosis especially in diagnosis and classification of different types of cancers. These microarray tools hold tremendous potential for pathogen detection, which will be comprised, of unique sets of genes (also referred to as “signatures”) able to unambiguously identify the species and strain of pathogens of interest.

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Abstract  

A rapid method for the solvent extraction of Hg(II) into chloroform has been developed, employing thioethylacetoacetate (HETAcAc) as a extracting agent. The extraction of Hg(II) was better than 99% over the pH range 0.3 to 7.3. The extraction equilibrium was reached within 2 min. The effect of various parameters such as anions and cations, solvent effect, etc., on the extraction coefficient has been studied. The stoichiometry metal: reagent was determined by the method of substoichiometric extraction and was found to be 14.

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Abstract  

A method has been developed for rapid and selective extraction of Au/III/ with ethyl thioacetoacetate /HETAcAc/ into chloroform at pH 4. The effect of various parameters on the extraction coefficient values have been studied. The stoichiometry of the extracted species 13 was obtained by the slope ratio method and by the method of substoichiometric extraction.

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Abstract  

The method described here involves the irradiation of biological samples and a g quantity of standard with thermal neutrons at the self-serve position in the CIRUS reactor, followed by dissolution of the sample and standard in the presence of milligram amounts of carrier. Both the sample and the standard are subjected to substoichiometric extraction under controlled experimental conditions with ethyl thioacetoacetate into chloroform. An aliquot of the organic phase is counted on a -spectrometer. The concentration of Hg in various biological samples and the accuracy, precision, and sensitivity of the method are discussed.

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Abstract  

Radiosynthesis of 99mTc-sitafloxacin (99mTc-STF) complex and its efficacy as a potential infection imaging agent was evaluated. Effect of sitafloxacin (STF) concentration, sodium pertechnetate (Na99mTcO4), stannous chloride dihydrate (SnCl2·2H2O), and pH on the % radiochemical purity yield (RCP) of 99mTc-STF complex was studied. A stable 99mTc-STF complex up to 120 min with maximum %RCP yield was observed by mixing 2 mg of STF with 3 mCi of Na99mTcO4 and 150 μL of SnCl2·2H2O (1 μg/μL in 0.01 N HCl) at a pH 5.5. Artificially infected rats with Staphylococcus aureus were used for studying the biodistribution behavior of the 99mTc-STF complex. After 30 min of the intravenous (I.V.) administration of the 99mTc-STF complex, 7.50 ± 0.10% was absorbed in the infected thigh of the rats and the uptake gradually increased to 18.50 ± 0.20% within 90 min. Rabbits with artificially induced infection were used for evaluating the scintigraphic accuracy. Higher uptake in the infected thigh was observed after 2 h of I.V. administration of the 99mTc-STF complex. Target to non-target organ ratio of the % absorbed dose incase of infected/normal muscle was 6.82 ± 0.40, 17.11 ± 0.60, and 23.13 ± 1.00% at 30, 60 and 90 min of administration. Stable and higher %RCP, higher uptake in the infected thigh, and spectral studies, recommend the 99mTc-STF for routine infection imaging.

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Summary

Titan yellow has been adsorbed on a strongly basic anion-exchange resin. The effects of concentration, pH, time, and temperature on adsorption of the dye by the resin have been studied. The effects of surfactants on the distribution coefficients of metal ions were also studied. On the basis of distribution coefficients several binary separations of analytical importance (Zn(II) from Hg(II), Zn(II) from Pb(II), Cu(II) from Pb(II), Cd(II) from Pb(II), and Cu(II) from Hg(II) have been achieved on a column containing the Titan yellow-modified resin. Hg(II) and Pb(II) were selectively analysed in synthetic mixtures.

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Abstract  

A sensitive spectrophotometric method has been developed for the determination of microamounts of thorium using 0.05% thorin in a 3M perchloric acid solution as a chromogenic reagent and measuring the absorbance at 544 nm. The complex of thorium thus formed, is stable for more than two months with a constant absorbance of ±0.55%. Beer's law is obeyed from 0 to 25 g g–1 of thorium in a solution with a molar absorptivity (544 nm) = 1.69×104 M–1 cm–1 at 26±1 °C. Among the anions tested, only phosphate, acetate and cyanide at >200-fold excess of thorium interfere in the determination, whereas cations like Zn(II), Al(III), Na(I), Mg(II), and Ca(II) do not effect the absorbance. Thorium can be determined in the presence of oxalate, nitrate, tartrate, sulfate, thiosulfate, citrate, and ascorbate. The accuracy of the method has been checked by measuring the known concentration of thorium in the range of 100 g-5 mg g–1 and found to be in the range of 7.7–0.9%. The method has been applied successfully to determine thorium at g g–1 level in local ore samples with a precision of ±0.3%. The sensitivity of the method on Sandell's scale is 0.082±0.002 g g–1 cm–1.

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Summary

An isocratic RP-HPLC-UV method for analysis of sumatriptan succinate in pharmaceutical dosage forms has been developed and validated. Best separation was achieved on a Thermo Hypersil C4 column (250 mm × 4.6 mm, 5 µm) using a mobile phase of 20 mM potassium dihydrogen phosphate adjusted to pH 4.0 with orthophosphoric acid and acetonitrile (65:35, v/v) at a flow rate of 1.0 mL min−1. UV detection was performed at 227 nm. The method was validated for specificity, linearity, precision, accuracy, limit of quantification, limit of detection, robustness, and solution stability. The calibration plot was linear over the concentration range 25–600 ng mL−1 (r 2 = 0.9998) and the limits of detection and quantification were 10 and 25 ng mL−1, respectively. Intra-day and inter-day precision and accuracy were between 1.25 and 2.95% and between −1.15 and 2.47%, respectively. The method was successfully used for analysis of sumatriptan succinate, in the presence of excipients, in orally disintegrating tablets prepared in our laboratory and in commercially available tablets (Imigran) and nasal spray (Suminat).

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