Preparation and Characterization of Phosphorylated Sesbania Galactomannan Gum Derivatives and Their Applications in Textile Printing

2012 ◽  
Vol 16 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Abd El-Thalouth I. ◽  
Rekaby M. ◽  
Abdel-Rahman A.H. ◽  
El-khabery Sh. A.
Keyword(s):  
Reaction Time ◽  
Phosphate Ester ◽  
Acid Dyes ◽  
Thickening Agent ◽  
Textile Printing ◽  
Wool Fabrics ◽  
Sesbania Gum ◽  
Constant Rate ◽  
The Stability ◽  
Thickening Agents

Galactomannan gum isolated from the seeds of sesbania is subjected to chemical modification via phosphorylation. This is conducted via heating moistened blends of the gum with a mixture of orthophosphate salt. Three different phosphate ester derivatives are prepared by changing the reaction time. The %P increases from 0.07 to 0.12 to 0.61 by increasing the reaction time from 30 to 60 to 90 minutes. Modification of sesbania gum via phosphorylation increases the stability of their pastes to storing. Investigation of the rhelogical properties of these pastes indicate that they are characterised by non-Newtonian pseudoplastic behaviour. As the extent of the reaction increases, i.e. %P, the apparent viscosity of the pastes at a constant rate of shear decreases, while storing does not change the rheological characteristics of the pastes. Utilization of these derivatives as thickening agents in printing wool fabrics by using acid dyes indicate that phosphate derivatives of sesbania seeds could be used as a thickening agent in printing wool fabrics with acid dyes, where the K/S slightly decreases less than the commercial thickening agent named (Meypro gum) while the overall fastness properties are nearly identical.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

Synthesis, Application and Antimicrobial activity of New Acid Dyes based on 3-Amino-2-thioxo-4-thiazolidinone nucleus on Wool and Silk fabrics

2021 ◽  
Vol 18 ◽  
Author(s):  
Fatma A. Mohamed ◽  
Shaban Elkhabiry ◽  
Ismail A. Ismail ◽  
Attia O. Attia
Keyword(s):  
Antimicrobial Activity ◽  
Fastness Properties ◽  
Acid Dyes ◽  
Light Fastness ◽  
Gram Positive ◽  
Gram Negative ◽  
Wool Fabrics ◽  
Infra Red ◽  
Dyed Fabrics ◽  
Silk Fabrics

: The dyes are synthesized by 3-Amino-2-thioxo-4thiazolidinone (N-Amino rhodanine) with glutaraldehyde or Terephthalaldehyde by 2:1 mole to form a and b then coupled with diazonium salts p-Amino benzenesulfonic acid and 4-Amino 3,4 disulfoazobenzeneazobenzene by 2:1 to form new different bis monoazo a1, b1 and diazo a2 and b2 acid dyes. Therefore, the synthesized dyes were applied to both silk and wool fabric materials. We also evaluated the antimicrobial activity for these dyed fabrics against two model gram-negative and gram-positive bacteria. Further, the chemical composition of these dyes is emphasized by elemental analysis Aims: This paper aims to synthesize, apply dye and antimicrobial to four new acid dyes based on derivatives of N-Amino rodanine as a chromophoric group. These dyes are used in dyeing silk and wool with the good lightfastness and are also excellent for washing, rubbing, and sweating fastness. Also, we measure antimicrobial activity for silk and wool fabrics toward Gram-negative, Gram-positive. Background: The search for a synthesis of new acid dyes has antimicrobial for gram-negative and gram-positive. These dyes are mainly used on silk and wool fabrics which have excellent for light fastness, washing, rubbing, and sweating fastness. Objective: The present studies were aimed at synthesis, characterization and antimicrobial toward gram- negative and gram-positive. Methods: The infra-red spectrum was recorded using an Infra-red spectrometer, Perkin Elmer/1650 FT-IR. The 1H-NMR spectra were recorded using a Varian 400MHz spectrometer. The absorbance of the dyes was measured in the ultraviolet-visible region between 300 and 700 nm by a UNICAM UV spectrophotometer. The dye uptake by wool and silk fabrics was measured using a Shimadzu UV-2401PC (UV/V is spectrophotometer at λmax) before and after dyeing. The produced dyes were found to have good antimicrobial activity against a variety of bacteria. Results and Discussion: The compounds a1, b1, a2 &b2 shows good antimicrobial activity toward gram-negative (E. coli), gram-positive (S. aurous). The data showed that exhaustion and the fastness properties of silk and wool dyed fabrics were both very high. Conclusion: This work prepares newly synthesized acid dyes based on 3-Amino-2-thioxo-4thiazolidinone derivatives and uses them for dyeing wool and silk fabrics. Both synthetic dyes have good light fastness and fastness properties. Also, all dyes have a good antimicrobial effect.

Stability of Enterocin AS-48 in Fruit and Vegetable Juices

2005 ◽  
Vol 68 (10) ◽  
pp. 2085-2094 ◽  
Author(s):  
MARIA J. GRANDE ◽  
ROSARIO LUCAS ◽  
EVA VALDIVIA ◽  
HIKMATE ABRIOUEL ◽  
MERCEDES MAQUEDA ◽  
...  
Keyword(s):  
Storage Temperature ◽  
Fruit Juices ◽  
Initial Activity ◽  
Fruit And Vegetable ◽  
Bacteriocin Activity ◽  
Green Beans ◽  
Food Components ◽  
Fruit And Vegetable Juices ◽  
The Stability ◽  
Thickening Agents

Enterocin AS-48 is a candidate bacteriocin for food biopreservation. Before addressing application of AS-48 to vegetable-based foods, the interaction between AS-48 and vegetable food components and the stability of AS-48 were studied. Enterocin AS-48 had variable interactions with fruit and vegetable juices, with complete, partial, or negligible loss of activity. For some juices, loss of activity was ameliorated by increasing the bacteriocin concentration, diluting the juice, or applying a heat pretreatment. In juices obtained from cabbage, cauliflower, lettuce, green beans, celery, and avocado, AS-48 was very stable for the first 24 to 48 h of storage under refrigeration, and decay of activity was markedly influenced by storage temperature. In fresh-made fruit juices (orange, apple, grapefruit, pear, pineapple, and kiwi) and juice mixtures, AS-48 was very stable for at least 15 days at 4°C, and bacteriocin activity was still detectable after 30 days of storage. Gradual and variable loss of activity occurred in juices stored at 15 and 28°C; inactivation was faster at higher temperatures. In commercial fruit juices (orange, apple, peach, and pineapple) stored at 4°C, the bacteriocin was completely stable for up to 120 days, and over 60% of initial activity was still present in juices stored at 15°C for the same period. Commercial fruit juices stored at 28°C for 120 days retained between 31.5% (apple) and 67.71% (peach) of their initial bacteriocin activity. Solutions of AS-48 in sterile distilled water were stable (120 days at 4 to 28°C). Limited loss of activity was observed after mixing AS-48 with some food-grade dyes and thickening agents. Enterocin AS-48 added to lettuce juice incubated at 15°C reduced viable counts of Listeria monocytogenes CECT 4032 and Bacillus cereus LWL1 to below detection limits and markedly reduced viable counts of Staphylococcus aureus CECT 976.

scholarly journals STABILITY STUDY OF AMLODIPINE BESYLATE AND BISOPROLOL FUMARATE IN AQUEOUS SOLUTIONS

2014 ◽  
Vol 5 (2) ◽  
Author(s):  
Irena Kasagić Vujanović ◽  
Dijana Jelić ◽  
Vesna Antunović ◽  
Biljana Jančić Stojanović ◽  
Darko Ivanović
Keyword(s):  
Relevant Information ◽  
Pharmaceutical Product ◽  
Stability Study ◽  
Amlodipine Besylate ◽  
Time Intervals ◽  
Constant Rate ◽  
Different Temperatures ◽  
The Media ◽  
Two Temperatures ◽  
The Stability

Valuable information concerning stability of compounds can be obtained by using different media (water, hydrochloric acid or sodium hydroxide) for dissolution of active pharmaceutical substances. Furthermore, additional knowledge is gained by performing experiments at different temperatures. This research paper deals with the stability of amlodipine besylate and bisoprolol fumarate in different media at different temperatures, whereby certain conclusions are drawn. For stability assessment, chemical kinetics approach was used, and constant rate (k), half-time (t1/2) and activation energy (Ea) were used for prediction of compound stability degree. The stability of amlodipine besylate and bisoprolol fumarate were tested, both separately and in mixture, in water and in 0.01M HCl. All the investigated solutions were treated at two temperatures 25° and 70°C at the following time intervals: 0, 1 h, 24 h, 48 h and 72 h. Hydrophilic Interaction Liquid Chromatography – HILIC method, previously developed and validated, was used. On the basis of obtained results it was concluded that amlodipine-besylate was more stable in water than in acid medium, more stable in mixture rather than individually and more stable at lower temperatures. This was confirmed by the obtained values of monitored parameters: amlodipine besylate Ea = 30.68 kJ mol-1, k (25 °C) = 0.000333 mM h-1, k (70 °C) = 0.00169 mM h-1; amlodipine besylate in mixture Ea = 42,414 kJ mol-1, k (25 °C) = 1.27∙10-4 mM h-1, k (70 °C) = 0.0012 mM h-1. Based on the obtained approximate Ea value for bisoprolol fumarate in acid (59 kJ mol-1) and in water (56 kJ mol-1), bisoprolol fumarate showed excellent stability against the media in which it was studied. On the other hand, the temperature had a significant effect on the stability of bisoprolol fumarate. These results provide the relevant information about the stability of the tested active substances, and may be of importance during the development of an appropriate pharmaceutical product. A bigger influence on the stability of bisoprolol fumarate had a temperature effect.

scholarly journals Activation of Soluble Polysaccharides with 1-Cyano-4-Dimethylaminopyridine Tetrafluoroborate (CDAP) for Use in Protein–Polysaccharide Conjugate Vaccines and Immunological Reagents. III Optimization of CDAP Activation

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 777
Author(s):  
Andrew Lees ◽  
Jackson F. Barr ◽  
Samson Gebretnsae
Keyword(s):  
Reaction Time ◽  
Low Temperature ◽  
Scale Up ◽  
Optimal Time ◽  
Conjugate Vaccines ◽  
Maximal Activation ◽  
Optimum Reaction ◽  
Rapid Reaction ◽  
The Stability ◽  
High Level

CDAP (1-cyano-4-dimethylaminopyridine tetrafluoroborate) is employed in the synthesis of conjugate vaccines as a cyanylating reagent. In the published method, which used pH 9 activation at 20 °C (Vaccine, 14:190, 1996), the rapid reaction made the process difficult to control. Here, we describe optimizing CDAP activation using dextran as a model polysaccharide. CDAP stability and reactivity were determined as a function of time, pH and temperature. While the rate of dextran activation was slower at lower pH and temperature, it was balanced by the increased stability of CDAP, which left more reagent available for reaction. Whereas maximal activation took less than 2.5 min at pH 9 and 20 °C, it took 10–15 min at 0 °C. At pH 7 and 0 °C, the optimal time increased to >3 h to achieve a high level of activation. Many buffers interfered with CDAP activation, but DMAP could be used to preadjust the pH of polysaccharide solutions so that the pH only needed to be maintained. We found that the stability of the activated dextran was relatively independent of pH over the range of pH 1–9, with the level of activation decreased by 40–60% over 2 h. The use of low temperature and a less basic pH, with an optimum reaction time, requires less CDAP, improving activation levels while making the process more reliable and easier to scale up.

scholarly journals Study on the stability of a shear-thinning suspension used in oil well drilling

2018 ◽  
Vol 73 ◽  
pp. 10 ◽  
Author(s):  
Flávia M. Fagundes ◽  
Nara B.C. Santos ◽  
João Jorge R. Damasceno ◽  
Fábio O. Arouca
Keyword(s):  
Gamma Ray ◽  
Drilling Fluid ◽  
Shear Thinning ◽  
Drilling Fluids ◽  
Oil Well ◽  
Drilling Process ◽  
Well Drilling ◽  
Constant Rate ◽  
The Stability ◽  
Solid Liquid

In order to avoid solid-liquid gravitational separation of particles in the drilling fluid and cuttings generated in this process, the oil industry has been developing drilling fluids with shear-thinning and thixotropic characteristics. In case of operational stops in the drilling process, the intense sedimentation of these particles can damage the equipment used and the well. In this context, this study simulated an operational stop to obtain information about stability of solids in a paraffin-based suspension with time-dependent shear-thinning behavior, which has already been used in current drilling processes. A long-term test using gamma-ray attenuation technique identified the separation dynamics of a set of micrometric particles belonging to and incorporated into the drilling fluid during operation. This test verified the typical regions of gravitational sedimentation and, through constant concentration curves, indicated that the sedimentation process did not occur at a constant rate. This study also proposed a constitutive equation for pressure on solids.

scholarly journals Appropriate usage of food thickening agents to prevent non-disintegration of magnesium oxide tablets

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Taisuke Matsuo ◽  
Airi Sato ◽  
Kenzo Kudo ◽  
Yasuyuki Sadzuka ◽  
Takashi Tomita
Keyword(s):  
Elderly Patients ◽  
Magnesium Oxide ◽  
Xanthan Gum ◽  
Moisture Absorption ◽  
Guar Gum ◽  
The Body ◽  
Significant Delay ◽  
Thickening Agent ◽  
Short Time ◽  
Thickening Agents

Abstract Food thickening agents are used to aid the administration of medicine to elderly patients with dysphagia. Magnesium oxide tablets are sometimes administered with food thickening agents. Non-disintegration and disintegration delay of these tablets in the body are problems associated with food thickening agent use. However, the appropriate usage of food thickening agents for administering tablets is not established. Here, the reasons for the non-disintegration of magnesium oxide tablets administered with food thickeners and appropriate usage of food thickeners were examined using a disintegration test of newly opened and moisture-absorbed magnesium oxide tablets. Immersion of magnesium oxide tablets for 10 and 30 min in xanthan and guar gum-based food thickening agents caused disintegration delay and non-disintegration in the first fluid (pH 1.2). However, tablets immersed for 1 min quickly disintegrated. The disintegration of xanthan gum-based food thickening agents was faster than guar gum-based food thickening agents. Moisture absorption by magnesium oxide tablets caused a significant delay in their disintegration in water. The tablets that absorbed moisture disintegrated within 1 min in the first fluid, even when immersed in food thickening agents for a short time. Overall, a short immersion of magnesium oxide tablets in food thickening agents can avoid non-disintegration.

Hopf Bifurcation of a Delayed Predator–Prey Model with Nonconstant Death Rate and Constant-Rate Prey Harvesting

2018 ◽  
Vol 28 (14) ◽  
pp. 1850179 ◽  
Author(s):  
Fengrong Zhang ◽  
Xinhong Zhang ◽  
Yan Li ◽  
Changpin Li
Keyword(s):  
Hopf Bifurcation ◽  
Time Delay ◽  
Differential Equations ◽  
Positive Constant ◽  
Death Rate ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Prey Model ◽  
Constant Rate ◽  
The Stability

This paper is concerned with a delayed predator–prey model with nonconstant death rate and constant-rate prey harvesting. We mainly study the impact of the time delay on the stability of positive constant solution of delayed differential equations and positive constant equilibrium of delayed diffusive differential equations, respectively. By choosing time delay [Formula: see text] as a bifurcation parameter, we show that Hopf bifurcation can occur as the time delay passes some critical values. In addition, the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are determined by using the normal form theory and center manifold theorem. Finally, some numerical simulations are carried out to depict our theoretical results.

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