scholarly journals THE ANTIMYCOBACTERIAL ACTIVITY OF VARIOUS AMINES RELATED TO SPERMINE IN CHEMICAL STRUCTURE

1953 ◽  
Vol 97 (3) ◽  
pp. 323-325 ◽  
Author(s):  
James G. Hirsch
Keyword(s):  
Liquid Medium ◽  
Chemical Structure ◽  
Antimycobacterial Activity ◽  
Final Concentration ◽  
Chemical Degradation ◽  
Amino Compounds

A final concentration of 3 x 10–5 M spermine or spermidine inhibited the growth of mammalian tubercle bacilli in a modified Dubos liquid medium. Various related amino compounds, including isolated portions of the spermine molecule and the products of its chemical degradation, did not manifest similar antimycobacterial activity.

scholarly journals Demystifying and Unravelling the Factual Molecular Structure of the Biopolymer Sporopollenin

2019 ◽  
Author(s):  
Abanoub Mikhael ◽  
Kristina Jurcic ◽  
Celine Schneider ◽  
David carr ◽  
Gregory L. Fisher ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Nuclear Magnetic Resonance ◽  
Chemical Structure ◽  
Pollen Grains ◽  
Outer Wall ◽  
Mass Spectrometric ◽  
Chemical Degradation ◽  
Ionization Mass ◽  
Soft Ionization ◽  
Biochemical Pathways

<p></p><p>Sporopollenin is a natural, highly cross-linked biopolymer composed of carbon, hydrogen, and oxygen, which forms the outer wall of pollen grains. Sporopollenin is resilient to chemical degradation.<sup> </sup>Because of this stability, its exact chemical structure and the biochemical pathways involved in its biosynthesis remains a mystery and unresolved.<sup> </sup></p> <p>We have identified and characterized the molecular structure of the clean, intact sporopollenin using soft ionization mass spectrometric and nuclear magnetic resonance techniques. These analyses showed that sporopollenin contained a poly(hydroxyacid) dendrimer-like network, which accounted for the sporopollenin empirical formula. In addition, the identified hydroxy acid monomers contained a beta diketone moiety, which most probably accounts for the known antioxidant activity of sporopollenin. Moreover, our elucidation studies allowed us to identify a unique circular polyhydroxylated tetraketide polymer. This polymer acted as the rigid backbone on which the poly(hydroxyacid) network can be built, forming the scaffold of the spherical sporopollenin exine.</p><br><p></p>

scholarly journals Mechano-chemical ageing of PES/PVP ultrafiltration membranes used in drinking water production

2013 ◽  
Vol 13 (2) ◽  
pp. 541-551 ◽  
Author(s):  
B. Pellegrin ◽  
E. Gaudichet-Maurin ◽  
C. Causserand
Keyword(s):  
Water Contamination ◽  
Chemical Structure ◽  
Multiple Scales ◽  
Membrane Damage ◽  
Chemical Degradation ◽  
Water Production ◽  
Drinking Water Production ◽  
The Impact ◽  
Chemical Ageing

In water treatment by microfiltration and ultrafiltration, a major concern is the integrity loss or failure of membrane induced by onsite operations, potentially leading to permeate water contamination. This study aims to provide a better understanding of the phenomena responsible for membrane damage by analyzing its causes and effects. The role of sodium hypochlorite exposure conditions and the impact of mechanical stress on membrane characteristics were investigated. Monitoring of hydraulic response, mechanical properties and the evolution of the chemical structure showed, on multiple scales, strong indications of membrane chemical degradation, involving radical mechanisms, accelerated by tensile stress application.

scholarly journals Degradation of Preservatives with the Formation of Off-Odor Volatile Compounds—The Case of Strawberry-Flavored Bottled Water

Beverages ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 67
Author(s):  
Barbara Sokołowska ◽  
Marzena Połaska ◽  
Agnieszka Dekowska ◽  
Łukasz Woźniak ◽  
Marek Roszko
Keyword(s):  
Liquid Medium ◽  
Volatile Compounds ◽  
Sodium Benzoate ◽  
Sorbic Acid ◽  
Final Concentration ◽  
Bottled Water ◽  
Potassium Sorbate ◽  
Numerous Species ◽  
Flavored Water ◽  
Odor Compounds

Foods preserved with sorbic acid or its salts can undergo spoilage with the formation of chemicals characterized by odors of plastic, hydrocarbons, or kerosene. 1,3-pentadiene, which is formed through the decarboxylation of sorbic acid or its salts, is one such compound. Numerous species of molds and yeasts have been reported as capable of degrading sorbic acid. This work is aimed to identify the off-odor compounds in samples of strawberry-flavored water preserved with potassium sorbate and sodium benzoate. In addition, the mold isolated from this drink was evaluated for the ability to form undesirable compounds, and the results revealed the presence of 1,4-pentadiene and benzaldehyde in the tested samples. The mold isolated from the samples was identified as Penicillium corylophilum. During its 5-day incubation at 25 °C in a liquid medium, potassium sorbate added at a final concentration of 200 and 400 mg/L was completely assimilated by the growing mycelium and converted into 1,4-pentadiene. The concentration of the latter was determined as 46.5 and 92.6 mg/L, respectively. The decrease in the concentration of sodium benzoate exceeded 53% in the broth spiked at 200 mg/L and 23% at 400 mg/L, resulting in the formation of benzaldehyde.

The Chemical Degradation of a Humic Acid

1973 ◽  
Vol 51 (10) ◽  
pp. 1554-1566 ◽  
Author(s):  
Morris Schnitzer ◽  
Maria Ines Ortiz de Serra
Keyword(s):  
Humic Acid ◽  
Chemical Structure ◽  
Degradation Products ◽  
Cupric Oxide ◽  
Chemical Degradation ◽  
Chromatographic Retention ◽  
Sequential Reaction ◽  
The Core ◽  
Preparative Gas Chromatography ◽  
Complex Core

A humic acid (HA) extracted from the A1 horizon of a Brunizem soil was degraded in the unmethylated and methylated form by sequential reaction with oxidants of increasing strength. The HA was first oxidized with alkaline cupric oxide; the products were then further degraded by oxidation with first alkaline KMnO4 and then with H2O2 in alkaline solution. Unmethylated HA was also degraded by Na-amalgam reduction. The degradation products were extracted into organic solvents, methylated, and separated by preparative gas chromatography into relatively pure components which were analyzed by mass spectrometry and micro-i.r. spectrophotometry. A matching of the mass and i.r. spectra and gas chromatographic retention times of the isolated components with those of authentic specimens led to their identification.The experimental data show that the HA contains a relatively easily degradable portion, which comprises guaiacyl and syringyl units and which may be lignin-derived (about 10% of the total weight). This material is degraded by CuO–NaOH oxidation and Na-amalgam reduction. The bulk of the HA structure, however, consists of a more condensed, chemically complex "core", which degrades on more drastic oxidation into complex phenolic and benzenepolycarboxylic acids. It is likely that the "core" originates in part from condensed lignin and in part from products of microbial synthesis. Of the methods investigated, the CuO–NaOH and the KMnO4 oxidation of methylated HA appear most promising for providing information on the chemical structure of the HA.

Investigation of Structure and Properties of PET Multifilament Irradiated with UV in Different Atmosphere

2012 ◽  
Vol 499 ◽  
pp. 40-43 ◽  
Author(s):  
Yu Wen Liu ◽  
Hai Yan Wang ◽  
Jiao Yan Li ◽  
Bin Sun
Keyword(s):  
Tensile Strength ◽  
Chemical Structure ◽  
Irradiation Time ◽  
Degradation Process ◽  
Skin Layer ◽  
Chemical Degradation ◽  
Accelerated Ageing ◽  
Thermal Stabilities ◽  
Pet Fibers ◽  
The Difference

Changes of mechanical properties and chemical structure of polyester (PET) fibers are studied through UV simulated accelerated ageing experiments with N2, air and O3 as the atmosphere. The structure, thermal stabilities and tensile strength are obtained by FTIR, DTA-TG, XRD, SEM and micro-mechanics test. The difference of degradation process in various atmospheres is discussed in this paper. The results show that the fracture tensile strength of PET multifilament decreases with the increase of UV irradiation time. And oxidation and then decarbonylation take place on the surface. Besides, Melting temperature (Tm), the temperature of quality loss by 10% (T10) and the crystallization also decrease. However, in O3 atmosphere the oxidation develops very quickly and fully, therefore, the carbonyl on the surface is eliminated and decreases significantly, and the tensile strength decreases much faster than those in N2 and air. The skin layer of irradiated fibers appears serious damaged. The mechanism of chemical degradation for samples irradiated in N2 environments is similar to those irradiated in air.

scholarly journals Demystifying and Unravelling the Factual Molecular Structure of the Biopolymer Sporopollenin

2019 ◽  
Author(s):  
Abanoub Mikhael ◽  
Kristina Jurcic ◽  
Celine Schneider ◽  
David carr ◽  
Gregory L. Fisher ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Nuclear Magnetic Resonance ◽  
Chemical Structure ◽  
Pollen Grains ◽  
Outer Wall ◽  
Mass Spectrometric ◽  
Chemical Degradation ◽  
Ionization Mass ◽  
Soft Ionization ◽  
Biochemical Pathways

<p></p><p>Sporopollenin is a natural, highly cross-linked biopolymer composed of carbon, hydrogen, and oxygen, which forms the outer wall of pollen grains. Sporopollenin is resilient to chemical degradation.<sup> </sup>Because of this stability, its exact chemical structure and the biochemical pathways involved in its biosynthesis remains a mystery and unresolved.<sup> </sup></p> <p>We have identified and characterized the molecular structure of the clean, intact sporopollenin using soft ionization mass spectrometric and nuclear magnetic resonance techniques. These analyses showed that sporopollenin contained a poly(hydroxyacid) dendrimer-like network, which accounted for the sporopollenin empirical formula. In addition, the identified hydroxy acid monomers contained a beta diketone moiety, which most probably accounts for the known antioxidant activity of sporopollenin. Moreover, our elucidation studies allowed us to identify a unique circular polyhydroxylated tetraketide polymer. This polymer acted as the rigid backbone on which the poly(hydroxyacid) network can be built, forming the scaffold of the spherical sporopollenin exine.</p><br><p></p>

scholarly journals Study of elution characteristics of anti-tuberculosis drugs mixed with bone cement

2021 ◽  
Vol 99 (4) ◽  
pp. 30-35
Author(s):  
E. O. Peretsmanas ◽  
A. A. Аrtyukhov ◽  
M. I. Shtilman ◽  
I. V. Esin ◽  
V. S. Zubikov ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Drug Release ◽  
Liquid Medium ◽  
Bone Cement ◽  
Chemical Structure ◽  
Drug Reservoir ◽  
Pure Substances ◽  
Static Conditions ◽  
Kinetics Of

The objective: to assess the elution characteristics of anti-tuberculosis drugs (isoniazid, cycloserine, rifampicin, amikacin, kanamycin, ethambutol) placed into bone cement samples and put in a liquid medium to determine the possibility of using such systems as a drug reservoir.Subjects and methods. For in vitro studies, pure substances of the drugs were used. The spectrophotometry was used to study the elution kinetics of the drugs. Absorption spectra of the drugs in the visible and ultraviolet regions were analyzed to reveal the absorption maxima, and the resistance of the chemical structure of the drugs to heating was assessed. Further, the changes of drug release from hardened bone cement samples under static conditions were studied.Results. It has been found that studied drugs demonstrated satisfactory parameters of thermal stability and elution which makes it possible to use them in a mixture with bone cement.

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