FTIR study of gamma-irradiated cis-1,4-polyisoprene

2006 ◽  
Vol 60 (5) ◽  
Author(s):  
J. Polovková ◽  
E. Klein ◽  
Z. Cibulková ◽  
V. Lukeš
Keyword(s):  
Chain Scission ◽  
Oxidation Products ◽  
Valuable Insight ◽  
Γ Irradiation ◽  
Γ Radiation ◽  
Small Doses ◽  
Ftir Technique ◽  
Gamma Irradiated ◽  
Higher Doses ◽  
Insight Into

AbstractThe effect of γ-irradiation on the structure and oxidation of cis-1,4-polyisoprene is investigated by ATR-FTIR technique. This method provides the valuable insight into the type of oxidation products produced and the extent and nature of intramolecular cyclization and chain scission reactions. The formation of ketones, alcohols and/or ethers, and hydroperoxides is apparent already at small doses of γ-radiation and it increases with the exposure time significantly. At the highest dose of 309 kGy a decrease in the intensity of C=O stretching mode of ketones (1717 cm−1) was observed while the overall area of the band remained the same as in the case of 188 kGy dose. The shoulders observed at 1740 cm−1 and 1772 cm−1 could be assigned to C=O stretching frequency of esters and five-membered-ring lactones, respectively. Higher doses of γ-radiation also cause the formation of two relatively strong bands in the region of conjugated double bonds. These could origin from the aromatic products or cycloenes with one double bond formed by cyclization and chain scission processes.

Oxidation Behavior of High Strength Chain-Extended Polyethylene Fibers

1988 ◽  
Vol 58 (9) ◽  
pp. 520-526 ◽  
Author(s):  
D. J. Carlsson ◽  
G. Colin ◽  
S. Chmela ◽  
D. M. Wiles
Keyword(s):  
High Strength ◽  
Chain Scission ◽  
Oxidation Products ◽  
Fiber Axis ◽  
Γ Radiation ◽  
Polyethylene Films ◽  
Photo Oxidation ◽  
Resistance To Oxidation ◽  
Polyethylene Fiber ◽  
Polarized Infrared Spectroscopy

The resistance to oxidation of polyethylene fiber intended for engineering applications has been compared with that of conventional polyethylene films. The highly ordered fiber was appreciably more resistant to γ-initiated oxidation and somewhat more resistant to photo-oxidation. Oxidation products from the γ-initiated oxidation were quite highly ordered with respect to the fiber axis as shown by polarized infrared spectroscopy. Photo-oxidation products showed random orientation, possibly as a result of the more extensive chain scission that must accompany the photo-process. Despite the higher resistance of γ-radiation damage of the chain-extended fiber structure as compared to unoriented film, the irradiated fiber did show a slow post-irradiation oxidation.

scholarly journals Influence of a Modified Plant Extract on Activity of Antioxidant Enzymes and Concentration of Pigments in Gamma-Irradiated Plants of Maize and Wheat

2018 ◽  
Vol 72 (1) ◽  
pp. 38-42
Author(s):  
Ibrahim Azizov ◽  
Elshan Shamilov ◽  
Asim Abdullayev ◽  
Zohra Muslimova ◽  
Gunel Mamedli ◽  
...  
Keyword(s):  
Antioxidant Enzymes ◽  
Free Radicals ◽  
Plant Extract ◽  
Photosynthetic Pigment ◽  
Average Dose ◽  
Γ Irradiation ◽  
Dose Power ◽  
Γ Radiation ◽  
Gamma Irradiated ◽  
Object Of Study

Abstract The influence of a medicinal plant extract, immobilised by ligands, on the activity of antioxidant enzymes and photosynthetic pigment concentration of wheat and maize was studied. The object of study was seed of drought-resistant firm durum wheat (Triticum durum Desf.) and maize (Zea mays L.). Seeds were subjected to general uniform γ-radiation from a 60Co source on a Rkhund installation at average dose power of MD = 0.306 Gy/sec. Before radiation seeds were treated in modified extract from medicinal plants. The treatment of seeds with 0.1 and 0.01% solution of modified extract from Hypericum, Dandelion, and Calendula caused significant reduction in processes initiated by radiation and in formation of free radicals. On the basis of the obtained results it was concluded that the used modified plant extract collection had a protective effect, reducing the amount of free radicals produced by γ-irradiation.

Study of the resistor material of an automotive spark plug by use of the charge-up effect along with elemental mapping in an electron microprobe

1991 ◽  
Vol 49 ◽  
pp. 742-743
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
J. S. Park ◽  
B. N. Juterbock
Keyword(s):  
Electron Microprobe ◽  
Present Report ◽  
Coated Sample ◽  
Valuable Insight ◽  
Elemental Mapping ◽  
Spark Plug ◽  
Carbon Coated ◽  
Electron Image ◽  
Electron Imaging ◽  
Insight Into

The electric and thermal properties of the resistor material in an automotive spark plug should be stable during its service lifetime. Containing many elements and many phases, this material has a very complex microstructure. Elemental mapping with an electron microprobe can reveal the distribution of all relevant elements throughout the sample. In this work, it is demonstrated that the charge-up effect, which would distort an electron image and, therefore, is normally to be avoided in an electron imaging work, could be used to advantage to reveal conductive and resistive zones in a sample. Its combination with elemental mapping can provide valuable insight into the underlying conductivity mechanism of the resistor.This work was performed in a CAMECA SX-50 microprobe. The spark plug used in the present report was a commercial product taken from the shelf. It was sectioned to expose the cross section of the resistor. The resistor was known not to contain the precious metal Au as checked on the carbon coated sample. The sample was then stripped of carbon coating and re-coated with Au.

Quantum Mechanical Interpretation of the Ultra-Low Energy Methyl-Rotation Dynamics in Porous Metal-Organic Frameworks Probed by Low-Frequency Vibrational Spectroscopy and ab initio Simulations

2018 ◽  
Author(s):  
Qi Li ◽  
Adam J. Zaczek ◽  
Timothy M. Korter ◽  
J. Axel Zeitler ◽  
Michael T. Ruggiero
Keyword(s):  
Ab Initio ◽  
Metal Organic Frameworks ◽  
Low Frequency ◽  
Rotor Dynamics ◽  
Quantum Mechanical ◽  
Valuable Insight ◽  
Void Space ◽  
Ab Initio Simulations ◽  
Metal Organic ◽  
Insight Into

<div>Understanding the nature of the interatomic interactions present within the pores of metal-organic frameworks</div><div>is critical in order to design and utilize advanced materials</div><div>with desirable applications. In ZIF-8 and its cobalt analogue</div><div>ZIF-67, the imidazolate methyl-groups, which point directly</div><div>into the void space, have been shown to freely rotate - even</div><div>down to cryogenic temperatures. Using a combination of ex-</div><div>perimental terahertz time-domain spectroscopy, low-frequency</div><div>Raman spectroscopy, and state-of-the-art ab initio simulations,</div><div>the methyl-rotor dynamics in ZIF-8 and ZIF-67 are fully charac-</div><div>terized within the context of a quantum-mechanical hindered-</div><div>rotor model. The results lend insight into the fundamental</div><div>origins of the experimentally observed methyl-rotor dynamics,</div><div>and provide valuable insight into the nature of the weak inter-</div><div>actions present within this important class of materials.</div>

A Review of Phytochemical and Pharmacological Studies of Inula Species

2020 ◽  
Vol 16 (5) ◽  
pp. 557-567
Author(s):  
Aparoop Das ◽  
Anshul Shakya ◽  
Surajit Kumar Ghosh ◽  
Udaya P. Singh ◽  
Hans R. Bhat
Keyword(s):  
Bacterial Infections ◽  
Chemical Constituents ◽  
Valuable Insight ◽  
Important Ingredient ◽  
Pharmacological Activities ◽  
Medicinal Uses ◽  
The Family ◽  
Pharmacological Studies ◽  
Perennial Herbs ◽  
Insight Into

Background: Plants of the genus Inula are perennial herbs of the family Asteraceae. This genus includes more than 100 species, widely distributed throughout Europe, Africa and Asia including India. Many of them are indicated in traditional medicine, e.g., in Ayurveda. This review explores chemical constituents, medicinal uses and pharmacological actions of Inula species. Methods: Major databases and research and review articles retrieved through Scopus, Web of Science, and Medline were consulted to obtain information on the pharmacological activities of the genus Inula published from 1994 to 2017. Results: Inula species are used either alone or as an important ingredient of various formulations to cure dysfunctions of the cardiovascular system, respiratory system, urinary system, central nervous system and digestive system, and for the treatment of asthma, diabetes, cancers, skin disorders, hepatic disease, fungal and bacterial infections. A range of phytochemicals including alkaloids, essential and volatile oils, flavonoids, terpenes, and lactones has been isolated from herbs of the genus Inula, which might possibly explain traditional uses of these plants. Conclusion: The present review is focused on chemical constituents, medicinal uses and pharmacological actions of Inula species and provides valuable insight into its medicinal potential.

Photolytic and thermal annealing of radical anions gamma-irradiated monocarboxylic acids

1979 ◽  
Vol 44 (12) ◽  
pp. 3632-3643 ◽  
Author(s):  
Karel Mach ◽  
Igor Janovský ◽  
Karel Vacek
Keyword(s):  
Thermal Annealing ◽  
Pivalic Acid ◽  
Esr Spectra ◽  
Paramagnetic Species ◽  
Radical Anions ◽  
Γ Irradiation ◽  
Before And After ◽  
Optical Bleaching ◽  
The Difference ◽  
Gamma Irradiated

Total yields of paramagnetic species, their optical bleaching and thermal annealing in acetic, propionic, a-butyric, isobutyric, and pivalic acid γ-irradiated at 77 K were followed by ESR spectroscopy. Radical anions, always found after irradiation, disappear during optical bleaching without formation of any paramagnetic product. During thermal annealing they are converted almost quantitatively into the α-radicals of the respective acid, with the exception of pivalic acid. Amounts of radical anions were estimated from the difference of integrated ESR spectra taken before and after optical bleaching. The results show that approximately equal amounts of the reduction and oxidation paramagnetic products of the γ-irradiation can be detected.

scholarly journals Compound heterozygous variants in LAMC3 in association with posterior periventricular nodular heterotopia

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Carla De Angelis ◽  
Alicia B. Byrne ◽  
Rebecca Morrow ◽  
Jinghua Feng ◽  
Thuong Ha ◽  
...  
Keyword(s):  
Cortical Development ◽  
Occipital Cortex ◽  
Compound Heterozygous ◽  
Valuable Insight ◽  
Periventricular Nodular Heterotopia ◽  
Case Presentation ◽  
Malformation Of Cortical Development ◽  
Nodular Heterotopia ◽  
Compound Heterozygous Variants ◽  
Insight Into

Abstract Background Periventricular nodular heterotopia (PNH) is a malformation of cortical development characterized by nodules of abnormally migrated neurons. The cause of posteriorly placed PNH is not well characterised and we present a case that provides insights into the cause of posterior PNH. Case presentation We report a fetus with extensive posterior PNH in association with biallelic variants in LAMC3. LAMC3 mutations have previously been shown to cause polymicrogyria and pachygyria in the occipital cortex, but not PNH. The occipital location of PNH in our case and the proposed function of LAMC3 in cortical development suggest that the identified LAMC3 variants may be causal of PNH in this fetus. Conclusion We hypothesise that this finding extends the cortical phenotype associated with LAMC3 and provides valuable insight into genetic cause of posterior PNH.

scholarly journals Detecting Convergence Trends among EU Universities

Economies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 42
Author(s):  
Maria Adamakou ◽  
Dimitris Kallioras ◽  
George Petrakos
Keyword(s):  
Methodological Approach ◽  
Basic Research ◽  
Valuable Insight ◽  
Traditional Role ◽  
University Ranking ◽  
Convergence Clubs ◽  
Development Processes ◽  
The Impact ◽  
The Empirical Analysis ◽  
Insight Into

Universities are emerging growth determinants. This is so as, in addition to the fulfillment of their traditional role in teaching and (basic) research, universities, as aptly described within the helix framework, are expected to engage in regional development processes. The paper aims to detect trends of convergence among EU universities in terms of performance. To the best of our knowledge, this topic has not hitherto been examined. The empirical analysis of the paper covers the period 2014–2021, utilizes data obtained from URAP (University Ranking by Academic Performance), and employs the methodological approach of convergence clubs. The findings of the paper provide valuable insight into both theory and policy-making. We conclude that despite the unification of EU educational space, trends of divergence among EU universities are still present, and notable divisions still remain. Consequently, this indicates that the impact of EU universities on the formation of spatial disparities across EU space is not neutral.

scholarly journals Exploration of Alternative Splicing Events in Mesenchymal Stem Cells from Human Induced Pluripotent Stem Cells

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 737
Author(s):  
Ji-Eun Jeong ◽  
Binna Seol ◽  
Han-Seop Kim ◽  
Jae-Yun Kim ◽  
Yee-Sook Cho
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Alternative Splicing ◽  
Functional Enrichment ◽  
Actin Binding ◽  
Pcr Analysis ◽  
Valuable Insight ◽  
Sequencing Analysis ◽  
Induced Pluripotent ◽  
Insight Into

Although comparative genome-wide transcriptomic analysis has provided insight into the biology of human induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs), the distinct alternative splicing (AS) signatures of iMSCs remain elusive. Here, we performed Illumina RNA sequencing analysis to characterize AS events in iMSCs compared with tissue-derived MSCs. A total of 4586 differentially expressed genes (|FC| > 2) were identified between iMSCs and umbilical cord blood-derived MSCs (UCB-MSCs), including 2169 upregulated and 2417 downregulated genes. Of these, 164 differentially spliced events (BF > 20) in 112 genes were identified between iMSCs and UCB-MSCs. The predominant type of AS found in iMSCs was skipped exons (43.3%), followed by retained introns (19.5%), alternative 3′ (15.2%) and 5′ (12.8%) splice sites, and mutually exclusive exons (9.1%). Functional enrichment analysis showed that the differentially spliced genes (|FC| > 2 and BF > 20) were mainly enriched in functions associated with focal adhesion, extracellular exosomes, extracellular matrix organization, cell adhesion, and actin binding. Splice isoforms of selected genes including TRPT1, CNN2, and AP1G2, identified in sashimi plots, were further validated by RT-PCR analysis. This study provides valuable insight into the biology of iMSCs and the translation of mechanistic understanding of iMSCs into therapeutic applications.

Craniopharyngioma: 10 Selected Works That Provide Comprehensive and Valuable Insight into These Complex Tumors

2019 ◽  
Vol 122 ◽  
pp. 710-712 ◽  
Author(s):  
José María Pascual ◽  
Ruth Prieto ◽  
Rodrigo Carrasco
Keyword(s):  
Valuable Insight ◽  
Insight Into
Sign in / Sign up

Export Citation Format

Share Document