scholarly journals Damage of polyesters by the atmospheric free radical oxidant NO3 •: a product study involving model systems

2013 ◽  
Vol 9 ◽  
pp. 1907-1916 ◽  
Author(s):  
Catrin Goeschen ◽  
Uta Wille
Keyword(s):  
Free Radical ◽  
Environmental Conditions ◽  
Hot Spots ◽  
Polymer Materials ◽  
Model Systems ◽  
Night Time ◽  
High Performing ◽  
Work Model ◽  
Product Study ◽  
Insight Into

Manufactured polymer materials are used in increasingly demanding applications, but their lifetime is strongly influenced by environmental conditions. In particular, weathering and ageing leads to dramatic changes in the properties of the polymers, which results in decreased service life and limited usage. Despite the heavy reliance of our society on polymers, the mechanism of their degradation upon exposure to environmental oxidants is barely understood. In this work, model systems of important structural motifs in commercial high-performing polyesters were used to study the reaction with the night-time free radical oxidant NO3 • in the absence and presence of other radical and non-radical oxidants. Identification of the products revealed ‘hot spots’ in polyesters that are particularly vulnerable to attack by NO3 • and insight into the mechanism of oxidative damage by this environmentally important radical. It is suggested that both intermediates as well as products of these reactions are potentially capable of promoting further degradation processes in polyesters under environmental conditions.

scholarly journals Mechanistic Insight into Antimicrobial and Antioxidant Potential of Jasminum Species: A Herbal Approach for Disease Management

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1089
Author(s):  
Acharya Balkrishna ◽  
Akansha Rohela ◽  
Abhishek Kumar ◽  
Ashwani Kumar ◽  
Vedpriya Arya ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Drug Resistance ◽  
Free Radicals ◽  
Free Radical ◽  
Microbial Pathogens ◽  
Free Radical Scavengers ◽  
Bioactive Constituents ◽  
Global Issues ◽  
Iridoid Glucosides ◽  
Insight Into

Drug resistance among microbial pathogens and oxidative stress caused by reactive oxygen species are two of the most challenging global issues. Firstly, drug-resistant pathogens cause several fatalities every year. Secondly aging and a variety of diseases, such as cardiovascular disease and cancer, are associated with free radical generated oxidative stress. The treatments currently available are limited, ineffective, or less efficient, so there is an immediate need to tackle these issues by looking for new therapies to resolve resistance and neutralize the harmful effects of free radicals. In the 21st century, the best way to save humans from them could be by using plants as well as their bioactive constituents. In this specific context, Jasminum is a major plant genus that is used in the Ayurvedic system of medicine to treat a variety of ailments. The information in this review was gathered from a variety of sources, including books, websites, and databases such as Science Direct, PubMed, and Google Scholar. In this review, a total of 14 species of Jasminum have been found to be efficient and effective against a wide variety of microbial pathogens. In addition, 14 species were found to be active free radical scavengers. The review is also focused on the disorders related to oxidative stress, and it was concluded that Jasminum grandiflorum and J. sambac normalized various parameters that were elevated by free radical generation. Alkaloids, flavonoids (rutoside), terpenes, phenols, and iridoid glucosides are among the main phytoconstituents found in various Jasminum species. Furthermore, this review also provides insight into the mechanistic basis of drug resistance, the generation of free radicals, and the role of Jasminum plants in combating resistance and neutralizing free radicals.

scholarly journals Elucidation and refinement of synthetic receptor mechanisms

2020 ◽  
Author(s):  
Hailey I. Edelstein ◽  
Patrick S. Donahue ◽  
Joseph J. Muldoon ◽  
Anthony K. Kang ◽  
Taylor B. Dolberg ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Functional Performance ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Performance Characteristics ◽  
Therapeutic Gene ◽  
High Performing ◽  
Synthetic Receptor ◽  
And Performance ◽  
Insight Into

ABSTRACTSynthetic receptors are powerful tools for engineering mammalian cell-based devices. These biosensors enable cell-based therapies to perform complex tasks such as regulating therapeutic gene expression in response to sensing physiological cues. Although multiple synthetic receptor systems now exist, many aspects of receptor performance are poorly understood. In general, it would be useful to understand how receptor design choices influence performance characteristics. In this study, we examined the modular extracellular sensor architecture (MESA) and systematically evaluated previously unexamined design choices, yielding substantially improved receptors. A key finding that might extend to other receptor systems is that the choice of transmembrane domain (TMD) is important for generating high-performing receptors. To provide mechanistic insights, we adopted and employed a Förster resonance energy transfer (FRET)-based assay to elucidate how TMDs affect receptor complex formation and connected these observations to functional performance. To build further insight into these phenomena, we developed a library of new MESA receptors that sense an expanded set of ligands. Based upon these explorations, we conclude that TMDs affect signaling primarily by modulating intracellular domain geometry. Finally, to guide the design of future receptors, we propose general principles for linking design choices to biophysical mechanisms and performance characteristics.

scholarly journals Effect of inorganic nanoparticles and organic complexes on their basis on free-radical processes in some model systems

2015 ◽  
Vol 31 (2) ◽  
pp. 138-145 ◽  
Author(s):  
K. A. Averchenko ◽  
N. S. Kavok ◽  
V. K. Klochkov ◽  
O. O. Sedyh ◽  
S. L. Yefimova ◽  
...  
Keyword(s):  
Free Radical ◽  
Inorganic Nanoparticles ◽  
Model Systems ◽  
Free Radical Processes ◽  
Organic Complexes ◽  
Radical Processes

scholarly journals The Performativity of Organizational Culture in a No Excuses Charter School

2018 ◽  
Author(s):  
Jason Radford
Keyword(s):  
Organizational Culture ◽  
Charter School ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Successful Performance ◽  
High Performing ◽  
Clear Insight ◽  
Cyclical Process ◽  
Insight Into ◽  
Successes And Failures

Theories developed by academics influence those they study, in some cases fundamentally shaping the world we study. This influential relationship, often called performativity, has gone largely unnoticed and uncommented on in organizational theory and research. The few studies investigating performativity in organizations or other fields typically focus on cases in which the ultimate success of theory's implementation is known. In this paper, I examine how one high-performing charter school sought to turn a prescribed organizational culture into reality. I find that path to successful performance is very narrow and ambiguous. The school succeeded and failed in many steps of the process, making it difficult to assess whether the initiative was successful and to attribute their successes and failures to the theory or their implementation. I conclude that performativity is a cyclical process occurring at multiple time scales. During these cycles, organizations iteratively test new implementations of the theory, seeking to gain clear insight into the success of their strategy and correctly attribute their successes and failures to decide whether the theory actually works or not.

scholarly journals Trends in the development of miRNA bioinformatics tools

2019 ◽  
Vol 20 (5) ◽  
pp. 1836-1852 ◽  
Author(s):  
Liang Chen ◽  
Liisa Heikkinen ◽  
Changliang Wang ◽  
Yang Yang ◽  
Huiyan Sun ◽  
...  
Keyword(s):  
Hot Spots ◽  
Target Prediction ◽  
Future Directions ◽  
Regulate Gene Expression ◽  
Small Noncoding Rnas ◽  
The Past ◽  
Manual Curation ◽  
Bioinformatics Tools ◽  
Insight Into ◽  
Epigenetic Processes

Abstract MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression via recognition of cognate sequences and interference of transcriptional, translational or epigenetic processes. Bioinformatics tools developed for miRNA study include those for miRNA prediction and discovery, structure, analysis and target prediction. We manually curated 95 review papers and ∼1000 miRNA bioinformatics tools published since 2003. We classified and ranked them based on citation number or PageRank score, and then performed network analysis and text mining (TM) to study the miRNA tools development trends. Five key trends were observed: (1) miRNA identification and target prediction have been hot spots in the past decade; (2) manual curation and TM are the main methods for collecting miRNA knowledge from literature; (3) most early tools are well maintained and widely used; (4) classic machine learning methods retain their utility; however, novel ones have begun to emerge; (5) disease-associated miRNA tools are emerging. Our analysis yields significant insight into the past development and future directions of miRNA tools.

scholarly journals Controlled Construction of Stable Network Structure Composed of Honeycomb-Shaped Microhydrogels

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 38 ◽  
Author(s):  
Masayuki Hayakawa ◽  
Satoshi Umeyama ◽  
Ken Nagai ◽  
Hiroaki Onoe ◽  
Masahiro Takinoue
Keyword(s):  
Cell Communication ◽  
Model Systems ◽  
Stable Component ◽  
Photosensitive Polymer ◽  
A Cell ◽  
External Stimuli ◽  
Structural Instabilities ◽  
Insight Into ◽  
Stable Network ◽  
Microfluidic Technique

Recently, the construction of models for multicellular systems such as tissues has been attracting great interest. These model systems are expected to reproduce a cell communication network and provide insight into complicated functions in living systems./Such network structures have mainly been modelled using a droplet and a vesicle. However, in the droplet and vesicle network, there are difficulties attributed to structural instabilities due to external stimuli and perturbations. Thus, the fabrication of a network composed of a stable component such as hydrogel is desired. In this article, the construction of a stable network composed of honeycomb-shaped microhydrogels is described. We produced the microhydrogel network using a centrifugal microfluidic technique and a photosensitive polymer. In the network, densely packed honeycomb-shaped microhydrogels were observed. Additionally, we successfully controlled the degree of packing of microhydrogels in the network by changing the centrifugal force. We believe that our stable network will contribute to the study of cell communication in multicellular systems.

Ammonium Sulfate Increases Efficacy of Sethoxydim Through Increased Absorption and Translocation

Weed Science ◽  
1992 ◽  
Vol 40 (3) ◽  
pp. 351-358 ◽  
Author(s):  
Anne M. Smith ◽  
William H. Vanden Born
Keyword(s):  
Ammonium Sulfate ◽  
Environmental Conditions ◽  
Dry Weight ◽  
Model Systems ◽  
Short Term ◽  
Wild Oats

The effect of ammonium sulfate (AMS) on efficacy and on absorption and translocation of sethoxydim in wild oats and barley was investigated under controlled environmental conditions. Increases in efficacy in the presence of AMS were relatively small. The rate of sethoxydim required to reduce dry weight 50% was reduced from 0.08 kg a.i. ha−1, for both species, to 0.07 and 0.06 kg ha−1for wild oats and barley, respectively, in the presence of added AMS. In short-term experiments, uptake of14C from14C-labeled sethoxydim 0.5 and 1 h after application was increased approximately twofold with the addition of AMS. AMS had little effect on sethoxydim absorption beyond 1 h after application. Translocation at 1 h after application was unaffected by AMS. However, translocation 12 and 24 h after application was increased with AMS. It is postulated that the translocation increase results indirectly from the increase in absorption. The observed increase in absorption with the addition of AMS is evident only when crop oil concentrate (COC) is also present In model systems, the addition of AMS enhanced sorption of sethoxydim into Isolated cuticles but had no effect on movement into excised roots.

Neuropsychological Characteristics of the Confusional State Following Traumatic Brain Injury

2019 ◽  
Vol 25 (3) ◽  
pp. 302-313 ◽  
Author(s):  
Rachel E. Keelan ◽  
Elaine J. Mahoney ◽  
Mark Sherer ◽  
Tessa Hart ◽  
Joseph Giacino ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Mixed Model ◽  
Recovery Period ◽  
Model Systems ◽  
National Database ◽  
Confusional State ◽  
High Performing ◽  
Neuropsychological Profile ◽  
Memory Control

AbstractObjectives: Individuals with moderate–severe traumatic brain injury (TBI) experience a transitory state of impaired consciousness and confusion often called posttraumatic confusional state (PTCS). This study examined the neuropsychological profile of PTCS. Methods: Neuropsychometric profiles of 349 individuals in the TBI Model Systems National Database were examined 4 weeks post-TBI (±2 weeks). The PTCS group was subdivided into Low (n=46) and High Performing PTCS (n=45) via median split on an orientation/amnesia measure, and compared to participants who had emerged from PTCS (n=258). Neuropsychological patterns were examined using multivariate analyses of variance and mixed model analyses of covariance. Results: All groups were globally impaired, but severity differed across groups (F(40,506)=3.44; p<.001; ŋp2 =.206). Rate of forgetting (memory consolidation) was impaired in all groups, but failed to differentiate them (F(4,684)=0.46; p=.762). In contrast, executive memory control was significantly more impaired in PTCS groups than the emerged group: Intrusion errors: F(2,343)=8.78; p<.001; ŋp2=.049; False positive recognition errors: F(2,343)=3.70; p<.05; ŋp2=.021. However, non-memory executive control and other executive memory processes did not differentiate those in versus emerged from PTCS. Conclusions: Executive memory control deficits in the context of globally impaired cognition characterize PTCS. This pattern differentiates individuals in and emerged from PTCS during the acute recovery period following TBI. (JINS, 2019, 25, 302–313)

scholarly journals Designing Model Systems for Enhanced Adhesion

MRS Bulletin ◽  
2007 ◽  
Vol 32 (6) ◽  
pp. 496-503 ◽  
Author(s):  
Edwin P. Chan ◽  
Christian Greiner ◽  
Eduard Arzt ◽  
Alfred J. Crosby
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Model Systems ◽  
Adhesion Forces ◽  
Synthetic Analogues ◽  
Jumping Spiders ◽  
Topographic Features ◽  
Considerable Research ◽  
Insight Into ◽  
Primary Strategy

AbstractNature provides inspiration for enhanced control of adhesion through numerous examples ranging from geckos to jumping spiders. The primary strategy in these examples is the incorporation of patterns, specifically high-aspect-ratio topographic features, to ingeniously maximize adhesion forces while maintaining ease of release. Recently, considerable research efforts have been devoted toward the understanding, development, and optimization of synthetic analogues to these examples in nature. In this article, we provide insight into the mechanisms that lead to enhanced control of interfacial properties through patterning, the strategies that can be used for fabricating synthetic patterns, and an overview of experimental results that have been used to gain understanding and guidance in this emerging field.

Absolute rate constants for hydrocarbon autoxidation. 33. A product study of the self-reaction of α-tetralylperoxyls in solution

1983 ◽  
Vol 61 (9) ◽  
pp. 2037-2043 ◽  
Author(s):  
A. Baignée ◽  
J. H. B. Chenier ◽  
J. A. Howard
Keyword(s):  
Steady State ◽  
Free Radical ◽  
Rate Constant ◽  
Rate Constants ◽  
The Self ◽  
Absolute Rate ◽  
Chain Reaction ◽  
Low Concentrations ◽  
A Chain ◽  
Product Study

The major initial products of the self-reaction of α-tetralylperoxyls (C10H11O2•) in chlorobenzene at 303–353 K are equal concentrations of α-tetralol and α-tetralone in ~90% yield based on the number of initiating radicals. These yields are consistent with the non-radical (Russell) mechanism for self-reaction. Low concentrations of bis(α-tetralyl) peroxide are produced, indicating that there is a small but detectable free-radical contribution towards termination. C10H11O2• undergoes β-scission in this temperature range but steady-state concentrations of C10H11• are too low to influence the termination rate constant 2kt, or react with C10H11O2• to give (C10H11O2. α-Tetralol to α-tetralone ratios and total yields of these products are significantly less than 1 and 100%, respectively, in methanol and acetonitrile. Formaldehyde is produced in methanol indicating the involvement of α-hydroxymethylperoxyls, derived from the solvent, in termination. There is no evidence for a chain reaction or a zwitterion intermediate for self-reaction of C10H11O2• in solution.

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