Role of weak intermolecular forces in fine-tuning the polarization responses in supramolecular aggregates

2006 ◽  
pp. 1251-1251
Author(s):  
Swapan Pati
Keyword(s):  
Intermolecular Forces ◽  
Fine Tuning ◽  
Weak Intermolecular Forces ◽  
Supramolecular Aggregates

Weak Intermolecular Forces, but High Melting Points

2017 ◽  
Vol 70 (5) ◽  
pp. 538 ◽  
Author(s):  
Jiabin Gao ◽  
Djamal Djaidi ◽  
Christopher E. Marjo ◽  
Mohan M. Bhadbhade ◽  
Alison T. Ung ◽  
...  
Keyword(s):  
Molar Mass ◽  
Intermolecular Forces ◽  
High Melting ◽  
High Melting Point ◽  
Enantiomerically Pure ◽  
X Ray ◽  
Drug Molecules ◽  
Poorly Soluble ◽  
Weak Intermolecular Forces

The poorly soluble racemic compound 6,6a,13,13a-tetrahydropentaleno[1,2-b:4,5-b′]diquinoline (4) has an exceptionally high melting point range of 352–354°C despite its low molar mass (308.38) and a structure containing only 40 atoms (38 of which are C and H). Analysis of the X-ray crystal structure and Hirshfeld surface of 4, along with comparison with its isostructural homologue 2, reveals how this occurs in the absence of Pauling-type hydrogen bonding. Excellent complementarity between homochiral molecules of 4 allows formation of enantiomerically pure layers using C–H⋯π, aromatic π⋯π, and C–H⋯N interactions. The alternating layers of opposite handedness are then crosslinked by means of aza-1,3-peri hydrogen interactions. This bifurcated C–H⋯N⋯H–C motif acts as a molecular clip creating a highly rigid network structure. The role of weaker intermolecular forces in influencing the solubility and bioavailability of potential drug molecules is discussed in the context of the popular Lipinski ‘rule of 5’ guidelines.

scholarly journals Selectivity of weak intermolecular forces and precursor state of elementary oxidation reactions, a new insight on Ne* + N2 chemiionization

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Stefano Falcinelli ◽  
Franco Vecchiocattivi ◽  
Fernando Pirani
Keyword(s):  
Open Shell ◽  
Intermolecular Forces ◽  
Collision Dynamics ◽  
Oxidation Reactions ◽  
Molecular Beam Scattering ◽  
Fundamental Interest ◽  
Precursor State ◽  
New Formulation ◽  
Weak Intermolecular Forces

AbstractThis paper reports on the collision dynamics of N2 with metastable Ne* promoting chemiionizations, prototype of barrier-less oxidation reactions of great interest for fundamental and applied research. Extending guidelines presented in previous papers for the atom–atom case, an innovative treatment of the reaction stereodynamics involving molecules in a quantum state-to-state resolution conditions is proposed that emphasizes the role of structure and stability of the precursor that is here the reaction transition state. A critical test of such treatment, carried out exploiting a new formulation both of real and imaginary parts of the optical potential driving the reaction dynamics, is represented by the detailed-combined description of all relevant findings, provided by high resolution molecular beam scattering experiments carried out in our and other laboratories. The present analysis casts light on basic electronic rearrangements of such prototype oxidation reaction which are expected to be of fundamental interest for many other reactions involving open shell atoms and free radicals.

It Keeps Me Seeking

2018 ◽  
Author(s):  
Andrew Briggs ◽  
Hans Halvorson ◽  
Andrew Steane
Keyword(s):  
Evolutionary Biology ◽  
Quantum Physics ◽  
Natural World ◽  
Theological Reflection ◽  
Fine Tuning ◽  
Good Argument ◽  
The Difference ◽  
Argument From Design ◽  
Relationship Of

Two scientists and a philosopher aim to show how science both enriches and is enriched by Christian faith. The text is written around four themes: 1. God is a being to be known, not a hypothesis to be tested; 2. We set a high bar on what constitutes good argument; 3. Uncertainty is OK; 4. We are allowed to open up the window that the natural world offers us. This is not a work of apologetics. Rather, the text takes an overview of various themes and gives reactions and responses, intended to place science correctly as a valued component of the life of faith. The difference between philosophical analysis and theological reflection is expounded. Questions of human identity are addressed from philosophy, computer science, quantum physics, evolutionary biology and theological reflection. Contemporary physics reveals the subtle and open nature of physical existence, and offers lessons in how to learn and how to live with incomplete knowledge. The nature and role of miracles is considered. The ‘argument from design’ is critiqued, especially arguments from fine-tuning. Logical derivation from impersonal facts is not an appropriate route to a relationship of mutual trust. Mainstream evolutionary biology is assessed to be a valuable component of our understanding, but no exploratory process can itself fully account for the nature of what is discovered. To engage deeply in science is to seek truth and to seek a better future; it is also an activity of appreciation, as one may appreciate a work of art.

scholarly journals Influence of the Electrolyte Salt Concentration on DNA Detection with Graphene Transistors

Biosensors ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Agnes Purwidyantri ◽  
Telma Domingues ◽  
Jérôme Borme ◽  
Joana Rafaela Guerreiro ◽  
Andrey Ipatov ◽  
...  
Keyword(s):  
Phosphate Buffer ◽  
Species Interactions ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Limit Of Detection ◽  
Debye Length ◽  
Intermolecular Forces ◽  
Single Layer Graphene ◽  
Dna Adsorption

Liquid-gated Graphene Field-Effect Transistors (GFET) are ultrasensitive bio-detection platforms carrying out the graphene’s exceptional intrinsic functionalities. Buffer and dilution factor are prevalent strategies towards the optimum performance of the GFETs. However, beyond the Debye length (λD), the role of the graphene-electrolytes’ ionic species interactions on the DNA behavior at the nanoscale interface is complicated. We studied the characteristics of the GFETs under different ionic strength, pH, and electrolyte type, e.g., phosphate buffer (PB), and phosphate buffer saline (PBS), in an automatic portable built-in system. The electrostatic gating and charge transfer phenomena were inferred from the field-effect measurements of the Dirac point position in single-layer graphene (SLG) transistors transfer curves. Results denote that λD is not the main factor governing the effective nanoscale screening environment. We observed that the longer λD was not the determining characteristic for sensitivity increment and limit of detection (LoD) as demonstrated by different types and ionic strengths of measuring buffers. In the DNA hybridization study, our findings show the role of the additional salts present in PBS, as compared to PB, in increasing graphene electron mobility, electrostatic shielding, intermolecular forces and DNA adsorption kinetics leading to an improved sensitivity.

scholarly journals Effect of tungsten disulfide nanotubes on crystallization of polylactide under uniaxial deformation and annealing

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Fausta Loffredo ◽  
Loredana Tammaro ◽  
Tiziana Di Luccio ◽  
Carmela Borriello ◽  
Fulvia Villani ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Structural Evolution ◽  
Tungsten Disulfide ◽  
Fine Tuning ◽  
Nanocomposite Films ◽  
Uniaxial Deformation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering

AbstractTungsten disulfide (WS2) nanotubes (NTs) are examined here as a filler for polylactide (PLA) for their ability to accelerate PLA crystallization and for their promising biocompatibility in relevant to biomedical applications of PLA-WS2 nanocomposites. In this work, we have studied the structural and thermal properties of PLA-WS2 nanocomposite films varying the concentration of WS2 NTs from 0 (neat PLA) to 0.6 wt%. The films were uniaxially drawn at 90 °C and annealed at the same temperature for 3 and 10 min. Using wide angle x-ray scattering, Raman spectroscopy and differential scanning calorimetry, we probed the effects of WS2 NT addition on the structure of the PLA films at various stages of processing (unstretched, stretching, annealing). We found that 0.6 wt% of WS2 induces the same level of crystallinity in as stretched PLA-WS2 as annealing in neat PLA for 10 min. These data provide useful insights into the role of WS2 NTs on the structural evolution of PLA-WS2 composites under uniaxial deformation, and extend their applicability to situations where fine tuning of PLA crystallinity is desirable.

scholarly journals Seed Gamma Irradiation of Arabidopsis thaliana ABA-Mutant Lines Alters Germination and Does Not Inhibit the Photosynthetic Efficiency of Juvenile Plants

Dose-Response ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 155932582097924
Author(s):  
Darya Babina ◽  
Marina Podobed ◽  
Ekaterina Bondarenko ◽  
Elizaveta Kazakova ◽  
Sofia Bitarishvili ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Growth Response ◽  
Dose Range ◽  
Fine Tuning ◽  
Plant Tolerance ◽  
Inhibitory Effects ◽  
Γ Irradiation ◽  
Photosynthetic Responses ◽  
Mutant Lines

Plant growth response to γ-irradiation includes stimulating or inhibitory effects depending on plant species, dose applied, stage of ontogeny and other factors. Previous studies showed that responses to irradiation could depend on ABA accumulation and signaling. To elucidate the role of ABA in growth and photosynthetic responses to irradiation, lines Col-8, abi3-8 and aba3 -1 of Arabidopsis thaliana were used. Seeds were γ-irradiated using 60Co in the dose range 50-150 Gy. It was revealed that the dose of 150 Gy affected germination parameters of aba3 -1 and Col-8 lines, while abi3-8 line was the most resistant to the studied doses and even showed faster germination at early hours after γ-irradiation at 50 Gy. These results suggest that susceptibility to ABA is probably more important for growth response to γ-irradiation than ABA synthesis. The photosynthetic functioning of 16-day-old plants mainly was not disturbed by γ-irradiation of seeds, and no indication of photosystem II photoinhibition was noticed, revealing the robustness of the photosynthetic system of A. thaliana. Glutathione peroxidase activity and ABA concentrations in plant tissues were not affected in the studied dose range. These results contribute to the understanding of germination and photosynthesis fine-tuning and of mechanisms of plant tolerance to ionizing radiation.

scholarly journals Decoding the temporal nature of brain GR activity in the NFκB signal transition leading to depressive-like behavior

2021 ◽  
Author(s):  
Young-Min Han ◽  
Min Sun Kim ◽  
Juyeong Jo ◽  
Daiha Shin ◽  
Seung-Hae Kwon ◽  
...  
Keyword(s):  
Inhibitory Action ◽  
Time Course ◽  
Molecular Mechanisms ◽  
Late Phase ◽  
Fine Tuning ◽  
Dependent Manner ◽  
Middle Phase ◽  
Temporal Shift

AbstractThe fine-tuning of neuroinflammation is crucial for brain homeostasis as well as its immune response. The transcription factor, nuclear factor-κ-B (NFκB) is a key inflammatory player that is antagonized via anti-inflammatory actions exerted by the glucocorticoid receptor (GR). However, technical limitations have restricted our understanding of how GR is involved in the dynamics of NFκB in vivo. In this study, we used an improved lentiviral-based reporter to elucidate the time course of NFκB and GR activities during behavioral changes from sickness to depression induced by a systemic lipopolysaccharide challenge. The trajectory of NFκB activity established a behavioral basis for the NFκB signal transition involved in three phases, sickness-early-phase, normal-middle-phase, and depressive-like-late-phase. The temporal shift in brain GR activity was differentially involved in the transition of NFκB signals during the normal and depressive-like phases. The middle-phase GR effectively inhibited NFκB in a glucocorticoid-dependent manner, but the late-phase GR had no inhibitory action. Furthermore, we revealed the cryptic role of basal GR activity in the early NFκB signal transition, as evidenced by the fact that blocking GR activity with RU486 led to early depressive-like episodes through the emergence of the brain NFκB activity. These results highlight the inhibitory action of GR on NFκB by the basal and activated hypothalamic-pituitary-adrenal (HPA)-axis during body-to-brain inflammatory spread, providing clues about molecular mechanisms underlying systemic inflammation caused by such as COVID-19 infection, leading to depression.

scholarly journals MicroRNAs: Biological Regulators in Pathogen–Host Interactions

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 113 ◽  
Author(s):  
Stephanie Maia Acuña ◽  
Lucile Maria Floeter-Winter ◽  
Sandra Marcia Muxel
Keyword(s):  
Immune Response ◽  
Infectious Diseases ◽  
Small Rnas ◽  
Immune Cell ◽  
Fine Tuning ◽  
Biological Processes ◽  
Host Interactions ◽  
The Past ◽  
Biological Aspects

An inflammatory response is essential for combating invading pathogens. Several effector components, as well as immune cell populations, are involved in mounting an immune response, thereby destroying pathogenic organisms such as bacteria, fungi, viruses, and parasites. In the past decade, microRNAs (miRNAs), a group of noncoding small RNAs, have emerged as functionally significant regulatory molecules with the significant capability of fine-tuning biological processes. The important role of miRNAs in inflammation and immune responses is highlighted by studies in which the regulation of miRNAs in the host was shown to be related to infectious diseases and associated with the eradication or susceptibility of the infection. Here, we review the biological aspects of microRNAs, focusing on their roles as regulators of gene expression during pathogen–host interactions and their implications in the immune response against Leishmania, Trypanosoma, Toxoplasma, and Plasmodium infectious diseases.

scholarly journals Imaging Implicit Morphological Processing: Evidence from Hebrew

2010 ◽  
Vol 22 (9) ◽  
pp. 1955-1969 ◽  
Author(s):  
Atira S. Bick ◽  
Ram Frost ◽  
Gadi Goelman
Keyword(s):  
Masked Priming ◽  
Statistical Correlation ◽  
Morphological Processing ◽  
Fine Tuning ◽  
Semantic Transparency ◽  
Lexical Structure ◽  
The Neural Networks ◽  
Distinct Aspect ◽  
The Brain

Is morphology a discrete and independent element of lexical structure or does it simply reflect a fine-tuning of the system to the statistical correlation that exists among orthographic and semantic properties of words? Hebrew provides a unique opportunity to examine morphological processing in the brain because of its rich morphological system. In an fMRI masked priming experiment, we investigated the neural networks involved in implicit morphological processing in Hebrew. In the lMFG and lIFG, activation was found to be significantly reduced when the primes were morphologically related to the targets. This effect was not influenced by the semantic transparency of the morphological prime, and was not found in the semantic or orthographic condition. Additional morphologically related decrease in activation was found in the lIPL, where activation was significantly modulated by semantic transparency. Our findings regarding implicit morphological processing suggest that morphology is an automatic and distinct aspect of visually processing words. These results also coincide with the behavioral data previously obtained demonstrating the central role of morphological processing in reading Hebrew.

scholarly journals AMPA receptor inhibition by synaptically released zinc

2015 ◽  
Vol 112 (51) ◽  
pp. 15749-15754 ◽  
Author(s):  
Bopanna I. Kalappa ◽  
Charles T. Anderson ◽  
Jacob M. Goldberg ◽  
Stephen J. Lippard ◽  
Thanos Tzounopoulos
Keyword(s):  
Dorsal Cochlear Nucleus ◽  
Fine Tuning ◽  
Receptor Inhibition ◽  
Endogenous Modulator ◽  
Excitatory Neurotransmission ◽  
Zinc Levels ◽  
Zinc Inhibition ◽  
Endogenous Modulators ◽  
Activity Dependent

The vast amount of fast excitatory neurotransmission in the mammalian central nervous system is mediated by AMPA-subtype glutamate receptors (AMPARs). As a result, AMPAR-mediated synaptic transmission is implicated in nearly all aspects of brain development, function, and plasticity. Despite the central role of AMPARs in neurobiology, the fine-tuning of synaptic AMPA responses by endogenous modulators remains poorly understood. Here we provide evidence that endogenous zinc, released by single presynaptic action potentials, inhibits synaptic AMPA currents in the dorsal cochlear nucleus (DCN) and hippocampus. Exposure to loud sound reduces presynaptic zinc levels in the DCN and abolishes zinc inhibition, implicating zinc in experience-dependent AMPAR synaptic plasticity. Our results establish zinc as an activity-dependent, endogenous modulator of AMPARs that tunes fast excitatory neurotransmission and plasticity in glutamatergic synapses.

Sign in / Sign up

Export Citation Format

Share Document