scholarly journals Spectral signatures of charge transfer in assemblies of molecularly-linked plasmonic nanoparticles

2017 ◽  
Vol 31 (24) ◽  
pp. 1740002 ◽  
Author(s):  
Sarah Lerch ◽  
Björn M. Reinhard
Keyword(s):  
Charge Transfer ◽  
Self Assembly ◽  
Experimental Studies ◽  
Blue Shift ◽  
Spectral Signatures ◽  
Sensor Platform ◽  
Interparticle Separation ◽  
Plasmon Spectrum ◽  
Significant Blue Shift

Self-assembly of functionalized nanoparticles (NPs) provides a unique class of nanomaterials for exploring and utilizing quantum-plasmonic effects that occur if the interparticle separation between NPs approaches a few nanometers and below. We review recent theoretical and experimental studies of plasmon coupling in self-assembled NP structures that contain molecular linkers between the NPs. Charge transfer through the interparticle gap of an NP dimer results in a significant blue-shift of the bonding dipolar plasmon (BDP) mode relative to classical electromagnetic predictions, and gives rise to new coupled plasmon modes, the so-called charge transfer plasmon (CTP) modes. The blue-shift of the plasmon spectrum is accompanied by a weakening of the electromagnetic field in the gap of the NPs. Due to an optical far-field signature that is sensitive to charge transfer across the gap, plasmonic molecules represent a sensor platform for detecting and characterizing gap conductivity in an optical fashion and for characterizing the role of molecules in facilitating the charge transfer across the gap.

Self-Assembly of Alkali Lignin in Tetrahydrofuran

2012 ◽  
Vol 550-553 ◽  
pp. 57-61
Author(s):  
Hao Li ◽  
Yong Hong Deng ◽  
Kai Huang
Keyword(s):  
Charge Transfer ◽  
Electrostatic Interaction ◽  
Self Assembly ◽  
The Self ◽  
Charge Transfer Complexes ◽  
Layer By Layer ◽  
Alkali Lignin ◽  
Higher Temperature ◽  
Effects Of Temperature

Alkali lignin (AL) was used as a polyanion to form layer-by-layer self-assembled film with PDAC as a polycation. The effects of temperature and concentration on the adsorption characteristics of AL were investigated. Iodine was added into AL solutions to study the role of π-π interaction in self-assembly of AL and PDAC. Results show that the self-assembly of AL/PDAC is mainly driven by π-π interaction and electrostatic interaction. A higher temperature or a larger concentration can enhance the aggregation of lignin. I2 can form lignin–iodine charge–transfer complexes with AL to reduce the degree of aggregation of AL, so the adsorbed amount of AL decreases significantly with increasing iodine contents.

Radical yields in DNA exposed to ionizing radiation: Role of energy and charge transfer

1990 ◽  
Vol 68 (9) ◽  
pp. 962-966 ◽  
Author(s):  
John H. Miller ◽  
Charles E. Swenberg
Keyword(s):  
Charge Transfer ◽  
Ionizing Radiation ◽  
Mechanistic Model ◽  
Experimental Studies ◽  
High Mobility ◽  
Orientation Dependence ◽  
Model Calculations ◽  
Insight Into ◽  
High Linear Energy Transfer

Theoretical and experimental studies of free-radical yields in oriented DNA samples exposed to ionizing radiation with high linear energy transfer at 77 K are discussed. The dependence of radical yields on the orientation of DNA chains relative to the particle flux is being investigated to gain insight into the role of intramolecular energy and charge transfer processes in radical production and decay. Model calculations based on a thermal-spike approximation are presented and their limitations for predicting the orientation dependence of radical yields observed after neutron irradiation (see C. M. Arroyo et al. Int. J. Radiat. Biol. 50, 789 (1986)) are discussed. A more mechanistic model based on the high mobility of excess electrons in hydrated DNA (D. van Lith et al. J. Chem. Soc. Faraday Trans. 1, 82, 2933 (1986)) is outlined.

Dynamic adjustment of emission from both singlets and triplets: the role of excited state conformation relaxation and charge transfer in phenothiazine derivates

2021 ◽  
Author(s):  
Weidong Qiu ◽  
Xinyi Cai ◽  
Mengke Li ◽  
Liangying Wang ◽  
Yanmei He ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Dynamic Adjustment ◽  
Twisted Intramolecular Charge Transfer

Dynamic adjustment of emission behaviours by controlling the extent of twisted intramolecular charge transfer character in excited state.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Helping when desire is low: The role of Expectancy in helping

2020 ◽  
Author(s):  
Małgorzata Kossowska
Keyword(s):  
Experimental Studies ◽  
Helping Behavior ◽  
Perceived Effectiveness ◽  
Do So

One might assume that the desire to help (here described as Want) is the essential driver of helping declarations and/or behaviors. However, even if desire to help is low, helping behavior may still occur if the expectancy regarding the perceived effectiveness of helping is high. We tested these predictions in a set of three experimental studies. In all three, we measured the desire to help (Want) and the Expectancy that the aid would be impactful for the victim; in addition, we manipulated Expectancy in Study 3. In Studies 1 and 3, we measured the participants’ declaration to help while in Study 2, their helping behavior was examined. In all three studies, we used variations of the same story about a victim. The results supported our hypothesis. Thus, the studies help to tease apart the determinants of helping behavior under conditions of lowered desire to do so, an issue of great importance in public policymaking.

The capacity of short term memory from an evolutionary perspective

2019 ◽  
Author(s):  
Majid Manoochehri
Keyword(s):  
Short Term Memory ◽  
Memory Span ◽  
Critical Role ◽  
Experimental Studies ◽  
Cognitive System ◽  
Evolutionary Approach ◽  
Evolutionary Perspective ◽  
Short Term ◽  
Term Memory

Memory span in humans has been intensely studied for more than a century. In spite of the critical role of memory span in our cognitive system, which intensifies the importance of fundamental determinants of its evolution, few studies have investigated it by taking an evolutionary approach. Overall, we know hardly anything about the evolution of memory components. In the present study, I briefly review the experimental studies of memory span in humans and non-human animals and shortly discuss some of the relevant evolutionary hypotheses.

The methodology of experimental research of the feed components extrusion process in order to improve its energy performance

2020 ◽  
pp. 147-152
Author(s):  
E. M. Ratnikov ◽  
D. O. Milko
Keyword(s):  
Experimental Studies ◽  
Energy Performance ◽  
Extrusion Process ◽  
Mathematical Methods ◽  
Screw Extruder ◽  
Mathematical Planning ◽  
Factors Affecting ◽  
Extrusion Processing ◽  
Definition Of

Annotation Purpose. Development of a program and methods for conducting experimental studies of the extrusion process with the definition of parameters and modes of operation of the extruder to improve its energy performance. Methods. Methods of mathematical statistics, synthesis, analysis, description and modeling were used. Results. The application of mathematical methods, in particular mathematical planning, reduces the number of experiments several times, and allows to evaluate the role of influencing factors, obtain a mathematical model of the process and determine the optimal conditions for its parameters and modes, etc. Conclusions. The methodology for experimental studies of a screw extruder is presented with the necessary equipment and methodology for processing the obtained experimental data. A mathematical method of planning, which reduces the number of experiments several times, allows us to evaluate the role of factors affecting productivity and energy intensity is presented. Keywords: extruder, auger, nutrients, research methodology, extrusion, processing, feed.

Directive Effect of Chain Length in Modulating Peptide Nano-assemblies

2020 ◽  
Vol 27 (9) ◽  
pp. 923-929
Author(s):  
Gaurav Pandey ◽  
Prem Prakash Das ◽  
Vibin Ramakrishnan
Keyword(s):  
Electron Microscopy ◽  
Amino Acids ◽  
Light Scattering ◽  
Chain Length ◽  
Self Assembly ◽  
The Self ◽  
Ionic Charge ◽  
Self Assembling ◽  
Biophysical Techniques

Background: RADA-4 (Ac-RADARADARADARADA-NH2) is the most extensively studied and marketed self-assembling peptide, forming hydrogel, used to create defined threedimensional microenvironments for cell culture applications. Objectives: In this work, we use various biophysical techniques to investigate the length dependency of RADA aggregation and assembly. Methods: We synthesized a series of RADA-N peptides, N ranging from 1 to 4, resulting in four peptides having 4, 8, 12, and 16 amino acids in their sequence. Through a combination of various biophysical methods including thioflavin T fluorescence assay, static right angle light scattering assay, Dynamic Light Scattering (DLS), electron microscopy, CD, and IR spectroscopy, we have examined the role of chain-length on the self-assembly of RADA peptide. Results: Our observations show that the aggregation of ionic, charge-complementary RADA motifcontaining peptides is length-dependent, with N less than 3 are not forming spontaneous selfassemblies. Conclusion: The six biophysical experiments discussed in this paper validate the significance of chain-length on the epitaxial growth of RADA peptide self-assembly.

ACE2/Angiotensin-(1-7)/Mas Receptor Axis in Human Cancer: Potential Role for Pediatric Tumors

2020 ◽  
Vol 21 (9) ◽  
pp. 892-901 ◽  
Author(s):  
Ana Luiza Ataide Carneiro de Paula Gonzaga ◽  
Vitória Andrade Palmeira ◽  
Thomas Felipe Silva Ribeiro ◽  
Larissa Braga Costa ◽  
Karla Emília de Sá Rodrigues ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Angiotensin Ii ◽  
Pediatric Cancer ◽  
Pediatric Patients ◽  
Human Cancer ◽  
Experimental Studies ◽  
At1 Receptor ◽  
Pediatric Tumors ◽  
Mas Receptor

Background: Pediatric tumors remain the highest cause of death in developed countries. Research on novel therapeutic strategies with lesser side effects is of utmost importance. In this scenario, the role of Renin-Angiotensin System (RAS) axes, the classical one formed by angiotensinconverting enzyme (ACE), Angiotensin II and AT1 receptor and the alternative axis composed by ACE2, Angiotensin-(1-7) and Mas receptor, have been investigated in cancer. Objective: This review aimed to summarize the pathophysiological role of RAS in cancer, evidence for anti-tumor effects of ACE2/Angiotensin-(1-7)/Mas receptor axis and future therapeutic perspectives for pediatric cancer. Methods: Pubmed, Scopus and Scielo were searched in regard to RAS molecules in human cancer and pediatric patients. The search terms were “RAS”, “ACE”, “Angiotensin-(1-7)”, “ACE2”, “Angiotensin II”, “AT1 receptor”, “Mas receptor”, “Pediatric”, “Cancer”. Results: Experimental studies have shown that Angiotensin-(1-7) inhibits the growth of tumor cells and reduces local inflammation and angiogenesis in several types of cancer. Clinical trials with Angiotensin-( 1-7) or TXA127, a pharmaceutical grade formulation of the naturally occurring peptide, have reported promising findings, but not enough to recommend medical use in human cancer. In regard to pediatric cancer, only three articles that marginally investigated RAS components were found and none of them evaluated molecules of the alternative RAS axis. Conclusion: Despite the potential applicability of Angiotensin-(1-7) in pediatric tumors, the role of this molecule was never tested. Further clinical trials are necessary, also including pediatric patients, to confirm safety and efficiency and to define therapeutic targets.

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