Excitation Time Research Articles

Towards an understanding of the mechanisms of therapeutic ultrasound on biomimetic models of cancer

Therapeutic ultrasound is transforming the treatment of a range of malignancies in a non-invasive and non-systemic manner. Low-intensity ultrasound (LIUS) has been proposed to selectively eradicate cancer cells but the underlying biological mechanisms remains unknown. To gain an understanding of this phenomenon, 2D breast cancer monocultures were sonicated at varying acoustic intensities (0.1–0.5 W·cm−2) and excitation times (1–10 minutes). Additionally, 2D monocultures consisting of healthy cell lines were sonicated at varying acoustic intensities (0.1–0.5 W·cm−2) to determine any distinguishing biological responses. To begin recapitulating in vivo conditions, breast cancer cells were also seeded into 3D collagen hydrogels. At a 1 MHz frequency, 20% duty cycle, 100 Hz pulse repetition frequency, a significant drop in cancer cell viability is observed at a sonication intensity of 0.5 W·cm−2 and over 10 minute excitation time. Healthy counterparts subjected to the same parameters revealed no distinguishing effects. Sonication of breast cancer cells seeded in 3D collagen hydrogels revealed no effect in cell viability compared to non-sonicated controls. The acoustic wave propagation software OptimUS was used to determine the influence culturing plates have on ultrasound propagation, revealing these materials can significantly vary the acoustic field at frequencies relevant to LIUS.

Study of optical properties birefringent of hema - DR13

The following paper is a detailed study of the optical properties of HEMA-DRI3 from optical birefringence can be induced azopolymeric material. Based on the method of two-photon absorption, anisotropy is generated due to the reorientation of the chromophores in the sample of HEMA-DR13. Using allow-power laser He-Ne, and a laser Nd-YAG medium power, it was possible to implement an optical system which allows observing the subsequent quantification of photoinduced bireftingence in said material. Subsequently comparing the results obtained with different theoretical models, thereby determining the characteristic times (time of excitation and relaxation time) of HEMA-DR13. Additionally, a study of the response signal based on the excitation power and the temperature of the material being able to obtain the relationship between this variables and the intensity of bircfringence.

1,1,1-Trifluoro-5,5-dimethyl-2,4-hexanedione based ternary complexes of Eu(III): Synthesis, structural and luminescence investigations

In this current study, we have synthesized four europium(III) complexes utilizing a tri-fluorinated β-diketone moiety: 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (TFDH) with auxiliary ligand: 2,2′- bipyridine and its derivatives. FTIR, UV–Vis and luminescence spectroscopic characterizations were implemented for evaluation of the bonding and luminous characteristics in synthesized europium(III) complexes. Eight-coordination environment around Eu3+ ion has been demonstrated by 1H NMR spectral data. Photoluminescence (PL) study of these complexes has been carried out in powdered form. Characteristic red emitting behavior of Eu(III) ion was observed corresponds to the transition of 5D0→7F2 in PL spectra of Eu(III) complexes. The CIE (Commission Internationale de l'Eclairage) chroma coordinates 1931 and CCT (Correlated Color Temperature) values were derived from the information obtained from the emission spectra. The Judd-Ofelt intensity parameters (Ωτ) and excited state deactivation time (τ) in solid state have also been estimated. In the synthesized Eu(III) complexes, the europium ion was present in a highly polarizable ligand field, as demonstrated by the higher values of Ω2. Values of band gap i.e. optical and electronic as well as the red luminous nature of prepared complexes showed up their utilization in display devices.

Timely Questions Emerging in Chronobiology: The Circadian Clock Keeps on Ticking.

Chronobiology investigations have revealed much about cellular and physiological clockworks but we are far from having a complete mechanistic understanding of the physiological and ecological implications. Here we present some unresolved questions in circadian biology research as posed by the editorial staff and guest contributors to the Journal of Circadian Rhythms. This collection of ideas is not meant to be comprehensive but does reveal the breadth of our observations on emerging trends in chronobiology and circadian biology. It is amazing what could be achieved with various expected innovations in technologies, techniques, and mathematical tools that are being developed. We fully expect strengthening mechanistic work will be linked to health care and environmental understandings of circadian function. Now that most clock genes are known, linking these to physiological, metabolic, and developmental traits requires investigations from the single molecule to the terrestrial ecological scales. Real answers are expected for these questions over the next decade. Where are the circadian clocks at a cellular level? How are clocks coupled cellularly to generate organism level outcomes? How do communities of circadian organisms rhythmically interact with each other? In what way does the natural genetic variation in populations sculpt community behaviors? How will methods development for circadian research be used in disparate academic and commercial endeavors? These and other questions make it a very exciting time to be working as a chronobiologist.

From Return to Normal to a “New Normal”? A Call to Revive Music Teacher Motivation and Reflection

What might the field of music education do to learn, grow, and reinvent itself as we emerge from COVID-19 and virtual learning? Implied in the “return to normal” discourse, permeating all areas of music education in the year or more following virtual learning is the felt need to keep going and return to music education as usual. Yet significant changes, both positive and negative, occurred during virtual learning and music teachers have not received adequate time to reflect and consider new possibilities. In this article, I reject the idea of “return to normal” and call for a “new normal.” While this new normal might take many forms, I offer one possibility for middle level general music focused on student (as well as teacher) motivation. As music educators, we face a potentially exciting time to re-envision the future of music education—but only if we pause, reflect, and imagine a “new normal.”

Spectral Fidelity

This is a very exciting time for the spectroscopic community. So much exquisite data are available in several fields, such as exoplanets, stars, galaxies and quasars, thanks to high-resolution, high-precision and accuracy spectrographs. It is time to discuss spectral fidelity and what we can expect from the future.

Double-Model Decay Strategy Integrating Persistent Photogenic Radicaloids with Dynamic Circularly Polarized Doublet Radiance and Triplet Afterglow.

Organic phosphors integrating circularly polarized persistent luminescence (CPPL) across the visible range are widespread for applications in optical information encryption, bioimaging, and 3D display, but the pursuit of color-tunable CPPL in single-component organics remains a formidable task. Herein, via in situ photoimplanting radical ion pairing into axial chiral crystals, we present and elucidate an unprecedented double-module decay strategy to achieve a colorful CPPL through a combination of stable triplet emission from neutral diphosphine and doublet radiance from photogenic radicals in an exclusive crystalline framework. Owing to the photoactivation-dependent doublet radiance component and an inherent triplet phosphorescence in the asymmetric environment, the CPL vision can be regulated by altering the photoactivation and observation time window, allowing colorful glow tuning from blue and orange to delayed green emission. Mechanism studies clearly reveal that this asymmetric electron migration environment and hybrid n-π* and π-π* instincts are responsible for the afterglow and radical radiance at ambient conditions. Moreover, we demonstrate the applications of colorful CPPL for displays and encryption via manipulation of both excitation and observation times.

Collisional-radiative modeling of shock-heated nitrogen mixtures

A three-temperature collisional-radiative model for shock-heated nitrogen–argon mixtures is developed to facilitate the study of nonequilibrium electronic excitation and ionization behind strong shock waves. Model predictions accurately reproduce measurements of N2 dissociation for mixtures of 2%–10% N2 in argon, with some discrepancies observed for 20% N2 mixtures. Potential causes of the discrepancies are discussed. Net dissociation in mixtures containing 20% N2 is significantly impacted by the dissociation of N2(A), the first excited electronic state of N2, indicating that molecular electronic excitation can affect net dissociation in shock-heated nitrogen flows. The collisional-radiative model successfully predicts the three-stage behavior and induction time observed in concentration measurements of atomic nitrogen in its fourth excited state, the 3s4P level, behind reflected shocks. Mechanisms for the observed behavior are discussed, which deviate from those inferred using a simpler kinetic model. Excited state number density predictions are strongly influenced by the modeling of radiation self-absorption and the inclusion of the measured non-ideal pressure rise. At higher N2 concentrations, the measured data indicate increased efficiency of atomic nitrogen electronic excitation in collisions with N as compared to collisions with N2 and Ar. A global sensitivity analysis of the excited state predictions is then performed, identifying the processes in the kinetic model that most sensitively influence the predicted excited state time history and further clarifying the dominant mechanisms affecting the experimental observables.

Quantifying Dielectric Material Charge Trapping and De-Trapping Ability Via Ultra-Fast Charge Self-Injection Technique.

Recently, utilizing the air breakdown effect in the charge excitation strategy proves as an efficient charge injection technique to increase the surface charge density of dielectric polymers for triboelectric nanogenerators (TENGs). However, quantitative characterization of the ability of dielectric polymers to trap reverse charges and the effect on the startup time of secondary self-charge excitation (SSCE) are essential for extensive applications. Here, an ultra-fast charge self-injection technique based on a self-charge excitation strategy is proposed, and a standard method to quantify the charge trapping and de-trapping abilities of 23 traditional tribo-materials is introduced. Further, the relationship among the distribution of dielectric intrinsic deep, shallow trap states, and transportation of trapped charges is systematically analyzed in this article. It shows that the de-trapping rate of charges directly determines the reactivation and failure of SSCE. Last, independent of TENG contact efficiency, an ultra-high charge density of 2.67 mC m-2 and an ultra-fast startup time of SSCE are obtained using a 15µm poly(vinylidene fluoride-trifluoroethylene) film, breaking the historical record for material modification. As a standard for material selection, this work quantifies the charge trapping and de-trapping ability of the triboelectric dielectric series and provides insights for understanding the charge transport in dielectrics.

Multicolor Afterglow Carbon Dots: Luminescence Regulation, Preparation, and Application

AbstractAfterglow materials have attracted much attention owing to their long luminescence lifetimes, large Stokes shifts, and emission without real‐time excitation. Compared with traditional organic afterglow materials, carbon dots (CDs), as a new afterglow material, have superior properties such as easy preparation, low toxicity, and low cost. The emission color of afterglow CDs can be regulated by external factors such as excitation wavelength, temperature, and time, which is highly significant for expanding the diversified applications to make them available for biotechnology and information applications. This review summarizes the research progress of multicolor afterglow CDs in recent years, including luminescence regulation strategies, preparation methods, and applications. First, the multicolor afterglow CDs are classified into three strategies: multicolor room temperature phosphorescence (RTP), thermally activated delayed fluorescence converted to RTP, and delayed fluorescence based on Förster resonance energy transfer, and the strategies for regulating their luminescence properties are analyzed. Second, the preparation methods of achieving multicolor afterglow CDs are summarized in both matrix‐free and matrix‐confined aspects. Then, applications in anticounterfeiting and information encryption, sensing and bioimaging are introduced in detail. Finally, the future challenges and opportunities of multicolor afterglow CDs are prospected to provide ideas for their controlled design and wide application.

Neuronal excitability modulates developmental time of Drosophila melanogaster

Developmental time is a fundamental life history trait that affects the reproductive success of animals. Developmental time is known to be regulated by many genes and environmental conditions, yet mechanistic understandings of how various cellular processes influence the developmental timing of an organism are lacking. The nervous system is known to control key processes that affect developmental time, including the release of hormones that signal transitions between developmental stages. Here we show that the excitability of neurons plays a crucial role in modulating developmental time. Genetic manipulation of neuronal excitability in Drosophila melanogaster alters developmental time, which is faster in animals with increased neuronal excitability. We find that selectively modulating the excitability of peptidergic neurons is sufficient to alter developmental time, suggesting the intriguing hypothesis that the impact of neuronal excitability on DT may be at least partially mediated by peptidergic regulation of hormone release. This effect of neuronal excitability on developmental time is seen during embryogenesis and later developmental stages. Observed phenotypic plasticity in the effect of genetically increasing neuronal excitability at different temperatures, a condition also known to modulate excitability, suggests there is an optimal level of neuronal excitability, in terms of shortening DT. Together, our data highlight a novel connection between neuronal excitability and developmental time, with broad implications related to organismal physiology and evolution.

Excitation time imaging condition reverse time migration based on physics-informed neural network traveltime calculation with wavefield decomposition using optical flow vector

Abstract Although the excitation-time imaging condition offers a lower memory consumption and higher computational efficiency compared to cross-correlation imaging condition, it has not been widely used in industrial applications because of the accuracy problem of traveltime calculation and the influence of low-wave-number noise. In this paper, we introduce the physics-informed neural network (PINN) algorithm to achieve a high-precision traveltime calculation of the source forward wavefield. Subsequently, we introduce a technique for high-precision wavefield decomposition of the reverse-time wavefield via the optical flow vector, enabling us to realize a correlation-weighted stacking imaging of each wavefield. Model experiments and real data processing show that the proposed traveltime calculation algorithm based on PINN offers high accuracy and good applicability in the excitation time reverse-time migration imaging of complex models, and correlation-weighted stacking imaging based on optical flow vector-based wavefield separation can significantly suppress the noise with low wavenumber and achieve high-precision imaging of complex models.

Detonation development in H2, CH4, and PRF-air mixtures under engine-relevant conditions: From a chemical perspective

The progression of highly boosted internal combustion engines (ICEs) faces impediments due to the super-knock phenomenon primarily associated with detonation development during end gas autoignition. Although it is well known that hot spot potentially triggers super-knock, quantitative prediction of super-knock and detonation development across diverse states and fuels remains a challenge. This study numerically investigates the transient autoignition process induced by a hot spot, considering different initial states and fuels (including alternative fuels H2, CH4, and conventional PRFs), with an emphasis on the chemical effects. It is found that the intense exothermic stage (IES) in a stoichiometric H2/air mixture greatly differs from those in hydrocarbon/air (CH4/air and PRF/air) and lean or diluted H2/air mixtures. Through sensitivity analysis, key elementary reactions dominating the autoignition are identified, attributing their impact on the IES primarily to their influence on the radical pool rather than on the heat release rate. It is found that only reactions H + O2⇌O+OH and H2O2(+M)⇌OH+OH(+M) significantly affect both excitation time and ignition delay time, suggesting that the kinetic pathway controlling the IES differs somewhat from that governing the overall ignition. For the autoignition induced by a hot spot, two types of detonation feature are identified: one corresponds to stoichiometric H2/air with broad detonation regime and short excitation time, while the other is associated with other fuel/air mixtures exhibiting relatively narrow detonation regime and prolonged excitation time. These findings highlight that the excitation time predominantly governs the detonation development. All hydrogen/air mixtures (stoichiometric, lean, and diluted) manifest a suppressed detonation intensity compared to hydrocarbon/air mixtures. Moreover, due to its significantly higher reactivity in the IES, stoichiometric H2/air has an additional normal detonation sub-mode for hot spot with larger temperature gradient. This sub-mode greatly expands the detonation regime and thereby results in a notably higher detonation propensity for the stoichiometric H2/air mixture.

Ho3+ codoping of GGAG:Ce: a detailed analysis of acceleration of scintillation response and scintillation efficiency loss.

In this study, we investigate the effects of Ho3+ codoping on the luminescence and scintillation properties of GGAG:Ce, with a particular focus on timing properties and scintillator efficiency. The research reveals that Ho3+ codoping and subsequent resonant energy transfer from Ce3+ to Ho3+ can significantly reduce the 5d1 excited state decay time of Ce3+ and shorten scintillation pulses of GGAG:Ce registered by using photomultipliers, although this reduces scintillator efficiency as well. The study presents a detailed analysis of the loss of scintillator efficiency due to Ho3+ codoping, identifying the most significant loss pathways and estimating their impact. The findings suggest that Ho3+ codoping is an effective method for accelerating the scintillation response of GGAG:Ce. Furthermore, the study presents a high level of consistency of the Ce3+ kinetics with the Inokuti-Hirayama model and with results obtained in the previous studies on similar systems, demonstrating the predictability of the effect of RE3+ codoping on scintillator properties.

Generalised performance of neural network controllers for feedforward active noise control of nonlinear systems

Advances in digital technologies have allowed for the development of complex active noise and vibration control solutions that have been utilised in a wide range of applications. Such control systems are commonly designed using linear filters, which cannot fully capture the dynamics of nonlinear systems. To overcome such issues, it has been shown that replacing linear controllers with Neural Networks (NNs) can improve control performance in the presence of nonlinearities. Many real systems are subject to non-stationary disturbances where the magnitude of the system excitation time dependent. However, within the literature, the performance of single NN controllers across different excitation levels has not been thoroughly explored. In this paper, a method of training Multilayer Perceptrons (MLPs) for single-input-single-output (SISO) feedforward acoustic noise control is presented. In a simple time-discrete simulation, the performance of the trained NNs is investigated for different excitation levels. The effects of the properties of the training data and NN controller on generalised performance are explored. It is demonstrated that the generalised control performance of the MLP controllers falls as the range of magnitudes included in the training data is increased, and that this performance can be recovered by increasing the number of hidden nodes within the controller.

Magnetic field modulation of polaron relaxation coherence effects in III-V semiconductor Gaussian quantum wells

We have theoretically investigated the effects of the cyclotron frequency of magnetic field, the initial depth and the range of the asymmetrical Gaussian confinement potential on the vibrational frequency, ground state energy, excited state energy and coherence time of polaron in III-V semiconductors by using a linear combination operator and unitary transformations methods. Through numerical calculations, we find some interesting phenomena that the polaron decreases the energy level and releases the energy of a phonon to jump. From the point of view of the energy level of the polaron, which is αℏωLO energy lower than that of the electron, and the transition of the polaron to the ground state will have a change in lattice position, and the lattice relaxation phenomenon will appear. The theoretical study of the quantum coherence effect of polaron energy levels will provide guidance for the development of optoelectronic devices and the transmission of quantum information.

Formation of Innovative Components in the Hospitality Industry Enterprise

Purpose: The article is devoted to the formation of innovative technologies at enterprises of the hospitality industry. It is substantiated that innovative technologies will allow hoteliers and restaurateurs to a chieve certain advantages over competitors; innovation is a source of long-term economic growth, because those enterprises that constantly apply innovative approaches will always work successfully and obtain high results from their production and economic activities. The objective of the article is to generalize and systematize the formation of the main components of the innovative development of enterprises in the hospitality industry and their significance and use at the modern stage of management. Design / Methodology / Approach: To achieve the aim of the study, the following scientific methods were used: historiographical, comparative, analysis and synthesis methods. Findings: We are living in the most exciting time in human history. Technology is developing exponentially, not linearly as it used to be, and the use of modern technologies and innovations has become an integral part of the survival of businesses in a pandemic and martial law. Modern technologies allow maintaining a high level of service, expanding the range of services, improving the management system, strengthening control over the work of staff, and ensuring a high level of security for guests. Therefore, their study is an urgent task today. Today’s realities of life dictate working conditions for all enterprises of various forms of ownership. Businesses in the hospitality industry are the most vulnerable to these changes. Therefore, hotels and restaurants must focus on their audience, and their owners must do everything possible to expand the number of consumers and protect their business from risks and losses. An important condition for their implementation should be the ability of entrepreneurs to adapt to the new conditions that have developed at this stage of business and to be able to timely and effectively implement various types of innovations (technological, production, logistic, economic, social, informational), skilfully connect them in management activities. For many enterprises, the inability of managers to understand the need and achieve innovative renewal remains a problem, as there is a mis understanding of the role of information as a basic resource of enterprise management. Because innovative technologies today, more than ever before, are becoming a valuable resource for hotel and restaurant businesses. Originality / Value: It is proved that innovation is an integral element in the development of hospitality industry enterprises. Practical Meaning: A number of features of innovative activity in the hospitality industry are highlighted. Further Research: Development of methodological support for the analysing the effectiveness of innovations at enterprises of the hospitality industry.

Research on near-infrared ultrafast excited carrier dynamics of a pyrene-based derivative and its application in femtosecond laser

Femtosecond laser, compared to continuous wave (c.w.) or nanosecond laser, has shown great promise in diversities of frontier applications because of its extremely short pulse width, high peak power and low thermal effect. In order to obtain femtosecond laser output, the design of suitable saturable absorber (SA) materials as a nonlinear modulation device is a key issue for a given laser system. However, the previous SA materials are limited in inorganic semiconductors, which have some constraints such as narrow working wavelength ranges, complex preparation process and high cost. By contrast, organic semiconductors have high molecular design freedom, good flexibility, simple preparation process, and low cost, and would act as an ideal SA material. Here, we report a novel strategy to tune and realize the femtosecond laser out by employing an organic small molecule SA of (Z)-2-(4-(pyrene-1-yl) phenyl)-3-(4-(1,2,2-triphenylvinyl) phenyl) acrylonitrile (Py-TPE). We show that Py-TPE has an ultrafast excited carrier relaxation time less than 20 ps, shorter than most of inorganic semiconductor materials. More importantly, by depositing such Py-TPE on the surface of tapered fiber as an SA device in Er-doped fiber laser system, an ultrafast fiber laser output with a pulse width as narrow as 447 fs and good stability was realized. This is the first report, to the best of our knowledge, to achieve femtosecond laser by taking advantage of the Py-TPE with ultrafast excited carrier relaxation time. These results demonstrate that Py-TPE is a novel organic saturable absorption material with great potential application in ultrafast laser and photonics.

Relationship between Cortical Excitability and Complex Reaction Time

Introduction: The purpose of this investigation was to investigate the relationships between cortical excitability and complex reaction times (RT).To carry out this study, we performed transcranial magnetic stimulation (TMS) to test cortical excitability and the Posner paradigm to investigate the RT and errors. Investigation of motor cortex excitability and reaction time. Methods: Twenty male right-handed participants were chosen for this investigation (Age: 23.5±2.1 years; Height 177.1±2.8 cm; Body mass 73.2±3.3 Kg). Results: A significant positive correlation emerged between resting motor threshold (rMT) and RT and between motor evoked potential (MEP) latency and RT(p<0.001). The results also show a significant positive correlation (p<0.001) between rMT and the percentage of errors and a significant positive correlation (p<0.05) between MEP latency (ms) and the percentage of errors. The main results of the study showed that subjects who showed lower motor activation thresholds were able to respond faster and they also showed a significantly lower error rate compared to subjects who showed higher motor activation thresholds. Conclusion: To the best of our knowledge, our study seems to confirm the presence of a relationship between neuro-physiological parameters (MEP latency and rMT), RT and percentage of correct answers.

Challenges in surface‐enhanced Raman scattering signal for ethephon detection: Theoretical and experimental approaches

AbstractEthephon, a widely used growth regulator in fruits and vegetables, requires careful monitoring because of its toxicity. However, as far as we know, only two works are found in the literature regarding surface‐enhanced Raman scattering (SERS) ethephon detection. Indeed, obtaining the SERS signal revealed to be challenging. Therefore, we have evaluated the SERS signal of ethephon using theoretical (as density functional theory and charge‐assisted fragment interaction) and experimental approaches, addressing this limited literature knowledge. Theoretical Raman spectra with Ag or Au atoms at reactive sites exhibited enhanced ethephon SERS signal via AgCl bonding, consistent with the experimental data. Multiple experimental procedures were employed to obtain the SERS signal, including pH variations, salt addition, excitation laser lines, time dependency, and different SERS substrates (Ag colloid and Ag island films). Salt addition (NaCl) improved SERS signal, correlating with Ag colloid aggregation. Analysis in Ag colloid showed the pH 7.0 as optimal for ethephon detection, using freshly prepared Ag colloid + ethephon dispersion with ethephon powder being directly dissolved into Ag colloid. Only the AgCl band intensity improved with time. Ag colloid (wet medium — 633 nm laser line) outperformed Ag island films (dry medium — 785 nm laser line).