Terms Of Energy Transfer Research Articles

Investigation of non-equilibrium phenomena in nitrogen RF inductively coupled plasma discharges: a state-to-state approach

Abstract This work presents a vibrational and electronic (vibronic) state-to-state (StS) model for nitrogen plasmas implemented within a multi-physics modular computational framework to study non-equilibrium effects in inductively coupled plasma (ICP) discharges. The vibronic master equations are solved in a tightly coupled fashion with the flow governing equations eliminating the need for invoking any simplifying assumptions when computing the state of the plasma, leading to a high-fidelity physical modeling. The model’s computational complexity is reduced via a maximum entropy coarse-graining approach, verified through zero-dimensional isochoric calculations. The coarse-grained StS model is employed to study the plasma discharge in the ICP facility at the von Karman Institute for Fluid Dynamics, Belgium. Results reveal pronounced discrepancies between StS predictions and those obtained based on local thermodynamic equilibrium (LTE) models, which are conventionally used in the simulation of such facilities. The analysis demonstrates a substantial departure of the internal state populations of atoms and molecules from the Boltzmann distribution. This has significant implications for energy coupling dynamics, affecting the discharge morphology. Further analysis reveals a quasi-steady-state population distribution in the plasma core, allowing for the construction of an efficient and ‘self-consistent’ macroscopic two-temperature (2T) formulation. Non-LTE simulations indicate significant disparities between the StS model and the commonly used Park 2T model, whereas the newly proposed 2T model aligns closely with StS simulations, capturing key features of non-equilibrium plasma formation. In particular, the current study highlights the importance of the vibrational-translational energy transfer term in shaping the plasma core morphology, suggesting a notable sensitivity to heavy-impact vibrational excitations and dissociative processes.

Internal Tide Energy Transfers Induced by Mesoscale Circulation and Topography Across the North Atlantic

AbstractThe interactions between the internal tide and the mesoscale circulation are studied from the internal tide energy budget perspective. To that end, the modal energy budget of the internal tide is diagnosed using a high resolution numerical simulation covering the North Atlantic. Compared to the topographic contribution, the advection of the internal tide by the low‐frequency flow component and the horizontal and vertical shear are found to be significant at global scale, while the buoyancy contribution is important locally. The advection of the internal tide by the low‐frequency currents is responsible for a net energy transfer from the large scale to smaller scale internal tide, without exchanges with the low‐frequency flow. On the opposite, the shear of the mesoscale circulation and the buoyancy field are responsible for exchanges between the internal tide and the low‐frequency flow. The importance of the shear increases in the northernmost part of the domain, and a partial compensation between the buoyancy and the shear contributions is found in some areas of the North Atlantic, such as in the Gulf Stream region. In addition, the temporal variability of these energy transfers is investigated. In contrast to topographic scattering, for which the spring‐neap cycle is the dominant frequency, the energy transfer terms driven by low‐frequency motions in areas of strong mesoscale activity are also modulated by variations of the low‐frequency current spatial distribution.

Probing the Nonlinear Interactions of Supertidal Internal Waves Using a High-Resolution Regional Ocean Model

Abstract The internal wave (IW) continuum of a regional ocean model is studied in terms of the vertical spectral kinetic energy (KE) fluxes and transfers at high vertical wavenumbers. Previous work has shown that this model permits a partial representation of the IW cascade. In this work, vertical spectral KE flux is decomposed into catalyst, source, and destination vertical modes and frequency bands of nonlinear scattering, a framework that allows for the discernment of different types of nonlinear interactions involving both waves and eddies. Energy transfer within the supertidal IW continuum is found to be strongly dependent on resolution. Specifically, at a horizontal grid spacing of 1/48°, most KE in the supertidal continuum arrives there from lower-frequency modes through a single nonlinear interaction, whereas at 1/384° and with sufficient vertical resolution KE transfers within the supertidal IW continuum are comparable in size to KE transfer from lower-frequency modes. Additionally, comparisons are made with existing theoretical and observational work on energy pathways in the IW continuum. Induced diffusion (ID) is found to be associated with a weak forward frequency transfer within the supertidal IW continuum. ID is also limited to the highest vertical wavenumbers and is more sensitive to resolution relative to spectrally local interactions. At the same time, ID-like processes involving high-vertical-wavenumber near-inertial and tidal waves as well as low-vertical-wavenumber eddy fields are substantial, suggesting that the processes giving rise to a Garrett–Munk-like spectra in the present numerical simulation and perhaps the real ocean may be more varied than in idealized or wave-only frameworks.

Sub-daily solar wind-magnetosphere energy transfer during major geomagnetic storms of solar cycle 23

The solar wind-magnetosphere energy transfer is one major way of quantifying the impacts of space weather on the Earth's environment. Studies on solar wind-magnetosphere energy transfer in terms of sub-daily time scales are quite sparse. Consequently, in order to investigate storm-time characteristics of the solar wind-magnetosphere energy transfer at a 4-hourly time scale over solar cycle 23, a total of 85 major geomagnetic storms (Dst ≤ −100 nT) were categorized into bins, using the points of minimum Dst values as reference points. Additionally, the monthly statistics of the storms occurrences over the solar cycle was carried out. The statistics followed a semi-annual periodicity, with a lesser peak in the months of May and August, and a major peak in October and November. Furthermore, the energy dissipated was estimated by the summation of aurora precipitation, Joule heating, and the ring current injection. Overall, from the data analyzed, we observed storm-time intensification of energy transfer. The magnetosphere received the highest energy during the time interval 0400–0800 UT (0900–1300 LT in the American sector, and most impactful there), while the lowest energy transfer was recorded between 0000 and 0400 UT (0200–0600 LT in the African/European sector, and least impactful there). We observed a synchrony between the energy dissipated and energy input for the storms’ main phases. Generally, storms driven by a composite of two Interplanetary Coronal Mass Ejections (ICMEs) transients transferred highest energy into the magnetosphere, while those driven by Co-rotating Interaction Regions (CIRs) transferred lowest energy.

Interpreting Negative IOD Events Based on the Transfer Routes of Wave Energy in the Upper Ocean

Abstract The present study adopts an energy-based approach to interpret the negative phase of Indian Ocean dipole (IOD) events. This is accomplished by diagnosing the output of hindcast experiments from 1958 to 2018 based on a linear ocean model. The authors have performed a composite analysis for a set of negative IOD (nIOD) events, distinguishing between independent nIOD events and concurrent nIOD events with El Niño–Southern Oscillation (ENSO). The focus is on investigating the mechanism of nIOD events in terms of wave energy transfer, employing a linear wave theory that considers the group velocity. The proposed diagnostic scheme offers a unified framework for studying the interaction between equatorial and off-equatorial waves. Both the first and third baroclinic modes exhibit interannual variations characterized by a distinct packet of eastward energy flux associated with equatorial Kelvin waves. During October–December, westerly wind anomalies induce the propagation of eastward-moving equatorial waves, leading to thermocline deepening in the central-eastern equatorial Indian Ocean, a feature absent during neutral IOD years. The development of wave energy demonstrates different patterns during nIOD events of various types. In concurrent nIOD–ENSO years, characterized by strong westerly winds, the intense eastward transfer of wave energy becomes prominent as early as October. This differs significantly from the situation manifested in independent nIOD years. The intensity of the energy-flux streamfunction/potential reaches its peak around November and then rapidly diminishes in December during both types of nIOD years. Significance Statement The present study provides an interpretation of wave energy transfer episodes in the upper ocean during the negative phase of the Indian Ocean dipole (IOD) based on the diagnosis of hindcast experiments. The results suggest that the reflection of Kelvin and Rossby waves at the eastern and western boundaries of the Indian Ocean (IO), respectively, accompanied by variations in thermocline depth, plays a crucial role in the development process of IOD events. Specifically, during the negative phase of the IOD, the tropical IO exhibits positive signals of energy-flux streamfunction in the Northern Hemisphere, along with positive signals of energy-flux potential associated with westerly wind anomalies occurring in October–December. These findings highlight the significance of these factors in shaping the characteristics of negative IOD events.

Comparison of forcing schemes to sustain homogeneous isotropic turbulence

Studies of forced homogeneous isotropic turbulence (HIT) of multiphase systems rely on a comprehensive understanding of the single-phase HIT flow to quantify any turbulence modifications due to injection of the dispersed phase. Here, we compare external forcing schemes to generate and sustain single-phase HIT. The considered forcing schemes, Lundgren, Arnold–Beltrami–Childress, and Mallouppas, are based on the application of the body force in physical space to inject energy into the flow at large length scales. Direct numerical simulations are performed in cubic periodic domains of 1283 and 2563 size using a lattice Boltzmann method. The range of the Taylor's Reynolds number achieved is ReλT=24.4–75.4. The Lundgren force takes the longest time to generate turbulence and produces significant fluctuations in the turbulence properties in the statistically stationary state. Additionally, this force interacts with the velocity field in the entire range of wavenumbers, which is not the case for the other two forces. However, the scale-by-scale analysis shows that for the considered forces, the behavior of the non-linear energy transfer, dissipation, and energy injection terms differs only within the initial 16% of the wavenumbers that represent large length scales. After that, all terms behave consistently among each other for different forcing schemes. We conclude that the three considered large-scale forcing schemes do not affect the generated turbulent flow fields at small scales and can be used to study turbulence modification by the dispersed phase.

Velocity and temperature scalings leading to compressible laws of the wall

We exploit the similarity between the mean momentum equation and the mean energy equation and derive transformations for mean temperature profiles in compressible wall-bounded flows. In contrast to prior studies that rely on the strong Reynolds analogy and the presumed similarity between the instantaneous and mean velocity and temperature signals, the discussion in this paper involves the Farve-averaged equations only. We establish that the compressible momentum and energy equations can be made identical to their incompressible counterparts under appropriate normalizations and coordinate transformations. Two types of transformations are explored for illustration purposes: Van Driest (VD)-type transformations and semi-local-type or Trettel–Larsson (TL)-type transformations. In our derivations, it becomes clear that VD-type velocity and temperature transformations hold exclusively within the logarithmic layer. On the other hand, TL-type transformations extend their applicability to incorporate wall-damping effects, at least in principle. Each type of transformation serves its distinct purpose and has its applicable range. However, it is noteworthy that while VD-type transformations can be assessed using measurements obtained from laboratory experiments, TL-type transformations necessitate viscosity and density information typically accessible only through numerical simulations. Finally, we justify the omission of the turbulent kinetic energy transfer term, a term that is unclosed, in the energy equation. This omission leads to closed-form temperature transformations that are valid for both adiabatic and isothermal walls.

Tuning Window Size to Improve the Accuracy of Battery State-of-Charge Estimations Due to Battery Cycle Addition

The primary indicator of battery level in a battery management system (BMS) is the state of charge, which plays a crucial role in enhancing safety in terms of energy transfer. Accurate measurement of SoC is essential to guaranteeing battery safety, avoiding hazardous scenarios, and enhancing the performance of the battery. To improve SoC accuracy, first-order and second-order adaptive extended Kalman filtering (AEKF) are the best choices, as they have less computational cost and are more robust in uncertain circumstances. The impact on SoC estimation accuracy of increasing the cycle and its interaction with the size of the tuning window was evaluated using both models. The research results show that tuning the window size (M) greatly affects the accuracy of SoC estimation in both methods. M provides a quick response detection measurement and adjusts the estimation’s character with the actual value. The results indicate that the precision of SoC improves as the value of M decreases. In addition, the application of first-order AEKF has practical advantages because it does not require pre-processing steps to determine polarization resistance and polarization capacity, while second-order AEKF has better capabilities in terms of SoC estimation. The robustness of the two techniques was also evaluated by administering various initial SoCs. The examination findings demonstrate that the estimated trajectory can approximate the actual trajectory of the SoC.

Born–Oppenheimer molecular dynamics study on collective protein dynamics invoked by ultrafast photoisomerization of retinal chromophore in bacteriorhodopsin

Large-scale quantum-chemistry-based Born–Oppenheimer molecular dynamics simulations of collective protein dynamics of bacteriorhodopsin initiated by photoinduced all-trans→ 13-cis isomerization of retinal Schiff base chromophore compensate for missing information from time-resolved serial femtosecond X-ray crystallography measurements in terms of electronic states, energy transfer, and details of structural dynamics.

Carbon-ion radiotherapy (CIRT) as treatment of pancreatic cancer at HIT: initial radiation plan analysis of the prospective phase II PACK-study

PurposeTo analyze the dose objectives and constraints applied at the prospective phase II PACK-study at Heidelberg ion therapy center (HIT) for different radiobiological models. MethodsTreatment plans of 14 patients from the PACK-study were analyzed and recomputed in terms of physical, biological dose and dose-averaged linear energy transfer (LETd). Both LEM-I (local effect model 1) and the adapted NIRS-MKM (microdosimetric kinetic model), were used for relative biological effectiveness (RBE)-weighted dose calculations (DBio|HIT and DBio|NIRS). A new constraint to the gastrointestinal (GI) tract was derived from the National Institute of Radiological Science (NIRS) clinical experience and considered for plan reoptimization (DBio|NIRS-const_48Gy and DBio|NIRS-const_50.4Gy). The Lyman-Kutcher-Burman (LKB) model of Normal Tissue Complication Probability (NTCP) for GI toxicity endpoints was computed. Furthermore, the computed LETd distribution was evaluated and correlated with Local Control (LC). ResultsOnly two patients showed a LETd98% in the GTV greater than 44 keV/μm. A HIT-dose constraint to the GI of D2cm3=48.6GyRBEHIT was derived from the NIRS experience, in alternative to the standard at HIT Dmax = 45.6 GyRBEHIT. In comparison with the original DBio|HIT,DBio|NIRS-const_48GyandDBio|NIRS-const_50.4Gy resulted in an increase in the ITV’s D98% of 8.7% and 11.3%. The NTCP calculation resulted in a probability for gastrointestinal bleeding of 4.5%, 12.3% and 13.0%, for DBio|NIRS, DBio|NIRS-const_48Gy and DBio|NIRS-const_50.4Gy, respectively. ConclusionThe results indicate that the current standards applied at HIT for CIRT closely align with the Japanese experience. However, to enhance tumor coverage, a more relaxed constraint on the GI tract may be considered. As the PACK-trial progresses, further analyses of various clinical endpoints are anticipated.

Photoluminescence, structural and antibacterial properties of co-doped β-Ca3(PO4)2-type phosphates Ca8CuRE(PO4)7 (RE = Eu–Er)

Novel Ca8CuRE (PO4)7 where RE3+ = Eu3+, Tb3+, Dy3+, Ho3+ and Er3+ were synthesized by a solid-state method in air. The structures of the samples were characterized by powder X-ray diffraction using Rietveld refinement to determine the occupation of crystal sites. The samples are found to have a centrosymmetric structure with space group R3¯c, as shown by dielectric measurements. These synthesized Ca8CuRE(PO4)7 samples have multifunctional properties. The Cu2+ ions provide antibacterial properties, while the rare earth elements ions exhibit luminescence properties, and the β-Ca3(PO4)2-type host is biocompatible. The photoluminescence properties of RE3+ ions were studied and compared with other simmilar Ca8MRE(PO4)7 phosphates, where M is a divalent metal. The photoluminescence intensity quenching in terms of energy transfer from RE3+ to Cu2+ is disscused. The bioactive properties were studied in relation to antibacterial activity against E. coli and S. aureus. All syntesized Ca8CuRE(PO4)7 samples demonstrate very high and stable inhibition of bacteria growth. The correlation between crystal structure and properties is discussed. By combining multiple approaches to the directional design of such materials, several important properties within a single chemical compound to achieve biovisualization and bioactive properties simultaneously can be combined.

(Invited) control of supercontinuum generation due to soliton propagation in fibers with varying dispersion

We demonstrate experimental and numerical studies of supercontinuum generation for silica fibers with longitudinally varying diameter and dispersion. The significant difference in the spectral and temporal transformations of the pump pulse depending on the direction of propagation in the researched fiber samples is shown. Numerical simulations demonstrate the possibility of the supercontinuum spectra management by controlling the longitudinal profile of the fiber. Ways to optimize the output in terms of spectral flatness and efficient energy transfer to the desired wavelength region are presented.

Scaling for Saturated Moist Quasigeostrophic Turbulence

Abstract Much of our conceptual understanding of midlatitude atmospheric motion comes from two-layer quasigeostrophic (QG) models. Traditionally, these QG models do not include moisture, which accounts for an estimated 30%–60% of the available energy of the atmosphere. The atmospheric moisture content is expected to increase under global warming, and therefore, a theory for how moisture modifies atmospheric dynamics is crucial. We use a two-layer moist QG model with convective adjustment as a basis for analyzing how latent heat release and large-scale moisture gradients impact the scalings of a midlatitude system at the synoptic scale. In this model, the degree of saturation can be tuned independently of other moist parameters by enforcing a high rate of evaporation from the surface. This allows for study of the effects of latent heat release at saturation, without the intrinsic nonlinearity of precipitation. At saturation, this system is equivalent to the dry QG model under a rescaling of both length and time. This predicts that the most unstable mode shifts to smaller scales, the growth rates increase, and the inverse cascade extends to larger scales. We verify these results numerically and use them to verify a framework for the complete energetics of a moist system. We examine the spectral features of the energy transfer terms. This analysis shows that precipitation generates energy at small scales, while dry dynamics drive a significant broadening to larger scales. Cascades of energy are still observed in all terms, albeit without a clearly defined inertial range. Significance Statement The effect of moist processes, especially the impact of latent heating associated with condensation, on the size and strength of midlatitude storms is not well understood. Such insight is particularly needed in the context of global warming, as we expect moisture to play a more important role in a warmer world. In this study, we provide intuition into how including condensation can result in midlatitude storms that grow faster and have features on both larger and smaller scales than their dry counterparts. We provide a framework for quantifying these changes and verify it for the special case where it is raining everywhere. These findings can be extended to the more realistic situation where it is only raining locally.

Waveform uncertainty quantification and interpretation for gravitational-wave astronomy

We demonstrate how to quantify the frequency-domain amplitude and phase accuracy of waveform models, and δφ, in a form that could be marginalized over in gravitational-wave inference using techniques currently applied for quantifying calibration uncertainty. For concreteness, waveform uncertainties affecting neutron-star inspiral measurements are considered, and post-hoc error estimates from a variety of waveform models are made by comparing time-domain and frequency-domain analytic models with multiple-resolution numerical simulations. These waveform uncertainty estimates can be compared to GW170817 calibration envelopes or to Advanced LIGO and Virgo calibration goals. Signal-specific calibration and waveform uncertainties are compared to statistical fluctuations in gravitational-wave observatories, giving frequency-dependent modeling requirements for detectors such as Advanced LIGO Plus, Cosmic Explorer, or Einstein Telescope. Finally, the distribution of waveform error for the GW170817 posterior is computed from tidal models and compared to the constraints on δφ or from GWTC-1 by Edelman et al. In general, δφ and can also be interpreted in terms of unmodeled astrophysical energy transfer within or from the source system.

Synthesis of novel luminous lanthanide complexes, crystal structure, thermal decomposition mechanism and fluorescence properties

Nine novel lanthanide complexes with 2-chlorobenzoic acid and 2,2′:6,2′'-terpyridine was synthesized in the ethanol solution. The structural formulae are [Ln (2-ClBA)3(terpy)(H2O)]2, Ln = La(1), Pr(2), Nd(3) and Ln (2-ClBA)3(terpy)(H2O), Ln = Sm(4), Eu(5), Gd(6), Tb(7), Dy(8), Ho(9), 2-ClBA= 2-chlorobenzoate, terpy= 2,2′:6′2’’-terpyridine. X-ray diffraction shows that these compounds form two types of structures: mononuclear and dimeric. Surprisingly, the complexes 4–9 have pseudo-dimeric supramolecular structures. The complexes were characterized by infrared and Raman spectroscopy. The thermal decomposition mechanism of nine complexes was studied by TG-DTG-DSC/FTIR coupling technique. Finally, the fluorescence of solid complexes 4, 5, 7, and 8 was tested, and the fluorescence lifetimes of complexes 5 and 7 are 637(6) and 331(5) μs, respectively. The fluorescence quantum yield of complex 5 is 14.3(8)%. The luminescence mechanism in terms of energy transfer is discussed.

Quantifying Daytime Heating Biases in Marine Air Temperature Observations from Ships

Abstract Marine air temperatures recorded on ships during the daytime are known to be biased warm on average due to energy storage by the superstructure of the vessels. This makes unadjusted daytime observations unsuitable for many applications including for the monitoring of long-term temperature change over the oceans. In this paper a physics-based approach is used to estimate this heating bias in ship observations from ICOADS. Under this approach, empirically determined coefficients represent the energy transfer terms of a heat budget model that quantifies the heating bias and is applied as a function of cloud cover and the relative wind speed over individual ships. The coefficients for each ship are derived from the anomalous diurnal heating relative to nighttime air temperature. Model coefficients, cloud cover, and relative wind speed are then used to estimate the heating bias ship by ship and generate nighttime-equivalent time series. A variety of methodological approaches were tested. Application of this method enables the inclusion of some daytime observations in climate records based on marine air temperatures, allowing an earlier start date and giving an increase in spatial coverage compared to existing records that exclude daytime observations. Significance Statement Currently, the longest available record of air temperature over the oceans starts in 1880. We present an approach that enables observations of air temperatures over the oceans to be used in the creation of long-term climate records that are presently excluded. We do this by estimating the biases inherent in daytime temperature reports from ships, and adjust for these biases by implementing a numerical heat-budget model. The adjustment can be applied to the variety of ship types present in observational archives. The resulting adjusted temperatures can be used to create a more spatially complete record over the oceans, that extends further back in time, potentially into the late eighteenth century.

Effect of heat source on kinetic energy transfer in compressible homogeneous shear turbulence

The effects of heat sources on kinetic energy transfer in compressible homogeneous shear turbulence are studied using numerical simulations at turbulent Mach numbers 0.1 and 0.4 for two levels of heat source. It is found that the strong heat source can significantly enhance both positive and negative components of subgrid-scale (SGS) kinetic energy flux and pressure–dilatation. After adding a strong heat source, compression motions enhance the positive SGS flux, and expansion motions enhance the negative SGS flux at a low turbulent Mach number. According to the Helmholtz decomposition, we found that the solenoidal and dilatational components of pressure–dilatation and SGS kinetic energy flux are increased greatly by a strong heat source at a low turbulent Mach number. The solenoidal mode plays a dominant role in the kinetic energy transfer process, but the contribution of the dilatational mode is not negligible. The dilatational component of the production term is increased by a strong heat source at a low turbulent Mach number, providing the main source of kinetic energy to the dilatational mode. The strong heat source also enhances the kinetic energy exchange between solenoidal mode and dilatational mode through nonlinear advection at a low turbulent Mach number. Moreover, the strong heat source enhances pressure anisotropy, redistribution of the kinetic energy of two transverse components, and energy transfer from internal energy to the kinetic energy through pressure–dilatation term. At a high turbulent Mach number, the strong heat source has little impact on the solenoidal and dilatational components of kinetic energy transfer terms.

Biological activity of some thiazolyl‐thiadiazines as BACE‐1 inhibitors for Alzheimer's disease in the light of density functional theory based quantum descriptors

AbstractThis paper presents first report on a systematic investigation on developing quantum chemical descriptors on understanding biological activity (pIC50) of a series of 10 thiazolyl‐thiadiazines (ID‐01 to ID‐10) as Beta site amyloid precursor protein cleaving enzyme 1 (BACE‐1) protein inhibitors for Alzheimer diseases, under density functional theory. The interactions between inhibitors and model biomolecule are studied in terms of charge and energy transfer, where the target biomolecule at the host BACE‐1 protein is identified from the family of 20 amino acids, which are universal to all living organisms. The present study identifies electron affinity (EA), total electronic energy (E), and the electron transfer with amino acid (∆E) of thiazolyl‐thiadiazines as promising descriptors, which can explain about 90% of observed biological activity. The developed regression model for training set is also validated for unknown test set of homologous compounds. The developed quantum chemical descriptors for prediction of the biological activity of thiazolyl‐thiadiazines will certainly be an excellent addition in the QSAR parlance of drug development.

Dosimetry and microdosimetry of monoenergetic neutrons using recombination chamber – Measurements and Monte Carlo simulations

The REM-2 tissue-equivalent recombination chamber was used for dosimetry measurements performed in monoenergetic neutron reference fields at National Physical Laboratory, UK for the neutron energy range from 144 keV to 5 MeV. Measurement data were used for the determination of the recombination index of radiation quality, ambient dose, and finally ambient dose equivalent, H*(10). Results justify the relevance of the application of this measuring method in mixed radiation fields with dominant neutron component, which are present, for example, at photon and proton radiotherapy facilities. The relative response of the chamber in terms of H*(10) in the investigated neutron energy range, resulted in the correction factor at the maximum level of 1.25. Analysis of the saturation curves and use of the recombination microdosimetric method, RMM resulted in the determination of dose distribution at a nanometric level in terms of restricted linear energy transfer, LΔ. Monte Carlo simulations performed with the FLUKA code allowed to obtain double-differential distributions of L which were compared with those obtained during measurements. Comparison between measured and simulated data showed that RMM is a reliable method for microdosimetric investigations in mixed neutron-gamma fields present around medical radiotherapeutic units.

Rose Bengal-Modified Upconverting Nanoparticles: Synthesis, Characterization, and Biological Evaluation.

High-quality upconverting NaYF4:Yb3+,Er3+ nanoparticles (UCNPs; 26 nm in diameter) based on lanthanides were synthesized by a high-temperature coprecipitation method. The particles were modified by bisphosphonate-terminated poly(ethylene glycol) (PEG) and Rose Bengal (RB) photosensitizer. The particles were thoroughly characterized using transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, FTIR, and X-ray photoelectron and upconversion luminescence spectroscopy in terms of morphology, hydrodynamic size, composition, and energy transfer to the photosensitizer. Moreover, the singlet oxygen generation from RB-containing UCNPs was investigated using 9,10-diphenylanthracene probe under 980 nm excitation. The cytotoxicity of UCNPs before and after conjugation with RB was evaluated on highly sensitive rat mesenchymal stem cells (rMSCs) and significant differences were found. Correspondingly, consi-derable variations in viability were revealed between the irradiated and non-irradiated rat glioma cell line (C6) exposed to RB-conjugated UCNPs. While the viability of rMSCs was not affected by the presence of UCNPs themselves, the cancer C6 cells were killed after the irradiation at 980 nm due to the reactive oxygen species (ROS) production, thus suggesting the potential of RB-conjugated PEG-modified UCNPs for applications in photodynamic therapy of cancer.