Probing the Nature of Single-Photon Emitters in a WSe2 Monolayer by Magneto-Photoluminescence Spectroscopy.

Monolayer transition metal dichalcogenides (TMDs) have emerged as promising materials to generate single-photon emitters (SPEs). While there are several previous reports in the literature about TMD-based SPEs, the precise nature of the excitonic states involved in them is still under debate. Here, we use magneto-optical techniques under in-plane and out-of-plane magnetic fields to investigate the nature of SPEs in WSe2 monolayers on glass substrates under different strain profiles. Our results reveal important changes on the exciton localization and, consequently, on the optical properties of SPEs. Remarkably, we observe an anomalous PL energy redshift with no significant changes of photoluminescence (PL) intensity under an in-plane magnetic field. We present a model to explain this redshift based on intervalley defect excitons under a parallel magnetic field. Overall, our results offer important insights into the nature of SPEs in TMDs, which are valuable for future applications in quantum technologies.

Dosimetry at cellular level for the alpha-emitting radionuclides actinium-225, astatine-211 and radium-223 for bone metastasis cells from castration resistant prostate cancer.

Objectives.The aim of this work is to evaluate energy deposition in the nucleus and cytoplasm in targeted alpha therapy of metastatic castration-resistant prostate cancer by modeling two cell lines, PC3 (osteolytic) and LNCaP C4-2 (osteoblastic), for actinium-225, astatine-211, and radium-223 and their progeny, using Monte Carlo simulations with the GATE/Geant4 code.Approach.We developed single cell and cell clusters models to Monte Carlo simulations, performed on the GATE platform version 9.3, with the GEANT4-DNA physics list emstandard_opt3_mixed_dna for At-211, Ac-225 and Ra-223 progenies. We considered three radionuclide distributions as a sources: the nucleus, the cytoplasm and the whole cell.Main results.When the nucleus was considered as a target, theS-values (N←N) calculated for At-211, Ac-225 and Ra-223 progenies were significantly higher, within 60%-90%, thanS-values (N←Cy), demonstrating less influence of cytoplasm only internalization. When the cytoplasm was considering as a target, theS-values (Cy←Cy) calculated for At-211, Ac-225 and Ra-223 progeny were significantly higher, within 30%-90%, than theS-values (Cy←N). When no progeny migration occurs and for target nucleus , the cumulativeS-values (N←N) calculated for At-211, Ac-225 and Ra-223 were significantly higher, within 50%-70%, than theS-values (N←N) computed for At-211, Ac-225, and Ra-223. Comparing the cumulativeS-values, Ac-225 and Ra-223 therapies is more effective, in terms of deposited energy in a target, than that with At-211.Significance.The data presented in this research indicates that Ac-225 therapy may be the optimum choice due to the energy deposited in the nucleus, as long as the recoil effects and redistribution of progeny are understood. In contrast, At-211 is an alternative to avoid progeny migration. However, to completely analyze the efficacy of radionuclide therapy, other parameters must be considered, such as biological half-life, stability of the transport molecule, progeny migration, excretion pathways, and uptake in different organs.

Cellular lethal damage of 64Cu incorporated in mammalian genome evaluated with Monte Carlo methods.

Purpose: Targeted Radionuclide Therapy (TRT) with Auger Emitters (AE) is a technique that allows targeting specific sites on tumor cells using radionuclides. The toxicity of AE is critically dependent on its proximity to the DNA. The aim of this study is to quantify the DNA damage and radiotherapeutic potential of the promising AE radionuclide copper-64 (64Cu) incorporated into the DNA of mammalian cells using Monte Carlo track-structure simulations. Methods: A mammalian cell nucleus model with a diameter of 9.3 µm available in TOPAS-nBio was used. The cellular nucleus consisted of double-helix DNA geometrical model of 2.3 nm diameter surrounded by a hydration shell with a thickness of 0.16 nm, organized in 46 chromosomes giving a total of 6.08 giga base-pairs (DNA density of 14.4 Mbp/µm3). The cellular nucleus was irradiated with monoenergetic electrons and radiation emissions from several radionuclides including 111In, 125I, 123I, and 99mTc in addition to 64Cu. For monoenergetic electrons, isotropic point sources randomly distributed within the nucleus were modeled. The radionuclides were incorporated in randomly chosen DNA base pairs at two positions near to the central axis of the double-helix DNA model at (1) 0.25 nm off the central axis and (2) at the periphery of the DNA (1.15 nm off the central axis). For all the radionuclides except for 99mTc, the complete physical decay process was explicitly simulated. For 99mTc only total electron spectrum from published data was used. The DNA Double Strand Breaks (DSB) yield per decay from direct and indirect actions were quantified. Results obtained for monoenergetic electrons and radionuclides 111In, 125I, 123I, and 99mTc were compared with measured and calculated data from the literature for verification purposes. The DSB yields per decay incorporated in DNA for 64Cu are first reported in this work. The therapeutic effect of 64Cu (activity that led 37% cell survival after two cell divisions) was determined in terms of the number of atoms incorporated into the nucleus that would lead to the same DSBs that 100 decays of 125I. Simulations were run until a 2% statistical uncertainty (1 standard deviation) was achieved. Results: The behavior of DSBs as a function of the energy for monoenergetic electrons was consistent with published data, the DSBs increased with the energy until it reached a maximum value near 500 eV followed by a continuous decrement. For 64Cu, when incorporated in the genome at evaluated positions (1) and (2), the DSB were 0.171 ± 0.003 and 0.190 ± 0.003 DSB/decay, respectively. The number of initial atoms incorporated into the genome (per cell) for 64Cu that would cause a therapeutic effect was estimated as 3,107 ± 28, that corresponds to an initial activity of 47.1 ± 0.4 × 10-3 Bq. Conclusion: Our results showed that TRT with 64Cu has comparable therapeutic effects in cells as that of TRT with radionuclides currently used in clinical practice.

Integrating Fluorescent Nanodiamonds into Polymeric Microstructures Fabricated by Two-Photon Polymerization.

Nitrogen-vacancy (NV) and other color centers in diamond have attracted much attention as non-photobleaching quantum emitters and quantum sensors. Since microfabrication in bulk diamonds is technically difficult, embedding nanodiamonds with color centers into designed structures is a way to integrate these quantum emitters into photonic devices. In this study, we demonstrate a method to incorporate fluorescent nanodiamonds into engineered microstructures using two-photon polymerization (2PP). We studied the optimal concentration of nanodiamonds in the photoresist to achieve structures with at least one fluorescent NV center and good structural and optical quality. Fluorescence and Raman spectroscopy measurements were used to confirm the presence and location of the nanodiamonds, while absorbance measurements assessed scattering losses at higher concentrations. Our results show the feasibility of fabricating microstructures embedded within fluorescent nanodiamonds via 2PP for photonics and quantum technology applications.

A machine learning-based model for a dose point kernel calculation.

PURPOSE: Absorbed dose calculation by kernel convolution requires the prior determination of dose point kernels (DPK). This study reports on the design, implementation, and test of a multi-target regressor approach to generate the DPKs for monoenergetic sources and a model to obtain DPKs for beta emitters. METHODS: DPK for monoenergetic electron sources were calculated using the FLUKA Monte Carlo (MC) code for many materials of clinical interest and initial energies ranging from 10 to 3000 keV. Regressor Chains (RC) with three different coefficients regularization/shrinkage models were used as base regressors. Electron monoenergetic scaled DPKs (sDPKs) were used to assess the corresponding sDPKs for beta emitters typically used in nuclear medicine, which were compared against reference published data. Finally, the beta emitters sDPK were applied to a patient-specific case calculating the Voxel Dose Kernel (VDK) for a hepatic radioembolization treatment with [Formula: see text]Y. RESULTS: The three trained machine learning models demonstrated a promising capacity to predict the sDPK for both monoenergetic emissions and beta emitters of clinical interest attaining differences lower than [Formula: see text] in the mean average percentage error (MAPE) as compared with previous studies. Furthermore, differences lower than [Formula: see text] were obtained for the absorbed dose in patient-specific dosimetry comparing against full stochastic MC calculations. CONCLUSION: An ML model was developed to assess dosimetry calculations in nuclear medicine. The implemented approach has shown the capacity to accurately predict the sDPK for monoenergetic beta sources in a wide range of energy in different materials. The ML model to calculate the sDPK for beta-emitting radionuclides allowed to obtain VDK useful to achieve reliable patient-specific absorbed dose distributions required short computation times.

Synthesis, vibrational spectroscopy and X-ray structural characterization of novel NIR emitter squaramides.

Two new 2-naphthyl squaramides, 3-methoxy -4-(2-naphtalenylamino)-3-cyclobutene-1,2-dione (SQ-NPh1) and bis-3,4-(2-naphtalenylamino)-3-cyclobutene-1,2-dione (SQ-NPh2) were synthesized via condensation reaction between the dimethylsquarate and 2-naphthylamine. The spectrometric characterization by 13C NMR confirmed the obtaining of the squaramide derivative and nor the squaraine analog. This hypothesis was corroborated by Raman and Infrared spectroscopy since the characteristic vibrational bands related to the oxocarbon portion of both structures have been assigned, such as the ones for SQ-NPh1 and SQ-NPh2. The single-crystal X-ray crystallography for SQ-NPh1 crystal structures have been solved and the structure of SQ-NPh2 have been refined using Powder Diffraction state-of-art. The SQ-NPh1 crystallizes in monoclinic system in P2/c space group. Both squaramides present absorption in the ultra-visible (220-370 nm) and fluorescent emission in the near-infrared (780-800 nm), besides they also presented high thermal stability (around 570 °C). Generally, only squaraines are reported as NIR emitters, this is the first description of NIR emission for squaramides, and since the synthesis of squaramides is very easy and the rational design of small-molecule NIR fluorophores is of high priority and great value, these results are very promising for the development of novel NIR fluorescent dyes.

Alpha emitter NORM crystal scales in industrial pipelines: A study case.

Radioactive related pollution due to suspended particulate matter dispersion is an important workplace and health care issue. Recycling oil production ducts and contaminated production equipment, represent a health hazard to workers and public alike. Radioactive plate-out NORM scales with crystal deposit is analyzed by different techniques; results provide proper information on physico-chemical features and emitted alpha particles. Recommendations for handling and recycling procedures are included in relation to health risk and radiological hazard.

Gotejadores aplicando proporções de tempo de irrigação com efluente da suinocultura e água de abastecimento / Drippers applying proportions of irrigation time with swine wastewater and water supply

Este trabalho objetivou analisar os efeitos de proporções de tempo de irrigação com água residuária da suinocultura (ARS) e água de abastecimento (AA) na alteração de indicadores de desempenho hidráulico de sistemas de irrigação com três modelos de gotejadores (G1 - não autocompensante de 2,0 L h-1, G2 - não autocompensante de 1,7 L h-1 e G3 - autocompensante de 3,6 L h-1). O experimento foi realizado junto ao Departamento de Engenharia Agrícola (DEA/UFV) em Viçosa-MG, tendo os seguintes tratamentos: i) 1E3A(1 h de ARS e 3 h de AA); ii) 2E2A (2 h de ARS 2 h de AA); iii) 3E1A (3 h de ARS e 1 h de AA); e iv 4E (4 h de ARS). As características físico-químicas e biológicas da ARS e AA foram determinadas a cada 20 h e 80 h, respectivamente. Os valores do coeficiente de variação de vazão (CVq), coeficiente de uniformidade estatística (Us) e coeficiente de vazão relativa média (DRA) foram obtidos a cada 20 h, durante 160 h de operação do sistema. Após 160 h, gotejadores e linhas laterais foram dissecados para investigação do material ocasionar de obstrução. A obstrução por biofilme foi mais acentuada nas combinações G1 x 2E2A e G1 x 3E1A, enquanto as combinações G2 x 1E3A e G3 x 4E apresentaram os maiores valores de desempenho hidráulico, minimizando a obstrução nas unidades de irrigação com biofilme.

This study aimed to analyze the effects of irrigation time with swine wastewater (ARS) and water supply (AA) on alteration of hydraulic performance indicators in irrigation systems with three models drippers (G1 - non pressure compensating for 2.0 L h-1, G2 ­ non pressure compensating for 1.7 h L-1 and G3 - pressure compensating for 3.6 h L-1). The experiment was conducted at the Agricultural Engineering Department (DEA/UFV) in Viçosa-MG, with the following treatments: i) 1E3A (ARS 1 h and 3 h AA); ii) 2E2A (ARS 2 h and 2 h AA); iii) 3E1A (ARS 3 h and 1 h of AA); and iv 4E (ARS 4 h). The physico-chemical and biological characteristics of ARS and AA were determined every 20 h and 80 h, respectively. The coefficient of variation of discharge (CVq), coefficient of statistical uniformity (Us) and coefficient of relative mean flow (Dra) were obtained every 20 h, during 160 h of operation. After 160 h, drippers and lateral lines were dissected to investigate the material cause of obstruction. The obstruction by biofilm was more pronounced in combinations G1 x 2E2A and G1 x 3E1A, while the combinations G2 x 1E3A and G3 x 4E showed higher hydraulic performance, minimizing the obstruction on irrigation units with biofilm.

Microaspersores entupidos devido a problemas de ferro na água / Microsprinkler clogged due to iron problems in the water

Um dos aspectos relevantes a ser considerado no manejo da irrigação é a uniformidade de distribuição de água pelo sistema. Este trabalho foi desenvolvido com o objetivo de avaliar a eficiência da cloração com a utilização de hipoclorito de sódio na desobstrução de microaspersores devido à utilização de águas com elevado teor de ferro. Um sistema com dez meses de uso apresentava setores com vazões de 5 por cento a 57 por cento menores que a vazão de projeto. Foi feito o tratamento químico da água de irrigação, utilizando-se hipoclorito de sódio com 12 por cento de cloro livre na dosagem de 100 mg L-1 e ácido sulfúrico, na concentração de 98 por cento, para manter o pH da água de irrigação em torno de 4,5. O resultado indicou que houve aumento significativo nas vazões médias dos microaspersores em todos os setores avaliados e diminuição na variação da vazão dos mesmos com relação à estimada no projeto.(AU)

An important aspect to be considered in irrigation managment is the uniformity distribution of water through the irrigation system. This research had the objective to evaluate the efficiency of chlorination in the use of sodium hypochlorite in clearing of microsprinkler due to the presence of high iron concentration in water. The equipment with less than a year of use presenting sectors with 5 percent and 57 percent lower flow than the original project flow. The chemical treatment of water irrigation utilized sodium hypochlorite with 12 percent free chlorine on 100mg L-1 concentration, and sulphuric acid 98 percent to maintain the pH of water irrigation about 4.5. The result demonstrated a significant increase in the average flow of the microsprinkler's variation in all evaluted setors, and decrease in their flow variation related to the estimated in the project.(AU)

Microaspersores entupidos devido a problemas de ferro na água / Microsprinkler clogged due to iron problems in the water

Um dos aspectos relevantes a ser considerado no manejo da irrigação é a uniformidade de distribuição de água pelo sistema. Este trabalho foi desenvolvido com o objetivo de avaliar a eficiência da cloração com a utilização de hipoclorito de sódio na desobstrução de microaspersores devido à utilização de águas com elevado teor de ferro. Um sistema com dez meses de uso apresentava setores com vazões de 5 por cento a 57 por cento menores que a vazão de projeto. Foi feito o tratamento químico da água de irrigação, utilizando-se hipoclorito de sódio com 12 por cento de cloro livre na dosagem de 100 mg L-1 e ácido sulfúrico, na concentração de 98 por cento, para manter o pH da água de irrigação em torno de 4,5. O resultado indicou que houve aumento significativo nas vazões médias dos microaspersores em todos os setores avaliados e diminuição na variação da vazão dos mesmos com relação à estimada no projeto.

An important aspect to be considered in irrigation managment is the uniformity distribution of water through the irrigation system. This research had the objective to evaluate the efficiency of chlorination in the use of sodium hypochlorite in clearing of microsprinkler due to the presence of high iron concentration in water. The equipment with less than a year of use presenting sectors with 5 percent and 57 percent lower flow than the original project flow. The chemical treatment of water irrigation utilized sodium hypochlorite with 12 percent free chlorine on 100mg L-1 concentration, and sulphuric acid 98 percent to maintain the pH of water irrigation about 4.5. The result demonstrated a significant increase in the average flow of the microsprinkler's variation in all evaluted setors, and decrease in their flow variation related to the estimated in the project.

The role of electron-emitting radiopharmaceuticals in the palliative treatment of metastatic bone pain and for radiosynovectomy: applications of conversion electron emitter Tin-117m

A variety of radionuclides continue to be investigated and/or clinically used for different therapeutic applications in nuclear medicine. The choice of a particular radionuclide with regard to appropriate emissions, linear energy transfer (LET), and physical half-life, etc., is dictated to a large extent by the character of the disease (e.g., solid tumor or metastatic disease), and by the carrier to selectively transport the radionuclide to the desired site. An impressive body of information has appeared in the recent literature that addresses many of these considerations. This article summarizes and discusses the role of high-LET electron emitters and their advantage in the treatment of cancer or for other disorders in specific situations. Areas such as bone pain palliation, bone malignancy therapy, and radiation synovectomy are covered in greater detail. Projections are made as to the future directions and progress in these areas. A discussion of the various issues related to the selection criteria that are useful for choosing the appropriate radionuclide for a particular application is included. Use of high-LET electron emitters is discussed in greater detail, with particular emphasis on the use of conversion electron emitter tin-117m for various therapeutic applications.

Uma variedade de radionuclídeos continua a ser investigada e/ou clinicamente utilizada para diferentes aplicações terapêuticas em medicina nuclear. A escolha de um radionuclídeo, considerando-se sua emissão apropriada, transferência linear de energia (LET) e meia-vida física é determinada na maior parte pelo caráter da doença (p.ex., tumor sólido ou doença metastática), e pelo carreador que transporta o radionuclídeo seletivamente para o sítio desejado. Um notável conjunto de informações voltadas para essas considerações tem aparecido na literatura recente. Esse trabalho resume e discute o papel de emissores de elétrons de alta-LET e sua vantagem no tratamento do câncer ou para outras doenças em situações específicas. Abordagens relacionadas com o alívio da dor óssea, a terapia da doença óssea e a sinovectomia por radiação são apresentadas detalhadamente. Projeções para o futuro e os progressos nessas áreas são indicadas. Uma profunda discussão relacionada aos critérios de seleção que são úteis para escolher o radionuclídeo apropriado para que uma aplicação particular seja incluída. O uso de emissores de elétrons de alta-LET é discutido em grande detalhe, com particular ênfase no uso do estanho-117m, um emissor de elétron de conversão, para várias aplicações terapêuticas.