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Determination of 2,3-dihydroxyphenol (DHP) phenolic compound in water and biodiesel samples exploiting functional groups of carbon black paste electrode.

The necessity of new drugs for lung cancer therapy and imaging is increasing each day. The development of new drugs that are capable of reaching the tumor with specificity and selectivity is required. In this direction, the design of nanoparticles for tumor therapy represents an important alternative. The aim of this study was to develop, characterize, and evaluate target-specific atezolizumab-conjugated poly(lactic acid)/poly(vinyl alcohol) (PLA/PVA) nanoparticles as pharmaceutical fragment candidates for new radiopharmaceuticals. For this purpose, PLA/PVA nanoparticle formulations were prepared by the double emulsifi-cation/solvent evaporation method with a high-speed homoge-nizer. A special focus was oriented to the selection of a suitable method for modification of the nanoparticle surface with a monoclonal antibody. For this purpose, atezolizumab was bound to the nanoparticles during the preparation by solvent evaporation or either by adsorption or covalent binding. PLA/PVA/atezolizumab nanoparticles are characterized by dynamic light scattering, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. An in vitro assay was performed to evaluate the antibody binding efficiency, stability, and cytotoxicity [A549 (lung cancer cell) and L929 (healthy fibroblast cell)]. The results showed that a spherical nanoparticle with a size of 230.6 +/- 1.768 nm and a zeta potential of-2.23 +/- 0.55 mV was produced. Raman spectroscopy demonstrated that the monoclonal antibody was entrapped in the nanoparticle. The high antibody binding efficiency (80.58%) demonstrated the efficacy of the nanosystem. The cytotoxic assay demonstrated the safety of the nanoparticle in L929 and the effect on A549. In conclusion, PLA/PVA/atezolizumab nanoparticles can be used as drug delivery systems for lung cancer diagnosis and therapy., Scientific and Technological Research Council of Turkey; [TUBITAK-220/S/361], Funding This study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK-220/S/361) within the scope of PhD thesis of Meliha Ekinci.

Photoelectrochemical systems based on half-photoelectrochemical cells have been widely exploited in the development of analytical methods. However, the development of self-powered systems based on dual-photoelectrode photoelectrochemical cells for the determination of many species is still a challenger. In this work, a two-compartment photoelectrochemical cell has been developed to determine tannic acid exploiting the effects of the analyte on the photoelectrochemical response of a CdS/TiO2/FTO photoanode. The photoactivity of the photoanode was characterised by electrochemical impedance spectroscopy (EIS) and measurements of the photocurrent. The spectroscopic characteristics of the photoanode were evaluated by Raman and Fourier-transform infrared spectroscopy (FT-IR) measurements, the structural characteristics were evaluated by powder X-ray diffraction (PXRD) measurements, the morphology of the surface was evaluated by scanning electron microscopy, and the composition analysis was evaluated by energy-dispersive X-ray spectroscopy. Electrochemical impedance measurements were performed under the incidence and absence of light to investigate the effects of photons on the charge transfer resistance of the photoanode. The nature of the semiconductor and the flat band potential of the photoanode were evaluated by Mott-Schottky analysis. The influence of the TA on the photoelectrochemical response of the CdS/TiO2/FTO electrode was evaluated by measuring the photocurrent of the system. The PEC platform presented a linear response range for TA from 10 to 500 μmol L−1. The PEC was successfully applied to the determination of the TA in orange juice samples with a mean recovery percentage of about 99%.

Zinc ferrites (ZnFe2O4), with spinel-like structure, were produced by combustion reaction synthesis in solution and heat-treated at temperatures of 400–1100 °C. The structural and chemical properties of the ZnFe2O4 samples were investigated by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), Field Emission Gun Scanning Electron Microscopy (FEG-SEM) with X-ray dispersive spectroscopy (EDS), and diffuse reflectance spectroscopy (DRS) in the ultraviolet (Uv–vis) region. The photocatalytic performance of this compound was investigated in order to evaluate the green malachite and rhodamine B dyes degradation under visible irradiation. The XRD patterns results reveal the presence of cubic ZnFe2O4 at all heat-treated temperatures and pure phase above 800 °C. The presence of spherical and porous agglomerate morphology was confirmed through SEM analysis. Absorption bands between 400 and 600 cm−1 in the infrared spectra confirmed the presence of the ferrite phase. Diffuse reflectance results on the ZnFe2O4 samples showed that absorption occurred in the visible light range. The best temperature of the photocatalytic degradation performance of the dyes was 400 °C. This was more pronounced for the green malachite dye when compared to rhodamine B due to secondary phases and smaller crystal sizes.

A novel label-free photoelectrochemical immunosensor was developed for the determination of prostate-specific antigen (PSA) based on fluorine-doped tin oxide (FTO) electrode modified with anatase and rutile titanium dioxide nanoparticles (TiO2(a-r)) as a platform for the electrodeposition of bismuth sulfide (Bi2S3). The photoelectrochemical response of the TiO2(a-r) platform sensitized with Bi2S3 for the ascorbic acid donor molecule (AA) was about 34-fold higher than that observed in the absence of Bi2S3. The Bi2S3/TiO2(a-r)/FTO platform was modified with PSA antibodies to produce the anti-PSA/Bi2S3/TiO2(a-r)/FTO immunosensor, which was incubated in solutions of PSA antigen to inhibit the photocurrent of the immunosensor for AA. The photocurrent of the anti-PSA/Bi2S3/TiO2(a-r)/FTO immunosensor presented a linear relationship with the logarithm of the PSA concentration ranging from 1 pg mL−1 to 100 ng mL−1 with good sensitivity and a limit of detection of 0.870 pg mL−1. The sensor was successfully employed for the determination of PSA in artificial blood plasma samples, with recoveries between 94.6 and 98.6%.

Cancer is a global epidemic disease responsible for over ten millions death worldwide. The early diagnosis and the precise treatment with reduced adverse reactions are the main goal worldwide. In this study, we produced, characterized and evaluated (

Alpha and beta particulate radiation are used for non-treated neoplasia, due to their ability to reach and remain in tumor sites. Radium-223 (223Ra), an alpha emitter, promotes localized cytotoxic effects, while radioactive gold (198Au), beta-type energy, reduces radiation in the surrounding tissues. Nanotechnology, including several radioactive nanoparticles, can be safely and effectively used in cancer treatment. In this context, this study aims to analyze the antitumoral effects of [223Ra]Ra nanomicelles co-loaded with radioactive gold nanoparticles ([198Au]AuNPs). For this, we synthesize and characterize nanomicelles, as well as analyze some parameters, such as particle size, radioactivity emission, dynamic light scattering, and microscopic atomic force. [223Ra]Ra nanomicelles co-loaded with [198Au]AuNPs, with simultaneous alpha and beta emission, showed no instability, a mean particle size of 296 nm, and a PDI of 0.201 (±0.096). Furthermore, nanomicelles were tested in an in vitro cytotoxicity assay. We observed a significant increase in tumor cell death using combined alpha and beta therapy in the same formulation, compared with these components used alone. Together, these results show, for the first time, an efficient association between alpha and beta therapies, which could become a promising tool in the control of tumor progression.

The present study reports the synthesis, characterization, and antibacterial properties of silver trimolybdate (Ag

The use of smart materials, especially the carbon-based nanomaterials, is increasing each day. Among the several carbon-based nanomaterials, graphene quantum dots are one of the most impressive ones, not only by its quantum behavior but due to the adsorption quality conferred by electrostatic interactions from the negatively charged groups as the huge surface area (2.630 m2/g). In this study, we developed and tested graphene quantum dots (GQDs) as smart nano-adsorbents of uranium (238U) from the radioactive industry waste. The GQDs were developed in a size range of 160–220 nm using a totally green route. The results showed that the GQDs were capable to adsorb almost 40% of the uranium (238U) in alamine 3366 solution. Also, the results demonstrated that using GQDs treatment-like smart nanomaterials for radioactive waste in a volume reduction of almost 90% is achieved, helping the storage process as the final disposal of this material. We may conclude that GQDs may represent a smart device for the treatment of radioactive waste as an alternative of absorbent in the radioactive industry.

Er3+ ions doped oxyhalide barium borate glasses were prepared by means of conventional melt quenching technique. In the studied glass system, besides the Er3+ doping, barium oxide was partially replaced by BaF2 and/or BaCl2. The amorphous nature of as-prepared glasses was confirmed by X-ray diffraction patterns. The effects of the compositional changes were investigated through spectroscopic techniques such as optical absorption, emission and decay lifetime. It was found that the luminescence and decay lifetime of Er3+: 4I13/2 → 4I15/2 transition are affected by both Er3+ doping and halide insertions. By applying the Judd-Ofelt (JO) theory, the JO intensity parameters (Ωt, t = 2, 4, and 6) were calculated, and the trend Ω2 > Ω4 > Ω6 was found, which is in accordance with previous studies. Optical properties such as electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission cross sections and radiative lifetimes were also obtained and discussed for many excited states of Er3+ ions. The lifetime of the 4I13/2 excited level was measured and compared with the calculated one.

In this work, several PGM-free materials supported on three types of carbon blacks (Vulcan XC-72, Monarch-1000, and Ketjenblack EC-600JD) and pyrolysed on N2 and NH3 atmosphere are investigated as catalysts for the oxygen reduction reaction (ORR) in acid and alkaline electrolytes. The synthesized materials are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The electrochemical characterization shows that for all N2- and NH3-treated catalysts, the ORR activity is higher in alkaline than acidic conditions, though in both cases, the main reaction product is water, thus evidencing a predominant occurrence of a 4-electron oxygen reduction mechanism. Further, a reasonable relationship is established between Fe-Nx coordination (pyridinic-N) and pyrrolic-N contents and the ORR activity of catalysts in acid media (FeNx supported on Monarch-1000). In alkaline conditions, the iron coordination with pyridinic-N, coupled to a high carbon surface area (Ketjenblack), enhances the ORR activity regardless of the pyrolysis atmosphere. Finally, the ORR performance in alkaline medium of the FeNx/Ketjenblack catalyst pyrolysed under N2 atmosphere is essentially the same as that achieved for the benchmark catalyst (Pt/C), while the durability of the best catalysts evidence to be quite promising in both acidic and alkaline media, as shown by a standard accelerated stability test.

Temperature-dependent Raman scattering and differential scanning calorimetry were applied to the study of the hybrid organic-inorganic azide-perovskite [(CH3)4N][Cd(N3)3], a compound with multiple structural phase transitions as a function of temperature. A significant entropy variation was observed associated to such phase transitions, |∆S| ~ 62.09 J&middot, kg&minus, 1 K&minus, 1, together with both a positive high barocaloric (BC) coefficient |&delta, Tt/&delta, P| ~ 12.39 K kbar&minus, 1 and an inverse barocaloric (BC) coefficient |&delta, P| ~ &minus, 6.52 kbar&minus, 1, features that render this compound interesting for barocaloric applications. As for the obtained Raman spectra, they revealed that molecular vibrations associated to the NC4, N3&ndash, and CH3 molecular groups exhibit clear anomalies during the phase transitions, which include splits and discontinuity in the phonon wavenumber and lifetime. Furthermore, variation of the TMA+ and N3&ndash, modes with temperature revealed that while some modes follow the conventional red shift upon heating, others exhibit an unconventional blue shift, a result which was related to the weakening of the intermolecular interactions between the TMA (tetramethylammonium) cations and the azide ligands and the concomitant strengthening of the intramolecular bondings. Therefore, these studies show that Raman spectroscopy is a powerful tool to gain information about phase transitions, structures and intermolecular interactions between the A-cation and the framework, even in complex hybrid organic-inorganic perovskites with highly disordered phases.

Monoclinic BiCrO3, synthesized at high pressure and high temperature, presents interesting properties with anomalies of magnetic origin observed around 110 and 80 K, which are associated, respectively, with the rise of a G-type antiferromagnetic structure and the spin reorientation along one of the monoclinic axes. In this study, we report a strong spin–phonon coupling in monoclinic BiCrO3 observed by Raman spectroscopy. The renormalization of the phonon energy confirms the coupling with the magnetic orderings. Interestingly, some phonons exhibit this effect at the rising temperature of the G-type antiferromagnetic ordering, whereas others are sensitive to the second magnetic event. A renormalization model based on the mean-field theory, previously applied to other perovskite compounds, was used to analyze the spin–phonon coupling showing different behaviors associated with each magnetic phase.

Copper(II) complexes of amino acids have been widely studied as potentials medicines and dietary supplementation, so the knowledge about the metal-ligand sites, thermal stability and behavior of these complexes is an important subject of study. Although the Raman spectroscopy could help to elucidate the nature of the interactions into crystal there are only few information about vibrational study of this compound in the literature and no data depending on the temperature. In addition, there is no temperature-dependent X-ray diffraction study of this material. We report here Raman Spectroscopy and Powder X-ray Diffraction measurements, both as a function of temperature and as a way of studying the thermal stability of the material. After the synthesis of the sample and confirmation of its crystal structure by Powder X-ray Diffraction, Raman measurements were performed in the 70–3600 cm−1 spectral region as a function of temperature from 10 up to 300 K. Some peaks become more evident during the cooling, due to a decrease in width and an increase in intensity. There is a discontinuity in the wavenumbers evolution around 110 K, that should be associated with a conformation of the structure. Optimized geometry and vibrational frequencies were obtained by means of Density Functional Theory and for the first time the analysis of the vibrational modes was done in terms of the Potential Energy Distribution. X-ray diffraction measurements as a function of temperature and Rietveld refinement showed discontinuities in the lattice parameters and degradation around 493 K (at air atmosphere) and 513 K (under vacuum). These results were corroborated by the thermal analysis which indicates that the compound is stable up to 493 K.

Malaria is the most common parasitic disease around the world, especially in tropical and sub-tropical regions. This parasitic disease can have a rapid and severe evolution. It is transmitted by female anopheline mosquitoes. There is no reliable vaccine or diagnostic test against malaria; instead, Artesunate is used for the treatment of severe malaria and Artemisinin is used for uncomplicated falciparum malaria. However, these treatments are not efficient against severe malaria and improvements are needed. Primaquine (PQ) is one of the most widely used antimalarial drugs. It is the only available drug to date for combating the relapsing form of malaria. Nevertheless, it has severe side effects. Particle drug-delivery systems present the ability to enhance the therapeutic properties of drugs and decrease their side effects. Here, we report the development of Polymeric Primaquine Microparticles (PPM) labeled with 99mTc for therapeutic strategy against malaria infection. The amount of primaquine encapsulated into the PPM was 79.54%. PPM presented a mean size of 929.47 ± 37.72 nm, with a PDI of 0.228 ± 0.05 showing a homogeneous size for the microparticles and a monodispersive behavior. Furthermore, the biodistribution test showed that primaquine microparticles have a high liver accumulation. In vivo experiments using mice show that the PPM treatments resulted in partial efficacy and protection against the development of the parasite compared to free Primaquine. These results suggest that microparticles drug delivery systems of primaquine could be a possible approach for malaria prevention and treatment.

The search for materials with strong magnetoelectric coupling has been intense since interesting properties were discovered in the perovskite TbMnO3. Among the manganese-based perovskite family (RMnO3), magnetic and electric orders coexist in the orthorhombic phase of the distorted perovskite TmMnO3. The antiferromagnetic phase induces ferroelectricity, leading to type–II multiferroic behavior. Although the temperature-dependent behavior of the Raman-active phonons of other members of the orthorhombic RMnO3 family was already reported, little information about orthorhombic TmMnO3 has been published. In this paper, bulk samples of orthorhombic TmMnO3 were obtained through HPHT treatment. Structural and magnetic properties of the synthesized samples were analyzed for phase confirmation. Temperature-dependent Raman spectra of bulk orthorhombic TmMnO3 revealed weak spin-phonon coupling in the incommensurate antiferromagnetic ordered phase around 44 K. Raman spectra are also sensitive to the magnetic transition from the incommensurate to E-type antiferromagnetic phase, where the frequency renormalization due to the spin-phonon coupling vanishes. This feature shows the existence of an orbital-spin-phonon coupling based on the magnetic ordering of the low-temperature phase.

An electrochemical sensor based on functionalized multiwalled carbon nanotubes (MWCNTf) has been developed and applied for determination of anticancer drug flutamide in pharmaceutical and artificial urine samples. The electrode was prepared by modifying a glassy carbon electrode with MWCNTf, denoted herein as MWCNTf/GCE. The MWCNTf/GCE electrode exhibited high catalytic activity, high sensitivity, and high stability and was applicable over a wide concentration range for flutamide. The effects of the scan rate, pH, and nature of the electrolyte on the electrochemical behavior of flutamide on the MWCNTf/GCE were investigated. The results showed that this electrode presented the best square-wave voltammetric response to flutamide in Britton–Robinson buffer solution at pH 5.0 at frequency of 50 Hz and amplitude of 0.06 V. The proposed sensor presents a wide linear response range from concentration of 0.1 μmol L−1 up to 1000 μmol L−1 (or 27.6 μg L−1 up to 0.27 g L−1), with limit of detection, limit of quantification, and sensitivity of 0.03 μmol L−1, 0.1 μmol L−1, and 0.30 μA μmol−1 L, respectively. The MWCNTf/GCE electrode was successfully applied for determination of flutamide in pharmaceutical formulations and artificial urine samples, giving results in agreement with those obtained by a comparative method described in literature. A paired Student’s t-test revealed no statistical difference between the reference and proposed method at 95% confidence level. The average recovery for fortified samples was 101 ± 1%.

Nanodrugs have in recent years been a subject of great debate. In 2017 alone, almost 50 nanodrugs were approved for clinical use worldwide. Despite the advantages related to nanodrugs/nanomedicine, there is still a lack of information regarding the biological safety, as the real behavior of these nanodrugs in the body. In order to better understand these aspects, in this study, we evaluated the effect of polylactic acid (PLA) nanoparticles (NPs) and magnetic core mesoporous silica nanoparticles (MMSN), of 1000 nm and 50 nm, respectively, on human cells. In this direction we evaluated the cell cycle, cytochemistry, proliferation and tubulogenesis on tumor cells lines: from melanoma (MV3), breast cancer (MCF-7, MDA-MB-213), glioma (U373MG), prostate (PC3), gastric (AGS) and colon adenocarcinoma (HT-29) and non-tumor cell lines: from human melanocyte (NGM), fibroblast (FGH) and endothelial (HUVEC), respectively. The data showed that an acute exposure to both, polymeric nanoparticles or MMSN, did not show any relevant toxic effects on neither tumor cells nor non-tumor cells, suggesting that although nanodrugs may present unrevealed aspects, under acute exposition to human cells they are harmless.

Graphene is one of the crystalline forms of carbon, along with diamond, graphite, carbon nanotubes, and fullerenes, and is considered as a revolutionary and innovating product. The use of a graphene-based nanolabels is one of the latest and most prominent application of graphene, especially in the field of diagnosis and, recently, in loco radiotherapy when coupled with radioisotopes. However, its biological behavior and mutagenicity in different cell or animal models, as well as the in vivo functional activities, are still unrevealed. In this study we have developed by a green route of synthesizing graphene quantum dots (GQDs) and characterized them. We have also developed a methodology for direct radiolabeling of GQDs with radioisotopes.Finally; we have evaluated in vivo biological behavior of GQDs using two different mice models and tested in vitro mutagenicity of GQDs. The results have shown that GQDs were formed with a size range of 160-280 nm, which was confirmed by DRX and Raman spectroscopy analysis, corroborating that the green synthesis is an alternative, environmentally friendly way to produce graphene. The radiolabeling test has shown that stable radiolabeled GQDs can be produced with a high yield (>90%). The in vivo test has demonstrated a ubiquitous behavior when administered to healthy animals, with a high uptake by liver (>26%) and small intestine (>25%). Otherwise, in an inflammation/VEGF hyperexpression animal model (endometriosis), a very peculiar behavior of GQDs was observed, with a high uptake by kidneys (over 85%). The mutagenicity test has demonstrated A:T to G:C substitutions suggesting that GQDs exhibits mutagenic activity.

We use polarized Raman spectroscopy to obtain the room temperature phonon modes of LiBaB 9 O 15 single crystal, that crystallizes in a trigonal structure belonging to the space group R 3 ¯ c ( D 3 d 6 ) with two molecules per primitive cell ( Z B =2). The structure of the LiBaB 9 O 15 crystal consists of a three-dimensional borate framework, formed by two BO 3 triangles and one BO 4 tetrahedra. Since BO 3 and BO 4 units share the oxygen atoms, we can not obtain a correlation scheme where their internal modes are distributed in terms of the irreducible representations of the D 3 d factor group. The only modes that can unambiguously be assigned are the ν 3 (BO 4 ) with A 1 g symmetry at 983 cm − 1 and the ν 1 (BO 3 ) with E g symmetry at 932 cm −1 . We observed 7 A 1 g +6 E g out of 11 A 1 g +25 E g vibrations predicted by the Group Theory.

Pentavalent metals have been used as donors in tin dioxide, giving it varistor characteristics when associated with densifiers such as CoO or MnO2. However, attempts to obtain varistor behavior in SnO2-based ternary systems using hexavalent donors such as W6+ have been unsuccessful to date, leading to typical linear behavior. Here it is shown that one can achieve nonlinear behavior in this kind of system, given a suitable choice of densifier (MnO2). In order to get insights into the role of WO3 content on the potential barriers responsible for varistor properties, a combination of experimental and theoretical techniques was used. Measurements revealed two minor but relevant phases, Mn3O4, and MnWO4, whose presence was explained by theoretical calculations and whose amount was estimated as a function of WO3 content. This estimate revealed a correlation between Mn3O4 amount and varistor properties, interpreted with basis on Mn defects at SnO2/Mn3O4 interfaces. WO3 content was varied to optimize the varistor properties, resulting in nonlinear coefficient α ≈ 6, breakdown electric field E b > 10 kV/cm and leakage current I l ≈ 200 μ A. This finding is expected to stimulate further investigations on SnO2-based ternary systems containing hexavalent oxides, especially using other densifiers, such as CoO.

Graphene quantum dots (GQDs) have special properties at nanosize zone, as highly tunable photoluminescence, electrochemiluminescence and multiphoton excitation, that make them promising nanoagents for drug delivery systems. In this direction the use of gels to formulate nanodrugs, for both in vitro and in vivo assay is required. However, the presence of GQDs nanoparticles may affect the rheological parameters. These changes may influence the biological behavior of this formulation as change the pharmacological application. In this study we evaluated the effect of adding GQDs to carbopol gels formulation, in terms of rheological properties. In this direction, carbopol gels alone and loaded with GQDs were studied. The results of pure carbopol formulation showed a non-Newtonian, pseudo-plastic fluid without thixotropic behavior. Otherwise, the presence of GQDs in the carbopol formulation (carbopol loaded with GQDs) caused a reduction on the viscosity and modified the interactions between the polymer chains leading to the transformation of the initial gel into a viscous fluid. This alteration can change drastically the use of these formulations, especially for drug delivery, since slightly changes in viscosity can influence the occlusion, retention and permeability of these nanoparticles into biological barriers.

In this work we investigate the effect of replacing Na2O by TiO2 on the structural and spectroscopic characteristics of the Nd2O3-doped 60B2O3–(20−x)Na2O–10PbO–10Al2O3:xTiO2:yNd2O3 borate glass matrix. Measurements of X-ray patterns, glass temperatures (Tg), vibrational (Raman and infrared (IR)) and optical (absorption and emission) spectra were carried out. The trend of Tg, the Judd–Ofelt parameters and Nephelauxetic ratio as the TiO2 and Nd2O3 concentration increases was interpreted quantitatively and qualitatively in terms of the network bonds and coordination numbers. Measurements of Tg across the Nd-doped glass series for different levels of Ti suggests changes in the rigidity of the matrix due to change of coordination of boron oxide resulting from the BO4–BO3 back conversion effect. The changes observed in the Raman and IR spectra are related to the BO3 → BO4 conversion effect. The variation of the Judd–Ofelt parameters Ω ( 2 ) and Ω ( 6 ) indicates that the average rare earth-ligand radius decreases establishing an electronic density distribution when Nd3+ concentration increases. This effect is interpreted in terms of Judd–Ofelt parameters and by the bonding parameter b 1 / 2 due to Nephelauxetic effect.

To evaluate the effect of incorporating niobium phosphate bioactive glass (NbG) into commercial etch-and-rinse adhesive systems, with and without silane, on their degree of conversion (DC) (%) and microtensile bond strength (μTBS). The NbG micro-filler was added to two etch-and-rinse adhesive systems: One Step (OS) and Prime & Bond (PB) at 40% concentration. The following groups were formed: control without glass addition OS; addition of unsilanized NbG (OSNbG); addition of silanized NbG (OSNbGS); control without glass PB; addition of unsilanized NbG (PBNbG); addition of silanized NbG (PBNbGS). The DC was determined using total Fourier spectroscopy reflection (FTIR/ATR). For μTBS testing, 48 human third molars (n=8) were restored and sliced to obtain specimens (0.8 mm2) and they were tested at two different time intervals: immediately and after 6 months. The fracture mode was evaluated with a stereoscopic loupe (40×) and by scanning electron microscopy (SEM). The data were subjected to ANOVA and Tukey tests (a=0.05). NbG addition did not compromise the adhesive system DC values (p>0.05). Furthermore, the NbG added to the adhesive systems did not affect μTBS values (p>0.05). Fracture occurred predominantly at the dentin-adhesive interface. NbG bioactive glass did not affect the DC or microtensile bond strength results. Resumo Avaliar o efeito da incorporação de vidro niobofosfato bioativo (NbG, 40% em peso) em dois sistemas adesivos simplificados convencionais (One Step [OS] e Prime & Bond {PB}) com e sem silano, no grau de conversão (%) e resistência de união (RU) após 6 meses. Os seguintes grupos foram testados: Controle OS: sem adição de partículas; OS e adição de NbG sem silano (OSNbG); OS e adição de partículas silanizadas NbG (OSNbGS); Controle PB: sem adição de partículas; PB e adição de partículas de NbG sem silano (PBNbG); PB e adição de partículas silanizadas NbG (PBNbGS). O grau de conversão (GC) foi determinado utilizando espectroscopia de Fourier (FTIR/ATR). Para RU, 48 terceiros molares humanos (n=8) foram restaurados e cortados para obter corpos-de-prova (0,8 mm2) e, em seguida, testados em dois momentos: imediato e após seis meses. O padrão de fratura foi avaliado com lupa estereoscópica (40×) e microscópio eletrônico de varredura (MEV). Os dados foram submetidos à análise de variância e Tukey (a=0,05). NbG não comprometeu valores de GC dos sistemas adesivos (p>0,05). Além disso, a adição de NbG aos sistemas adesivos não afetou os valores de RU (p>0,05). O padrão de fratura ocorreu predominantemente na interface dentina-adesivo. NbG não afetou os resultados de GC e RU.

Single crystals of potassium tantalate niobate, KTa 1− x Nb x O 3 (KTN x , x = 0.45, 0.50, and 0.55), were synthesized by the top-seeded solution growth method. The Raman scattering technique is used to investigate the sequence of phase transitions undergone by KTN x crystals. We discuss what features in the phonon spectrum are associated to each phase transition.

The room temperature phonon modes of both the alkali metal doped and pure CBN (CaxBa1−xNb2O6) crystals were determined using the Raman scattering technique. Owing to the intrinsic disorder of the tetragonal lattice we observe few and broad bands. The wavenumber of the internal modes observed shifts upwards when the volume of the unit cell increases. This blue shift is likely to be related to the closer packing of the NbO6 octahedrons. The Curie temperatures of the ferroelectric to paraelectric phase transition for the CBN-like crystals were obtained from DSC measurements. The Raman spectra of CBN32 in the temperature range from 300 to 568 K were also recorded in order to investigate the phase transformation.

Optical and vibrational studies have been carried out on 60B{sub 2}O{sub 3}.(20-x)Na{sub 2}O.10PbO.10Al{sub 2}O{sub 3}:xTiO{sub 2} (x=0, 1, 2, 3, 4, and 5 mol%) glasses, in order to understand the role of TiO{sub 2} in the 60B{sub 2}O{sub 3}.20Na{sub 2}O.10PbO.10Al{sub 2}O{sub 3} glass matrix. The X-ray patterns reveal homogeneous glasses over the entire compositional range. The absorption spectra show that the energy of the optical band gap ({Delta}E{sub opt}) and Urbach's energy (E{sub U}) decreases as TiO{sub 2} content increases. The changes observed in the Raman and IR spectra are related to the BO{sub 4}{yields}BO{sub 3} back conversion effect and the appearance of 'loose' BO{sub 4}{sup -} groups. The data indicate that titanium ions act as a network modifier. - Graphical abstract: Behavior of the relative integrated intensity of the IR bands, Ar=A{sub 4}/A{sub 3}, as TiO{sub 2} content increases. A decrease of 45% of Ar indicates that the number of BO{sub 4} groups is decreasing due to the BO{sub 4}{yields}BO{sub 3} back conversion. Highlights: > The XRD data show the amorphous character of all measured glasses. > The optical absorption results evidenced possible change of the glass structure. > The Raman data have revealed some vibrational modifications. > Themore » overall results indicate that titanium acts as a network modifier.« less

The room temperature phonon modes of the isostructural (Nd,Yb):Y{sub x}Gd{sub 1-x}(VO{sub 4}) laser crystals were determined using the Raman scattering technique, and the observed wavenumbers follow the overall mode distribution expected for REVO{sub 4} (RE=rare earth) compounds with the tetragonal zircon structure, D{sub 4h}{sup 19}. They were assigned according to the group theory in terms of the internal modes of the VO{sub 4} tetrahedron and the external modes of the Y{sub x}Gd{sub 1-x}(VO{sub 4}) lattice. No appreciable changes in the phonon wavenumbers were observed for Yb:GdVO{sub 4} (Yb=0.008, 0.015, 0.020, 0.025, and 0.035), indicating that the force fields in the GdVO{sub 4} lattice are not strongly altered by Yb doping at the Gd site. However, most of the phonon wavenumbers in the systems (Nd,Yb):Y{sub x}Gd{sub 1-x}(VO{sub 4}) shifts upwards (one-phonon-like behavior) when Y replaces for Gd. -- Graphical abstract: Plot of the observed wavenumbers of Nd:Y{sub x}Gd{sub 1-x}(VO{sub 4}) versus Y content (x). The linear trend indicates that most of the observed wavenumbers exhibit a one-phonon-like behavior. Display Omitted Research highlights: > Force fields in the GdVO{sub 4} lattice are not strongly altered by Yb doping at the Gd site when the doping content of Yb is below 3.5 at%.more » > Most of the phonon wavenumbers in the systems (Nd,Yb):Y{sub x}Gd{sub 1-x}(VO{sub 4}) shifts upwards with x increasing. > The upward shifting is related to the decrease of the RE-O distance due to the lattice contraction. > Most of the observed wavenumbers exhibits a one-phonon-like behavior.« less

The third-order optical susceptibility and dispersion of the linear refractive index of Er3+-doped lead phosphate glass were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index obtained from the third-order susceptibility was found to be five times higher than that of silica, indicating that Er3+-doped lead phosphate glass is a potential candidate to be used as the base component for the fabrication of photonic devices. For comparison purposes, the Z-scan technique was also employed to obtain the values of the nonlinear refractive index of Er3+-doped lead phosphate glass at several wavelengths, and the values obtained using the two techniques agree to within 15%.

Polarized Raman Spectroscopy was used to investigate the room-temperature phonon characteristics of a series of rare-earth arsenate (REAsO4, RE = Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu) single crystals. The Raman data were interpreted in a systematic manner based on the known tetragonal zircon structure of these compounds, and assignments and correlations were made for the observed bands. We found that the wavenumber of the internal modes of the AsO4 tetrahedron increased with increasing atomic number, and for three out of four lattice wavenumbers observed, this tendency was not nearly so marked as in the case of the internal mode wavenumber.

This paper reports on the spectroscopic study of YbVO{sub 4} in the range 10-300 K. All the Raman phonons were properly assigned. Temperature-dependent Raman spectra showed no anomalous changes, which indicate that neither structural phase transition nor strong electron-phonon coupling occur, at least within this temperature range. This result is sharp contrast to those of YbPO{sub 4} where strong mixing of the upper crystal-field states {Gamma}{sub 6} and {Gamma}{sub 7} with an E{sub g}{sup 3} phonon at room-temperature occurs. A possible explanation for the absence of electron-phonon coupling in YbVO{sub 4} is the occurrence of the {Gamma}{sub 6} state at energy higher than the E{sub g}{sup 3} phonon, unlike the coincidence of {Gamma}{sub 6} and E{sub g}{sup 3} energies in YbPO{sub 4}.

The room temperature phonon modes of trigallium phosphorus heptaoxide (Ga3PO7) single crystal have been determined by polarized Raman spectroscopy. The Ga3PO7 single crystal exhibits a trigonal structure belonging to the space group R3m (C3v5) with three molecules per unit cell (Z=3). The framework structure of the Ga3PO7 crystal consists of PO4 tetrahedra and Ga3O10 clusters. Since the PO4 tetrahedra are more tightly bound than the GaO5 trigonal bipyramids, only the internal modes of the PO4 are observed. We observed 7A1(TO)+7E(TO) out of 7A1(TO)+10E(TO) vibrations predicted by the Group Theory.

In this work, we have used the thermal lens technique combined with conventional spectroscopy to characterize the thermo-optical properties of Er3+-doped lead pyrophosphate-based glasses. More precisely, we have investigated and quantified experimentally the fluorescence quantum efficiencies of the Er3+ levels, and we describe the role of concentration quenching effects. The fluorescence quantum efficiency of the 4I13/2 level is very high when compared to other phosphate glasses, while that of the green-coupled levels is very small. Other important photonic materials parameters, such as the thermal diffusivity and temperature coefficient of the optical path length change, were obtained and compared with those of other glass systems. The cumulative results obtained here for the Er-doped lead pyrophosphate glass show that this material is a good candidate for photonic applications with a characteristic Er3+ infrared emission around 1550 nm.