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Nanoparticle mediated hyperthermia has been explored as a method to increase cancer treatment efficacy by heating tumours inside-out. With that purpose, nanoparticles have been designed and their properties tailored to respond to external stimuli and convert the supplied energy into heat, therefore inducing damage to tumour cells. Moreover, the combination of hyperthermia with chemotherapy has been described as a more effective strategy due to the synergy between the high temperature and the drug's effects, also associated with a remote controlled and on-demand drug release. In this review, the methods behind nanoparticle mediated hyperthermia, namely material design, external stimuli response and energy conversion will be discussed and critically analysed. We will address the most relevant studies on hyperthermia and temperature triggered drug release for cancer treatment. Finally, the advantages, difficulties and challenges of this therapeutic strategy will be discussed, while giving insight for future developments. [Display omitted] • Nanoparticles correct the non-specific mode of action of chemotherapy. • Hyperthermia works as an adjuvant in cancer therapy • Hyperthermia sensitizes cancer cells to chemotherapy. • Hyperthermia can be induced through several external stimuli. • Stimuli responsive nanomaterials allow for a remote-controlled drug release. [ABSTRACT FROM AUTHOR]

Eu0.8Y0.2MnO3 has been widely studied due to its very distinctive phase diagram, where it is still poorly understood the actual ferroelectric character of the low temperature magnetic phases. In order to figure out what is the origin of the microscopic mechanisms that drive its behavior, we carried out a detailed study of the displacement currents for both different starting conditions and polarizing electric fields, and of the field dependent magnetodielectric effect in Eu0.8Y0.2MnO3 ceramics. The experimental results provide clear evidence for the existence of two dipolar systems, one stemming from an electric field-induced process, likely associated with the isovalent substitution of Eu3+ by the smaller off-center Y3+ ions at A-lattice sites, which is independent of any cooperative phenomena occurring in the system. The other dipolar system, strongly dependent on the existence of the first one, drives the polar behavior of the nonmodulated magnetic phase AFM-2, stable in the temperature range of 23–30 K, and is associated with the ferroelectric character of this phase. The magnetic field dependence of the complex dielectric constant clearly shows that the magnetodielectric effect is strongly dependent on the phase it is being considered, and provides further evidence for the ferroelectric character of the AFM-2 phase referred to above. [ABSTRACT FROM AUTHOR]

Long period fiber gratings (LPFGs) were used to monitor the characteristics of copper (Cu) thin films when annealed in air atmosphere up to ∼680 °C. The wavelength and the optical power shift of the resonant bands of the LPFGs when coated with the Cu thin films, were measured as a function of the annealing temperature, and were found to exhibit a different evolution comparing to a bare LPFGs. Thin films of Cu deposited on quartz (SiO 2 ) substrates were annealed and analyzed by XRD, SEM/EDS and Raman spectroscopy, allowing to identify the formation of two distinct oxide phases at different temperatures, cuprous (Cu 2 O-cuprite) and cupric (CuO-tenorite) oxides, respectively. The observed features of the resonant bands of the LPFGs were found to be associated with the Cu oxide phase transitions, indicating the possibility of using LPFGs to monitor, in real time, the oxidation states of Cu thin films by following specific characteristics of the attenuation bands. In addition, LPFGs over coated with the two distinct oxidation phases of Cu were characterized for refractive index sensing in the range between 1.300 to 1.600, leading to the conclusion that the sensitivity to the refractive index of the surrounding medium of Cu coated LPFGs sensing systems can be temperature tuned. [ABSTRACT FROM AUTHOR]

The biointeractions of graphene-based materials depend on their physico-chemical properties. These properties can be manipulated by polymer adsorption. Graphene nanoplatelets (GNP-C) were modified with PVA, HEC, PEG, PVP, chondroitin, glucosamine, and hyaluronic acid. These materials were characterized by SEM, DLS, XPS, Raman spectroscopy, and TGA. Surface adsorption was confirmed for all polymers. Biocompatibility evaluation showed that all of these materials induced low haemolysis (<1.7%) at concentrations up to 500 μg mL −1 . GNP-C-PVA and GNP-C-HEC presented the lowest haemolysis percentages and were therefore more thoroughly studied. The morphology of HFF-1 cells was investigated by microscopy (optical, fluorescence, TEM) in order to evaluate interactions with GNP materials. Small GNP-C nanoplatelets were observed to enter cells independently of the surface treatment. For pristine GNP-C at a concentration of 50 μg mL −1 , ROS production increased 4.4-fold. This effect is lower for GNP-C-PVA (3.3-fold) and higher for GNP-C-HEC (5.1-fold). Resazurin assays showed that GNP-C caused toxicity in HFF-1 cells at concentrations above 20 μg mL −1 at 24 h, which decreased at 48 and 72 h. PVA surface adsorption rendered GNP-C non-toxic at concentrations up to 50 μg mL −1 . LIVE/DEAD assays showed that at 20 and 50 μg mL −1 cell death is significantly lower for GNP-C-PVA compared to pristine GNP-C. Modification of nanoplatelets with HEC resulted in no benefit in terms of biocompatibility, whereas PVA considerably improved the biocompatibility. [ABSTRACT FROM AUTHOR]

YMnO3thin films were prepared based on a chemical solution deposition route. Their structure was studied as a function of the annealing temperature using X-ray diffraction, Raman spectroscopy, and electron backscatter diffraction. For annealing temperatures above 850°C the films, though crystallizing predominantly in aP63cmhexagonal structure, exhibit a thin Pnma orthorhombic phase close to the film-substrate interface. It is shown that the residual orthorhombic structure is associated with a substrate induced strain state, characterized by an expansion in the in-planeadirection, and a compression in the out of plaincdirection. [ABSTRACT FROM PUBLISHER]

In this work, we analyzed GdMnO3 magnetoelectric thin films prepared by a general sol-gel method. The film formation temperature is analyzed by a thermogravimetric analysis, while the lattice parameters of the Pbnm orthorhombic films are determined from the analysis of the X-ray spectra. The X-ray results also reveal that GdMnO3 films are under compression along the b axis. The lattice dynamic analysis carried out by a Raman spectroscopy confirms the formation of films with a Pbnm orthorhombic structure. Moreover, the analysis of the Raman spectra suggests that besides film-substrate interaction, texture and grain size influence can alter lattice dynamics relative to the bulk ones. Magnetic measurements show that the film response is different from that observed in ceramic and single crystal; mainly, in the shape and temperature where the transitions are taking place. The magnetic study also reveals that GdMnO3 films are paramagnetic above 80K, showing a ferromagnetic-like response at low temperatures (T≤15K). The dielectric analysis carried out on the 850°C annealed film shows the formation of a relaxation process at low temperature, which is associated with a polaronic process. Moreover, it is also observed a small anomaly at T~27K that might be related to the magnetic transition taking place in this temperature range. [ABSTRACT FROM AUTHOR]

Abstract: This work is addressed to studying GdMnO3 thin films, prepared by a chemical solution method on oriented Pt substrates. Alterations regarding structure and magnetic response of both ceramics and single crystals show that the behaviour of the as-prepared films can be understood by assuming a continuously changing of the in-plane stress state in the film induced by mechanical coupling with the substrate. The emerging of a ferromagnetic response in the thin films is a consequence of the structural deformations induced by matching both film and substrate during the growth process, which alters the balance between competitive antiferromagnetic and ferromagnetic interactions. [Copyright &y& Elsevier]

We present a study of the effect of very high pressure on the orthorhombic perovskite GdMn03 by Raman spectroscopy and synchrotron x-ray diffraction up to 53 GPa. The experimental results yield a structural and insulator-to-metal phase transition close to 50 GPa, from an orthorhombic to a metrically cubic structure. The phase transition is of first order with a pressure hysteresis of about 6 GPa. The observed behavior under very high pressure might well be a general feature in rare-earth manganites [ABSTRACT FROM AUTHOR]

Abstract: Hexagonal LuMnO3 thin films have been prepared based on a chemical solution deposition method. These films were deposited by spin-coating technique and annealed at different temperatures from 750°C up to 850°C, based on the thermogravimetric and differential thermal analysis results. An amorphous phase is observed in the film annealed at 750°C, while a pure LuMnO3 hexagonal phase is reached in the films annealed at 800°C and 850°C, along with a visible enhancement in the grain morphology as the annealing temperature increase. Low temperature magnetic analysis of the LuMnO3 films annealed at 850°C reveals several magnetic transitions, which are consistent with those reported for both LuMnO3 ceramics and single crystals. Moreover, the emergence of a canted spin arrangement was evidenced from the temperature dependence of the specific induced magnetization and magnetic hysteretic cycles. No significant effect of the substrate on the magnetic properties was also sorted out. Dielectric measurements reveal the existence of a complex frequency behavior of the dielectric permittivity, which can be associated with relaxation processes arising from the interfaces film/electrodes. [Copyright &y& Elsevier]

EuMnO3 and GdMnO3 ceramics have been synthesised by urea sol-gel combustion method. The dielectric and magnetic properties of high quality ceramics of both compounds were performed in the 5 K-300 K temperature range. The magnetic phase transitions in both compounds are marked by anomalies in the temperature behaviour of both dielectric constant and induced magnetization. The experimental results are discussed and compared with those ones obtained in single crystals. [ABSTRACT FROM AUTHOR]

In this work we present a detailed study of the temperature evolution (290 K–20 K) of the polarized Raman spectra in a single crystal of glycinium phosphite. The phase transition manifests itself by the activation of new Raman bands and by the occurrence of anomalies in the temperature dependence of the wavenumber of some external and internal modes. The results show that occurring deformations in molecular units contribute relevantly to the spontaneous polarization in GPI. The anomalous behaviour of the wavenumber and of the damping constant of some bands is in good agreement with a theoretical model based in a pseudospin-phonon interaction. [ABSTRACT FROM AUTHOR]

Betaine calcium perchlorate monohydrate (here designate by BCPM) is a new compound of the amino acid betaine with a triclinic symmetry and with the space group P..., at room temperature. In this work we present a detailed study of dielectric properties and of Raman scattering spectra of BCPM, which disclose interesting structural changes in the temperature range 20 K-300 K. [ABSTRACT FROM AUTHOR]

In this work we present a detailed study of the temperature dependence (35 K- 290 K) of the Raman spectra in a single crystal of betaine phosphite. A softening of a relaxational mode is observed above and below the para-ferroelectric phase transition at Tc2 ∼ 213 K, which appears to have its primary origin in the different internal dynamic deformations and reorientations of molecular units. Our results suggest the existence of a certain degree of local disorder between 110 K and 170 K. [ABSTRACT FROM AUTHOR]

Betaine cadmium chloride monohydrate undergoes a phase transition at 241 K. This transition was disclosed by using thermal differential analysis and Raman spectroscopy. This phase transition is clearly related to a structural change where the water molecules lose their degrees of freedom, becoming more tightly bonded, on cooling. [ABSTRACT FROM AUTHOR]

We report a detailed experimental study of infrared reactivity and Raman spectroscopies in strongly deuterated betaine arsenate: BA 0.08 DBA 0.92 . The temperature dependence of the frequency of the hydrogen bonds stretching modes shows a different critical behaviour for the different types of hydrogen bonds. At 163 K , there is evidence for the proton ordering in the shorter hydrogen bond. A progressive softening of the dynamical central peak revelead some aspects of an order-disorder mechanism. [ABSTRACT FROM AUTHOR]

The constant change in microplastics (MP) due to exposure to environmental conditions leads to physical and chemical changes that enhance their ability to transport other pollutants, increasing the concern about their widespread presence in the environment. This work aimed to simulate the aging process of six MP (polyamide 6, unplasticized polyvinyl chloride, low-density polyethylene, polystyrene, polyethylene-co-vinyl acetate, polypropylene) in freshwater and seawater ecosystems at laboratory scale and evaluate its effects through optical microscope observation, Fourier transform infrared spectroscopy-Attenuated Total Reflectance (FTIR-ATR), Raman spectroscopy, and thermal gravimetric analysis (TGA). Through a combined experimental study of aged MP, the degradation by UV interaction was evidenced by the appearance of new infrared bands in the FTIR spectra assigned to ketones and hydroxyl groups. While Raman analysis and microscope images reveal the appearance of pores, wrinkles, and roughness in the MP surfaces. Variations in the temperature of the maximum weight loss of the MP were observed in the TGA analysis. The adsorption of chlorpyrifos (CPF), a common pesticide widely used in agriculture, by the pristine and aged MP was also studied. The highest affinity for CPF was observed for pristine LDPE and the lowest for PP. The batch adsorption studies revealed an increase in adsorption capacity as a consequence of the aging process for both MP. These results proved that the weathering effects caused changes in the behavior of MP, namely in the interaction with other pollutants. [ABSTRACT FROM AUTHOR]

In this article, the author discusses about two experimental approaches explaining the buoyancy concept relating Newtonian mechanics with fluid mechanics which can help students in understanding of physics. He states that the increase of the value measured at the balance corresponds to the change in the water pressure at the bottom of the container, due to the increase of the free surface level of the water.

This work aims to understand the alterations induced by film/substrate lattice mismatch in structure, lattice dynamics and magnetic response of orthorhombic Eu 1-x Lu x MnO 3 thin films within the range 0 ≤  x  ≤ 0.4, when compared to results reported for ceramics with analogous composition. Thin films, which have been deposited onto Pt/Ti/SiO2/Si(100) oriented substrates via chemical method, exhibit noteworthy modifications in the magnetic ordering properties and, contrary to ceramics, do not show any sharp phase transition to the paramagnetic state. This reveals an induced ferromagnetic response in the films which is stable up to 100 K. X-ray diffraction and Raman spectroscopy measurements have been performed to identify the mechanically compressive state induced by the substrate and Lu doping. This facilitates insight into the magnetoelastic coupling effect in these films which is driven by alterations in electronic orbital overlapping and the associated antiferromagnetic superexchange interactions. [ABSTRACT FROM AUTHOR]

We investigate the interplay of magnetization and lattice vibrations in rare-earth orthoferrites RFeO3, with a specific focus on non-symmetry-breaking anomalies. To do so, we study the magnetization, magnon excitations and lattice dynamics as a function of temperature in NdFeO3, TbFeO3, EuFeO3 and GdFeO3. The magnetization shows distinct temperature anomalous behavior for all investigated rare-earth orthoferrites, even in the compounds with no phase transitions occurring at those temperatures. Through spin–phonon coupling, these magnetic changes are mirrored by the FeO6 rotation mode for all the studied RFeO3, revealing a common magnetostructural effect associated with the octahedra rotations. The R3+ oscillation modes evidence a Fe3+/R3+ spins cross-talk for the NdFeO3 and TbFeO3 cases. Our work sheds light into the common magnetostructural coupling in rare-earth orthoferrites, and the important role of magnetic anisotropy and spin–orbit coupling strength of the R–Fe interactions on the spin-reorientation transition at high temperatures. [ABSTRACT FROM AUTHOR]

The morphology, crystallinity, and electrical conductivity (σ′ and σ″) as a function of frequency of polypropylene (PP) melt-extruded with different amounts of as-grown carbon nanofibers (CNFs) from 0 to 1.4 vol. % are examined. The PP/CNF composites present CNF aggregates randomly distributed within the PP and an insulator–conductor transition at CNF contents near 0.9 vol. %. The degree of crystallinity of PP/CNF composites with loadings of 1.4 vol. % increases ∼15% with respect to the neat PP (∼34%), with σ´ ∼ 8.6 × 10−5 S m−1 (σ″ ∼ 8.3 × 10−4 S m−1) at 2 MHz. In addition, the values of the electrical conductivity σint´ ∼2.9 × 10−6 S m−1 (σint″∼3.7 × 10−4 S m−1) at 2 MHz, as a result of the interphase (ϕint ∼0.05 vol. %) of the 1.4 vol. % PP/CNF composites, are estimated by the use of a modified generalized effective medium model (GEM). The analysis gathered in here indicates that the interphase between the polymer and the conducting particle may have a quantifiable effect on the electrical properties of carbon-based polymer composites, and this fact should not be neglected in the production of conducting polymer composites (CPCs) with enhanced electrical properties. [ABSTRACT FROM AUTHOR]

In this work, NaTaO3 ceramics are prepared by conventional mixed oxide method and NaTaO3 films are deposited by RF magnetron sputtering on Si/SiO2/TiO2/Pt substrates. The dielectric response of the obtained NaTaO3 ceramics and films is analyzed as a function of frequency and temperature. Between 1 kHz and 1 MHz, the dielectric permittivity of NaTaO3 ceramics is frequency independent and increases on cooling up to ∼324, which is the highest value ever reported for NaTaO3 ceramics. In contrast, NaTaO3 films exhibit a dielectric relaxation between ∼20 and 30 K, following the Arrhenius law with activation energy ∼51 meV and pre-exponential term ∼10-15 s and attributed to polaron hopping. [ABSTRACT FROM AUTHOR]

In this work, different weight contents of as-grown carbon nanofibers (CNFs), produced by chemical vapor deposition, were melt-extruded with polypropylene (PP) and their morphologic, structure and dielectric properties examined. The morphologic analysis reveals that the CNFs are randomly distributed in the form of agglomerates within the PP matrix, whereas the structural results depicted by Raman analysis suggest that the degree of disorder of the as-received CNFs was not affected in the PP/CNF composites. The AC conductivity of PP/CNF composites at room temperature evidenced an insulator–conductor transition in the vicinity of 2 wt.%, corresponding to a remarkable rise of the dielectric permittivity up to ∼ 12 at 400 Hz, with respect to the neat PP (∼ 2.5). Accordingly, the AC conductivity and dielectric permittivity of PP/CNF 2 wt.% composites were evaluated by using power laws and discussed in the framework of the intercluster polarization model. Finally, the complex impedance and Nyquist plots of the PP/CNF composites are analyzed by using equivalent circuit models, consisting of a constant phase element (CPE). The analysis gathered in here aims at contributing to the better understanding of the enhanced dielectric properties of low-conducting polymer composites filled with carbon nanofibers. [ABSTRACT FROM AUTHOR]

In this work, we revisit the phase transition sequence and the effect of the sintering process on the structural, dielectric and polar properties of K 0.5 Na 0.5 NbO 3 ceramics prepared by conventional sintering, spark plasma sintering and spark plasma texturing. Herein, comparative experimental study of the lattice dynamics, polar and dielectric properties is presented. We observe that the phase transition sequence includes an unreported structural and polar phase at low temperatures, independently on the processing method. Contrarily, we observe apparent changes of the stability temperature interval of the different phases. The dielectric strength and the emergence of a dielectric relaxation phenomenon are also noticeably dependent on the processing method, which can be understood as an effect of the different grain size. The results here reported clearly show the possibility to change physical properties following different sintering routes in order to improve device performance. Image 1 [ABSTRACT FROM AUTHOR]

The effect of Sr vacancies on the behavior of strontium titanate with trivalent dopants (La3+, Gd3+, and Y3+) substituting Sr2+ ions is reported. A remarkable shift of the antiferrodistortive transition temperature Ta is revealed by Raman spectroscopy for just a small content of dopant. It is shown that a unique linear dependence of Ta versus tolerance factor is obtained when Sr-vacancies are taken into account. A vacancy size value of ∼1.54 Å is estimated, which is ∼7% larger than Sr2+ radius. This size difference enables explaining the unexpected increase of lattice parameter with increasing Bi3+ content in Sr1-1.5xBixTiO3. [ABSTRACT FROM AUTHOR]

Abstract Doped polyaniline (PANI) exhibits excellent electrical properties that can be used in composite materials to replace metallic or carbonaceous nanofillers commonly used in composites for sensor applications. Polymer blends based on PANI and thermoplastic elastomer styrene-ethylene/butylene-styrene (SEBS) copolymer have been prepared by solvent casting showing large strain yield (>10% for 40 wt% PANI content), high electrical conductivity, 1 S/m, after the percolation threshold at ≈10 wt% PANI. Further, the composites show suitable piezoresistive response with gauge factor (GF) between GF ≈ 1.5 and 2.4 for deformations up to 10%. The overall properties of the solution casted PANI/SEBS blends indicate their suitability for advanced electromechanical sensors applications, with simple integration and processable by solution printing technologies. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

This work reports thermal annealing induced effect on the structural, optical, chemical and ferroelectric properties of ion-beam sputtered lead-free ferroelectric 0.5 Ba(Zr 0.2 Ti 0.8 )O 3 – 0.5 (Ba 0.7 Ca 0.3 )TiO 3-δ (0.5BZT–0.5BCT) thin films. X-ray diffraction studies reveal that the tetragonality increases with the annealing temperature (T a ), while photoluminescence and X-ray photoelectron spectroscopy studies confirm that this effect is associated with the annihilation of the oxygen vacancies as well as changes in the Ba 2+ coordination. The films annealed at 750 °C show a remarkable remnant polarization of P r  = 45.0 μC/cm 2 , with a coercive field of 32 kV/cm. The temperature dependence of the spontaneous polarization of the 0.5BZT–0.5BCT film reveals a mean field behavior of the polarization and the fatigue study reveals that P r only decreases 3% after passing 10 9 cycles. Therefore the high remnant polarization and its high P r stability make these films as promising candidates for memory applications. [ABSTRACT FROM AUTHOR]

In this work, we investigate the photovoltaic response of Pt/0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (0.5BZT-0.5BCT)/ITO structures through the insertion of a semiconductor ZnO layer at different positions. The values of short-circuit photocurrent density ( J sc ) of the Pt/ZnO/0.5BZT-0.5BCT/ITO, Pt/0.5BZT-0.5BCT/ZnO/ITO and Pt/ZnO/0.5BZT-0.5BCT/ZnO/ITO capacitors are around 5.31, 0.0034 and 0.052 mA/cm 2 , respectively. The enhanced photovoltaic (PV) effect is observed when ZnO layer is inserted between Pt and the 0.5BZT-0.5BCT layer. The built-in field developed at the ZnO/ferroelectric interface in the same direction of the depolarizing field, provides a favorable electric potential for the efficient separation and transportation of photo generated e-h pairs. Furthermore, the polarization-dependent interfacial coupling effect enhances PV effect, which is confirmed by investigating the role of polarization flipping on switchable photo response. This work provides an efficient pathway in tuning the PV response in ferroelectric-based solar cells. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) composites with different carbonaceous nanofillers, prepared by solution casting, were studied their chemical, mechanical, electrical and electro-mechanical properties evaluated. Few-layer graphene (FLG) nanoplatelets (G-NPL), graphene oxide (GO) and reduced graphene oxide (rGO) and single-walled carbon nanohorns (SWCNH)) were found to have a strong influence in the overall properties of the composites prepared with up to 5 wt% nanofiller contents. The mechanical strain of carbonaceous nanofillers/PVDF composites decreases from 15% to near 5% of maximum strain. The electrical percolation threshold depends on the nanofiller type, being below 1 wt% for rGO and near 2 wt% for the remaining nanofillers. The electrical conductivity shows a maximum increase of nine orders of magnitude, from σ ≈ 5 × 10 −11 S/m of pure PVDF to σ ≈ 1 × 10 −2 S/m for rGO/PVDF composites with 5 wt% nanofillers. The conduction mechanism being related to hopping between the carbonaceous nanofillers for concentrations higher than the percolation threshold. Furthermore, the composites show electro-mechanical properties, except for G-NPL materials, with rGO/PVDF composites with 5 wt% nanofiller content showing higher Gauge factor (GF) values, reaching GF≈ 11 for deformations between 0.5 and 2 mm in 4-point bending experiments. These results demonstrate the suitability of the composites for strain sensing applications. [ABSTRACT FROM AUTHOR]

This work addresses the effect of substituting Mn 3+ by Fe 3+ at the octahedral site of TbMnO 3 on the magnetic phase sequence, ferroelectric and magnetoelectric properties, keeping the Fe 3+ concentration below 5%. The temperature dependence of the specific heat, dielectric permittivity and electric polarization was studied as a function of Fe 3+ concentration and applied magnetic field. From the experimental results a strong decrease of the electric polarization with increasing Fe 3+ substitution is observed, vanishing above a concentration of 4%. However, within this range, a significant increase of the magnetic sensitivity of the electric polarization is obtained by increasing Fe 3+ concentration. For Fe 3+ concentration above 4%, a non-polar phase emerges, whose spin structure prevents ferroelectricity according to the Dzyaloshinskii-Moriya model. The experimental results here reported reveal the crucial effect of B-site substitution on the magnetic phase sequence, as well as, on the polar and magnetoelectric properties, evidencing the important role played by the e g electrons on the stabilization of the magnetic structures that are suitable for the emergence of electric polarization. [ABSTRACT FROM AUTHOR]

This work reports the effect of partial oxygen pressure, used in the deposition of the ZnO layer, on the band alignment at ZnO – 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (0.5BZT-0.5BCT) interface and on the resistive switching (RS) behavior of pulsed laser deposited ZnO/0.5BZT-0.5BCT heterostructures. X-ray photoelectron spectroscopy (XPS) has been employed to measure the valence band offset and the conduction band offset of the ZnO/0.5BZT-0.5BCT heterojunctions. The valence and conduction band offsets of the ZnO/0.5BZT-0.5BCT heterostucture with ZnO deposited at 10 −2 mbar of partial oxygen pressure were found to be 0.27 and 0.80 eV, respectively. The RS effect in heterostructures is explained on the base of the charge coupling between the switchable polarization of ferroelectric layer and the non-switchable polarization of semiconductor layer. The heterostructure with ZnO deposited at 10 −2 mbar of partial oxygen pressure displays optimum RS characteristics, with a switching ratio ≥ 10 4 and excellent retention and endurance characteristics. The optimum RS characteristics are attributed to a good interface quality with enough carrier concentration in ZnO, as evidenced by XPS. [ABSTRACT FROM AUTHOR]

In this work, the structural and ferroelectric properties of 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (0.5BZT-0.5BCT) thin films deposited at different pulse repetition rates were studied. The films deposited at pulse repetition rate of 1 Hz display the optimum values of ferroelectric polarization and dielectric permittivity and are chosen for the investigation of resistive switching and photovoltaic studies. The Pt/0.5BZT-0.5BCT/ITO capacitors show the electroforming free resistive switching (RS) and is explained based on the polarization modulation of the Schottky barrier at the 0.5BZT-0.5BCT/ITO interface. Furthermore, it is shown that the RS ratio and switching voltage can be tuned with white light illumination. The capacitors display photovoltaic effect with the open circuit voltage ≈0.8 V and the short circuit current density ≈72.6 μAcm −2 . The photovoltaic efficiency is found to be ≈0.010% and is greater than that of other perovskite ferroelectric thin films. The underlying mechanism for enhanced RS and photovoltaic effects is highlighted. [ABSTRACT FROM AUTHOR]

We present the magnetic phase diagram of TbMn 1 − x Fe x O 3 substitutional solid solutions in the whole concentration range 0 ≤ x ≤ 1 as determined from magnetization and specific-heat measurements and as supported by already known magnetic structures published on this substitutional system. We have found that the dominant magnetic ion in the concentration range 0 ≤ x < 0.2 is Mn, while Fe ions do not create an independent magnetic structure, but strongly affect the magnetic properties of the parent compound by suppressing the magnetic-ordering temperature as well as the magnetic order-order transition to a cycloidal phase. The magnetism in the concentration range 0.2 ≤ x ≤ 1 is driven by the Fe sublattice. The Mn ions again do not order in a long-range magnetic ordered state, but stabilize five magnetic phases of the Fe sublattice above 2 K. Magnetic ordering of the Tb sublattice is observed at temperatures below 8.2 K over entire concentration range. [ABSTRACT FROM AUTHOR]

We acknowledge funding from NORTE-01-0145-FEDER-022096, UID/NAN/50024/2019 and PTDC/NAN-MAT/28538/2017 projects and R.V. to the grant from PTDC/NAN-MAT/0098/2020." now reads: "We are deeply acknowledged to J. L. Ribeiro for the fruitful discussion regarding the interpretation of the magnetic data, and P. Bouvier suggestions on the analysis of some specific phonons. We acknowledge funding from NORTE-01-0145-FEDER-022096, UIDB/04968/2020 and PTDC/NAN-MAT/28538/2017 projects and R.V. to the grant from PTDC/NAN-MAT/0098/2020." "We are deeply acknowledged to J. L. Ribeiro for the fruitful discussion regarding the interpretation of the magnetic data, and P. Bouvier suggestions on the analysis of some specific phonons. [Extracted from the article]

In this work, 150 nm thick polycrystalline BaTiO 3 (BTO) films were deposited on Pt/TiO 2 /SiO 2 /Si substrate by ion beam assisted sputter deposition technique. The bias voltage dependent resistive switching (RS) and ferroelectric polarization characteristics of Au/BTO/Pt devices are investigated. The devices display the stable bipolar RS characteristics without an initial electroforming process. Fittings to current–voltage (I–V) curves suggest that low and high resistance states are governed, respectively, by filamentary model and trap controlled space charge limited conduction mechanism, where the oxygen vacancies act as traps. Presence of oxygen vacancies is evidenced from the photoluminescence spectrum. The devices also display P–V loops with remnant polarization ( P r ) of 5.7 μC/cm 2 and a coercive electric field ( E c ) of 173.0 kV/cm. The coupling between the ferroelectric polarization and RS effect in BTO films is demonstrated. [ABSTRACT FROM AUTHOR]

Graphene-based materials (GBMs) have recognized potential for biomedical applications, however different production methods and treatments originate divergent biocompatibility. In this work, two commercially available graphene nanoplatelets (GNP) were studied, differing in platelet size: GNP-C, with 1–2 μm, and GNP-M, with 5 μm. GNP-M was oxidized using KMnO 4 in different ratios (1:3 and 1:6), leading to GNP-M-ox-1:3 and GNP-M-ox-1:6. The effect of oxidation and size on biocompatibility was evaluated in vitro . Hemolysis was below 3% for all GBMs from 100 to 500 μg mL −1 . GNP-C entered human fibroblasts (HFF-1) inducing reactive oxygen species production after 1 h for 10 μg mL −1 , leading to metabolic activity decreases at 24 h, which reverted at 48 h and 72 h. GNP-C was toxic to HFF-1 for 50 μg mL −1 . Despite that, GNP-C did not cause damages on cell membrane, opposed to GNP-M and GNP-M-ox-1:3, which were toxic for 20 μg mL −1 . GNP-M-ox-1:6 did not decrease metabolic activity or cause membrane damages until 100 μg mL −1 (highest tested) for 72 h. This is explained by complete oxidation causing folding of GNP-M sharp edges, therefore preventing damages. Thus, GNP-M-ox-1:6 has potential for biomedical applications. Equivalent metabolic activity results were obtained for all materials with HPMEC (Human Pulmonary Microvascular Endothelial Cells). [ABSTRACT FROM AUTHOR]

In this work, Ba0.8Sr0.2TiO3 (BST)/ITO structures were grown on glass substrate and laser assisted annealing (LAA) was performed to promote the crystallization of BST. Atomic force microscopy and X-ray diffraction studies confirm the crack free and polycrystalline perovskite phase of BST. White light controlled resistive switching (RS) effect in Au/BST/ITO device is investigated. The device displays the electroforming-free bipolar RS characteristics and are explained by the modulation of the width and height of barrier at the BST/ITO interface via ferroelectric polarization. Moreover, the RS effect is significantly improved under white light illumination compared to that in the dark. The enhanced RS and photovoltaic effects are explained by considering depolarization field and charge distribution at the interface. The devices exhibit stable retention characteristics with low currents (≤μA), which make them attractive for non volatile memory devices. [ABSTRACT FROM AUTHOR]

The nominal BaTiO 3 compound often exhibits an assortment of controversial magnetic signals which can be simply explained through minute presence of spurious magnetic elements in the perovskite matrix, even when this compound is synthesized from high grade Ba and Ti precursors. Proton Induced X-Ray Emission (PIXE) technique enable to confirm ∼100 ppm of Fe contaminant which masks the utterly BaTiO 3 diamagnetism. Nevertheless, besides the expected paramagnetism of highly diluted Fe ions, it is also possible to observe a cooperative magnetic moment signature which exhibits an intricate relation with the phase transitions of the BaTiO 3 matrix. Such magneto-electric coupling signature is further corroborated by Raman spectroscopy, dielectric and X-ray diffraction measurements, indicating to a partial segregation of a rich Fe oxide phase, having a local structure clamped to the perovskite crystallites, hence acting as a practical probe sensitive to the local structural transitions of the host material. [ABSTRACT FROM AUTHOR]

We report a high-pressure study of orthorhombic rare-earth manganites AMnO3 using Raman scattering (for A = Pr, Nd, Sm, Eu, Tb, and Dy) and synchrotron x-ray diffraction (XRD), for A = Pr, Sm, Eu, and Dy. In all cases, a phase transition was evidenced by the disappearance of the Raman signal at a critical pressure that depends on the A cation. For the compounds with A = Pr, Sm, and Dy, XRD confirms the presence of a corresponding structural transition to a noncubic phase, so that the disappearance of the Raman spectrum can be interpreted as an insulator-to-metal transition. We analyze the compression mechanisms at work in the different manganites via the pressure dependence of the lattice parameters, the shear strain in the ac plane, and the Raman bands associated with out-of-phase MnO6 rotations and in-plane O2 symmetric stretching modes. Our data show a crossover across the rare-earth series between two different kinds of behavior. For the smaller A cations considered in this study (Dy and Tb), the compression is nearly isotropic in the ac plane, with only small evolutions of the tilt angles and cooperative Jahn-Teller distortion. As the radius of the A cation increases, the pressure-induced reduction of Jahn-Teller distortion becomes more pronounced and increasingly significant as a compression mechanism, while the pressure-induced tilting of octahedra chains becomes conversely less pronounced. We finally discuss our results in light of the notion of chemical pressure and show that the analogy with hydrostatic pressure works quite well for manganites with the smaller A cations considered in this paper but can be misleading with large A cations. [ABSTRACT FROM AUTHOR]

Freshwater quality has been changing due to the ever greater use of water resources and the contamination load resulting from human activities. Management of these systems, thus, requires constant diagnose of water quality with fast and efficient methodologies. The conventional methods adopted are, however, time-consuming, often very expensive, and require specialised expertise. Raman spectroscopy (RS) is a simple, fast and label-free technique that can be applied to environmental diagnosis using diatoms. Here, we developed a diagnostic method based on Raman spectroscopy applied to freshwater diatoms. For this, Raman spectra were recorded from diatoms of three lakes of a natural city park. The data acquired was analysed by chemometrics methods to describe the data (Partial Least Squares Regression), infer relationships in the dataset (Cluster Analysis) and produce classification models (Artificial Neural Network). The classification models developed diagnosed the lakes with excellent accuracy (89%) without requiring taxonomic information about the diatom species recorded. This study provides a proof-of-concept for the application of diatom Raman spectroscopy to diagnosing water quality, laying an important foundation for future environmental studies aiming at assessing freshwater systems, to be replicated at larger scales and to varied geographic settings. • Using Raman spectroscopy applied to diatoms to diagnose environmental quality. • PLS and ANN chemometric methods employed in the analysis of the Raman data. • Environmental conditions diagnosed with excellent accuracy. • Diatom Raman spectroscopy showed to be an expeditious and cost-effective biosensor. [ABSTRACT FROM AUTHOR]

Silver nanoparticle (AgNP) thin films were deposited by pulsed laser deposition onto glass substrates, at different fixed temperatures, under inert gas ambience and vacuum. Their morphology, surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) activities were investigated. AFM analysis of the films showed the formation of densely packed nanoparticles of varying size and shape by changing the ambience and deposition temperature (Ts). A SPR peak is not evidently observed in the spectrum of films deposited at room temperature, in either high vacuum or neon ambience. The SPR frequency blue shifts from 569 to 470 nm and from 581 to 574 nm with increasing Ts for the films processed in high vacuum and in neon ambience, respectively, while the absorption band becomes narrower with increasing Ts. The SERS intensity of Rhodamine B (RhB) adsorbed on a AgNP substrate grown at 600 °C in neon ambience exhibits a higher intensity compared with that of RhB adsorbed on the SERS active substrates at other values of Ts. Good correlation has been observed between the SPR and SERS activities and the morphology of the NPs. [ABSTRACT FROM AUTHOR]

This article studies the incorporation of sucrose in amino polymers produced by the strongly acid process and its role on the physico-mechanical properties and aldehyde emis-sion of the resulting particleboards. The incorporation of sucrose at different pH environ-ments was studied and differences on molecular weight of resins were analyzed by gel permeation chromatography/size exclusion chromatography (GPC/SEC) and characteristic chemical bands by Raman spectroscopy. A reaction mechanism was proposed to explain the observed differences in GPC/SEC chromatograms and was supported by Raman spec-tra. It was observed that small amounts of sucrose incorporated in polymeric matrix are sufficient to improve the physico-mechanical properties of particleboards; the sucrose addition protocol plays a key role on these improvements. [ABSTRACT FROM AUTHOR]

Abstract: Thin Zn0.98Co0.02O films were grown by pulsed laser deposition at different oxygen partial pressure (PO2) and its influence on their structural and electrical properties was investigated. Raman and photoluminescence studies revealed that zinc interstitial defects significantly decreased with increase of PO2. Complex impedance spectroscopy has been made to elucidate conduction mechanism and electronic relaxation process in Zn0.98Co0.02O films. Resistivity/impedance in the films grown at 0.1 mbar decreased as the temperature increases while the films grown at 0.01 and 0.001 mbar have shown opposite trend. The change in resistivity/impedance with temperature in the films grown at low and high PO2 is attributed to annihilation of defects and thermal activation of free carriers respectively. The relaxation time in the films grown at low PO2 increases with the temperature. It exhibits an exponential dependence on the inverse temperature with three different slopes. The corresponding energies estimated from Arrhenius type relation are very close to the energies for electronic relaxation of zinc interstitials, zinc antisities and oxygen vacancies respectively. Impedance analysis and current–voltage characteristics suggest that the resistivity of Zn0.98Co0.02O films is mainly due to bulk effect of the films. [Copyright &y& Elsevier]

In this work an electric-field gradient and magnetic hyperfine field study of the multiferroic AgCrO2 triangular spin lattice is presented. Perturbed angular correlation measurements at different temperatures, revealed the coexistence of two electric-field gradients, i.e., two distinct local environments at temperatures below 100 K. The emerging second local environment appears as a distortion of the Cr surrounding resulting in a local symmetry lowering. This local distortion emerges much above TN and concomitantly with the onset of short-range magnetic correlations. We claim that, through a magnetoelastic instability, distinct Cr-Cr exchange interaction pathways appear providing a channel for magnetic frustration release. [ABSTRACT FROM AUTHOR]

In the article titled "Investigation of Stereometric and Fractal Patterns of Spin-Coated LuMnO SB 3 sb Thin Films" [[1]], the authors Joaquim Agostinho Moreira and Abilio Almeida were affiliated to "Departamento de Física da Universidade do Porto, IFIMUP, and IN-Institute of Nanoscience and Nanotechnology, Porto 4169-007, Portugal", which is incorrect. The correct affiliation for the authors is "IFIMUP-Institute of Physics for Advanced Materials, Nanotechnology and Photonics, and Department of Physics and Astronomy of Faculty of Sciences, University of Porto, Rua do Campo Alegre s/n. 4169-007, Portugal.". [Extracted from the article]

CoOOH/Ni(OH) 2 and Ni(OH) 2 /CoOOH bilayer films were obtained through electrochemical deposition of Ni(OH) 2 and Co(OH) 2 single layers onto steel plate substrate, with subsequent electrochemical oxidation of Co(OH) 2 to form CoOOH. The films were structurally characterized using X-ray diffraction and Raman spectroscopy techniques. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques were used to perform the electrochemical characterization of the prepared bilayers. It was verified that during the electrochemical oxidation, CoOOH formation occurs without Ni(OH) 2 oxidation. Ni(OH) 2 films deposited on CoOOH (CoOOH/Ni(OH) 2) showed a superior electrochemical performance, with 324.27 mA h g−1 and 96.82% at 1.0 mA cm−2 for the specific capacity and capacity retention respectively. It was also determined that the relaxation time constant under this condition is 17.05 s. These results suggested that the CoOOH/Ni(OH) 2 bilayer films might be potential candidates for application as electrode in energy storage devices. • The preparation and electrochemical characterization of CoOOH/Ni(OH) 2 and Ni(OH) 2 /CoOOH bilayer films is report. • The CoOOH layer in the CoOOH/Ni(OH) 2 bilayer films result in a better electrochemical performance. • The relaxation time constant under this condition was 17.05 s • The CoOOH/Ni(OH) 2 bilayer films might be a potential candidate for electrode applications. [ABSTRACT FROM AUTHOR]

• Review of Raman spectroscopy applied to diatom research and applications. • Spectral profiles according to excitation wavelength and mode assignments reviewed. • Raman spectroscopy for taxonomic identification of diatoms. • Raman spectroscopy and diatom physiological responses to environmental cues. • Application to water quality assessment and environmental diagnosis. Diatom species are good pollution bioindicators due to their large distribution, fast response to changes in environmental parameters and different tolerance ranges. These organisms are used in ecological water assessment all over the world using autoecological indices. Such assessments commonly rely on the taxonomic identification of diatom species-specific shape and frustule ornaments, from which cell counts, species richness and diversity indices can be estimated. Taxonomic identification is, however, time-consuming and requires years of expertise. Additionally, though the diatom autoecological indices are region-specific, they are often applied indiscriminately across regions. Raman spectroscopy is a simpler, fast and label-free technique that can be applied to environmental diagnosis with diatoms. However, this approach has been poorly explored. This work reviews Raman spectroscopy studies involving the structure, location and conformation of diatom cell components and their variation under different conditions. A critical appreciation of the pros and cons of its application to environmental diagnosis is also given. This knowledge provides a strong foundation for the development of environmental protocols using Raman spectroscopy in diatoms. Our work aims at stimulating further research on the application of Raman spectroscopy as a tool to assess physiological changes and water quality under a changing climate. [Display omitted] [ABSTRACT FROM AUTHOR]

This work aims at studying the effect of La and Mn substituents on the structural, electrical and magnetic properties of Bi 1-x La x Fe 1-y Mn y O 3 (0≤ x ≤0.30; 0≤ y ≤0.20) at room temperature, in order to find out the optimal compositions that provide both high resistivity and remnant magnetization. The analysis of the XRD patterns and Raman spectra suggest a progressive transition from a rhombohedral for x < 0.15 with y = 0, and x = 0 with y ≤0.20 to an orthorhombic structure for x + y >0.20. Moreover, we observe satellite peaks associated with an incommensurate modulated (IM) orthorhombic structure for x ≥0.15 with y = 0, and x = 0.20 with y = 0.10. We were able to achieve a decrease by several orders of magnitude of the leakage current density and the emergence of a weak ferromagnetic response in the range of compositions 0.10< x ≤0.3 and 0< y <0.1. These improved physical properties are a consequence of the absence of secondary phases and the breaking of the spiral cycloid spin structure. In particular, the compositions within 0.18≤ x ≤0.30 and 0.01< y <0.05 with IM orthorhombic structure exhibit the lowest conductivity and highest remnant magnetization. The outcome of this work suggests an alternative route to enhance multiferroic properties of BiFeO 3 , with simultaneous La (0.10≤ x ≤0.30) and moderate Mn (0.01< y <0.1) substitution. Image 1 • Structural, magnetic, and leakage current studies of Bi 1-x La x Fe 1-y Mn y O 3. • Rhombohedral to orthorhombic structural transformation at x + y ≈0.2 with mixed phase at the intermediate compositions. • Incommensurate modulated orthorhombic structures for compositions within 0.18≤ x ≤0.30 and 0.01< y <0.05 • 0.10≤ x ≤0.30 and 0.01< y <0.1 compositions exhibit higher remnant magnetization and lower leakage currents. [ABSTRACT FROM AUTHOR]

Simple Summary: Neoplastic diseases are among the leading causes of death worldwide and constitute the main health problem in both human and veterinary medicine, particularly as the occurrence of the disease continues to increase. Comparative oncology is a quickly expanding field that examines both cancer risk and tumor development across species. Characterized by interdisciplinary collaboration, its goal is the improvement of both human and animal health. Canine neoplastic disease occurs spontaneously and has comparable clinical presentation and pathophysiology to corresponding human cancers. Since the nature of the disease is spontaneous, the complex interactions between tumor cells, tissues and the immune system can be better studied. Such relations are otherwise difficult to study in other experimental animal models. Raman spectroscopy has proved to be a suitable technique to detect and study breast microcalcifications. Raman spectroscopy is a specific and sensitive tool for identifying biomarkers of oncologic disease and also shows further potential in differentiating malignant and benign tumors, and these tumors from healthy tissue. Breast cancer is a health problem that affects individual life quality and the family system. It is the most frequent type of cancer in women, but men are also affected. As an integrative approach, comparative oncology offers an opportunity to learn more about natural cancers in different species. Methods based on Raman spectroscopy have shown significant potential in the study of the human breast through the fingerprinting of biological tissue, which provides valuable information that can be used to identify, characterize and discriminate structures in breast tissue, in both healthy and carcinogenic environments. One of the most important applications of Raman spectroscopy in medical diagnosis is the characterization of microcalcifications, which are highly important diagnostic indicators of breast tissue diseases. Raman spectroscopy has been used to analyze the chemical composition of microcalcifications. These occur in benign and malignant lesions in the human breast, and Raman helps to discriminate microcalcifications as type I and type II according to their composition. This paper demonstrates the recent progress in understanding how this vibrational technique can discriminate through the fingerprint regions of lesions in unstained histology sections from canine mammary glands. [ABSTRACT FROM AUTHOR]

The effect of platinum (Pt) bottom electrode texture on the tetragonality, dielectric, ferroelectric, and polarization switching response of pulsed laser deposited Ba0.8Sr0.2TiO3 (BST) thin films has been studied. The x-ray diffraction and Raman analysis revealed the higher tetragonality of BST films when they were grown on higher (111) textured Pt layer. The properties like dielectric permittivity, polarization, switching time, and leakage currents were found to be correlated to tetragonality and orientation of the BST films. The polarization current was observed to be higher in BST films on Pt epitaxial layer and it exhibits exponential dependence on the electric field. The voltage-current measurements displayed Ohmic behavior of leakage current irrespective of Pt texture for low voltages (up to 1 V), whereas at higher voltages the conduction mechanism was found to be dependent on texture selection of bottom Pt electrode. [ABSTRACT FROM AUTHOR]

Corrigendum to "Dielectric relaxation of near-percolated carbon nanofiber polypropylene composites" [Physica B: Phys. The bands at 998 cm SP -1 sp and 973 cm SP -1 sp are assigned to CH bending and wagging vibration and CH SB 3 sb rocking vibration and to CH SB 3 sb rocking, CH SB 2 sb wagging and CH bending vibrations, respectively. Furthermore, another decreasing of transmittance in the region from 750 to 500 cm SP -1 sp is found for PP/CNF composites, thus indicating the contribution from the CNF. [Extracted from the article]