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The TeO2–Nb2O5–Bi2O3 system was investigated by differential scanning calorimetry and temperature programmed X-ray diffraction. A large glass-forming domain was evidenced and the complex structural evolution with temperature of these glasses was followed. The glass transition and crystallisation temperatures and the nature of crystalline phases formed were determined. Moreover, this study confirmed the existence of the metastable γ-TeO2 polymorph and of a new crystalline compound, BiNbTe2O8. [Copyright &y& Elsevier]

The ability of assembling inorganic, organic, and even bioactive components in a single material unfolds an exciting direction in the development of novel multifunctional hybrid materials. Recently, we have observed that the hydrophilic/hydrophobic character of the organic polymeric moieties determines the swelling/diffusion control of the drug release. In this work, the antitumor cisplatin (CisPt) molecules incorporated into the ureasil-PEO (poly(ethylene oxide)) hybrid material was used as a probe for the in situ and simultaneous UV-vis and Raman spectroscopies monitoring of the kinetics of both the water uptake as well as the CisPt release by the hybrid matrix. Drug molecules were incorporated during the hydrolysis and polycondensation steps. The monolithic xerogel were analyzed by X-ray absorption spectroscopy and differential scanning calorimetry, while the drug release properties were monitored by Raman as well as UV-vis spectroscopies. The results show that the molecular structure of the CisPt is preserved in the one pot sol-gel route used in synthesizing the CisPt-loaded PEO1900 hybrid. The in situ monitoring of water uptake clearly points out the key contribution of the osmotic flow on the stepped profile of the CisPt delivered from the PEO1900 hybrid matrix.

The thermal and optical properties of 60TeO2-20K2TeO3-10WO3-10Nb2O5 (in mol%) glasses doped with Ho2O3, Er2O3, and Tm2O3 were explored in the present work. The thermal stability, refractive index n, extinction coefficient k, absorption coefficient α, and optical band gap of the glasses were evaluated. The UV–Vis–NIR absorption spectra, the Judd–Ofelt intensity parameter, the spectroscopic quality factor, and the emission and absorption cross-sections were calculated to investigate the effects of Er3+ and Tm3+, respectively, on the band spectroscopic properties of Ho3+ ions. The results showed that the maximum emission cross-section was approximately 8 × 10 − 21   c m 2 , and the values of the full width at half maximum ( F W H M) , quality factor ( σ e × F W H M) , and gain coefficient of Ho3+: 5I7 → 5I8 were also reported. The value of the F W H M × σ e was 1200 × 10 − 28   c m 3 , which showed greater gain characteristics than earlier study results. For 2   μ m mid-infrared solid-state lasers, the glasses that were examined might be a good host material. [ABSTRACT FROM AUTHOR]

High thermal stable glasses of 30TeO2–40B2O3–(30−x)BaO–xNa2O (0 ≤ x ≤ 30 mol%) were synthesized by melt quenching technique. Experimental tools like XRD, EDX, XPS, FTIR, Raman, DSC, Optical absorption and DC conductivity were used for characterization. The broad hump in XRD and endotherms in DSC asserted the short range order of samples. The changes in physical properties were correlated with structure and other investigations. Vibrational and DSC investigations displayed that bond strength of Te4+–O/B3+–O is higher in presence of Ba2+ than Na+ ions. The addition of Na2O decreased the glass transition temperature (Tg) and increase fragility for these glasses. The values of the optical band gap (Eopt) and Urbach energy (ΔE) were observed in 3.49–3.23 and 0.312–0.384 eV range, respectively. Variations in all the optical properties suggest that Na2O converted the Lewis acid into Lewis base glass. DC conductivity studies disclose that conductivity increases with raise in Na2O mol% and temperature. [ABSTRACT FROM AUTHOR]

Developing a method for the growth of ultrathin metal chalcogenides, potentially targeting the two-dimensional (2D) limit, has a pivotal impact on various nanotechnological device applications. Here, we employed a vapor deposition scheme, based on tellurization, to induce the heterogenous chemical reaction between solid Ag and Au precursors, in the form of ultrathin films, and Te vapors. We characterized the morphological and structural properties of the grown tellurides by using atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction techniques. The developed tellurization methodology provides a key advancement in the picture of growing ultrathin noble metal tellurides and holds great potential for applications in different technological fields. [ABSTRACT FROM AUTHOR]

In this work, we report the first attempt to investigate the dependence of thioacetamide (TAA) on the size of ZnO nanoparticles (NPs) in forming ZnS nanostructures from ZnO. Size-controlled B(blue)_, G(green)_, and Y(yellow)_ZnO quantum dots (QDs) and NC (nanocrystalline)_ZnO NPs were synthesized using a sol–gel process and a hydrothermal method, respectively, and then reacted with an ethanolic TAA solution as a sulfur source. ZnO QDs/NPs began to decompose into ZnS QDs through a reaction with TAA for 5~10 min, so rather than forming a composite of ZnO/ZnS, ZnO QDs and ZnS QDs were separated and remained in a mixed state. At last, ZnO QDs/NPs were completely decomposed into ZnS QDs after a reaction with TAA for 1 h irrespective of the size of ZnO QDs up to ~50 nm. All results indicate that ZnS formation is due to direct crystal growth and/or the chemical conversion of ZnO to ZnS. [ABSTRACT FROM AUTHOR]

Antibacterial resistance is a growing global vital medical problem when the innovation and development of new antibiotics are dwindling. Different nanomaterials were synthesized and developed as safe and effective alternative antimicrobial agents. The current study highlights the effect of the antibacterial activity of newly biosynthesized zinc oxide nanoparticles (ZnO NPs) obtained from Kombucha extract. Production of ZnO NPs was optimized and the synthesized nanoparticles were characterized using UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential and transmission electron microscope (TEM) analysis. The optimum conditions for ZnO NPs production were at temperature 30 °C, pH 9 and 25 mM of Zn(NO3)2.6H2O. The ZnO NPs biosynthesis was detected in the extract within 24 h. at 35 °C in dark conditions. The XRD pattern displayed 100, 101, 110, and 103 crystal planes. FTIR spectrum showed bands of 1° and 2° amines at 2922.6 cm−1 and a stretching vibration band of vinyl at 1657.5 cm−1. In addition, the results confirmed the positive charge (19 ± 3 mV) and crystalline nature of spherical-shaped ZnO NPs with an average size of 23 ± 1.5 nm. The antibacterial activity of ZnO NPs was tested against different American-type culture collection strains. ZnO NPs exhibited minimum inhibition concentration (MIC) values of 25 µg/ml against Escherichia coli ATCC25922, 30 µg/ml against Staphylococcus aureus ATCC25923 and Pseudomonas aeruginosa ATCC27853, 35 µg/ml against Serratia liquefaciens OQ071699.1 and S. saprophyticus OQ071703.1 and 40 µg/ml against Lysinibacillus fusiformis OQ071701.1 and Klebsiella pneumoniae ATCC33495. Ultrastructure TEM study of the treated bacteria by MIC of ZnO NPs confirmed their highly toxic action on the bacterial cell wall, resulting in bacterial cell membrane rupture. Treated bacteria appeared as extensively damaged cells with the formation of vacuoles and lipids. The provided approach of ZnO NPs in combination with Kombucha SCOBY has a promising future in overcoming bacterial resistance problems in place of using antibiotics.Article highlights: A green, cheap, and facile approach was used to biosynthesize ZnO NPs. Optimal concentrations of Zn(NO3)2.6H2O solution, concentrations of cell-free Kombucha biomass extract, incubation periods, pH values, and temperatures enhance ZnO NPs biosynthesis performance. Incorporation of ZnO NPs to Kombucha SCOBY is more effective for increasing its antibacterial activity than single SCOBY. [ABSTRACT FROM AUTHOR]

The application of mesenchymal stem cells (MSC) in bone tissue regeneration can have unpredictable results due to the low survival of cells in the process since the lack of oxygen and nutrients promotes metabolic stress. Therefore, in this work, polymeric membranes formed by organic–inorganic hybrid materials called ureasil-polyether for modified glucose release were developed in order to overcome the problems posed by a of lack of this nutrient. Thus, membranes formed by polymeric blend of polypropylene oxide (PPO4000) and polyethylene oxide (PEO500) with 6% glucose incorporation were developed. Physical–chemical characterization techniques were performed, as well as tests that evaluated thermal properties, bioactivity, swelling, and release in SBF solution. The results of the swelling test showed an increase in membrane mass correlated with an increase in the concentration of ureasil-PEO500 in the polymeric blends. The membranes showed adequate resistance when subjected to the application of a high compression force (15 N). X-ray diffraction (XRD) evidenced peaks corresponding to orthorhombic crystalline organization, but the absence of glucose-related peaks showed characteristics of the amorphous regions of hybrid materials, likely due to solubilization. Thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses showed that the thermal events attributed to glucose and hybrid materials were similar to that seen in the literature, however when glucose was incorporated into the PEO500, an increase in rigidity occurs. In PPO400, and in the blends of both materials, there was a slight decrease in Tg values. The smaller contact angle for the ureasil-PEO500 membrane revealed the more hydrophilic character of the material compared to other membranes. The membranes showed bioactivity and hemocompatibility in vitro. The in vitro release test revealed that it is possible to control the release rate of glucose and the kinetic analysis revealed a release mechanism characteristic of anomalous transport kinetics. Thus, we can conclude that ureasil-polyether membranes have great potential to be used as a glucose release system, and their future application has the potential to optimize the bone regeneration process. [ABSTRACT FROM AUTHOR]

The two new scandium oxotellurates(IV) Sc2Te3O9 and Sc2Te4O11 were synthesized through firing appropriate mixtures of Sc2O3, TeO2 and CsBr (as flux) in evacuated glassy silica ampoules at 850 °C for 10 days. Both of them crystallize in the monoclinic space group P21/c with Z = 4 (Sc2Te3O9: a = 523.36(3), b = 2438.23(14), c = 731.98(4) pm, β = 116.221(3)°; Sc2Te4O11: a = 949.51(6), b = 779.12(5), c = 1341.93(9) pm, β = 90.829(3)°). Both crystal structures contain two crystallographically unique Sc3+ cations. In the case of Sc2Te3O9, they reside in six- and sevenfold oxygen coordination arranged as distorted uncapped or capped octahedra, while for Sc2Te4O11, they only exhibit six oxygen atoms in the coordination polyhedra, but one of them has also a certain tendency to thrive for a higher coordination number (C.N. = 6 + 1). The [(Sc1)O6)]9− and [(Sc2)O6+1)]11− polyhedra in Sc2Te3O9 are condensed via common edges to form serrated ∞ 1 { [ Sc 2 O 6 / 1 t O 1 / 2 v O 4 / 2 e ] 11 − } chains running along [100], whereas the two [ScO6]9− octahedra in Sc2Te4O11 only share common vertices, generating ∞ 1 { [ Sc 2 O 6 / 1 t O 3 / 2 v ] 9 − } double strands along [010]. In both compounds, the three-dimensional framework and the charge balance are accomplished by the discrete ψ1-tetrahedral [TeO3]2− anions with non-bonding lone-pair electrons located at their central Te4+ cations. Moreover, strong secondary Te4+···O2− interactions, which are generally quite common for rare earth metal(III) oxotellurates(IV), occur in both crystal structures, but much more pronounced in Sc2Te4O11, where three quarters of the Te4+ cations reside in the centers of ψ eq 1 -trigonal bipyramids [TeO4]4− as compared to Sc2Te3O9, which can well be written as Sc2[TeO3]3. [ABSTRACT FROM AUTHOR]

The formation of ZnO nanomaterials from different Zn acetylacetonate precursor solutions was studied in situ by employing simultaneous, time-resolved X-ray diffraction (XRD) and X-ray absorption spectroscopy (EXAFS) at the Zn K-edge. The precursor solutions were heated from room temperature to the desired reaction temperatures in a hermetically sealed cell dedicated to X-ray experiments. In general, the first indications for the formation of hexagonal ZnO were found for elevated temperatures of about 80 °C both by XRD and EXAFS, and the contributions increase with temperature and time. However, no reaction intermediates could be proved in addition to the Zn precursors and the formed hexagonal ZnO materials. Furthermore, the results show that the efficiency of the reaction, i.e., the conversion of the precursor material to the ZnO product, strongly depends on the solvent used and the reaction temperature. ZnO formation is accelerated by an increased temperature of 165 °C and the use of 1-octanol, with a conversion to ZnO of more than 80% after only a ca. 35 min reaction time according to a detailed analysis of the EXAFS data. For comparison, an identical concentration of Zn acetylacetonate in water or dilute alkaline NaOH solutions and a reaction temperature of around 90 °C leads to a smaller conversion of approximately 50% only, even after several hours of reaction. The particle size determined from XRD for different orientations shows a preferred orientation along the c-direction of the hexagonal crystal system, as well in accordance with scanning electron microscopy. The LaMer model explained this highly non-uniform growth of needle-like ZnO crystallites. [ABSTRACT FROM AUTHOR]

Zinc oxide is an environmentally friendly and readily synthesized semiconductor with many industrial applications. ZnO powders were prepared by alkali precipitation using different [Zn(acetate)2(amine)x] compounds to alter the particle size and aspect ratio. Slow precipitations from 95 °C solutions produced micron-scale particles with morphologies of hexagonal plates, rods, and needles, depending on the precursor used. Powders prepared at 65 °C with rapid precipitation yielded particles with minimal morphology differences, but particle size was dependent on the precursor used. The smallest particles were produced using precursors that yielded crystals with low aspect ratios during high-temperature synthesis. Particles produced during rapid synthesis had sizes ranging from 21–45 nm. The materials were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, BET, and diffuse reflectance. The materials prepared using precursors with less-volatile amines were found to retain more organic material than ZnO produced using precursors with more volatile amines. The amount of organic material associated with the nanoparticles influenced the photocatalytic activity of the ZnO, with powders containing less organic material producing faster rate constants for the decolorizing of malachite green solutions under ultraviolet illumination, independent of particle size. [Zn(acetate)2(hydrazine)2] produced ZnO with the fastest rate constant and was recycled five times for dye degradation studies that revealed minimal to no reduction in catalytic efficiency. [ABSTRACT FROM AUTHOR]

1Eu2O3–3BaO–20Nb2O5–76TeO2 glass and the corresponding glass-ceramics were synthesized with the aim to investigate the effect of glass crystallization on the photoluminescence and scintillation characteristics. Glass ceramics containing mainly the Nb2Te4O13 crystalline phase were obtained by heat treatment of the glass at 540 °C for 1, 2, or 4 h. For the glass and glass ceramics, emission peaks originating from the 4f → 4f transitions of Eu3+ appeared under irradiation with 530 nm light or X-rays. Among the samples, the highest emission intensity in the photoluminescence and X-ray-induced scintillation spectra was obtained for the glass. Furthermore, typical photoluminescence and scintillation decay time constants originating from the 4f → 4f transitions of Eu3+ were obtained for the glass and glass ceramics. The afterglow level of the glass was comparable to that of the glass ceramics. [ABSTRACT FROM AUTHOR]

Tellurium dioxide (TeO2) thin films were deposited on silicon substrates through the Pechini method, after which they were heat treated at different temperatures. The heat treatment temperatures were defined from the thermogravimetry-differential scanning calorimetry (TG-DSC) data of the precursor gel. The effects of the heat treatment on the structural properties were investigated through X-ray diffraction (XRD), atomic force microscopy, and Raman spectroscopy. The TG-DSC data showed four different weight loss steps due to the reduction of telluric acid to tellurium, the removal of the excess ethylene glycol, the decomposition of citric acid, and the degradation of polyester. The XRD and Raman data showed the presence of the γ- and α-TeO2 phases in the films treated at 400–500 °C. Lattice parameters of the observed crystalline phases were determined by Rietveld refinement, with which it was possible to evaluate the crystallite size and microstrain using the Williamson-Hall method. The heat treatment temperature directly influenced the crystallite size and the surface roughness of the films, which showed similar behaviors with the temperature. Highlights: Good quality TeO2 thin films obtained through the Pechini method. Phase transformation observed by different techniques. Heat treatment temperature versus TeO2 crystalline phases. The coexistence of α- and γ-TeO2 phases increases films´ strain. [ABSTRACT FROM AUTHOR]

The structure of Ag2O–TeO2 glasses is being investigated to make the interpretation of the more complex PbI2–Ag2O–TeO2 glasses easier. Using Raman vibrational, X-ray diffraction (XRD) and electron diffraction pattern (EDP) spectroscopy, the local environment of Te atoms and the crystallization behaviour of glasses were studied. The XRD spectra revealed that certain crystalline phases develop in the binary Ag2O–TeO2 glasses. The well-crystalline species are metastable Ag2Te4O9 and Ag2Te2O5. The results of transmission electron microscope and EDP agree well with those of X-ray diffraction (XRD), suggesting that crystalline-clustered species develop in glasses enriched with Ag2O. The distinguishing feature of glasses in the trenay system containing PbI2 is their amorphous nature. The Raman spectra are well-resolved, with distinct characteristics that identify various structural units of telluride. The primary building telluride structural units are [TeO4] and [TeO3+1]. But TeO3–, TeO32– and Ag–Te species, on the other hand, are formed when PbI2 concentration is increased [ABSTRACT FROM AUTHOR]

In the presented work, the tellurite glasses TeO2-WO3-ZnO doped with Tm3+ and Ho3+ ions were prepared by the same glass forming method. X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques were used to study the effects of the forming technology on the thermal and structural properties of the fabricated glasses. After controlled crystallization of investigated glasses, the emission in the VIS- and NIR range was determined. The effect of silver doping on emission intensity was investigated. The value of the activation energy of the glass crystallization process was determined, while the Ea value for pure TeO2 glass was much lower than for tellurite glasses TeO2-WO3-ZnO. [ABSTRACT FROM AUTHOR]

In the field of multimaterial optical fibers, the demand for high‐performance single‐crystal core glass‐clad multimaterial optical fibers is increasing. However, the applications of single‐crystal fibers are restricted by the complex fabrication processes and the slow growth of single‐crystal materials. Here, a two‐step method is demonstrated to achieve single‐crystal tellurium (Te) core fibers with high crystal quality over the length of the fiber. This method starts with the thermal drawing of a fiber preform into polycrystalline Te core multimaterial fibers (precursor fibers) that are long and mechanically stable. A 532‐nm continuous laser is then employed to recrystallize the Te core in the precursor fiber into a single crystal state along the entire length of the fiber. Experimental studies of these single‐crystal fibers demonstrate that the single‐crystal Te core fibers possess high transmittance (>90% at 2–10 μm) and high thermoelectric performance (ZT values from 0.03 to 0.13 at 300 K temperature). They are superior to previous reports and our previous work. This method works for fabricating various single‐crystal fibers and has important applications in the field of optical fibers, functional fibers, and their integrated devices. [ABSTRACT FROM AUTHOR]

This paper reviews the main techniques of optical spectroscopy used for the characterization of sol-gel materials in different forms, including a brief description of instrumentation, followed by a series of selected examples from the literature that illustrate the main methodologies and results which can be obtained and including the main advantages and disadvantages of the different approaches adopted. The review includes separate sections on UV/Vis/NIR spectroscopy, spectroscopic ellipsometry, M-line spectroscopy, infrared and Raman spectroscopies, and photoluminescence spectroscopy. Highlights: This paper reviews the main techniques of optical spectroscopy for the characterization of sol–gel materials. UV/Vis/NIR, M-line, Infrared, Raman and Photoluminescence Spectroscopy are highlighted, as well as Spectroscopic Ellipsometry. Instrumentation, advantages and disadvantages, and selected examples are described. [ABSTRACT FROM AUTHOR]

A thermo-reversible sol–gel transition in solutions made of titanium n-butoxide, ethanol, water, and nitric acid is studied by in situ temperature-dependent Fourier transform infrared spectroscopy. Infrared spectra show that at temperatures departing from 45 °C, the nitrate ion substitutes the partially hydrolyzed butoxide ligands, by forming bridges and mono- and bidentate chelates. The exposed oxygen atoms in the nitrate ion favor the assembly between oligomers of low molecular weight through hydrogen bonds where water molecules work as binding agents, leaving to the gel formation. When the material returns to room temperature, the nitrate ion comes back to its free state, regenerating the sol. The suspension evolves with aging time from transparent to white, indicating the formation of TiO2 particles, although the thermo-reversible effect is still observed upon heating. Infrared results suggest that gel formation proceeds through the same mechanism, however, the chelates and bridges occur through exposed Ti–OH moieties onto the particle surfaces. Additionally, after an aging period, a gel is formed at room temperature, that recovers the fluid state upon mechanical perturbation. In this case, TiO2 particles join directly by week interactions such as hydrogen bonds. The dynamic rheological studies of the temperature-dependent viscoelastic behavior indicate that the elastic component is the most important in the material's structure. Highlights: Thermo-reversible (TR) sol-gel transition observed in Ti but-EtOH-H2O in the presence of NO3−. From 45 ºC NO3− form chelates and bidentate bridges with Ti atoms, forming the TR gel. Small weight oligomers are the building blocks of the TR gel in the early stages. Condensation reactions lead to slow TiO2 formation. TiO2 particles bridged thru surface groups are the building blocks of the gel in the latter stages. [ABSTRACT FROM AUTHOR]

The structure of copper tellurite and borotellurite glasses is studied by x-ray and neutron diffraction, reverse Monte Carlo (RMC) simulations, FTIR, Raman and 11B MAS-NMR spectroscopy. Copper tellurite sample with 15 mol% CuO forms precipitates of tetragonal TeO² within the glass matrix on melt quenching. The glass forming ability of the xCuO-(100-x)TeO2 system enhances with increase in CuO concentration from 15 to 20 mol% and also with the addition of B2O3. RMC simulations on the neutron diffraction data found that the Cu-O and Te-O bond lengths are approximately at equal distances in the range: 1·96 to 1·98±0·02 Å, while the nearest O-O distance is at 2·71±0·02 Å. Neutron and Raman results on the Te-O speciation are in agreement and confirmed that the Te-O coordination decreases with an increase in CuO and B2O3 molar concentrations in the tellurite and borotellurite glasses, respectively. RMC studies found that Cu2+ has tetrahedral coordination with oxygen, as predicted by Jahn-Teller distortion and that Cu-O and Te-O structural units have very similar size and geometry. The copper tellurite glass-ceramic sample with 15 mol% CuO was heat treated and it formed crystalline precipitates of TeO2 and CuTe2O5 upon devitrification; the average Te-O coordination was significantly smaller in the glass as compared to that in the crystalline sample. [ABSTRACT FROM AUTHOR]

Tellurite glasses, made from the conditional glass former TeO2, show potential for use in optical applications. Alkali and alkaline earth tellurite glasses, along with single component, rapidly cooled, TeO2 are reported and studied here. Thermal properties of boron, potassium, lithium, sodium, rubidium, cesium, barium, and strontium tellurites were obtained via differential scanning calorimetry and related to structural changes observed using Raman spectroscopy. Additionally, coordination numbers of barium and strontium tellurites versus amount of modifier are also calculated. By understanding the thermal properties and coordination numbers of alkali and alkaline earth tellurites, the goal is to better elucidate the structure of amorphous TeO2. [ABSTRACT FROM AUTHOR]

Radiations are widely used in hospitals and health services in radiotherapy and molecular imaging using x-ray and gamma radiation which considered as the most penetrating radiations and very difficult to shield. In this study, the radiation shielding properties of different zinc oxide (ZnO) concentrations of the (95-x)TeO2-5TiO2-xZnO (x=5, 10, 15, 20, 25, 30 and 40 mol%) glass system was investigated to be introduced as a new transparency effective shielding material. In order to study shielding properties, mass attenuation coefficients in the energy range of 0.015–15 MeV photon energies for the current glass system were calculated using ParShield software. Moreover, half value layer, mean free path and effective atomic number were evaluated using the obtained attenuation coefficient. The results indicated that if ZnO was added to the current glass system the mass attenuation coefficient will be decreased as well as effective atomic number values. The highest mass attenuation coefficient at all energies was found to be in TT5Z5 glass sample as well as the effective atomic number value. [ABSTRACT FROM AUTHOR]

Abstract—: This paper presents a systematic Raman scattering study of novel nanostructured materials based on synthetic opal and Bi2TeO5 nanocrystals, which offer high photorefractive sensitivity. Bismuth tellurite was introduced into opal pores in a molten state. The crystal structure of the material in the opal pores was determined by Raman spectroscopy. Comparison of the measured Raman spectra of the opal-Bi2TeO5 nanocomposite and those of polycrystalline powders and single crystals made it possible to reveal a number of new bands and analyze their origin. The observed variation in the intensity of Raman bands from point to point on the sample surface can be interpreted as due to structural light focusing and excitation field localization at surface and volume defects of the photonic crystal structure of the material. [ABSTRACT FROM AUTHOR]

ZnO/ZnS heterostructures have emerged as an attractive approach for tailoring the properties of particles comprising these semiconductors. They can be synthesized using low temperature sol-gel routes. The present work yields insight into the mechanisms involved in the formation of ZnO/ZnS nanostructures. ZnO colloidal suspensions, prepared by hydrolysis and condensation of a Zn acetate precursor solution, were allowed to react with an ethanolic thioacetamide solution (TAA) as sulfur source. The reactions were monitored in situ by Small Angle X-ray Scattering (SAXS) and UV-vis spectroscopy, and the final colloidal suspensions were characterized by High Resolution Transmission Electron Microscopy (HRTEM). The powders extracted at the end of the reactions were analyzed by X-ray Absorption spectroscopy (XAS) and X-ray diffraction (XRD). Depending on TAA concentration, different nanostructures were revealed. ZnO and ZnS phases were mainly obtained at low and high TAA concentrations, respectively. At intermediate TAA concentrations, we evidenced the formation of ZnO/ZnS heterostructures. ZnS formation could take place via direct crystal growth involving Zn ions remaining in solution and S ions provided by TAA and/or chemical conversion of ZnO to ZnS. The combination of all the characterization techniques was crucial to elucidate the reaction steps and the nature of the final products. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the use of silver cation as nucleating agent in germanotellurite glass matrix of compositions (100− x) [70TeO2-10GeO2-10Nb2O5-10K2O]- xAg2O ( x=0-6 mol%), in order to promote bulk crystallization. Density measurements, differential scanning calorimetry, X-ray diffraction, UV-Vis, and Raman spectroscopies have been performed to study the crystallization process. We have observed bulk crystallization of a unique noncentrosymmetric phase, K[Nb1/3Te2/3]2O4.8, which has been investigated for its second-order optical activity. Transparent to translucent glass-ceramics have been successfully tailored under thermal treatment and second harmonic generation signals were recorded on the glass-ceramic samples as a function of their synthesis procedure. It is suggested that the second-order optical properties observed are strongly related to the organization of crystallites within phase-separated domains. [ABSTRACT FROM AUTHOR]

Guided bone regeneration (GBR) technique helps to restore bone tissue through cellular selectivity principle. Currently no osteoinductive membrane exists on the market. Osteogenic growth peptide (OGP) acts as a hematopoietic stimulator. This association could improve the quality of bone formation, benefiting more than 2.2 million patients annually. The objective of this work was to develop membranes from ureasil-polyether materials containing OGP. The membranes were characterized by differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS). OGP was synthesized by the solid phase method. Sterilization results using gamma radiation at 24 kGy did not change the structure of the material, as confirmed by DSC. The SAXS technique revealed the structural homogeneity of the matrix. OGP was incorporated in 66.25 × 10 -10  mol and release results showed that the ureasil-PPO400/PEO500 and ureasil-PPO400/PEO1900 membranes released 7% and 21%, respectively, after 48 h. In vivo results demonstrated that the amount and quality of bone tissue formed in the bone defects in the presence of ureasil-polyether membranes with OGP were similar to commercial collagen material with BMP. The results allow us to conclude that membranes with OGP have characteristics that make them potential candidates for the GBR., (© 2021 John Wiley & Sons Ltd.)

This is a review of hybrid materials based on silica as an inorganic phase used as drug delivery systems (DDS). Silica based DDS have shown effectivity when compared with traditional delivery systems. They present advantages such as: (a) ability to maintain the therapeutic range with minor variations; (b) prevention of local and systemic toxic effects; (c) plasma concentrations increase of substances with a short half-life; and (d) reduction of the number of daily doses, which may increase patient adherence to the treatment. These advantages occur due to the physical, chemical and optical properties of these materials. Therefore, we discuss the properties and characteristics of them and we present some applications, using different approaches of DDS to ensure therapeutic effectiveness and side effects reduction such as implantable biomaterial, film-forming materials, stimuli-responsive systems and others. [ABSTRACT FROM AUTHOR]

The longitudinal ultrasonic attenuation in xNbO−(1− x)TeO, 0.1PbO − xNbO−(0.9 − x)TeO and 0.2PbO − xNbO− (0.8 − x)TeO tellurite glass systems was measured using the pulse echo technique at ultrasonic frequencies 2, 4, 6 and 8 MHz in the temperature range from 150 to 300 K. The absorption curves showed the presence of well-defined broad peaks at various temperatures depending upon the glass composition and operating frequency. The maximum peaks move to higher temperatures with the increase of operating frequency, indicating the presence of some kind of relaxation process. This process has been described as a thermally activated relaxation process, which happens when ultrasonic waves disturb the equilibrium of an atom vibrating in a double-well potential in the glass network structure. Results proved that the average activation energy of the process depends mainly on the modifier content. This dependence was analysed in terms of the loss of standard linear solid type, with low dispersion and a broad distribution of Arrhenius-type relaxation with temperature-independent relaxation strength. The experimental acoustic activation energy has been quantitatively analysed in terms of the number of loss centres (number of oxygen atoms that vibrate in the double-well potential). [ABSTRACT FROM AUTHOR]

Herein, we used tri-ureasil organic-inorganic hybrid material (tU5000) in order to enhance the solubility of nonsteroidal anti-inflammatory drugs and fine tuning the drug delivery profile. For the first time, we used tU5000 as a film-forming agent in order to provide an alternative vehicle for transdermal drug delivery systems which the cell viability of practically 100 % for the highest and the lowest tested concentrations of pure tU5000 indicated that the material was not cytotoxic. The physicochemical properties of the tU5000 drug carrier and drug-loaded hybrids were systematically studied using powder X-ray diffraction, differential scanning calorimetry, small-angle X-ray scattering, and Fourier-transform infrared spectroscopy. The structural changes of tU5000 as well as the relationships between the drug content and in vitro drug release behaviors were investigated. The results showed that the ibu molecules were homogeneously distributed in the tU5000 xerogels contributing to fine-tuning the drug delivery profile. Considering the ability to incorporated high drug content, simple and mild preparation procedure by one-pot sol-gel route, high stability of the materials, sustained-release property, this class of hybrid based on polymers and inorganic compounds may have potential applications in the design of pharmaceutical formulation as ophthalmic (contact lenses), transdermal (patches) and implantable (soft tissue) drug delivery systems. [ABSTRACT FROM AUTHOR]

The effect of chitosan addition on the structure and drug release properties of ureasil-polyethylene oxide (U-PEO) hybrid materials was examined. The hybrids and the blends were prepared by the sol-gel route and their structural features were characterized by infrared spectroscopy, differential scanning calorimetry, X-ray powder diffraction, and small angle X-ray scattering. The different characterization techniques revealed the formation of transparent, rubbery, flexible, water-insoluble, and low crystalline chitosan/(U-PEO hybrid) blends, which could easily dissolve pramoxine (used as a model drug). The results showed that the combined addition of chitosan and pramoxine improved the compatibility of the organic and inorganic components of the U-PEO matrix, and provided a means of tailoring the amount of drug released at steady state equilibrium. [ABSTRACT FROM AUTHOR]

Urea-cross-linked polyether-siloxane hybrid blends with tuneable hydrophilic/hydrophobic features were prepared from a mixture of poly(ethylene oxide) (PEO1900) and poly(propylene oxide) (PPO400), hybridized by end-chain functionalization with (3-isocyanatopropyl)triethoxysilane. The aim of this study was to demonstrate that the combination of the different polyether phases produces materials with hydrophilic and hydrophobic properties. An anti-fog coating and a transparent monolithic swellable hydrogel were produced from the PEO1900 hybrid. Swellability and drug release profiles could be easily tuned by varying the ureasil-PEO/ureasil-PPO ratio in the hybrid matrix. Differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS) analyses indicated that the nanostructure of the hybrid blends could be described by the existence of a biphasic mixture of PEO1900-rich and PPO400-rich phases, with a fraction of the lamellar domains being derived from the PEO1900 crystallinity. A correlation between the nanoscopic features and the kinetics of the swelling mechanism is proposed, based on the results of in situ SAXS analyses. In vitro monitoring using UV-Vis spectroscopy indicated that the kinetics of drug release from the PEO1900:PPO400 hybrid blends could be controlled by varying the proportions of the hydrophilic (PEO1900) and hydrophobic (PPO400) hybrids. The response to pH change and to application of a magnetic field to the PEO1900-magnetite nanocomposite indicated that the production of stimuli-responsive delivery devices based on ureasil-PE should be feasible in the near future. [ABSTRACT FROM AUTHOR]

The theoretical calculations indicated that the monoclinic low-temperature phase of silver telluride $$(\upbeta \hbox {-Ag}_{2}\hbox {Te})$$ is a new binary topological insulator with highly anisotropic single Dirac cone surface. We obtained $$\upbeta \hbox {-Ag}_{2}\hbox {Te}$$ crystal ingots containing few grains by the Bridgman method. We also deposited thin films of tellurium, $$\hbox {Ag}_{5}\hbox {Te}_{3}\hbox { and }(\hbox {Te+Ag}_{5}\hbox {Te}_{3})$$ by thermal evaporation method. The Raman spectra of $$\upbeta \hbox {-Ag}_{2}\hbox {Te}$$ , tellurium and $$\hbox {Ag}_{5}\hbox {Te}_{3}$$ were measured at three excitation wave lengths: 633, 515 and 488 nm. The Raman active modes of $$\upbeta \hbox {-Ag}_{2}\hbox {Te}$$ , tellurium and $$\hbox {Ag}_{5}\hbox {Te}_{3}$$ are situated at frequencies below 300 $$\hbox {cm}^{-1}$$ while vibrations of other phases appear at higher frequencies. [ABSTRACT FROM AUTHOR]