Tetracycline Removal through the Synergy of Catalysis and Photocatalysis by Novel NaYF4:Yb,Tm@TiO2-Acetylacetone Hybrid Core-Shell Structures.

Novel hybrid core-shell structures, in which up-converting (UC) NaYF4:Yb,Tm core converts near-infrared (NIR) to visible (Vis) light via multiphoton up-conversion processes, while anatase TiO2-acetylacetonate (TiO2-Acac) shell ensures absorption of the Vis light through direct injection of excited electrons from the highest-occupied-molecular-orbital (HOMO) of Acac into the TiO2 conduction band (CB), were successfully synthesized by a two-step wet chemical route. Synthesized NaYF4:Yb,Tm@TiO2-Acac powders were characterized by X-ray powder diffraction, thermogravimetric analysis, scanning and transmission electron microscopy, diffuse-reflectance spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence emission measurement. Tetracycline, as a model drug, was used to investigate the photocatalytic efficiencies of the core-shell structures under irradiation of reduced power Vis and NIR spectra. It was shown that the removal of tetracycline is accompanied by the formation of intermediates, which formed immediately after bringing the drug into contact with the novel hybrid core-shell structures. As a result, ~80% of tetracycline is removed from the solution after 6 h.

Synergistic anti-biofouling effect of Ag-exchanged zeolite and D-Tyrosine on PVC composite against the clinical isolate of Acinetobacter baumannii.

Due to their susceptibility to bacterial biofilm formation, commercial tubes for medical use are one of the main sources of hospital infections with Acinetobacter baumannii. The anti-biofouling activity of novel composites against the clinical isolate of the multi-drug resistant A. baumannii is reported here. The composites were prepared by addition of micronised silver-exchanged natural zeolite (Ag-NZ) into poly(vinyl chloride) (PVC), followed by coating of the composites with D-Tyrosine (D-Tyr). The Ag-NZ composites (containing 1-15 wt% of Ag-NZ) coated with D-Tyr (Ag-NZ-Tyr) showed a bactericidal effect (100% or a 6.9 log CFU reduction) towards immobilised bacterial cells. The uncoated Ag-NZ composites showed a reduction of up to 70% (4.4 log CFU) of immobilised bacteria in comparison with the original PVC. Rheological testing of the composites revealed that the addition of Ag-NZ slightly affected processability and formability of the PVC and increased the elasticity of the polymer matrix.

Temperature Sensing Properties of Biocompatible Yb/Er-Doped GdF3 and YF3 Mesocrystals.

Y0.8-xGdxF3:Yb/Er mesocrystals with a biocompatible surface and diverse morphological characteristics were successfully synthesized using chitosan-assisted solvothermal processing. Their structural properties, studied using X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and energy dispersive X-ray analysis, were further correlated with the up-conversion emission (λexc = 976 nm) recorded in function of temperature. Based on the change in the visible green emissions originating from the thermally coupled 2H11/2 and 4S3/2 levels of Er3+, the corresponding LIR was acquired in the physiologically relevant range of temperatures (25-50 °C). The detected absolute sensitivity of about 0.0042 °C-1, along with the low cytotoxicity toward both normal human lung fibroblasts (MRC-5) and cancerous lung epithelial (A549) cells, indicate a potential for use in temperature sensing in biomedicine. Additionally, their enhanced internalization in cells, without suppression of cell viability, enabled in vitro labeling of cancer and healthy cells upon 976 nm laser irradiation.

Experimental study of an implantable fiber-optic microphone on human cadavers.

In this paper, we present the results of an experimental study about a novel fiber optical vibrometer, aimed to be used as a totally implantable fiber-optic microphone for hearing aids. The sensor head, implanted inside the human cadaver middle ear, detects the amplitude of the incus vibrations, which are produced by an external acoustical source. The probe beam of coherent vertical cavity surface emitting laser (VCSEL) radiation is directed to the incus and the phase-modulated reflected beam is captured and demodulated. The problem of interferometric fading was solved using two quasi-quadrature signals, passively produced by the 3 × 3 single-mode fiber-optic coupler, processed by a special embedded algorithm. The implanted optoelectronic module works with very low-power consumption, performs real-time signal processing and outputs an analogue signal proportional to the incus vibration. The amplitude of the incus vibrations at different sound pressure levels (SPL) from 40 to 90 dB and at frequencies from 100 Hz to 10 kHz were measured by the implanted system. The system was evaluated on five cadaver skulls. The measured amplitudes were in the range of 1 pm to 5 nm, depending on the subjected skull and the applied sound pressure.

Validation and quality assessment of macromolecular structures using complex network analysis.

Validation of three-dimensional structures is at the core of structural determination methods. The local validation criteria, such as deviations from ideal bond length and bonding angles, Ramachandran plot outliers and clashing contacts, are a standard part of structure analysis before structure deposition, whereas the global and regional packing may not yet have been addressed. In the last two decades, three-dimensional models of macromolecules such as proteins have been successfully described by a network of nodes and edges. Amino acid residues as nodes and close contact between the residues as edges have been used to explore basic network properties, to study protein folding and stability and to predict catalytic sites. Using complex network analysis, we introduced common network parameters to distinguish between correct and incorrect three-dimensional protein structures. The analysis showed that correct structures have a higher average node degree, higher graph energy, and lower shortest path length than their incorrect counterparts. Thus, correct protein models are more densely intra-connected, and in turn, the transfer of information between nodes/amino acids is more efficient. Moreover, protein graph spectra were used to investigate model bias in protein structure.

Response surface methodology for optimisation of edible coatings based on dextran from Leuconostoc mesenteroides T3.

The aim of this study was to develop dextran-based edible films plasticized by sorbitol. In order to optimise the film-forming formulation, response surface methodology was used. The influence of dextran and sorbitol concentration on the mechanical and water vapour barrier properties of obtained films was investigated. The results showed that both parameters exhibited significant effect on the water vapour permeability of a film. Both dextran and sorbitol concentration had significant influence on tensile strength and elongation at break, whereas only sorbitol concentration had significant effect on Young's modulus. After optimisation by desirability approach, it was found that a film made of 3.40 wt% of dextran and 20.43 wt% of sorbitol showed the lowest water vapour permeability and the highest tensile strength and elasticity.

In-vitro and in-vivo measurement of the animal's middle ear acoustical response by partially implantable fiber-optic sensing system.

The main obstacle in realization of a totally implantable hearing aid is a lack of reliable implantable microphone. In this paper we have described a potentially miniature fiber-optic vibrometer based on a modified Michelson interferometer, designed to serve as a middle-ear microphone for totally implantable cochlear- or middle-ear hearing aids. A model of the sensing system was used for in-vitro and in-vivo investigation of acoustical response of sheep's middle-ear ossicles. Surgical and implantation procedure of introducing the sensing optical fiber into the middle-ear and its aiming at the incus was investigated and described here in detail. The frequency responses of the incus was measured while a cadaver and living sheep was exposed to the sinusoidal acoustical excitation of 40-90dB SPL, in the frequency range from 100Hz to 10kHz. The amplitude of the incus vibration was found to be in the range between 10pm to 100nm, strongly depending on the frequency, with a lot of resonant peaks, corresponding mainly to the natural outer ear canal gain. The noise floor in the experiments was about 2pm/Hz1/2, but recently we have decreased it to < 0.5pm/Hz1/2, which corresponds to a minimal detectable sound level of 31-35dB(A) SPL for humans. The histological examination of temporal bones of cadaver animals and the intensity of in-vivo optical signal demonstrated that the aiming of the sensing fiber to the target has been preserved for five months after the implantation.

Effect of thermal misfit between different veneering ceramics and zirconia frameworks on in vitro fracture load of single crowns.

Thermal misfit is deemed as one reason for the chipping of veneered zirconia restorations. Aim of the present study was to assess the effect of thermal misfit on the fracture load of veneered zirconia frameworks and to evaluate the applicability of a universal veneering ceramic for both zirconia and titanium frameworks. Fracture loads of zirconia and titanium frameworks veneered with different ceramics were measured. Differences in the thermal expansion coefficients of core and veneer (Delta alpha), as well as differences between glass transition temperatures of the veneering ceramics and room temperature (Delta T)--which is considered as the effective temperature range for stress formation, were determined. In the zirconia group, fracture load ranged from 818.0 +/- 127.2 to 935.2 +/- 186.3 N without significant differences (Student's t-test, p < 0.05). Moreover, zirconia and titanium crowns veneered with the universal veneering ceramic revealed high fracture load. Results also showed a correlation to the product Delta alpha x Delta T, such that if 185 x 10(-6) < Delta alpha x Delta T < 1120 x 10(-6), a veneering ceramic adapted for titanium might be likewise applicable for zirconia.

Demodulation of quasi-quadrature interferometric signals for use in the totally implantable hearing aids.

We propose and experimentally prove an algorithm for demodulation of interferometric signals, modified for use in a totally implantable hearing aid device. A fiber optic configuration, which generates two quasi-quadrature signals by a passive 3x3 coupler, for a non-contact detection of the middle ear ossicle vibration is employed. We simulated the ossicle vibration and large movements and demonstrated the effectiveness of the algorithm to compensate changes of the signal DC values and the phase shift introduced by the coupler. Applying the proposed algorithm we obtained the output signal stability better than 0.5 dB, and the system equivalent input noise of about 31 dB (A) SPL @ 1 kHz.

A single-retainer zirconium dioxide ceramic resin-bonded fixed partial denture for single tooth replacement: a clinical report.

This clinical report describes a treatment for the replacement of a missing mandibular anterior tooth using a cantilever single-retainer resin-bonded fixed partial denture (RBFPD), fabricated from zirconium dioxide (ZrO2) ceramic. No clinical complications were observed at the 2-year 6-month follow-up examination after placement of the ZrO2 ceramic RBFPD, and satisfactory functional and esthetic results were achieved. A treatment modality using a cantilever ZrO2 ceramic RBFPD is an alternative for single anterior tooth replacement. Further clinical studies are required to evaluate the long-term potential of cantilever single-retainer ZrO2 ceramic RBFPDs.

Influence of different adhesive resin cements on the fracture strength of aluminum oxide ceramic posterior crowns.

STATEMENT OF PROBLEM: The influence of different types of adhesive resin cements on the long-term prognosis of aluminum oxide ceramic posterior crowns is unclear. PURPOSE: The purpose of this study was to evaluate the fracture resistance of aluminum oxide ceramic on maxillary posterior crowns cemented with different resin luting agents before and after cyclic thermomechanical loading. Material and methods Forty-eight maxillary first molars were prepared and restored with standardized aluminum oxide ceramic (In-Ceram Alumina) crowns. The test specimens were randomly divided into 3 groups (n=16). The crowns were luted with an acrylic resin cement (Super-Bond C&B, control, Group SB) and 2 composite luting agents (Panavia F, Group PV; and Rely X Unicem, Group RX). Half of the specimens were exposed to thermomechanical fatigue in a masticatory simulator. All specimens were tested for fracture strength (N) using quasistatic loading. The Wilcoxon rank sum test was used to compare the fracture strength (alpha=.05). RESULTS: All specimens survived the exposure to the simulator. The following median fracture strength values were obtained without/with thermomechanical fatigue loading: Group SB, 2726 N/2673 N; Group PV, 2520 N/2083 N; and Group RX, 2036 N/2369 N. The fracture strength in Group PV after thermomechanical fatigue loading was significantly lower compared to the fracture strength in Group PV without artificial aging (P =.016), as well as significantly lower compared to Group SB with artificial aging (P =.003). CONCLUSION: Within the limitations of this study, all tested cements are capable of successfully luting aluminum oxide ceramic crowns. The fracture strength of Group PV after artificial aging was comparatively low.