Biomechanical Comparison of Asymmetric Implant Configurations for All-on-Four Treatment Using Three-Dimensional Finite Element Analysis.

The aim of this study is to examine the effect of unilaterally more posterior placement of implants (Straumann BLT 4.1 mm in diameter and 12 mm long) applied according to the all-on-four concept on the stress distribution on bone, implants, and other prosthetic components, using the finite element analysis method. Three scenarios were modelled: For Model 1 (M1), anterior implants were placed symmetrically perpendicular to the bone in the right and left lateral incisor region, while the necks of the posterior implants placed symmetrically in the second premolar region were angled at 30 degrees. For Model 2 (M2) the implant in the left second premolar region was placed to the first molar region unilaterally. For Model 3 (M3) the implant in the left lateral incisor region was placed to the canine region unilaterally. Vertical and oblique forces (100 N) were applied in the right first molar region. The von Mises and maximum (Pmax) and minimum (Pmin) principal stresses were obtained. The highest stress concentration on the cortical bone was observed in the second premolar region in all models when oblique forces were applied. M1 was highest (8.992 MPa) followed closely by M3 (8.780 MPa) and M2 was lowest (3.692 MPa). The highest stress concentration on the prosthetic parts was observed in this framework when oblique forces were applied. M2 was highest (621.43 MPa) followed by M3 (409.16 MPa) and the lowest was M1 (309.43 MPa). It is thought that placing the implant further posterior to first molar region may prevent the bone resorption that occurs with high stress around the crestal bone. However, increased stress on the implants and prosthetic parts may lead to failures.

Acoustic sorting of airborne particles by a phononic crystal waveguide.

A two-dimensional phononic crystal linear defect waveguide is utilized for size-based sorting of millimeter-sized solid particles in the air through acoustic radiation force. The waveguide channels ultrasonic waves at 20 kHz, as calculated through Finite-Element Method simulations. Spherical solid particles released from rest at the top of the vertically aligned waveguide experience the combined effect of the acoustic radiation, gravity, and drag forces. When the particles are released from the symmetry plane of the waveguide, they follow straight paths where the ones with radii smaller than a threshold value are trapped at the waveguide nodal planes, whereas larger particles are let pass through. This requires input sound pressure levels between 173 dB and 177 dB. Moreover, such particles can also be differentiated with respect to density. Alternatively, the release of particles with a slight offset from the symmetry center induces unbalanced acoustic radiation potential, and thus uneven radiation force, resulting in the initiation of horizontal displacement whose extent depends on particle radius. Thus, both simulation results and experimental findings suggest that this scheme can be employed in size-based particle separation. Sorting of spherical glass particles with 0.5 mm and 1.0 mm radii are experimentally demonstrated for low ultrasonic transducer acoustic power output up to 90 W. The proposed approach can be utilized in applications where contact-free separation of airborne particles is required.

Broad omnidirectional acoustic band gaps in a three-dimensional phononic crystal composed of face-centered cubic Helmholtz resonator network.

Broad omnidirectional band gaps in a three-dimensional phononic crystal consisting of a face-centered cubic array of spherical air voids connected by cylindrical conduits in solid background are numerically and experimentally demonstrated. With a low material filling fraction of 37.7%, the first bandgap covers 3.1-13.6 kHz frequency range with 126.1% gap-over-midgap ratio. Finite-element method is employed in band structure and numerical transmission analyses. Omnidirectional band gaps are observed in only two-period thick slabs in the 100, 110, and 111 orientations. Experimental transmission characteristics are in good agreement with numerical data. The phononic crystal can be employed in low-frequency sound proofing.

First record of Cercyon (s. str.) inquinatus Wollaston, 1854 from Turkey with notes about this problematic species (Coleoptera: Hydrophilidae: Sphaeridiinae: Megasternini).

Cercyon (s. str.) inquinatus Wollaston, 1854 is recorded for the first time from Turkey. It was found in the darkest part of a vast cave occupied by an underground river and pools. The specimens were collected, in or near water, without being sure that they are aquatic and subterranean. Bright and black or blackish body, pronotum with a slight partial and median groove, rather convex interstries, male genitalia are quite characteristic. The habitat and sampling methods are described. The difficulty of identifying the insect with existing keys is exposed and analyzed. Photos of Turkish specimen and a list of the associated fauna are provided.

Combat medic course: evaluation of trainees' perception of learning and academic-self perception.

INTRODUCTION: In response to the Syrian Civil War, the Turkish Armed Forces has focused its attention on internal security and border operations, thereby cushioning against both the threat of terrorist activities and supporting international peace efforts. This study was performed to evaluate the level of knowledge, skills and any behavioural changes after the combat medic course to enhance future courses. METHODS: A cross-sectional descriptive study was conducted between 25 December 2017 and 22 March 2018 using 40 combatant personnel undertaking the combat medic training course. Attendants' perception of self- sufficiency was assessed using a specifically designed questionnaire using a 5-point Likert-type scale. RESULTS : Trainee perception of self-confidence had the highest mean increase post course (4.1±0.7). Trainee academic self-perception demonstrated the lowest mean post course score in the domain of "using of the tactical emergency medications and liquids" (3.80±1.02). The highest mean was in the domain of bleeding control (4.63±0.49). CONCLUSIONS: Improvements to specific components of the course have been identified and implemented to ensure greater success in the operational field environment. In particular, the total course hours will be increased and simulation encouraged using the most recent equipment used in the field.

Ultrasonic Gas Sensing by Two-Dimensional Surface Phononic Crystal Ring Resonators.

An acoustic ring resonator employing a two-dimensional surface phononic crystal is proposed for high-sensitivity detection in binary gas mixtures. Band analyses and frequency-domain simulations via the finite-element method reveal that a single band for spoof surface acoustic waves appears at ultrasonic frequencies around 58 kHz where modification of its dispersion due to varying gas composition results in a linear shift of the resonance frequency. The shift rate is -17.3 and 8.8 mHz/ppm for CO2 and CH4, respectively. The linear shift of resonance frequency is experimentally validated. In addition, the ring resonator can also be employed to track acoustic intensity variation with gas concentration, where exponentially decaying intensity for low concentrations leverages high-sensitivity operation.

Plasmofluidic Microlenses for Label-Free Optical Sorting of Exosomes.

Optical chromatography is a powerful optofluidic technique enabling label-free fractionation of microscopic bioparticles from heterogenous mixtures. However, sophisticated instrumentation requirements for precise alignment of optical scattering and fluidic drag forces is a fundamental shortcoming of this technique. Here, we introduce a subwavelength thick (<200 nm) Optofluidic PlasmonIC (OPtIC) microlens that effortlessly achieves objective-free focusing and self-alignment of opposing optical scattering and fluidic drag forces for selective separation of exosome size bioparticles. Our optofluidic microlens provides a self-collimating mechanism for particle trajectories with a spatial dispersion that is inherently minimized by the optical gradient and radial fluidic drag forces working together to align the particles along the optical axis. We demonstrate that this facile platform facilitates complete separation of small size bioparticles (i.e., exosomes) from a heterogenous mixture through negative depletion and provides a robust selective separation capability for same size nanoparticles based on their differences in chemical composition. Unlike existing optical chromatography techniques that require complicated instrumentation (lasers, objectives and precise alignment stages), our OPtIC microlenses with a foot-print of 4 µm × 4 µm open up the possibility of multiplexed and high-throughput sorting of nanoparticles on a chip using low-cost broadband light sources.

Acoustic Tamm states of three-dimensional solid-fluid phononic crystals.

In this work, the existence and propagation of acoustic Tamm states at the interface of air and a face-centered cubic solid-fluid phononic crystal composed of spherical air voids interconnected by cylindrical air channels are demonstrated. Supercell band structure computations via the finite element method reveal surface bands for Tamm states on (100), (110), and (111) surfaces of the phononic crystal. The states decay sharply into the phononic crystal so that only a two-row slab is sufficient to guide them over the respective surfaces without leakage, as confirmed by finite element simulations. In addition, surface wave propagation along the [10] direction of the (100) surface is experimentally demonstrated. Ability to confine the Tamm states in all three dimensions is a key aspect in designing few-layer-thick acoustic circuits. Low material filling fraction of the phononic crystal could be leveraged to realize lightweight all-acoustic systems where either bulk or surface states can be incorporated.

Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens.

We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

Antioxidant and antiapoptotic effects of erdosteine in a rat model of ovarian ischemia-reperfusion injury.

OBJECTIVES: To evaluate the protective effect of erdosteine, an antiapoptotic and antioxidant agent, on torsion-detorsion evoked histopathological changes in experimental ovarian ischemia-reperfusion (IR) injury. MATERIALS AND METHODS: Eighteen female Wistar albino rats were used in control, IR, and IR+Edosteine (IR-E) groups, (n=6 in each). The IR-E group received the erdosteine for seven days before the induction of torsion/retorsion, (10 mg/kg/days). The IR and IR-E groups were exposed to right unilateral adnexal torsion for 3 hr. Three hours later, re-laparotomy was performed, and the right ovaries were surgically excised. Oxidant and antioxidants levels were determined in serum. The ovarian tissue samples were received and fixed with 10% neutral buffered formalin. The sections were stained with H&E, anti-PCNA, and TUNEL. RESULTS: The IR group were showed severe acute inflammation, polynuclear leukocytes and macrophages, stromal oedema and haemorrhage. Treatment with erdosteine in rats significantly retained degenerative changes in the ovary PCNA (+) cell numbers were significantly decreased in the IR and IR-E groups unlike the control group. However, its numbers were significantly increased in the IR-E group unlike the IR group. TUNEL (+) cell numbers were significantly increased in the IR group unlike the control and the IR-E groups. In erdosteine treated group, TUNEL (+) cells were detected significantly less than the IR group (P<0.05). CONCLUSION: In conclusion, erdosteine maybe a protective agent for ovarian damage and decreasing lipid peroxidation products and leukocytes aggregation after adnexal torsion in animals.

Phononic crystal surface mode coupling and its use in acoustic Doppler velocimetry.

It is numerically shown that surface modes of two-dimensional phononic crystals, which are Bloch modes bound to the interface between the phononic crystal and the surrounding host, can couple back and forth between the surfaces in a length scale determined by the separation of two surfaces and frequency. Supercell band structure computations through the finite-element method reveal that the surface band of an isolated surface splits into two bands which support either symmetric or antisymmetric hybrid modes. When the surface separation is 3.5 times the lattice constant, a coupling length varying between 30 and 48 periods can be obtained which first increases linearly with frequency and, then, decreases rapidly. In the linear regime, variation of coupling length can be used as a means of measuring speeds of objects on the order of 0.1m/s by incorporating the Doppler shift. Speed sensitivity can be improved by increasing surface separation at the cost of larger device sizes.

Sharp bends of phononic crystal surface modes.

Sharp bending of surface waves at the interface of a two-dimensional phononic crystal (PnC) of steel cylinders in air and the method of using a diagonally offset cylindrical scatterer are numerically demonstrated by finite-element method simulations. The radii of the diagonally offset scatterer and the cylinder at the PnC corner, along with the distance between them, are treated as optimization parameters in the genetic algorithm optimization of sharp bends. Surface wave transmittance of at most 5% for the unmodified sharp bend is significantly enhanced to approximately 75% as a result of optimization. A series of transmittance peaks whose maxima increase exponentially, as their widths reduce, with increasing frequency is observed for the optimized sharp bend. The transmittance peaks appear at frequencies corresponding to integer plus half-beat periods, depending on the finite surface length. The optimal parameters are such that the cylinder radius at the PnC corner is not significantly modified, whereas a diagonally offset scatterer having a diameter of almost two periods and a shortest distance of about 0.7 periods between them is required for the strongest transmittance peak. Utilization of PnC surface sharp bends as acoustic ring resonators is demonstrated.

Role of irradiation in the green synthesis of silver nanoparticles mediated by fig (Ficus carica) leaf extract.

Biosynthesis of silver nanoparticles in an aqueous mixture of fig (Ficus carica) leaf extract and AgNO3 solution exposed to a set of irradiances at different wavelengths are studied. Nanoparticle formation for irradiances between 6.5 mW/cm(2) and 13.3 mW/cm(2) in the 330-550 nm wavelength range is investigated and the results are compared to those of the nanoparticles synthesized in the dark and under direct sunlight. Ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy, along with particle size analysis and transmission electron microscopy are employed for the characterization of samples and extracts. Irradiance is found to have profound influence on the reduction rates. However, size and spherical shape of the nanoparticles are persistent, irrespective of irradiance and wavelength. Irradiance is discussed to influence the particle formation and aggregation rates through the formation of free radicals in the fig extract.

Acoustic waveguiding by pliable conduits with axial cross sections as linear waveguides in two-dimensional sonic crystals.

Pliable conduits composed of periodically arranged concentric aluminum tori in air, with their axial cross sections acting as linear waveguides in two-dimensional sonic crystals, are numerically shown to guide acoustic waves in three dimensions in a flexible manner. Waveguide band structures are obtained by exploiting axial symmetry in a super-cell approach through two-dimensional finite-element simulations under the periodic boundary conditions. One isolated band having a bandwidth of 19.66% or 10.10% is observed for each guide, whose cross section is either in square or triangular geometry, respectively. Corresponding mode profiles indicate efficient guiding, as the acoustic energy is mainly concentrated in the hollow-core region of the guides. Transmittance spectra calculated through finite-element simulations are in agreement with the computed guiding bands. Transmittance along the waveguides with square and triangular axial cross sections around mid-band frequencies of their guiding bands varies slightly from -6.05 and -6.65 dB to -5.98 and -8.86 dB, respectively, as the guide length is increased from 10 to 200 periods. Efficient guiding across the smooth bends over circular arcs up to 90 deg is also demonstrated through three-dimensional finite-element method simulations.

Refraction-based photonic crystal diode.

A system composed of air holes in a dielectric host to form two square photonic crystals, with the same orientation and lattice constant but different scatterer radii, making an interface along their body diagonals, is numerically demonstrated to facilitate unidirectional light transmission. Band structure computations are carried out via the plane wave expansion method, whereas finite-difference time-domain simulations are carried out to investigate the transient behavior. Unidirectional light transmission is achieved over two adjacent stop bands along the ΓX direction, which are circumvented in the forward direction by scaling down the wave vector and rotating the surface normal. Contrast ratios as high as 0.9 are attained within the lower stop band.

Polarization-independent waveguiding with annular photonic crystals.

A linear waveguide in an annular photonic crystal composed of a square array of annular dielectric rods in air is demonstrated to guide transverse electric and transverse magnetic modes simultaneously. Overlapping of the guided bands in the full band gap of the photonic crystal is shown to be achieved through an appropriate set of geometric parameters. Results of Finite-Difference Time-Domain simulations to demonstrate polarization-independent waveguiding with low loss and wavelength-order confinement are presented. Transmission through a 90 degrees bend is also demonstrated.