Seismic Performance and Nonlinear Strain Analysis of Mechanical Splices for High-Strength Reinforcement in Concrete Structures

This study investigates the strain development in reinforcing bars within the plastic hinge regions of beams and columns, with the main objective of modifying the current acceptance criteria for mechanical bar splices to accommodate high-strength reinforcement. The investigation utilizes numerical analysis based on moment-curvature and deformation analysis of typical beam and column sections in a special moment frame. The results indicate that the use of higher grade reinforcement, such as Grade 550 or 690, results in lower strain demands in the plastic hinge regions compared to Grade 420 reinforcement. To validate the modified seismic loading protocol, over 100 samples of mechanical coupling systems were tested in Taiwan. The test results demonstrate that the majority of these systems can successfully complete the modified seismic loading protocol and are suitable for use in critical plastic hinge regions of special moment frames. However, caution is advised for slender mortar-grouted coupling sleeves, as they were unable to fulfill the seismic loading protocols. These sleeves may be conditionally used in plastic hinge regions of precast columns, provided they meet specific conditions and demonstrate seismic performance through structural testing. The findings of this study offer valuable insight into the design and application of mechanical splices in high-strength reinforcement scenarios.

Comparison of hand-sewn versus modified coupled arterial anastomoses in head and neck reconstruction: a single operator's experience

Microvascular coupler devices have gained wide acceptance as an alternative to the traditional hand-sewn technique in reconstructive surgery. However, no study has directly compared the efficacy of the coupler and hand-sewn techniques in arterial anastomosis during head and neck reconstruction surgery. A total of 123 patients who underwent surgery performed by a single surgeon between 2016 and 2018 were included in this retrospective study. The patients were divided into the coupler group and the hand-sewn group according to the technique of arterial anastomosis used. Patients in the coupler group underwent a special procedure including arterial bifurcation to enlarge the recipient artery diameter. Of the 123 free flap surgeries performed, 56 were done using a coupler and 67 with the standard suture technique. One flap in the coupler group failed due to simultaneous arterial and venous thromboses. One flap in the hand-sewn group was lost due to venous compromise. The overall flap survival rate was 98.4% (n=121). There was a significant decrease in anastomotic time when a coupler was used (P<0.001). The complication and flap loss rates were similar in the coupler and hand-sewn groups. The application of the coupler helped to decrease the anastomotic time and achieved satisfactory vessel patency.

An Ultrashort Wavelength Multi/Demultiplexer via Rectangular Liquid-Infiltrated Dual-Core Polymer Optical Fiber

We propose a rectangular liquid-infiltrated dual-core polymer optical fiber (POF) for short-range communication systems by the beam propagation method (BPM). The POF multi/demultiplexer (MUX/DEMUX) at the wavelengths of 0.52/0.65-μm, 0.57/0.65-μm, and 0.52/0.57-μm are devised. The simulation results demonstrate that the ultrashort length of three ultrashort POF couplers are 183.6 μm, 288 μm, and 799.5 μm. Compared with the conventional optical fiber couplers, these results could have significant applications in the miniaturization of optical devices for visible light communication.

Microvascular coupling devices: neglected resource with a short learning curve

Microvascular couplers have a record of efficiency and efficacy. They have been used in anastomoses in the head and neck in Sunderland since November 2013, where we have investigated the time taken for anastomosis, patency, and cost. We also completed a national survey of the use of couplers in the United Kingdom, in which we recorded the time of anastomosis. The mean (range) time was 4minutes (2minutes 40seconds - 4minutes 10seconds). One flap partially failed. This shows that couplers can save time, they have successful outcomes, and the technique is quick and easy to learn.

Benefits of active middle ear implants in mixed hearing loss: Stapes versus round window

OBJECTIVES/HYPOTHESIS

We compared the audiologic benefits of active middle ear implants with those of passive middle ear implants with hearing aids in mixed hearing loss, and also compared the outcomes of stapes vibroplasty with those of round window vibroplasty.

STUDY DESIGN

Retrospective chart review.

METHODS

Thirty-four patients with mixed hearing loss due to chronic otitis media were treated with a middle ear implant. Of these, 15 were treated with a passive middle ear implant (conventional ossiculoplasty with a partial ossicular replacement prosthesis), nine with an active middle ear implant coupling to the stapes, and 10 with an active middle ear implant coupling to the round window. Patients underwent pure-tone/free-field audiograms and speech discrimination tests before surgery and 6 months after surgery, and the results of these tests were compared.

RESULTS

The active middle ear implant resulted in better outcomes than the passive middle ear implant with hearing aids at mid to high frequencies (P < .05). Patients who received either a stapes vibroplasty or a round window vibroplasty showed comparable hearing gain except at 8,000 Hz (48.9 dB vs. 31.0 dB, P < .05). Patients who received a stapes vibroplasty showed an improvement even in bone conduction at 1,000 Hz and 2,000 Hz (both P < .05).

CONCLUSIONS

Active middle ear implantation could be a better option than treatment with passive middle ear implants with hearing aids for achieving rehabilitation in patients with mixed hearing loss. Vibroplasty via either oval window or round window stimulation shares similar good results.

LEVEL OF EVIDENCE

4 Laryngoscope, 127:1435-1441, 2017.

Polarization-selective coupling to long-range surface plasmon polariton waveguides

We demonstrate polarization-selective coupling from an optical fiber to long-range surface plasmon polariton waveguide modes using plasmonic antenna arrays. The arrays allow the sorting of two distinct (not necessarily orthogonal) polarizations to counter-propagating waveguide modes. The polarization-selective behavior of the devices is described by a compact formalism based on Stokes vectors that offers a clear graphical representation of the response. We experimentally observe polarization-controlled switching and unidirectional coupling with extinction ratios greater than 30 dB and coupling efficiencies comparable to those of a conventional grating coupler.