Nanograin network memory with reconfigurable percolation paths for synaptic interactions.

The development of memory devices with functions that simultaneously process and store data is required for efficient computation. To achieve this, artificial synaptic devices have been proposed because they can construct hybrid networks with biological neurons and perform neuromorphic computation. However, irreversible aging of these electrical devices causes unavoidable performance degradation. Although several photonic approaches to controlling currents have been suggested, suppression of current levels and switching of analog conductance in a simple photonic manner remain challenging. Here, we demonstrated a nanograin network memory using reconfigurable percolation paths in a single Si nanowire with solid core/porous shell and pure solid core segments. The electrical and photonic control of current percolation paths enabled the analog and reversible adjustment of the persistent current level, exhibiting memory behavior and current suppression in this single nanowire device. In addition, the synaptic behaviors of memory and erasure were demonstrated through potentiation and habituation processes. Photonic habituation was achieved using laser illumination on the porous nanowire shell, with a linear decrease in the postsynaptic current. Furthermore, synaptic elimination was emulated using two adjacent devices interconnected on a single nanowire. Therefore, electrical and photonic reconfiguration of the conductive paths in Si nanograin networks will pave the way for next-generation nanodevice technologies.

Simultaneous Effects of Carboxyl Group-Containing Hyperbranched Polymers on Glass Fiber-Reinforced Polyamide 6/Hollow Glass Microsphere Syntactic Foams.

The hollow glass microsphere (HGM) containing polymer materials, which are named as syntactic foams, have been applied as lightweight materials in various fields. In this study, carboxyl group-containing hyperbranched polymer (HBP) was added to a glass fiber (GF)-reinforced syntactic foam (RSF) composite for the simultaneous enhancement of mechanical and rheological properties. HBP was mixed in various concentrations (0.5-2.0 phr) with RSF, which contains 23 wt% of HGM and 5 wt% of GF, and the rheological, thermal, and mechanical properties were characterized systematically. As a result of the lubricating effect of the HBP molecule, which comes from its dendritic architecture, the viscosity, storage modulus, loss modulus, and the shear stress of the composite decreased as the HBP content increased. At the same time, because of the hydrogen bonding among the polymer, filler, and HBP, the compatibility between filler and the polymer matrix was enhanced. As a result, by adding a small amount (0.5-2.0 phr) of HBP to the RSF composite, the tensile strength and flexural modulus were increased by 24.3 and 9.7%, respectively, and the specific gravity of the composite was decreased from 0.948 to 0.917. With these simultaneous effects on the polymer composite, HBP could be potentially utilized further in the field of lightweight materials.

Cervical pedicle screw placement using the "key slot technique": the feasibility and learning curve.

STUDY DESIGN: A retrospective study. OBJECTIVES: To present the accuracy and safety of a novel "key slot (KS)" technique for cervical pedicle screw (CPS) placement with the learning curve. SUMMARY OF BACKGROUND DATA: Safety and learning curve are the issues preventing wide acceptance of CPS. On the basis of the local anatomy of the pedicle, the authors modified the conventional technique to increase the accuracy and comfortableness of CPS placement with minimal bone loss. METHODS: A total of 277 subaxial CPS in 50 patients had been inserted using author's technique were reviewed. The KS-shaped entry was created on the medial half of the lateral mass with a 3 mm cutting burr. The shape of entry was a right-angled triangle on the axial plane. The apex of triangle was the virtual pedicle inlet and the oblique side was same as pedicle axis. After making entry, the pedicle was probed with a curved awl along the medial wall. On the postoperative vascular-enhanced computed tomography scan, we analyzed the direction and grade of pedicle perforation (grade 0: no perforation, 1:< 25%, 2: 20% to 50%, 3: > 50% of screw diameter) on the chronological group of consecutive 10 cases. Grade 2 and 3 were considered as incorrect position. RESULTS: The correct position was found in 250 screws (90.3%); grade 0 - 215 screws, 1 - 35 screws and the incorrect position in 27 screws (9.7%); grade 2 - 21 screws, grade 3 - 6 screws. The incidence of incorrect screw position was 18% in the initial 20 cases and 2.7% after that. There was no neurovascular complication related with CPS. CONCLUSIONS: We performed CPS placement using the KS technique and with 90% correct position without clinical complications. After the learning curve, the incidence was 2.7%. This technique could be considered relatively concrete and safe modification of conventional technique with minimal bone loss.

Adult cor triatriatum presenting as cardioembolic stroke.

Cor triatriatum is a rare congenital cardiac malformation characterized by a fibromuscular membrane that divides the left atrium into two distinct chambers. In almost all cases, it is diagnosed in childhood, whereas adult cases are extremely rare. Herein, we describe an unusual case of cor triatriatum in a 55-year-old woman who presented with embolic cerebral infarction. The patient experienced sudden-onset, transient left-sided homonymous hemianopsia and echocardiography and multidetector computed tomography detected a membrane-like structure across the left atrium, confirming the diagnosis of a cor triatriatum. The laboratory examination for hypercoagulopathy was negative. She was conservatively treated with anticoagulation and her neurological manifestation gradually improved.