AI-driven robotic chemist for autonomous synthesis of organic molecules.

The automation of organic compound synthesis is pivotal for expediting the development of such compounds. In addition, enhancing development efficiency can be achieved by incorporating autonomous functions alongside automation. To achieve this, we developed an autonomous synthesis robot that harnesses the power of artificial intelligence (AI) and robotic technology to establish optimal synthetic recipes. Given a target molecule, our AI initially plans synthetic pathways and defines reaction conditions. It then iteratively refines these plans using feedback from the experimental robot, gradually optimizing the recipe. The system performance was validated by successfully determining synthetic recipes for three organic compounds, yielding that conversion rates that outperform existing references. Notably, this autonomous system is designed around batch reactors, making it accessible and valuable to chemists in standard laboratory settings, thereby streamlining research endeavors.

Amorphous BN-Based Synaptic Device with High Performance in Neuromorphic Computing.

The von Neumann architecture has faced challenges requiring high-fulfillment levels due to the performance gap between its processor and memory. Among the numerous resistive-switching random-access memories, the properties of hexagonal boron nitride (BN) have been extensively reported, but those of amorphous BN have been insufficiently explored for memory applications. Herein, we fabricated a Pt/BN/TiN device utilizing the resistive switching mechanism to achieve synaptic characteristics in a neuromorphic system. The switching mechanism is investigated based on the I-V curves. Utilizing these characteristics, we optimize the potentiation and depression to mimic the biological synapse. In artificial neural networks, high-recognition rates are achieved using linear conductance updates in a memristor device. The short-term memory characteristics are investigated in depression by controlling the conductance level and time interval.

Improved Uniformity of TaOx-Based Resistive Switching Memory Device by Inserting Thin SiO2 Layer for Neuromorphic System.

RRAM devices operating based on the creation of conductive filaments via the migration of oxygen vacancies are widely studied as promising candidates for next-generation memory devices due to their superior memory characteristics. However, the issues of variation in the resistance state and operating voltage remain key issues that must be addressed. In this study, we propose a TaOx/SiO2 bilayer device, where the inserted SiO2 layer localizes the conductive path, improving uniformity during cycle-to-cycle endurance and retention. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) confirm the device structure and chemical properties. In addition, various electric pulses are used to investigate the neuromorphic system properties of the device, revealing its good potential for future memory device applications.

An assistance approach for a powered knee exoskeleton during level walking and the effects on metabolic cost.

In this paper, we propose a walking assistance method based on intrinsic gait events for level walking in a powered knee exoskeleton. The proposed method utilizes three gait events in order to determine the timing of initiation and termination for assistance torque profiles. This method plans uni-directional torque profiles for each flexion and extension movement for the next step and executes them in a feedfor-ward manner. It has the advantages of easy to adjust the assistance timing, intensity, and duration according to wearer's preference. In experiments, we investigated that the increase of metabolic cost was close to zero when worn and walked with our portable powered knee exoskeleton by the proposed assistance method compared with walking without wearing it on the treadmill.

Natural gait event-based level walking assistance with a robotic hip exoskeleton.

In this paper, we present an assistance strategy for level walking by using a robotic hip exoskeleton. Our strategy utilizes a foot contact event estimated by an inertial measurement unit (IMU) on the pelvis. The gait cycle is composed of three phases. The transitions between the phases are established upon natural gait events that are inevitable and perceived reliably by sensors attached to our exoskeleton. The presented strategy provides a systematic way of adjusting the quantity of assistance that corresponds to the wearer's preference and needs, and also provides explicit principles for the initiation and termination of assistance. When a step begins, the maximum torque and duration of assistance are decided, and the torque profile for the entire step is designed in advance. We conduct experiments in order to investigate the effect on metabolic cost when walking on a motorized treadmill.

A wearable hip-assist robot reduces the cardiopulmonary metabolic energy expenditure during stair ascent in elderly adults: a pilot cross-sectional study.

BACKGROUND: Stair ascent is one of the most important and challenging activities of daily living to maintain mobility and independence in elderly adults. Recently, various types of wearable walking assist robots have been developed to improve gait function and metabolic efficiency for elderly adults. Several studies have shown that walking assist robots can improve cardiopulmonary metabolic efficiency during level walking in elderly. However, there is limited evidence demonstrating the effect of walking assist robots on cardiopulmonary metabolic efficiency during stair walking in elderly adults. Therefore, the aim of this study was to investigate the assistance effect of a newly developed wearable hip assist robot on cardiopulmonary metabolic efficiency during stair ascent in elderly adults. METHODS: Fifteen healthy elderly adults participated. The Gait Enhancing Mechatronic System (GEMS), developed by Samsung Electronics Co., Ltd., Korea, was used in the present study. The metabolic energy expenditure was measured using a K4b2 while participants performed randomly assigned two conditions consecutively: free ascending stairs without the GEMS or robot-assisted ascending stair with the GEMS. RESULTS: There were significant differences in the oxygen consumption per unit mass (ml/min/kg), metabolic power per unit mass (W/kg) and metabolic equivalents (METs) values between the GEMS and NoGEMS conditions. A statistically significant difference was found between the two conditions in net oxygen consumption and net metabolic power, with a reduction of 8.59% and 10.16% respectively in GEMS condition (p < 0.05). The gross oxygen consumption while climbing stairs under the GEMS and NoGEMS conditions was equivalent to 6.38 METs and 6.85 METs, respectively. CONCLUSION: This study demonstrated that the GEMS was helpful for reducing cardiopulmonary metabolic energy expenditure during stair climbing in elderly adults. The use of the GEMS allows elderly adults to climb stairs with less metabolic energy, therefore, they may experience more endurance in stair climbing while using the GEMS. TRIAL REGISTRATION: NCT03389165 , Registered 26 December 2017 - retrospectively registered.

Assessing amblyopia treatment using multifocal visual evoked potentials.

BACKGROUND: To evaluate the effect of occlusion treatment for anisometropic amblyopia using multifocal visual evoked potentials (mfVEPs). METHODS: The patients for this study comprised 19 patients (mean age 6.05 ± 1.65 years) with anisometropic amblyopia underwent mfVEP analysis using the RETIscan® system before and after occlusion treatment. After dividing the area into six ring areas and four quadrants, we analyzed the amplitudes and latencies of the mfVEPs. RESULTS: The amplitudes of ring 1 (central field) in amblyopic eyes after treatment were significantly higher than those in the other rings (p = 0.001). The mfVEP amplitudes in each of the six rings between amblyopic eyes and fellow eyes at diagnosis and after occlusion treatment showed no significant differences. In quadrant 1 the amplitudes of the amblyopic eyes and fellow eyes were significantly different at the time of diagnosis (p = 0.005), whereas after occlusion treatment there was no significant difference (p = 0.888). The amplitudes for each of the six rings at diagnosis and after occlusion treatment in amblyopic eyes versus fellow eyes showed no significant difference. There were also no differences in the amplitudes in each of the four quadrants at the time of diagnosis and after occlusion treatment in amblyopic eyes versus fellow eyes. No significant difference was found in the comparison of latency values in each of the six rings or in each of the four quadrants at diagnosis and after occlusion treatment in amblyopic eyes versus their fellow eyes. CONCLUSIONS: The amplitudes of quadrant 1 in amblyopic eyes compared with those of the fellow eyes at diagnosis were increased after occlusion treatment. Changes of the difference between amblyopic eyes and fellow eyes in quadrant 1 after occlusion treatment could be a useful, objective method for monitoring improvement in visual acuity.

Effects of assistance timing on metabolic cost, assistance power, and gait parameters for a hip-type exoskeleton.

There are many important factors in developing an exoskeleton for assisting human locomotion. For example, the weight should be sufficiently light, the assist torque should be high enough to assist joint motion, and the assistance timing should be just right. Understanding how these design parameters affect overall performance of a complex human-machine system is critical for the development of these types of systems. The present study introduces an assistance timing controller that regulates assistance timing such that peak joint velocity and peak assistance power are offset by a reference value for our hip-type exoskeleton. This is followed by measuring the manner in which various assistance timing references affect an important metric for performance, namely metabolic cost. The results indicate that net metabolic cost exhibits a concave up pattern with the most reduction of 21%, when compared to walking without the exoskeleton, at 0% assistance timing reference. The study also examines assistance timing's effect on gait parameters; increase in assistance timing reference increases step length, decreases cadence, and increases walk ratio (i.e. step length/cadence ratio) during treadmill walking.

Carboxymethyl chitosan-modified magnetic-cored dendrimer as an amphoteric adsorbent.

Carboxymethyl chitosan-modified magnetic-cored dendrimers (CCMDs) were successfully synthesized in a three step method. The synthesized samples were characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometer, thermogravimetry analysis, zeta potential analyzer, X-ray photoelectron spectroscopy, surface area analysis, and Fourier transform infrared spectroscopy. The CCMD exhibited selective adsorption for anionic and cationic compounds at specific pH conditions. With the substitution of amino groups of MD with carboxymethyl chitosan moieties, the adsorption sites for cationic compounds were greatly increased. Since the adsorption onto CCMD was mainly electrostatic interaction, the adsorption of MB and MO was significantly affected by the pHs. The optimal adsorption pH values were 3 and 11 for MO and MB. The maximal adsorption of MO and MB on the CCMD at pH values of 3 and 11 were 20.85mgg(-1) and 96.31mgg(-1), respectively. Reuse of the CCMD as an adsorbent was experimentally tested through adsorption and desorption with simple pH control. More than 99% and 91% of the initial adsorption of MB and MO on the CCMD was maintained with five consecutive recycling.

Clinical Outcomes and Radiologic Changes After Microsurgical Bilateral Decompression by a Unilateral Approach in Patients With Lumbar Spinal Stenosis and Grade I Degenerative Spondylolisthesis With a Minimum 3-Year Follow-Up.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze the clinical outcomes and radiologic changes after microsurgical bilateral decompression via a unilateral approach in patients with lumbar spinal stenosis (LSS) and degenerative spondylolisthesis (DS). SUMMARY OF BACKGROUND DATA: Satisfactory short-term results have been observed after minimally invasive decompressive procedures, but intermediate-term and long-term outcomes have not been assessed. It is not yet clear whether decompressive laminectomy with concomitant fusion is the optimal surgical treatment for spinal stenosis combined with mild DS. We, therefore, evaluated minimum 3-year clinical outcomes and radiologic changes in patients with LSS and grade 1 DS, who underwent microsurgical bilateral decompression via a unilateral approach, without fusion. METHODS: We assessed 21 consecutive patients who underwent surgery conducted by a single surgeon of our hospital, between 2005 and 2007. The Oswestry Disability Index was determined preoperatively, just before discharge, and at last follow-up. Plain dynamic x-rays were used to determine slip percentages. RESULTS: Average patient age and clinical and radiologic follow-up periods were 67 years, 49.3 months, and 18 months, respectively. Preoperative, immediate postoperative, and last follow-up average Oswestry Disability Indices were 59.52±9.00, 50.19±7.23, and 26.19±12.42, respectively. However, 1 patient experienced aggravated symptoms and later underwent a fusion procedure. Of the 22 levels with spondylolisthesis, 15 had no sagittal motion as the difference in slip percentage on dynamic x-rays, but 7 showed sagittal motion. Average slip percentages increased from 13.90±5.41% to 14.60±5.78% for levels without sagittal motion on dynamic x-ray, and from 13.12±3.48% to 18.58±4.55% for levels with sagittal motion. CONCLUSIONS: Despite small case series with retrospective design and the absence of a control group, our study suggests that bilateral decompression via a unilateral approach in patients with LSS and grade 1 DS showed good mid-term clinical outcomes, despite an increase in slip percentage.However, more marked increases in slippage were observed in patients with sagittal motion in spondylolisthesis levels on preoperative dynamic x-ray, than in patients without sagittal motion. Therefore, bilateral decompression via a unilateral approach can aggravate symptoms related to instability in patients with preoperative sagittal motion on dynamic x-ray, and needs a longer term follow-up than in our study.

Surgical strategies for removal of intra- and extraforaminal dumbbell-shaped schwannomas in the subaxial cervical spine.

PURPOSE: Spinal dumbbell-shaped schwannoma is common neoplasm, usually occurring in the cervical spine. Posterior or anterolateral approaches are frequently used to remove this benign tumor. We analyzed how much amount of tumor could be possible to be totally removed with posterior approach. METHOD: Surgery was performed on 41 cases of cervical, dumbbell-shaped subaxial schwannomas with both intra- and extraforaminal involvement. The same surgeon performed all the procedures. Mean follow-up was 42.5 months (24-108 months). A combined anterolateral and posterior approach was used if the extraforaminal tumor was larger than 10 mm. A posterior approach and unilateral facet removal were used if it was smaller than 10 mm. We performed MRI and serial dynamic X-rays for postoperative 2 years. RESULTS: We used the posterior approach with facetectomy in 35 cases and the combined approach in six. Complete removal was achieved with the combined approach in all six, and with the posterior approach in 28 of 35 cases. With the posterior approach, the extraforaminal dimension of totally resected tumors ranged from 3 to 5.4 mm. Subtotal resection was limited to extraforaminal tumors larger than 5.7 mm. On follow-up, instability on dynamic X-ray was not observed before 24 months in any patient after unilateral facetectomy. CONCLUSION: Total removal of intra- and extraforaminal cervical subaxial schwannomas could be possible using a posterior approach with facet removal if the size of extraforaminal tumor was less than 5.4 mm.

Iron oxide nanotube layer fabricated with electrostatic anodization for heterogeneous Fenton like reaction.

Iron oxide nanotubes (INT) were fabricated with potentiostatic anodization of zero valent iron foil in 1M Na2SO4 containing 0.5wt% NH4F electrolyte, holding the potential at 20, 40, and 60V for 20min, respectively. Field emission scanning electron microscopy and X-ray diffractometry were used to evaluate the morphology and crystalline structure of the INT film. The potential of 40V for 20min was observed to be optimal to produce an optimal catalytic film. Cyanide dissolved in water was degraded through the Fenton-like reaction using the INT film with hydrogen peroxide (H2O2). In case of INT-40V in the presence of H2O2 3%, the first-order rate constant was found to be 1.7×10(-2)min(-1), and 1.2×10(-2)min(-1) with commercial hematite powder. Degradation of cyanide was much less with only H2O2. Therefore, this process proposed in this work can be an excellent alternative to traditional catalysts for Fenton-like reaction.

Does plate profile affect postoperative dysphagia following anterior cervical spine surgery?

Dysphagia following anterior cervical spine surgery is a significant problem. The risk factors for such dysphagia have not been established. We examined whether plate profile affected the incidence of dysphagia. This study enrolled 50 consecutive patients undergoing one-level corpectomy or one- or two-level discectomies with plate fixation performed by the same surgeon from 2004 to 2009. The anterior cervical plates used were either the Codman (Johnson and Johnson Professional Inc., Raynham, MA, USA; width 17.58 mm, thickness 2.69 mm; 27 patients) or the Zephir (Medtronic Sofamor Danek Inc., Memphis, TN, USA; width 15 mm, thickness 1.6 mm; 23 patients). Dysphagia was assessed via telephone interviews, and was classified as short-term (occurring within 6 months postoperatively) or persistent (persisting beyond 6 months postoperatively). The overall short-term and persistent dysphagia rates were 20% and 14%, respectively. The short-term and persistent dysphagia rates were 26% and 13% for the Zephir plate, and 14.8% and 14.8% for the Codman plate, and analysis showed that the rates were similar for both types of plate. Age and sex were not found to correlate with dysphagia. In patients undergoing anterior cervical spine surgery with plate fixation, we found that postoperative dysphagia did not correlate with plate profile up to a plate size of 17.58 mm wide and 2.69 mm thick. Dysphagia occurred at the same incidence in patients with a smaller plate that was 15 mm wide and 1.6 mm thick.

Progression of lumbar spinal stenosis is influenced by polymorphism of thrombospondin 2 gene in the Korean population.

PURPOSE: The aim of this study is to determine the contribution of thrombospondin 2 (THBS2) polymorphisms to the development and progression of lumbar spinal stenosis (LSS) in the Korean population. METHODS: We studied 148 symptomatic patients with radiographically proven LSS and 157 volunteers with no history of back problems from our institution. Magnetic resonance images were obtained for all the patients and controls. Quantitative image evaluation for LSS was performed to evaluate the severity of LSS. All patients and controls were genotyped for THBS2 allele variations using a polymerase chain reaction-based technique. RESULTS: We found no causal single nucleotide polymorphism (SNPs) in THBS2 that were significantly associated with LSS. Two SNPs (rs6422747, rs6422748) were over-represented in controls [P = 0.042, odds ratio [OR] = 0.55 and P = 0.042, OR = 0.55, respectively]. Haplotype analysis showed that the ''AGAGACG'' haplotype (HAP4) and ''AAGGACG'' haplotype (HAP5) were over-represented in severe LSS patients (P = 0.0147, OR = 2.02 and P = 0.0137, OR = 2.48, respectively). In addition, the ''AAAGGGG'' haplotype (HAP1) was over-represented in controls (P = 0.0068, OR = 0.30). CONCLUSIONS: Although no SNPs in THBS2 were associated with LSS, haplotypes (HAP4 and HAP5) were significantly associated with progression of LSS in the Korean population, whereas another haplotype (HAP1) may play a protective role against LSS development.

Nano zero-valent iron impregnated on titanium dioxide nanotube array film for both oxidation and reduction of methyl orange.

Here, we demonstrated that nano zero-valent iron (nZVI) impregnated onto self-organized TiO(2) nanotube thin films exhibits both oxidation and reduction capacities in addition to the possible electron transfer from TiO(2) to nZVI. The TiO(2) nanotubes were synthesized by anodization of titanium foil in a two-electrode system. Amorphous TiO(2) (amTiO(2)) nanotubes were annealed at 450 °C for 1 h to produce crystalline TiO(2) (crTiO(2)) nanotubes. The nZVI particles were immobilized on the TiO(2) array film by direct borohydride reduction. Field emission scanning electron microscopy (FE-SEM) analysis of the crystalline TiO(2) nanotube with nZVI (nZVI/crTiO(2)) indicated that the nZVI particles with a mean particle diameter of 28.38 ± 11.81 nm were uniformly distributed onto entire crTiO(2) nanotube surface with a mean pore diameter of 75.24 ± 17.66 nm and a mean length of 40.07 µm. Environmental applicability of our proposed nZVI/TiO(2) nanotube thin films was tested for methyl orange (MO) degradation in the aqueous system with and without oxygen. Since oxygen could facilitate the nZVI oxidation and inhibit electron transfer from crTiO(2) to nZVI surface, MO degradation by nZVI/crTiO(2) in the presence of oxygen was significantly suppressed whereas nZVI/crTiO(2) in the absence of oxygen enhanced MO degradation. MO degradation rate by each sample without oxygen were in following order: nZVI/crTiO(2) (k(obs) = 0.311 min(-1)) > nZVI/amTiO(2) (k(obs) = 0.164 min(-1)) > crTiO(2) (k(obs) = 0.068 min(-1)). This result can be explained with a synergistic effect of the significant reduction by highly-dispersed nZVI particles on TiO(2) nanotubes as well as the electron transfer from the conduction band of crTiO(2) to the nZVI on the crTiO(2) for the degradation of MO.

Fabrication of zero valent iron (ZVI) nanotube film via potentiostatic anodization and electroreduction.

Zero valent iron has been successfully used for the degradation of a wide range of contaminants. However, this reaction of using ZVI particle produces a large quantity of iron sludge. To solve the problem, we report the synthesis of self-organized nanoporous zero valent iron film treated with anodization and electro-reduction of iron foil. The iron nanotubes were fabricated in 1 M Na(2)SO(4) + 0.5 wt% NaF electrolyte by supplying constant electric currents of 50 mV/s, and holding the potential at 20, 40 and 60 V for 20 min. Nanoporous shape was produced by anodic oxidation of iron film. After anodizing process, electro-reduction of nanoporous iron film converted crystallization iron oxide to zero valent iron. Electro-reduction process was carried out by electro-reducing with powersupply to and holding the potential at 20 V for 20 min. The surface of iron nanotube film was examined by BET and the thickness of the oxidized films was evaluated by scanning electron microscope (SEM). The crystalline structures of the fabricated films were evaluated using X-ray diffraction (XRD).