The Influence of Systolic Blood Pressure at the Time of Extubation on the Development of Postoperative Spinal Epidural Hematoma.

Background: The most common cause of neurological complications after a biportal endoscopic spine surgery (BESS) is postoperative spinal epidural hematomas (POSEH). The objective of this study was to determine the influence of systolic blood pressure at extubation (e-SBP) on POSEH. Methods: A total of 352 patients who underwent single-level decompression surgery including laminectomy and/or discectomy with BESS under the diagnosis of spinal stenosis and herniated nucleus pulposus between August 1, 2018, and June 30, 2021, were reviewed retrospectively. The patients were divided into two, a POSEH group and a normal group without POSEH (no neurological complication). The e-SBP, demographic factors, and the preoperative and intraoperative factors suspected to influence the POSEH were analyzed. The e-SBP was converted to a categorical variable by the threshold level that was decided by maximum area under the curve (AUC) in receiver operating characteristic (ROC) curve analysis. Antiplatelet drugs (APDs) were taken in 21 patients (6.0%), discontinued in 24 patients (6.8%), and not taken in 307 patients (87.2%). Tranexamic acid (TXA) was used in 292 patients (83.0%) in the perioperative period. Results: Of the 352 patients, 18 patients (5.1%) underwent revision surgery for the removal of POSEH. The POSEH and normal groups were homogenous in age, sex, diagnosis, operation segments, operation time, and lab findings that were related to blood clotting, whereas there were differences in e-SBP (163.7 ± 15.7 mmHg in POSEH group and 154.1 ± 18.3 mmHg in normal group), APD (4 takers, 2 stoppers, 12 non-takers in POSEH group and 16 takers, 22 stoppers, 296 non-takers in normal group), and TXA (12 use, 6 not use in POSEH group and 280 use, 54 not use in normal group) in single variable analysis. The highest AUC in the ROC curve analysis was 0.652 for 170 mmHg e-SBP (p < 0.05). There were 94 patients in the high e-SBP group (≥ 170 mmHg) and 258 patients in the low e-SBP group. In multivariable logistic regression analysis, only high e-SBP was a significant risk factor for POSEH (p = 0.013; odds ratio, 3.434). Conclusions: High e-SBP (≥ 170 mmHg) can influence the development of POSEH in biportal endoscopic spine surgery.

Drawing Guideline for JKMS Manuscripts (03): Pyramid Charts.

The appropriate plot effectively conveys the author's conclusions to the readers. Journal of Korean Medical Science (JKMS) will provide a series of special articles to show you how to make consistent and excellent plots more easily. In this article, we will cover pyramid charts. A pyramid chart is a simple yet popular tool for looking at the structure of a population by age and gender. Other variables can also be applied. This article helps researchers use these charts more easily by introducing effective tools and explaining how to use them.

The Influence of Femoral Internal Rotation on Patellar Tracking in Total Knee Arthroplasty Using Gap Technique.

BACKGROUD: Femoral internal rotation in total knee arthroplasty (TKA) is well known as one of the main causes of patellar maltracking. Although femoral internal rotation in TKA is considered unacceptable due to the risk of patellar maltracking, it is sometimes required for ligament balancing. We evaluated the influence of femoral internal rotation on patellar tracking in TKA performed using the gap technique. METHODS: From April 2008 to May 2018, 1,612 cases of TKA were done. Among them, 245 cases of TKA for osteoarthritis were followed up for at least 1 year and included in this study. We compared patellar tracking in two groups; group I consisted of 99 cases whose femoral rotation was less than 0° and group II consisted of 146 cases whose femoral rotation was 3°-5° external rotation. Preoperative femoral rotation was measured with the condylar twist angle (CTA) by using computed tomography. The patella was replaced in all cases. Patellar tracking was evaluated with patellar tilt angle (lateral tilt [+] and medial tilt [-]) in the merchant radiograph. Statistical analysis was done using Mann-Whitney U-test. Clinical assessment was performed using the Knee Society clinical rating system. RESULTS: The preoperative CTA was 5.3° ± 1.6° in group I and 5.4° ± 1.6° in group II, showing no statistically significant difference between groups (p = 0.455). Intraoperative femoral rotation was -0.5° ± 0.8° in group I and 3.9° ± 0.8° in group II when the gap technique was used (p < 0.001). The postoperative patellar tilt angle was -0.4° ± 3.6° in group I and 0.1° ± 4.1° in group II with no statistically significant difference (p = 0.251). CONCLUSIONS: Compared with femoral external rotation, femoral internal rotation with ligament balance in TKA was not more associated with patellar maltracking. Therefore, patellar tracking might be related with ligament balance in flexion regardless of the anatomic femoral rotational alignment.

Drawing Guideline for 'Hip and Pelvis': Plot with Error Bar.

The appropriate plots effectively convey the author's conclusions to the readers. 'Hip and Pelvis' will provide a series of special articles to show how to make consistent and excellent plots easier. In this article, we will cover plots with error bars.

Deep-UV microsphere projection lithography.

In this Letter, we present a single-exposure deep-UV projection lithography at 254-nm wavelength that produces nanopatterns in a scalable area with a feature size of 80 nm. In this method, a macroscopic lens projects a pixelated optical mask on a monolayer of hexagonally arranged microspheres that reside on the Fourier plane and image the mask's pattern into a photoresist film. Our macroscopic lens shrinks the size of the mask by providing an imaging magnification of ∼1.86×10(4), while enhancing the exposure power. On the other hand, microsphere lens produces a sub-diffraction limit focal point-a so-called photonic nanojet-based on the near-surface focusing effect, which ensures an excellent patterning accuracy against the presence of surface roughness. Ray-optics simulation is utilized to design the bulk optics part of the lithography system, while a wave-optics simulation is implemented to simulate the optical properties of the exposed regions beneath the microspheres. We characterize the lithography performance in terms of the proximity effect, lens aberration, and interference effect due to refractive index mismatch between photoresist and substrate.

Bimetallic non-alloyed NPs for improving the broadband optical absorption of thin amorphous silicon substrates.

We propose the use of bimetallic non-alloyed nanoparticles (BNNPs) to improve the broadband optical absorption of thin amorphous silicon substrates. Isolated bimetallic NPs with uniform size distribution on glass and silicon are obtained by depositing a 10-nm Au film and annealing it at 600°C; this is followed by an 8-nm Ag film annealed at 400°C. We experimentally demonstrate that the deposition of gold (Au)-silver (Ag) bimetallic non-alloyed NPs (BNNPs) on a thin amorphous silicon (a-Si) film increases the film's average absorption and forward scattering over a broad spectrum, thus significantly reducing its total reflection performance. Experimental results show that Au-Ag BNNPs fabricated on a glass substrate exhibit resonant peaks at 437 and 540 nm and a 14-fold increase in average forward scattering over the wavelength range of 300 to 1,100 nm in comparison with bare glass. When deposited on a 100-nm-thin a-Si film, Au-Ag BNNPs increase the average absorption and forward scattering by 19.6% and 95.9% compared to those values for Au NPs on thin a-Si and plain a-Si without MNPs, respectively, over the 300- to 1,100-nm range.

Localized surface plasmon resonance with broadband ultralow reflectivity from metal nanoparticles on glass and silicon subwavelength structures.

Metal nanoparticles (NPs) are well known to increase the efficiency of photovoltaic devices by reducing reflection and increasing light trapping within device. However, metal NPs on top flat surface suffer from high reflectivity losses due to the backscattering of the NPs itself. In this paper, we experimentally demonstrate a novel structure that exhibits localized surface plasmon resonance (LSPR) along with broadband ultralow reflectivity over a wide range of wavelength. Experimental results show that by depositing Ag NPs and Au NPs onto glass subwavelength structures (SWS) the backscattering effect of NPs can be suppressed, and the reflections can be considerably reduced by up to 87.5% and 66.7% respectively, compared to NPs fabricated on a flat glass substrate. Broadband ultralow reflection (< 2%) is also observed in the case of Ag NPs and Au NPs fabricated on cone shaped SWS silicon substrate over a wavelength range from 200 nm to 800 nm. This broadband ultralow reflectivity of Ag NPs and Au NPs on silicon SWS structure leads to a substantial enhancement of average absorption by 66.53% and 66.94%, respectively, over a broad wavelength range (200-2000 nm). This allows light absorption by NPs on SWS silicon structure close to 100% over a wavelength range from 300 nm to 1000 nm. The mechanism responsible for the increased light absorption is also explained.

Antireflective disordered subwavelength structure on GaAs using spin-coated Ag ink mask.

We present a simple, cost-effective, large scale fabrication technique for antireflective disordered subwavelength structures (d-SWSs) on GaAs substrate by Ag etch masks formed using spin-coated Ag ink and subsequent inductively coupled plasma (ICP) etching process. The antireflection characteristics of GaAs d-SWSs rely on their geometric profiles, which were controlled by adjusting the distribution of Ag etch masks via changing the concentration of Ag atoms and the sintering temperature of Ag ink as well as the ICP etching conditions. The fabricated GaAs d-SWSs drastically reduced the reflection loss compared to that of bulk GaAs (>30%) in the wavelength range of 300-870 nm. The most desirable GaAs d-SWSs for practical solar cell applications exhibited a solar-weighted reflectance (SWR) of 2.12%, which is much lower than that of bulk GaAs (38.6%), and its incident angle-dependent SWR was also investigated.

Wafer-scale broadband antireflective silicon fabricated by metal-assisted chemical etching using spin-coating Ag ink.

We report broadband antireflective disordered subwavelength structures (d-SWSs), which were fabricated on 4-inch silicon wafers by spin-coating Ag ink and metal-assisted chemical etching. The antireflection properties of the d-SWSs depend on its dimensions and heights, which were changed by the sintering temperature of the spin-coated Ag ink and etching time. The fabricated d-SWSs drastically reduced surface reflection over a wide range of wavelengths and incident angles, providing good surface uniformity. The d-SWSs with the most appropriate geometry for practical solar cell applications exhibit only 1.23% solar-weighted reflectance in the wavelength range of 300-1100 nm and average reflectance <5% up to an incident angle of 55° in the wavelength range of 300-2500 nm. This simple and low-cost nanofabrication method for antireflection could be of great importance in optical device applications because it allows mass production without any lithography processes or sophisticated equipment.

Antireflective property of thin film a-Si solar cell structures with graded refractive index structure.

We report the antireflective property of thin film amorphous silicon (a-Si) solar cell structures based on graded refractive index structure together with theoretical analysis. Optimizations of the index profile are performed using the rigorous coupled-wave analysis method. The graded refractive index structure fabricated by oblique angle deposition suppresses optical reflection over a wide range of wavelength and incident angle, compared to the conventional structure. The average reflectance of thin film a-Si solar cell structure with the graded refractive index structure is suppressed by 54% at normal incidence due to the effective refractive index matching between ITO and a-Si, indicating a reasonable agreement with calculated results.

Multifunctional light escaping architecture inspired by compound eye surface structures: From understanding to experimental demonstration.

We present bioinspired artificial compound eye surface structures that consist of antireflective subwavelength structures (SWSs) on hexagonally patterned microstructures (MSs), for the purpose of efficient light escaping inside light-emitting materials/devices. Theoretical understanding and geometrical optimization of SWSs on MSs are described together with rigorous coupled-wave analysis. As a proof of this concept, AlGaInP red light-emitting diodes (LEDs) with SWS/MSs were fabricated, and a light output power enhancement of 72.47% was achieved as compared to that of conventional LEDs. The artificial compound eye structures are not limited to LEDs, and the fabrication process is compatible with most semiconductor device manufacturing processes; hence, this concept opens up new possibilities for improving the optical performance of various optoelectronic device applications.

Antireflective properties of porous Si nanocolumnar structures with graded refractive index layers.

We report on the antireflective characteristics of porous silicon (Si) nanocolumnar structures consisting of graded refractive index layers and carry out a rigorous coupled-wave analysis simulation. The refractive index of Si is gradually modified by a tilted angle electron beam evaporation method. For the fabricated Si nanostructure with a Gaussian index profile of 100 nm, reflectivity (R) of less than 7.5% is obtained with an average value of approximately 2.9% at the wavelength region of 400-800 nm. The experimental results are reasonably consistent with the simulated results for the design of antireflective Si nanostructures.