Reconstruction of Large Orbital Posterior Floor Wall Fracture Considering Orbital Floor Slope Using Endoscope.

PURPOSE: Reconstruction of a large orbital fracture extending to the posterior wall of the maxillary sinus is difficult and challenging. In this study, the authors present transconjunctival or transcaruncular approach using endoscopy and layered porous polyethylene barrier sheets to manage large orbital floor wall fracture. METHODS: A retrospective review of all patients who underwent reconstruction of large orbital floor wall fractures between June 2009 and July 2015 was conducted. Patient demographics, degree of enophthalmos, ocular motility and diplopia test results, and surgical complications were reviewed. RESULTS: This study included 53 eyes of 53 patients. The mean time from trauma to surgery was 34.1 days (range, 1-360 days). The average postoperative follow-up period was 6.1 months (range, 3-14 months). The degrees of enophthalmos preoperatively, and 1 week, 1 month, and 3 months postoperatively were -1.98 mm (range, -1.5 to -3 mm), 0.13 mm (range, -1.0 to +1.5 mm), -0.09 mm (range, -2.0 to +1.5 mm), and -0.43 mm (range, -2.0 to +1.0 mm), respectively. The mean improvement in enophthalmos at 3 months postoperation was 1.55 mm (P < 0.001). There was only 1 patient with residual 2 mm enophthalmos at 3 months postoperation. There were no definite surgical complications in any patient. CONCLUSION: Sufficient dissection to the posterior extent of the fracture and reconstruction of the orbital floor slope are the most important surgical factors to prevent residual enophthalmos. The authors believe using an endoscope and layered porous polyethylene are effective techniques in challenging patients with large orbital wall fracture.

Using the Endoscopic Transconjunctival and Transcaruncular Approach to Repair Combined Orbital Floor and Medial Wall Blowout Fractures.

PURPOSE: To demonstrate the effectiveness of the endoscopic transcaruncular and transconjunctival approach in the repair of combined medial and inferior orbital wall fractures. METHODS: A retrospective chart review was conducted on 160 patients with combined medial and inferior orbital wall fractures. All patients underwent surgery via an endoscopic transcaruncular and transconjunctival approach without lateral canthotomy, performed by a single surgeon. Porous polyethylene sheets (1.0 mm in thickness) were implanted to cover the orbital defects. The minimal postoperative follow-up period was 6 months. The authors evaluated enophthalmos, diplopia, and ocular motility pre and postoperatively and report surgical complications. RESULTS: A total of 160 patients were included, comprising 121 men and 39 women. The mean patient age was 33.9 ±â€Š14.1 years, and the mean postoperative follow-up period was 12 months. The average enophthalmos was 3.20 mm preoperatively, and the mean improvement at 6 months after surgery was 2.82 mm. One patient suffered a canalicular laceration after surgery, and another retrobulbar hemorrhage; however, both of these complications resolved with appropriate management. Otherwise, there were no significant surgical complications including newly developed diplopia, decreased visual acuity, or cerebrospinal fluid leakage. CONCLUSIONS: The endoscopic transcaruncular and transconjunctival approach is a useful and promising technique to repair combined medial and inferior orbital wall fractures.

Modified Full Thickness Graded Blepharotomy for Upper Eyelid Retraction Associated With Thyroid Eye Disease in East Asians.

PURPOSE: To evaluate the functional and cosmetic outcomes of modified full thickness graded blepharotomy when used for East Asian patients with upper eyelid retraction of thyroid eye disease (TED). METHOD: Medical records of each patient who underwent modified full-thickness blepharotomy at Korea University Guro Hospitals from January 2009 to February 2014 to correct upper eyelid retraction resulting from TED were retrospectively reviewed. RESULTS: Modified full-thickness graded blepharotomies were performed on 22 eyelids of 18 patients. The most common preoperative upper eyelid retraction-associated symptom was asymmetry of the upper eyelid (14 patients, 77.7%) followed by discomfort (10 patients, 55.5%), photophobia (5 patients, 27.7%), and epiphora (4 patients, 22.2%). Most preoperative symptoms improved after blepharotomy (Table 1). Preoperatively, upper eyelid retraction (MRD1; midpupil marginal reflex distance) ranged from 2.3 mm to 6.8 mm (mean, 5.23 ± 0.89) in 22 lids; postoperatively, lid retraction significantly decreased to 3.26 ± 1.23 mm (P = 0.03 by independent t test) (Table 2). Lid retraction was divided into 3 groups according to severity; a severe group (5 eyelids, 27.7%), a moderate group (14 eyelids, 63.6%), and a mild group (3 eyelids, 13.6%). The MRD1 improved regardless of severity (P = 0.03 in the severe group, P = 0.02 in the moderate group, and P = 0.04 in the mild group by independent t test). The MRD1 improvement did not differ significantly among groups (P = 0.08 by Pearson χ t test). At 6 months postoperatively, the midpupil marginal reflex distance was the perfect height in 13 of 22 lids (59.0%), with a mean reduction of 3 mm, whereas 7 of 22 eyelids (31.8%) were at acceptable height and 2 eyelids (9.0%) showed failure. Overall, 18 eyelids (90.9%) exhibited objectively satisfactory results (perfect or acceptable) at 6 months after surgery (Table 3). CONCLUSIONS: Modified graded full thickness eyelid blepharotomy is a reliable and safe method for upper eyelid lengthening for East Asian patients with upper eyelid retraction of TED that offers excellent functional and cosmetic results.

Clinical Results of Modified Frontalis Suspension Technique Using Preserved Fascia Lata for Congenital Ptosis.

PURPOSE: The purpose of this study was to evaluate the clinical results of modified frontalis suspension technique with preserved fascia lata and to analyze the results according to age and preoperative ptosis degree. METHODS: This study involved a retrospective review of the electronic medical records of congenital ptosis patients who underwent unilateral or bilateral frontalis sling surgery using preserved fascia lata between March 1, 2004 and December 31, 2012. RESULTS: Seventy-seven patients (99 eyes) were included in the study. The mean age of the patients at the time of surgery was 6.2 ±â€Š6.7 years. Mean follow-up time was 5.4 ±â€Š3.2 years. Among 77 patients, 22 patients (28.5%) had a mild degree of ptosis, 39 (50.6%) had moderate, and 16 (20.7%) had a severe degree of ptosis. A satisfactory result (good and fair) was achieved in 65 of the 77 patients (84.4%) and a poor result was recorded in 12 patients (15.5%). Preoperative ptosis degree had no effect on the surgical success rate (19/22 [86.3%] in the mild group versus 34/39 [87.1%] in the moderate group versus 12/16 [75%] in the severe group, P = 0.243). There was no significant difference in surgical success rate between the unilateral and bilateral ptosis groups (45/55 [81.8%] versus 20/22 [90.9%], P = 0.479 respectively), between sexes (41/46 [89.1%] in male versus 24/31 [77.4%] in female, P = 0.271), or age groups (52/60 [86.6%] in younger group versus 13/17 [76.4%] in elder group, P = 0.526). Recurrence of ptosis did not differ according to the preoperative ptosis degree (3/22 [13.6%] in the mild group, 5/39 [12.8%] in the moderate group, and 2/16 [12.5%] in the severe group, P = 0.994). Age also had no influence on the ptosis recurrence. The preoperative marginal reflex distance 1 of 0.41 ±â€Š1.06 mm increased to 1.67 ±â€Š0.80 mm postoperatively (P = 0.000). CONCLUSIONS: The authors identified the long-term efficacy of preserved fascia lata in frontalis sling surgery with a modified frontalis suspension method for all age groups of patients. There was a small rate of recurrence (12.9%) over a maximum of 9 years of follow-up, which was corrected with additional surgery.

Analysis of Surgical Outcome After Levator Advancement by Assessing Changes in Eyelid Contour.

PURPOSE: The authors analyzed changes in eyelid contour after levator advancement by measuring multiple radial midpupil lid distance (MPLD). METHODS: The study enrolled 61 eyes of 61 patients with involutional ptosis who underwent levator advancement from 2 oculoplastic surgeons from September 2008 to December 2013. An analysis of upper lid contours was performed using front gaze photographs of the preoperative and postoperative states and comparing them to the front gazes of normal patients. Conventional and 12 oblique midpupil lid distances were measured every 15 degrees across the temporal (105, 120, 135, 150, 165, and 180 degrees) and nasal (75, 60, 45, 30, 15, and 0 degrees) fields of the eyelid fissure using custom software. RESULTS: Ptosis patients had low temporal eyelid height and significantly decreased MPLD at all angles compared with normal controls. Compared with the preoperative eyelid, all MPLD angles were significantly increased after surgery, and the temporal peak height of the eyelid was recovered. CONCLUSIONS: The normal shape and temporal peak height of eyelids should be considered for levator advancement surgery with ptosis. The authors retrospectively compared postoperative changes in eyelid contour to modify the method of surgery.

Analysis of Lid Contour in Thyroid Eye Disease With Upper and Lower Eyelid Retraction Using Multiple Radial Midpupil Lid Distances.

PURPOSE: The aim of this study was to analyze upper and lower eyelid contours in adult patients with thyroid eye disease (TED) and normal adults using a software program that measures multiple radial midpupil lid distance (MPLD). METHODS: Analysis targeted 61 eyes from 61 normal adults who had never undergone eyelid surgery or ophthalmic surgery and 63 eyes from 63 patients with TED. Digital pictures of primary gaze were analyzed using custom software. Conventional MPLD (90°, 270°) and 12 oblique MPLDs were collected every 15° across the temporal (105°, 120°, 135°, 150°, 165°, 180°) and nasal (75°, 60°, 45°, 30°, 15°, 0°) sectors of the upper eyelid. For lower eyelid contours, 9 oblique MLPDs in the temporal sector (255°, 240°, 225°, 210°, 195°) and nasal sector (285°, 300°, 315°, 330°) of the lower eyelid were analyzed. RESULTS: From all angles, the MPLD of patients with TED was larger than that of the control group. The mean difference between the 2 groups was larger for the upper eyelid (0° ∼ 180°) than the lower eyelid (195° ∼ 330°). When comparing symmetry by dividing into each angle, the ratio of 90°/270° (MRD1/MRD2) demonstrated greater in patients with TED (P = 0.000). Temporal/nasal eyelid contour symmetry in the upper eyelid, investigated using the distance ratio of the nasal sector/temporal sector (15°/165°, 30°/150°, 45°/135°, 60°/120°, 75°/105°), was significantly smaller in patients with TED (P < 0.05). However, there was no significant difference between the 2 groups regarding temporal/nasal eyelid contour symmetry of the lower eyelid (330°/210°, 315°/225°, 300°/240°, 285°/255°). CONCLUSIONS: Radial MPLD is effective for analyzing eyelid contour. In our study, lateral flare of upper lid retraction and flat appearance of lower lid retraction were distinct characteristics in patients with TED. Consideration of eyelid contour in patients with TED may improve corrective surgery for eyelid retraction.

Endoscopic Reconstruction of Isolated Orbital Floor Wall Fracture Considering Orbital Floor Slope.

PURPOSE: To present a surgical technique for the reconstruction of the orbital floor slope in patients of isolated orbital floor fracture and to evaluate the effectiveness of this technique. METHODS: The authors conducted a retrospective review of all patients who underwent reconstruction of isolated orbital floor wall fracture between June 2010 and July 2015. The authors reviewed patient demographics, degree of enophthalmos, ocular motility and diplopia test results, and surgical complications. RESULTS: This study included 33 eyes from 33 patients. The mean time interval from trauma to surgery was 24.9 days (range, 5-360 days). The average postoperative follow-up period was 7.4 months (range, 3-28 months). The degree of enophthalmos preoperatively and 1 week, 1 month, and 3 months postoperatively was -1.55 mm (range, -3 to -0.5 mm), 0.22 mm (range, -0.5 to +1.0 mm), -0.06 mm (range, -1.0 to +1.0 mm), and -0.13 mm (range, -0.5 to +0.5 mm), respectively. The mean improvement in enophthalmos at postoperative 3 months was 1.41 mm compared with that in the preoperative data (P value <0.001). There were no patients with residual enophthalmos greater than 1 mm after reconstruction. CONCLUSION: Endoscopic orbital floor slope reconstruction in isolated orbital floor wall fracture using a layered porous polyethylene barrier implant is a very useful surgical technique for safely identifying the posterior margin of a fracture and easily reconstructing the orbital floor slope. The demonstration of slight exophthalmos of the corrected side about 1 to 2 mm at the end of the operation was also necessary.

Secondary Reconstruction of Residual Enophthalmos Using an Endoscope and Considering the Orbital Floor and Medial Wall Slope.

PURPOSE: To present a transconjunctival and transcaruncular endoscopy approach involving layered porous polyethylene barrier implants to manage residual posttraumatic enophthalmos and to evaluate the effectiveness of this technique. METHODS: The authors performed a retrospective review of all patients who underwent secondary reconstruction of orbital wall fractures because of residual enophthalmos between June 2008 and July 2015. Patients' demographics, degree of enophthalmos, ocular motility, diplopia test results, and surgical complications were reviewed. RESULTS: This study included 16 eyes (4 right eyes and 12 left eyes) of 16 patients (14 males and 2 females). The mean time interval from trauma to surgery was 7.1 months (range, 1-18 months). The average postoperative follow-up period was 6.4 months (range, 3-18 months). The degree of enophthalmos preoperatively and at 1 week, 1 month, and 3 months postoperatively was -2.47 mm (range, -2 to -3 mm), 0.5 mm (range, -0.5 to +2.5 mm), -0.06 mm (range, -0.5 to +1.5 mm), and -0.44 mm (range, -1.5 to +1.0 mm), respectively. There were no definite surgical complications in any patients. CONCLUSION: Dissection to the posterior margin of the fracture and reconstruction of the orbital floor slope are the most important surgical factors to prevent residual enophthalmos and scarring with recurrent diplopia. Demonstration of slight exophthalmos of the corrected side of about 1 to 2 mm at the end of the operation is also necessary. The authors believe that surgery using an endoscope and layered porous polyethylene is very useful for secondary reconstruction.

Association of rhinostomy shape and surgical outcome after endoscopic endonasal dacryocystorhinostomy.

PURPOSE: The purpose of this study was to investigate surgical outcomes and complications after endoscopic endonasal dacryocystorhinostomy (EDCR) in relation to rhinostomy shape. METHODS: A retrospective electronic medical record review of patients who underwent EDCR for primary acquired nasolacrimal duct obstruction (PANDO) was performed. Surgical success rates and postoperative complications were compared among three groups of patients in relation to rhinostomy shape (alcove, cavern, or concealed cavern). RESULTS: A total of 280 patients (358 eyes) were included in the study. Of the 358 eyes, 194 rhinostomies were alcove-shaped, 157 were cavern-shaped, and 7 were concealed cavern-shaped. There were no patients with flat-shaped rhinostomies. The nasal cavity was wider in patients in the alcove group than those in the cavern and concealed cavern groups (p = 0.012). The mean time to tube removal was longest in the concealed cavern group (p = 0.029). There were no significant differences in anatomical success rates among the three groups (p = 0.338). With regard to functional success for patients with anatomically patent DCR, the cavern and concealed cavern groups had significantly poorer results than the alcove group (p = 0.001). Functional success rates were 91.6 %, 84.8 %, and 57.1 % for the alcove, cavern, and concealed cavern groups, respectively. Development of postoperative granuloma was more frequent in the concealed cavern group (85.7 %) than in the alcove (29.3 %) or cavern groups (26.1 %) (p= 0.003). Multiple logistic regression models for surgical outcome showed that rates of functional failure after EDCR were influenced by patient age and rhinostomy shape (odds ratio 1.824, p = 0.045 for age; odds ratio = 9.605, p = 0.000 for rhinostomy shape) (Table 5). CONCLUSIONS: The incidence rate of symptomatic epiphora after EDCR was approximately 12 %, and this result may have been associated with cavernous and concealed rhinostomy shapes. For patients with persistent epiphora and anatomically patent DCR, it is important to identify rhinostomy shape by endoscopy in order to differentiate causes of functional failure.

The Paradoxical Predominance of Medial Wall Injuries in Blowout Fracture.

PURPOSE: To evaluate the type and cause of orbital blowout fractures in Korea. DESIGN: Retrospective, observational case series. METHODS: Patients who underwent reconstruction for blowout fracture from March 2004 to April 2013 at Korea University Guro and Ansan Hospitals were included in this study. Patient demographics and orbital computed tomography (CT) scans were reviewed. On CT, ethmoid air cell septa, blowout fracture type, and other combined fractures were analyzed. Blowout fracture was classified as affecting up to 4 areas: the floor lateral to the infraorbital canal, the floor medial to the canal, the maxilla-ethmoidal strut ("inferomedial" strut), and the medial wall. Furthermore, trauma type and associated injury were reviewed. The results of adolescent patients and adult patients were compared, as were those of males and females. RESULTS: The study included 659 eyes of 659 patients; mean patient age was 31.01 ±â€Š14.27 years. In total, 513 (77.85%) patients were male and 146 (22.15%) were female. The most common blowout fracture type was medial wall fracture, followed by floor wall, floor and medial wall without inferomedial strut, and floor and medial wall fracture with inferomedial strut, in that order. Interestingly, patients with floor wall blowout fracture were younger (26.87 ±â€Š12.90 y) than other groups: medial wall fracture (32.35 ±â€Š14.64 y, P < 0.0001), floor and medial wall fracture (35.22 ±â€Š14.49 y, P < 0.0001), and floor and medial wall fracture involving the maxillaethmoidal strut (32.62 ±â€Š13.75 y, P = 0.002). The number of ethmoidal air cell septa was lowest in the medial wall fracture group (3.62 ±â€Š0.67): floor wall fracture (4.07 ±â€Š0.69, P < 0.0001), floor and medial wall fracture (3.90 ±â€Š0.78, P < 0.0001), and floor and medial wall fracture involving the maxilla-ethmoidal strut (4.05 ±â€Š0.72, P = 0.001). CONCLUSIONS: Our study demonstrated that the blowout fracture type distribution in Korea varied from the results of many other studies. Medial wall fracture is the most common among the 4 types, and anatomic variance, such as number of ethmoid air cell septa, could influence blowout fracture type, especially in medial wall fracture.

Effectiveness of Synthetic Polyurethane Foam as a Nasal Packing Material in Endoscopic Endonasal Dacryocystorhinostomy.

PURPOSE: To compare the effects of 2 nasal packing materials, synthetic polyurethane foam (absorbable) and expandable polyvinyl acetate (nonabsorbable), on the surgical success rate and postoperative complications after endoscopic endonasal dacryocystorhinostomy (EDCR). METHODS: A retrospective medical review of 459 patients (580 eyes) who underwent EDCR for primary acquired nasolacrimal duct obstruction at Korea University Guro Hospitals from January 2009 to February 2014. Surgical success rate (anatomical, functional), postoperative complications (granuloma, synechia, bleeding, and infection) were compared between the 2 groups, absorbable (318 eyes) and nonabsorbable (262 eyes). RESULTS: The absorbable group showed better results in surgical success rate regarding anatomical (90.5% versus 76.3%, P = 0.00) and functional (89.3% versus 75.9%, P = 0.00). Granulomas developed less frequently in the absorbable group (24.5% versus 38.9%, P = 0.00). Also, bleeding and crust were less frequent in the absorbable group (P = 0.00). Infections were less frequent in the nonabsorbable group (1.52%) compared with the absorbable group (7.86%, P = 0.00). The rate of revision surgery was lower in the absorbable group (7.86% versus 20.9%, P = 0.00). As for the influence of secondary outcomes to the surgical success by multiple logistic regression, granulomas had the largest effect on surgical success either anatomical or functional (odds ratio = 82.393 to anatomical and 44.058 to functional). Synechia had the second largest effect on surgical success (odds ratio = 11.897 to anatomical and 9.605 to functional). CONCLUSIONS: The authors suggest that using a synthetic polyurethane foam as a nasal packing material is not only a surgical option, but also a crucial and essential procedure in EDCR.

Epidemiology of Oculoplastic and Reconstructive Surgeries Performed by a Single Specialist With 15 Years' Experience at a Tertiary Center.

PURPOSE: To evaluate the prevalence of oculoplastic surgeries performed in a tertiary hospital in South Korea and to highlight the proper choice of surgery according to disease. METHOD: Retrospective chart review was conducted over a 12-month period (March 2013 to February 2014) on all of the patients who underwent oculoplastic and reconstructive surgery by a single oculoplastic specialist with 15 years' experience. RESULTS: A total of 656 patients were enrolled in the current study. Of them, 355 patients (54.1%) had eyelid surgery, 151 patients (23.0%) had orbital surgery, and 150 patients (22.8%) had lacrimal surgery. Orbital surgery was more commonly performed in men (122 male patients versus 29 female patients, P = 0.00 by Pearson chi-squared test) and was also more common in younger patients than in other surgery groups (56.3 years in eyelid surgery versus 39.3 years in orbital surgery versus 46.9 years in lacrimal surgery, P = 0.001 by Pearson chi-squared test). Blepharoplasty was the most common eyelid surgery, contributing 24.2% of total eyelid surgeries, followed by lid mass excision (68 patients, 19.1%), Hotz operation (59 patients, 16.6%), and levator advancement (47 patients, 13.2%). Among orbital surgeries, reconstruction of orbital wall fractures was the most common, and was performed in 89 patients (58.9%) of total orbital surgeries, followed by orbital tumor debulking surgery (25 patients, 16.5%) and orbital decompression for dysthyroid optic neuropathy (19 patients, 12.5%). Endoscopic endonasal dacryocystorhinostomy (DCR) was the most common lacrimal surgery (84 patients), occurring in 56% of total lacrimal surgeries, followed by Monoka tube intubation (16 patients, 10.6%) for congenital nasolacrimal duct obstruction and conjunctivo-DCR using Jones tube (12 patients, 8%). CONCLUSIONS: Eyelid-related conditions, especially cosmetic blepharoplasty, were among the most commonly encountered surgeries in the Oculoplastics Department of a tertiary care hospital in South Korea. Blowout fracture repair and endoscopic DCR were the most common in orbital and lacrimal surgery. The authors hope that the current survey will contribute to the surgical training of ophthalmology residents and, on a larger scale, health care policies.

Postoperative pain assessment for upper lid blepharoplasty in Asians.

This study was undertaken to investigate the pain intensity, time to peak of pain, bruise, swelling, itching, life limitation, blurred vision, and duration of pain after upper lid blepharoplasty using a survey of pain scale, and to provide objective evidence to aid in education and preoperative counseling of our patients. After upper lid blepharoplasty under local anesthesia, patients were asked to rate their pain on a standardized 11-point pain scale (0-10). After pain assessment of the immediate postoperative period, the evaluation was repeated after 2 to 4 hours, 24 hours, 2 days, 3 days, 7 days, and 1 month. Time to peak of pain, bruise, swelling, itching, life limitation, and blurred vision after surgery were investigated. A total of 60 eyelids (30 patients) were included. Average pain score during the immediate postoperative period was 3.5 in males and 2.2 in females. Pain measurement was maintained up to 7 days after surgery. A significant difference in these pain scores according to gender was observed during the immediate postoperative period and up to 24 hours after surgery. Time to peak after upper lid blepharoplasty was as follows: pain 4.4 hours; swelling 17.3 hours; bruise 33.6 hours; itching 21.1 hours; limitation of life 16.6 hours; and blurred vision 8.7 hours. Most severe pain was observed during the immediate postoperative period and up to 2 to 4 hours after surgery. Pain after upper lid blepharoplasty was mostly mild to moderate and did not exceed a score of 4, which would require reevaluation, and could remain persistent for up to 7 days after surgery. Specific pain-targeted assessment and treatment based on these results are warranted.

Ultrawideband electromagnetic metamaterial absorber utilizing coherent absorptions and surface plasmon polaritons based on double layer carbon metapatterns.

An ultrawideband electromagnetic metamaterial absorber is proposed that consists of double-layer metapatterns optimally designed by the genetic algorithm and printed using carbon paste. By setting the sheet resistance of the intermediate carbon metapattern to a half of that of the top one, it is possible to find an optimal intermediate metapattern that reflects and absorbs the EM wave simultaneously. By adding an absorption resonance via a constructive interference at the top metapattern induced by the reflection from the intermediate one, an ultrawideband absorption can be achieved without increasing the number of layers. Moreover, it is found that the metapatterns support the surface plasmon polaritons which can supply an additional absorption resonance as well as boost the absorption in a broad bandwidth. Based on the simulation, the [Formula: see text] absorption bandwidth is confirmed from 6.3 to 30.1 GHz of which the fractional bandwidth is 130.77[Formula: see text] for the normal incidence. The accuracy is verified via measurements well matched with the simulations. The proposed metamaterial absorber could not only break though the conventional concept that the number of layers should be increased to extend the bandwidth but also provide a powerful solution to realize a low-profile, lightweight, and low cost electromagnetic absorber.

A New Class of Carbon Nanostructures for High-Performance Electro-Magnetic and -Chemical Barriers.

It is of importance to explore a new carbon nanomaterial possessing vital functions to fulfill the high standards for practical achievement of the electromagnetic (EM) barrier for blocking EM waves and the electrochemical (EC) barrier as a functional separator for EC energy storage. Herein, facile synthesis of a new class of carbon nanostructures, which consist of interconnected N-doped graphitic carbon nanocubes partially embedded by nickel nanoparticles, is described. The hollow interior of graphitic nanocube induces internal reflection of EM waves and confines active materials of EC energy storage. Nitrogen functionalities implanted in graphitic structure enhance electrical conductivity as well as improve chemical interaction with active materials. Furthermore, nickel nanoparticles in graphitic nanocube function as an EM wave-absorbing material and an electrocatalyst for EC energy storage. Through comprehensive assessments, remarkable performances originating from distinctive nanostructures give new insights into structural design for the carbon nanostructure-based high-performance EM and EC barriers.

High-throughput thermal plasma synthesis of FexCo1-x nano-chained particles with unusually high permeability and their electromagnetic wave absorption properties at high frequency (1-26 GHz).

Herein, we introduce novel 1-dimensional nano-chained FeCo particles with unusually-high permeability prepared by a highly-productive thermal plasma synthesis and demonstrate an electromagnetic wave absorber with exceptionally low reflection loss in the high-frequency regime (1-26 GHz). During the thermal plasma synthesis, spherical FeCo nanoparticles are first formed through the nucleation and growth processes; then, the high temperature zone of the thermal plasma accelerates the diffusion of constituent elements, leading to surface-consolidation between the particles at the moment of collision, and 1-dimensional nano-chained particles are successfully fabricated without the need for templates or a complex directional growth process. Systematic control over the composition and magnetic properties of FexCo1-x nano-chained particles also has been accomplished by changing the mixing ratio of the Fe-to-Co precursors, i.e. from 7 : 3 to 3 : 7, leading to a remarkably high saturation magnetization of 151-227 emu g-1. In addition, a precisely-controlled and uniform surface SiO2 coating on the FeCo nano-chained particles was found to effectively modulate complex permittivity. Consequently, a composite electromagnetic wave absorber comprising Fe0.6Co0.4 nano-chained particles with 2.00 nm-thick SiO2 surface insulation exhibits dramatically intensified permeability, thereby improving electromagnetic absorption performance with the lowest reflection loss of -43.49 dB and -10 dB (90% absorbance) bandwidth of 9.28 GHz, with a minimum thickness of 0.85 mm.

Synthesis of high quality 2D carbide MXene flakes using a highly purified MAX precursor for ink applications.

The practical application of 2D MXenes in electronic and energy fields has been hindered by the severe variation in the quality of MXene products depending on the parent MAX phases, manufacturing techniques, and preparation parameters. In particular, their synthesis has been impeded by the lack of studies reporting the synthesis of high-quality parent MAX phases. In addition, controllable and uniform deposition of 2D MXenes on various large-scale substrates is urgently required to use them practically. Herein, a method of pelletizing raw materials could synthesize a stoichiometric Ti3AlC2 MAX phase with high yield and processability, and fewer impurities. The Ti3AlC2 could be exfoliated into 1-2-atom-thick 2D Ti3C2T x flakes, and their applicability was confirmed by the deposition and additional alignment of the 2D flakes with tunable thickness and electrical properties. Moreover, a practical MXene ink was fabricated with rheological characterization. MXene ink exhibited much better thickness uniformity while retaining excellent electrical performances (e.g., sheet resistance, electromagnetic interference shielding ability) as those of a film produced by vacuum filtration. The direct functional integration of MXenes on various substrates is expected to initiate new and unexpected MXene-based applications.

EMI Shielding of the Hydrophobic, Flexible, Lightweight Carbonless Nano-Plate Composites.

The cost-effective spray coated composite was successfully synthesis and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction techniques. The one step synthetic strategy was used for the synthesis of nanoplates that have a crystalline nature. The composites are amorphous and hydrophobic with micron thickness (<400 m). The maximum contact angle showed by composite is 132.65° and have wetting energy of -49.32 mN m-1, spreading coefficient -122.12 mN m-1, and work of adhesion 23.48 mN m-1. The minimum thickness of synthesized nanoplate is 3 nm while the maximum sheet resistance, resistivity, and electrical conductivity of the composites are 11.890 ohm sq-1, 0.4399 Ω.cm-1, and 8.967 S.cm-1, respectively. The cobalt nanoplate coated non-woven carbon fabric (CoFC) possesses excellent sheet resistance, hydrophobic nature, and EMI shielding efficiency of 99.99964%. The composite can block above 99.9913% of incident radiation (X band). Hence, the composite can be utilized in application areas such as medical clothes, mobile phones, automobiles, aerospace, and military equipment.

Fabrication of Flexible, Lightweight, Magnetic Mushroom Gills and Coral-Like MXene⁻Carbon Nanotube Nanocomposites for EMI Shielding Application.

MXenes, carbon nanotubes, and nanoparticles are attractive candidates for electromagnetic interference (EMI) shielding. The composites were prepared through a filtration technique and spray coating process. The functionalization of non-woven carbon fabric is an attractive strategy. The prepared composite was characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and Raman spectroscopy. The MXene-oxidized carbon nanotube-sodium dodecyl sulfate composite (MXCS) exhibited 50.5 dB (99.999%), and the whole nanoparticle-based composite blocked 99.99% of the electromagnetic radiation. The functionalization increased the shielding by 15.4%. The composite possessed good thermal stability, and the maximum electric conductivity achieved was 12.5 Scm-1. Thus, the composite shows excellent potential applications towards the areas such as aeronautics, mobile phones, radars, and military.

Controlled Grafting of Colloidal Nanoparticles on Graphene through Tailored Electrostatic Interaction.

Nanoparticle/graphene hybrid composites have been of great interest in various disciplines due to their unique synergistic physicochemical properties. In this study, we report a facile and generalized synthesis method for preparing nanoparticle/exfoliated graphene (EG) composites by tailored electrostatic interactions. EG was synthesized by an electrochemical method, which produced selectively oxidized graphene sheets at the edges and grain boundaries. These EG sheets were further conjugated with polyethyleneimine to provide positive charges at the edges. The primary organic ligands of the colloidal nanoparticles were exchanged with Cl- or MoS42- anions, generating negatively charged colloidal nanoparticles in polar solvents. By simple electrostatic interactions between the EG and nanoparticles in a solution, nanoparticles were controllably assembled at the edges of the EG. Furthermore, the generality of this process was verified for a wide range of nanoparticles, such as semiconductors, metals, and magnets, on the EG. As a model application, designed composites with size-controlled FeCo nanoparticle/EG were utilized as electromagnetic interference countermeasure materials that showed a size-dependent shift of the frequency ranges on the electromagnetic absorption properties. The current generalized process will offer great potential for the large-scale production of well-designed graphene nanocomposites for electronic and energy applications.