Surface modification of polypropylene hollow fiber membranes using fluorosilane for CO2 absorption in a gas-liquid membrane contactor.

Conventional methods for improving the hydrophobicity of polypropylene (PP) membranes to prevent wetting phenomena require complex pretreatment procedures in order to activate the surface for enabling the reaction with fluorosilane (FS)-based materials. This study successfully prepared PP membrane contactors with enhanced hydrophobicity through a simple single-step dip-coating method using perfluoroether-grafted silanes for CO2 capture. The FS coating layer on the PP membrane surface was confirmed through ATR-FTIR spectroscopy, XPS, FE-SEM, and EDS. Furthermore, the evaluation of the CO2 absorption performance and long-term stability of the FS-coated PP membrane according to the variation of the gas flow rate (50, 100, 200, 400, and 800 mL/min) confirmed the superior chemical stability and durability of our membranes to those of previously reported hydrophobic membranes. The as-prepared FS-coated PP membrane expands the application scope of gas-liquid membrane contactors for CO2 capture from the flue gas of coal-fired power plants.

Non-thermal plasma coupled with a wet scrubber for removing odorous VOC.

Odorous volatile organic compounds (VOCs) deteriorate the quality of life and affect human health. In this study, a process was developed to remove an odorous VOC using a combined non-thermal plasma (NTP) and wet scrubber (WS) system. The low removal efficiency of WSs and the large amount of ozone generated by NTP were resolved. Compared to the decomposition effects when using a WS and NTP separately, the NTP + WS system improved the removal efficiency of ethyl acrylate (EA) and significantly reduced ozone emissions. The maximum EA removal efficiency was 99.9%. Additionally, an EA removal efficiency of over 53.4% and a 100% ozone removal efficiency were achieved even at discharge voltages lower than 4.5 kV. Ozone catalysis was confirmed to occur in the NTP + WS system. Furthermore, we verified the removal of by-products such as residual ozone and formaldehyde, which is a representative organic intermediate of EA. This study demonstrates that the NTP + WS system is a green technology for removing odorous VOCs.

Laser-assisted failure recovery for dielectric elastomer actuators in aerial robots.

Insects maintain remarkable agility after incurring severe injuries or wounds. Although robots driven by rigid actuators have demonstrated agile locomotion and manipulation, most of them lack animal-like robustness against unexpected damage. Dielectric elastomer actuators (DEAs) are a class of muscle-like soft transducers that have enabled nimble aerial, terrestrial, and aquatic robotic locomotion comparable to that of rigid actuators. However, unlike muscles, DEAs suffer local dielectric breakdowns that often cause global device failure. These local defects severely limit DEA performance, lifetime, and size scalability. We developed DEAs that can endure more than 100 punctures while maintaining high bandwidth (>400 hertz) and power density (>700 watt per kilogram)-sufficient for supporting energetically expensive locomotion such as flight. We fabricated electroluminescent DEAs for visualizing electrode connectivity under actuator damage. When the DEA suffered severe dielectric breakdowns that caused device failure, we demonstrated a laser-assisted repair method for isolating the critical defects and recovering performance. These results culminate in an aerial robot that can endure critical actuator and wing damage while maintaining similar accuracy in hovering flight. Our work highlights that soft robotic systems can embody animal-like agility and resilience-a critical biomimetic capability for future robots to interact with challenging environments.

Multilevel Anti-Counterfeiting Based on Covert Structural Features Embedded in Femtosecond-Laser-Treated Gold Nanocluster/Graphene Hybrid Layer.

The conventional nanoscale anti-counterfeiting scheme, exhibiting limited encoding capacity, faces growing challenges of being falsified with the advent of advanced high-resolution equipment. In this study, we propose a multilevel anti-counterfeiting device based on a femtosecond laser (fs-laser) treated plasmonic gold nanocluster/graphene (AuNC/Gr) hybrid structure integrated with a resonant cavity. The covert structural features encoded in random colored patterns, optical reflection spectra, and Raman spectra constitute three classes of anti-counterfeiting signatures, which originate from the AuNC-covered Gr, which initiates plasmonic and thermal couplings. The attendant inverted thermal distribution is presumed to confine the structural features to the AuNC-Gr interface while leaving no detectable traces on the surface of AuNC/Gr even under advanced high-resolution equipment. Therefore, the proposed approach achieves multilevel anti-counterfeiting accomplishing physically unclonable functions in the form of random colored patterns, reflection spectra, and Raman spectra. As the first report for realizing remarkable optical modulation (i.e., random colored patterns) without any surface trace or damage via fs-laser-AuNC/Gr interaction, our study also discloses the outstanding performance of Gr in fs-laser-induced optothermoplasmonic lithography on near-percolation metal films. Simultaneously, the demonstrated fs-laser-processed plasmonic hybrid structure in conjunction with a resonant cavity is anticipated to expand the encoding capabilities for nanoscale anti-counterfeiting while avoiding the risk of being imitated because of the covert structural features.

A High-Lift Micro-Aerial-Robot Powered by Low-Voltage and Long-Endurance Dielectric Elastomer Actuators.

Dielectric elastomer actuators (DEAs) are a special class of artificial muscles that have been used to construct animal-like soft robotic systems. However, compared with state-of-the-art rigid actuators such as piezoelectric bimorphs and electromagnetic motors, most DEAs require higher driving voltages, and their power density and lifetime remain substantially lower. These limitations pose significant challenges for developing agile and powered autonomous soft robots. Here, a low-voltage, high-endurance, and power-dense DEA based on novel multiple-layering techniques and electrode-material optimization, is reported. When operated at 400 Hz, the 143 mg DEA generates forces of 0.36 N and displacements of 1.15 mm. This DEA is incorporated into an aerial robot to demonstrate high performance. The robot achieves a high lift-to-weight ratio of 3.7, a low hovering voltage of 500 V, and a long lifetime that exceeds 2 million actuation cycles. With 20 s of hovering time, and position and attitude error smaller than 2.5 cm and 2°, respectively, the robot demonstrates the longest and best-performing flight among existing sub-gram aerial robots. This important milestone demonstrates that soft robots can outperform their state-of-the-art rigid counterparts, and it provides an important step toward realizing power autonomy in soft robotic flights.

Trap-Assisted Charge Injection into Large Bandgap Polymer Semiconductors.

The trap-assisted charge injection in polyfluorene-poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) model systems with an Al or Al/LiF cathode is investigated. We find that inserting 1.3 nm LiF increases electron and hole injections simultaneously and the increase of holes is greater than electrons. The evolution of internal interfaces within polymer light-emitting diodes is observed by transmission electron microscopy, which reveals that the introduction of LiF improves the interface stability at both the cathode (cathode/polymer) and the anode (indium tin oxide (ITO)/PEDOT:PSS). Above-mentioned experimental results have been compared to the numerical simulations with a revised Davids model and potential physical mechanisms for the trap-assisted charge injection are discussed.

Modeling methane production in anaerobic forward osmosis bioreactor using a modified anaerobic digestion model No. 1.

Anaerobic membrane bioreactor (AnMBR) using microfiltration (MF) or ultrafiltration (UF) membranes was introduced to enhance poor biomass retention of conventional anaerobic digestion (CAD). Recently, forward osmosis (FO) membrane have been applied to AnMBR, which is called AnFOMBR. FO membrane assures not only high biomass retention but also high removal efficiency for low molecular weight (LMW) matters. Methane production rates in CAD, AnMBR, and AnFOMBR were compared using a modified IWA anaerobic digestion model No. 1 (ADM1) in this work. Accumulation of biomass in AnMBR/AnFOMBR results in enhanced biochemical reaction and gains more methane production. AnFOMBR may experience a significant inhibition by accumulated free ammonia and cations, although concentrated soluble substrates rejected by FO membrane are favorable for more methane production. Rejection rate of inorganic nitrogen is a key parameter to determine the inhibition in methane production of AnFOMBR.

Aqueous Boron Removal by Using Electrospun Poly(vinyl alcohol) (PVA) Mats: A Combined Study of IR/Raman Spectroscopy and Computational Chemistry.

We report the use of a novel and efficient method to remove aqueous boron by using electrospun, water-resistant poly(vinyl alcohol) (PVA) mats stabilized in methanol. The removal of the primary aqueous boron species as (B(OH)3), was accomplished by chemical adsorption in reactions with -OH (hydroxyl) groups on the PVA mat surface. The chemical adsorption of B(OH)3 was qualitatively confirmed by the analysis of IR and Raman spectra. The bands, corresponding to the molecular vibration modes of chemically bonded boron in PVA, were identified by using the frequency calculation from the computational chemistry for the first time. The adsorption capacities of PVA mats for aqueous boron were then quantitated at a low boron concentration (range: 0.0010 to 0.0025 g of aqueous boron per g of PVA mats) by the Carmine method. The PVA mats were prepared by a well-established electrospinning technique, which make these substrates promising potential candidates for use as boron-selective sorbent media in applications such as reverse osmosis desalination processes.

Effect of transcranial direct current stimulation on visual perception function and performance capability of activities of daily living in stroke patients.

[Purpose] The purpose of this study was to examine the effects of transcranial direct current stimulation (tDCS) on visual perception and performance of activities of daily living in patients with stroke. [Subjects and Methods] Thirty subjects were assigned equally to a tDCS plus traditional occupational therapy group (experimental group) and a traditional occupational therapy group (control group). The intervention was implemented five times per week, 30 minutes each, for six weeks. In order to assess visual perception function before and after the intervention, the motor-free visual perception test (MVPT) was conducted, and in order to compare the performance of activities of daily living, the Functional Independence Measure scale was employed. [Results] According to the results, both groups improved in visual perception function and in performance of activities of daily living. Although there was no significant difference between the two groups, the experimental group exhibited higher scores. [Conclusion] In conclusion, the application of tDCS for the rehabilitation of patients with stroke may positively affect their visual perception and ability to perform activities of daily living.

Evaluation of Humic Acid and Tannic Acid Fouling in Graphene Oxide-Coated Ultrafiltration Membranes.

Three commercially available ultrafiltration (UF) membranes (poly(ether sulfone), PES) that have nominal molecular weight cut-offs (5, 10, and 30 kDa) were coated with graphene oxide (GO) nanosheets. Field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, confocal laser scanning microscopy, water contact angle measurements, and X-ray photoelectron spectroscopy were employed to determine the changed physicochemical properties of the membranes after GO coating. The water permeability and single-solute rejection of GO-coated (GOC) membranes for humic acid (HA) molecules were significantly higher by approximately 15% and 55%, respectively, compared to those of pristine UF membranes. However, the GOc membranes for single-solute tannic acid (TA) rejection showed similar trends of higher flux decline versus pristine PES membranes, because the relatively smaller TA molecules were readily adsorbed onto the membrane pores. When the mixed-solute of HA and TA rejection tests were performed, in particular, the adsorbed small TA molecules resulted in irreversible membrane fouling due to cake formation and membrane pore blocking on the membrane surface for the HA molecules. Although both membranes showed significantly higher flux declines for small molecules rejection, the GOc membranes showed better performance than the pristine UF membranes in terms of the rejection of various mixed-solute molecules, due to higher membrane recovery and antifouling capabilities.

Graphene as an Interfacial Layer for Improving Cycling Performance of Si Nanowires in Lithium-Ion Batteries.

Managing interfacial instability is crucial for enhancing cyclability in lithium-ion batteries (LIBs), yet little attention has been devoted to this issue until recently. Here, we introduce graphene as an interfacial layer between the current collector and the anode composed of Si nanowires (SiNWs) to improve the cycling capability of LIBs. The atomically thin graphene lessened the stress accumulated by volumetric mismatch and inhibited interfacial reactions that would accelerate the fatigue of Si anodes. By simply incorporating graphene at the interface, we demonstrated significantly enhanced cycling stability for SiNW-based LIB anodes, with retentions of more than 2400 mAh/g specific charge capacity over 200 cycles, 2.7 times that of SiNWs on a bare current collector.

Modeling full-scale osmotic membrane bioreactor systems with high sludge retention and low salt concentration factor for wastewater reclamation.

A full-scale model was developed to find optimal design parameters for osmotic membrane bioreactor (OMBR) and reverse osmosis (RO) hybrid system for wastewater reclamation. The model simulates salt accumulation, draw solution dilution and water flux in OMBR with sludge concentrator for high retention and low salt concentration factor. The full-scale OMBR simulation results reveal that flat-sheet module with spacers exhibits slightly higher flux than hollow-fiber; forward osmosis (FO) membrane with high water permeability, low salt permeability, and low resistance to salt diffusion shows high water flux; an optimal water recovery around 50% ensures high flux and no adverse effect on microbial activity; and FO membrane cost decreases and RO energy consumption and product water concentration increases at higher DS flow rates and concentrations. The simulated FO water flux and RO energy consumption ranges from 3.03 to 13.76LMH and 0.35 to 1.39kWh/m(3), respectively.

Efficacy of 5% imiquimod cream on vulvar intraepithelial neoplasia in Korea: pilot study.

BACKGROUND: Various therapeutic options, including surgery, electrocautery, cryotherapy, 5-fluorouracil treatment, laser therapy, radiotherapy, photodynamic therapy, and interferon-α/γ injection, have been employed to treat vulvar intraepithelial neoplasia (VIN) with varying degrees of success. To truly cure VIN, human papillomavirus elimination is considered important. OBJECTIVE: To investigate the efficacy of 5% imiquimod cream used to treat VIN in Korean patients. METHODS: We performed a prospective, uncontrolled, observational study. Nine patients with histologically confirmed VIN applied 5% imiquimod cream to their vulvar lesions three to five times a week until a clinical response was apparent. All lesions were photo-documented, and therapeutic efficacy was assessed in terms of local adverse effects lesion number, size, and hyperpigmentation. RESULTS: The mean treatment duration was 30.2 months, and the median follow-up period after therapy completion was 30 months. Of the nine patients recruited, six (66.6%) experienced complete responses (CR) or partial responses (PR). Hyperpigmented patches in the VIN lesions were evident in five subjects (55.6%), and all experienced either CR or PR. Only three patients (33.3%) suffered from local adverse effects, which were relieved after temporary suspension of therapy, and better outcomes were attained ultimately. CONCLUSION: The imiquimod cream was more efficacious when used to treat VIN of the hyperpigmented type compared with lesions lacking pigmentation. The unifocal nature of a lesion and the development of local adverse effects are useful factors when imiquimod cream is prescribed. However, although the cream is convenient and effective, regional resistance may develop, and close follow-up is essential because VIN may become malignant.

Scale-up of osmotic membrane bioreactors by modeling salt accumulation and draw solution dilution using hollow-fiber membrane characteristics and operation conditions.

A full-scale osmotic membrane bioreactor (OMBR) model was developed to simulate salt accumulation, draw solution (DS) dilution, and water flux over the hollow-fiber membrane length. The model uses the OMBR design parameters, DS properties, and forward osmosis (FO) membrane characteristics obtained from lab-scale tests. The modeling results revealed a tremendous water flux decline (10→0.82LMH) and short solids retention time (SRT: 5days) due to salt accumulation and DS dilution when OMBR is scaled up using commercially available DS and FO membrane. Simulated water flux is a result of interplay among reverse salt flux, internal and external concentration polarization (ICP and ECP). ECP adversely impacts water flux considerably in full-scale OMBR although it is often ignored in previous works. The OMBR model makes it possible to select better DS properties (higher flow rate and salt concentration) and FO membranes with higher water flux propensity in full-scale operation.

Simultaneous occurrence of papulonecrotic tuberculid and erythema induratum in a patient with pulmonary tuberculosis.

Although papulonecrotic tuberculid is an uncommon cutaneous manifestation of tuberculosis (TB) associated with Mycobacterium tuberculosis infection, the simultaneous occurrence of papulonecrotic tuberculid and erythema induratum is even rarer. Papulonecrotic tuberculid occurs predominantly in young adults and is characterized by eruptions of necrotizing papules that heal with varioliform scars. Histopathologic findings include wedge-shaped necrosis of the dermis, poorly formed granulomatous infiltration, and vasculitis. Stainings and culture for acid-fast bacilli from skin biopsies are usually negative for M. tuberculosis, although the eruptions resolve with antitubercular therapy. Few patients with papulonecrotic tuberculid, especially with concurrent occurrence of erythema induratum, have been reported in the English literature. Here we report a case of a 12-year-old girl with simultaneous occurrence of papulonecrotic tuberculid and erythema induratum accompanying pulmonary TB.

Colorimetric and resistive polymer electrolyte thin films for real-time humidity sensors.

We have developed fast responsive, colorimetric and resistive-type polymeric humidity sensors from a series of self-assembled poly(styrenesulfonate-methylbutylene) (PSS-b-PMB) block copolymers with tailored hygroscopic properties. In dry state, the PSS-b-PMB films exhibit hexagonal cylindrical morphology where hydrophobic PMB cylinders are dispersed within a PSS matrix. Under levels of humidity, the PSS-b-PMB thin films self-displayed discernible reflective color changes, covering almost entire visible light regions from violet (RH = 20%) to red (RH = 95%). The sensors also revealed a few orders of magnitude changes in impedance with exposure to humid air by taking advantages of strong polymer electrolytes characteristics. Remarkably, the time to complete the changes in the signals was only a few seconds, as rationalized by good connectivity of the PSS domains and short water diffusion pathways in nanometer scales. Repeated hydration/dehydration tests demonstrated reliable sensor properties, which is in sharp contrast to the poor stability of PSS homopolymer sensors lacking organization.

Analysis of cardiovascular risk factors and metabolic syndrome in korean patients with psoriasis.

BACKGROUND: In previous studies, psoriasis has been reported to be associated with metabolic syndrome. OBJECTIVE: The purpose of this study was to evaluate risk factors for metabolic syndrome in psoriasis patients and to compare the prevalence of metabolic syndrome in psoriasis and control groups. METHODS: All patients (n=490) and controls (n=682) were investigated for cardiovascular risk factors, including central obesity, hypertension, fasting plasma glucose levels, and blood levels of triglycerides and high-density lipoprotein (HDL). RESULTS: We found no statistical association between psoriasis and the prevalence of metabolic syndrome when controlling for age and gender. Among individual components of metabolic syndrome, only increased triglyceride levels was significantly prevalent in patients psoriasis. The incidence of other factors such as central obesity, hypertension, fasting plasma glucose and HDL in the psoriasis group were similar to or lower than those in the control group. Although psoriasis patients with metabolic syndrome had severe and large plaque-type psoriasis, the association of metabolic syndrome with the severity or clinical subtype of psoriasis was not significant after adjusting for age and gender. CONCLUSION: Our results suggest that there is no close correlation between psoriasis and metabolic syndrome in Korean patients.

Delayed diagnosis of scrofuloderma misdiagnosed as a bacterial abscess.

An 82-year-old woman presented with a four-month history of an ulcerative plaque overlying her left neck. This lesion had developed as a subcutaneous nodule, gradually increased in size, and evolved into ulcers. Before visiting our Dermatology clinic, the patient had been diagnosed as having a bacterial abscess, but treatments with antibiotics were unsuccessful. The presence of a purulent discharge and prominent ulceration caused further confusion as bacterial abscess, and radiologic evaluation on computed tomography also led to the possibilities of secondary lesions from an abscess or malignancy. However, the characteristic appearance of her lesion allowed us to discern cutaneous tuberculosis, especially scrofuloderma. Based on clinical examinations, staining for acid-fast bacilli, and positive findings of polymerase chain reaction, a quick diagnosis of scrofuloderma was made. After that, she was treated successfully with anti-tuberculosis therapy and the ulcer healed. Our case highlights the problem of delayed diagnosis of scrofuloderma presenting as a bacterial abscess. In conclusion, having a high index of suspicion is needed to diagnose cutaneous tuberculosis correctly.

Lichen striatus occurring after allogenic peripheral blood stem cell transplantation in an adult with aplastic anemia.

Lichens striatus (LS) is an acquired, self-limiting inflammatory dermatosis that follows the lines of Blaschko. The etiology of the eruption is unknown, but several theories have been proposed with focus on environmental factors, viral infection, cutaneous injury, hypersensitivity, and genetic predisposition. We describe a 19-year-old woman who developed a unilateral linear eruption 17 months after allogenic peripheral blood stem cell transplantation. Histopathology revealed features, which were consistent with LS. To the best of our knowledge, our patient is the first case describing the appearance of LS occurring after allogenic stem cell transplantation. We speculate that this condition represents an unusual form of localized, chronic graft-versus-host disease.

Topical tacrolimus ointment for the treatment of lichen sclerosus, comparing genital and extragenital involvement.

Lichen sclerosus is a chronic inflammatory dermatosis presenting with significant sclerosis, atrophy and pruritus. The treatment for this condition remains unsatisfactory, with potent corticosteroids being the most effective therapy. In this study, we investigated the efficacy and safety of tacrolimus ointment in patients with genital and extragenital lichen sclerosus. Sixteen patients with active lichen sclerosus (10 with anogenital and six with extragenital localization) were treated with topical tacrolimus ointment twice daily. The therapeutic effects were evaluated according to 3 grades: complete response (>75% improvement), partial response (25-75% improvement), or no response (<25% improvement). Applications were continued until complete disappearance or stabilization of the cutaneous lesions. In addition, we conducted telephone surveys to determine the long-term treatment outcome and relapse rate. Objective response to therapy occurred in nine of 10 patients (90%) with anogenital and one of six patients (16.7%) with extragenital lesions. Out of 10 patients with anogenital lichen sclerosus, five showed more than 75% improvement. Complete, partial and no response were achieved in five (50%), four (40%) and one (10%) patient, respectively. During the follow-up period of a mean of 29.3 months, six of nine patients had a relapse of symptoms. However, most patients with extragenital involvement did not respond to tacrolimus, except one patient showing partial response. No significant adverse effects were observed. Topical tacrolimus ointment was a safe and effective treatment for genital lichen sclerosus and should be used for long-term duration to prevent relapse. However, it was not useful for patients with extragenital lichen sclerosus.