Verapamil-containing silicone gel reduces scar hypertrophy.

A hypertrophic scar is a common dermal fibroproliferative lesion usually treated with topical silicone. Verapamil, a type of calcium channel blocker, is considered a candidate drug for the treatment of hypertrophic scars. Here, we report that the addition of verapamil to topical silicone gel enhances treatment outcomes of hypertrophic scars. Upon creation of hypertrophic scars with the rabbit ear model, varying concentrations of verapamil-added silicone gel (0.1, 1, and 10 mg/g) were applied daily for 28 days. After the animals were euthanised, microscopic measurement was performed for (a) scar elevation index (SEI), (b) fibroblast count, and (c) capillary count. On gross analysis, features of hypertrophic scars were significantly alleviated in the verapamil-added groups. On histologic examination, verapamil-added groups showed (a) reduced SEI (1.93 (1.79-2.67) for control vs 1.34 (1.21-1.51) for silicone only and 1.13 (1.01-1.65) for verapamil-added silicone), (b) fibroblast count 700.5 (599.5-838.5) for control, 613.25 (461-762.5) for silicone only, and 347.33 (182.5-527) for verapamil-added silicone), and (c) capillary formation (52 (35.5-96.5) for control, 46 (28-64.5) for silicone only, and 39.83(24-70) for verapamil-added silicone) (Kruskal-Wallis test, P < .05). On western blot, expression levels of collagen I protein was lower in the 1 mg/g and 10 mg/g verapamil-added silicone compared with control. Therefore, we suggest a therapeutic concentration of verapamil-added silicone gel of at least over 1 mg/g. Further study regarding maximally effective concentration and deeper insight into the mechanism of action should follow.

Investigation of optimum ohmic heating conditions for inactivation of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in apple juice.

BACKGROUND: Control of foodborne pathogens is an important issue for the fruit juice industry and ohmic heating treatment has been considered as one of the promising antimicrobial interventions. However, to date, evaluation of the relationship between inactivation of foodborne pathogens and system performance efficiency based on differing soluble solids content of apple juice during ohmic heating treatment has not been well studied. This study aims to investigate effective voltage gradients of an ohmic heating system and corresponding sugar concentrations (°Brix) of apple juice for inactivating major foodborne pathogens (E. coli O157:H7, S. Typhimurium, and L. monocytogenes) while maintaining higher system performance efficiency. RESULTS: Voltage gradients of 30, 40, 50, and 60 V/cm were applied to 72, 48, 36, 24, and 18 °Brix apple juices. At all voltage levels, the lowest heating rate was observed in 72 °Brix apple juice and a similar pattern of temperature increase was shown in18-48 °Brix juice samples. System performance coefficients (SPC) under two treatment conditions (30 V/cm in 36 °Brix or 60 V/cm in 48 °Brix juice) were relatively greater than for other combinations. Meanwhile, 5-log reductions of the three foodborne pathogens were achieved after treatment for 60 s in 36 °Brix at 30 V/cm, but this same reduction was observed in 48 °Brix juice at 60 V/cm within 20 s without affecting product quality. CONCLUSIONS: With respect to both bactericidal efficiency and SPC values, 60 V/cm in 48 °Brix was the most effective ohmic heating treatment combination for decontaminating apple juice concentrates.

Flexible piezoelectric nanogenerators based on a transferred ZnO nanorod/Si micro-pillar array.

Flexible piezoelectric nanogenerators (PNGs) based on a composite of ZnO nanorods (NRs) and an array of Si micro-pillars (MPs) are demonstrated by a transfer process. The flexible composite structure was fabricated by hydrothermal growth of ZnO NRs on an electrochemically etched Si MP array with various lengths followed by mechanically delaminating the Si MP arrays from the Si substrate after embedding them in a polydimethylsiloxane matrix. Because the Si MP arrays act as a supporter to connect the ZnO NRs electrically and mechanically, verified by capacitance measurement, the output voltage from the flexible PNGs increased systematically with the increased density ZnO NRs depending on the length of the Si MPs. The flexible PNGs showed 3.2 times higher output voltage with a small change in current with increasing Si MP length from 5 to 20 µm. The enhancement of the output voltage is due to the increased number of series-connected ZnO NRs and the beneficial effect of a ZnO NR/Si MP heterojunction on reducing free charge screening effects. The flexible PNGs can be attached on fingers as a wearable electrical power source or motion sensor.

Flexible ZnO nanorod-based piezoelectric nanogenerators on carbon papers.

We report on the fabrication of ZnO nanorod (NR)-based flexible piezoelectric nanogenerators (PENGs) on carbon paper (CP). Structural investigations indicate that the ZnO NRs grew well along the porous CP surface. Optical investigation shows that the crystal quality of the ZnO NRs on the CP was comparable to that of NRs grown on Si substrate. As the molar concentration increased from 10-70 mM, the output voltage and current increased consistently from 3.6-6.8 V and 0.79-1.45 µA, respectively. The enhancements of the voltage and current were attributed to the enhanced accumulation of the potentials generated by the increased number of ZnO NRs in the PENG devices. Therefore, the porous CP enhanced the PENG performance due to the higher surface area, and provided a super-flexible self-powering platform.

Output power enhancement from ZnO nanorods piezoelectric nanogenerators by Si microhole arrays.

We demonstrate the enhancement of output power from a ZnO nanorod (NR)-based piezoelectric nanogenerator by using Si microhole (Si-µH) arrays. The depth-controlled Si-µH arrays were fabricated by using the deep reactive ion etching method. The ZnO NRs were grown along the Si-µH surface, in holes deeper than 20 µm. The polymer layer, polydimethylsiloxane, which acts a stress diffuser and electrical insulator, was successfully penetrated into the deep Si-µH arrays. Optical investigations show that the crystalline quality of the ZnO NRs on the Si-µH arrays was not degraded, even though they were grown on the deeper Si-µH arrays. As the depth of the Si-µH arrays increase from 0 to 20 µm, the output voltage was enhanced by around 8.1 times while the current did not increase. Finally, an output power enhancement of ten times was obtained. This enhancement of the output power was consistent with the increase in the surface area, and was mainly attributed to the accumulation of the potentials generated by the series-connected ZnO NR-based nanogenerators, whose number increases as the depth of the Si-µH increases.

Application of hyaluronic acid/sodium alginate-based microparticles to prevent tissue adhesion in a rabbit model.

PURPOSE: Postsurgical adhesion formation is a concern in every field of surgery. We evaluated the efficacy of hyaluronic acid/sodium alginate-based microparticle anti-adhesive agents (MP) for the prevention of postsurgical adhesion formation in a standardized rabbit model. METHOD: To evaluate the anti-adhesion effect, a uterus-abdominal wall abrasion model was created in rabbits. On the surface of the injured uterus, an anti-adhesive agent, Interceed(®) or MP, was applied (positive control and study groups, respectively; n = 10 each). In another group of 10 animals, neither agent was applied (negative control group). The adhesion levels were graded 3 weeks after surgery. Acute and chronic toxicity was also evaluated. RESULTS: The grade of adhesion was significantly lower in the MP group than in the negative control and positive control groups. No evidence of acute or chronic toxicity induced by this material was found in blood and tissue analysis. CONCLUSION: MP shows potential as an effective novel type of resorbable biomaterial to reduce postoperative adhesion. The easy placement and handling of this material make the MP powder attractive as a tissue adhesion barrier.

Comparative Analysis of Radiographic Hip Joint Geometry Using Measurement Tools on Picture Archiving and Communication System: A Prospective Study of 100 Pelvic Radiographs of Koreans.

BACKGROUND: A contralateral normal hip joint has been often used as a reference standard in preoperative planning and intraoperative assessment of hip arthroplasty, with the assumption that bilateral hip joint geometries have no significant differences. However, one previous study using analog measurements on hardcopy films reported significant bilateral variation in hip joint geometry. We therefore investigated the level of agreement between the right and left hips for each measurement and determined index values and the range of normal bilateral variations. METHODS: We assessed 100 standard anteroposterior radiographs of the pelvis in this study. Two independent observers measured the actual value of femoral head diameter, location of the femoral head center, acetabular offset, femoral offset, hip offset, greater trochanteric height, neck-shaft angle, medullary canal diameter, and proximal femoral diameter. Intraclass correlation coefficients (ICCs) and values of mean difference were calculated for each measurement. RESULTS: The results demonstrated perfect agreement (ICC >0.8) between the right and left hips for most parameters and substantial agreement for greater trochanteric height (ICC = 0.735) and femoral offset (ICC = 0.773). The mean difference and standard deviation in the measurement between the right and left hips for the location of the femoral head center and the acetabular offset were 0.60 ± 0.48 mm and 0.42 ± 0.30 mm, respectively. CONCLUSION: Hip joint geometry is not influenced by side. In hip arthroplasty, a contralateral normal hip can be reliably used as a guide for preoperative planning using measurement tools on a picture archiving and communication system.

Development of quantitative detection methods for four Alzheimer's disease specific biomarker panels using electrochemical immunosensors based on enzyme immunoassay.

Accurate and timely diagnosis of Alzheimer's disease (AD) is necessary to maximize the effectiveness of treatment and using biomarkers for diagnosis is attracting attention as a minimally invasive method with few side effects. Electrochemical immunosensor (EI) is a method that is in the spotlight in the medical and bioanalytical fields due to its portability and field usability. Here, we quantified four AD specific biomarkers using EIs based on enzyme immunoassay. We selected and developed quantitative methods for the biomarkers using screen-printed gold electrodes. For three biomarkers, quantification was performed using competition immunoassays in which antigen-antibody premix mixtures were applied to antigen-immobilized electrodes and the limit of detection (LOD) values were secured, 1.20 ng/ml, 1.30 ng/ml, and 1.74 ng/ml, respectively. For the other, a sandwich immunoassay using antibody pair was selected for quantification and LOD was also achieved as 0.077 ng/ml. All four biomarkers in buffer samples were successfully quantified and reliable R2 values were obtained, and reliable calibration curves were secured for three biomarkers in spiked human serum samples. The immunosensors developed and will be optimized are expected to be used in various fields, including detection of biomarkers for not only AD but also related diseases.

Effect of electropermeabilization by ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in buffered peptone water and apple juice.

The effect of electric field-induced ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in buffered peptone water (BPW) (pH 7.2) and apple juice (pH 3.5; 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at different temperatures (55°C, 58°C, and 60°C) and for different times (0, 10, 20, 25, and 30 s) by ohmic heating compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm for BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (P<0.05) from that resulting from conventional heating at 58°C and 60°C in BPW and at 55°C, 58°C, and 60°C in apple juice for intervals of 0, 10, 20, 25, and 30 s. These results show that electric field-induced ohmic heating led to additional bacterial inactivation at sublethal temperatures. Transmission electron microscopy (TEM) observations and the propidium iodide (PI) uptake test were conducted after treatment at 60°C for 0, 10, 20, 25 and 30 s in BPW to observe the effects on cell permeability due to electroporation-caused cell damage. PI values when ohmic and conventional heating were compared were significantly different (P<0.05), and these differences increased with increasing levels of inactivation of three food-borne pathogens. These results demonstrate that ohmic heating can more effectively reduce bacterial populations at reduced temperatures and shorter time intervals, especially in acidic fruit juices such as apple juice. Therefore, loss of quality can be minimized in a pasteurization process incorporating ohmic heating.

Surface plasmon-enhanced light-emission mechanism of Ag-coated ZnO/Al2O3 core/shell nanorod structures.

Surface plasmon (SP)-enhanced light emission mechanism has been investigated for the Ag-coated ZnO/Al2O3 core/shell nanorods (NRs). Structural characterizations showed that the ZnO NRs were covered by conformal Al2O3 layer and coated by Ag nanoparticles (NPs). The optical studies by photoluminescence (PL) showed abnormal variation of PL intensity with increasing the thickness of Al2O3. For the Ag NPs-coated ZnO NRs without Al2O3 shell layer, the PL emission quenched due to direct transfer of the photo-excited electrical carriers from ZnO NRs to Ag NPs. With thin Al2O3 layers less than 15 nm, the PL intensity increased with increasing the thickness of Al2O3 layers due to weakening of the Förster-type energy transfer while strong SP-mediated PL emission enhancement. For thicker Al2O3 layers than 15 nm, however, the PL intensity decreased with increasing the thickness of Al2O3 layers due to weakening of SP-mediated PL emission enhancement.

Fabrication and characterization of hybrid Si/ZnO subwavelength structures as efficient antireflection layer.

In this study, we fabricated and characterized three dimensional (3D) silicon (Si)/zinc oxide (ZnO) hybrid subwavelength structures to investigate their antireflective properties. Si nanorods (SiNRs) were fabricated by electrochemical etching, and subsequentially we grew ZnO NRs on SiNR as templates by using hydrothermal synthesis. The morphological and optical properties of hybrid Si/ZnO subwavelength structures were investigated by scanning electron microscopy (SEM) and ultra violet-visible-near infrared (UV-VIS-NIR) spectrophotometer, respectively. The reflectance on SiNRs is greatly reduced comparing with that on the conventional textured Si surface. Moreover, the hybrid SiNR/ZnO NR structures gave the lowest reflectance (< 3%) throughout the broadband spectrum range. We suggest that the combination of SiNRs and ZnO NRs trap light, leading to suppressing light reflection and increasing light scattering to the hybrid structures.

Electrostatic Induction Nanogenerator Boosted by One-Dimensional Metastructure: Application to Energy and Information Transmitting Smart Tag System.

The recent application of the internet of things demands the ubiquitous utilization of data and electrical power. Even with the development of a wide variety of energy-harvesting technologies, few studies have reported a device transporting electrical energy and data simultaneously. This paper reports an electrostatic induction nanogenerator (ESING) consisting of a one-dimensional metastructure that can modulate the output voltage based on the resonance of ultrasound waves to transmit energy and data simultaneously. The ESING device is fabricated using electronegative poly(vinylidene fluoride) (PVDF) membrane using a phase inversion process. The output voltage from the ESING device exhibits periodic resonant peaks as the gap between the PVDF membrane and the Al electrode changes, showing an up to 35-fold difference between the maximum and minimum output voltages depending on the resonance state. The energy and electrical signal can be transmitted simultaneously in free space because the ESING converts energy from high-frequency ultrasound waves. This paper provides proof of concept for a data and energy-transferable smart tag device based on ESING devices exhibiting resonant and non-resonant states. A device consisting of four ESINGs for a 4-bit signal is implemented to demonstrate 16 signals.

Monolithic Multicolor Emissions of InGaN-Based Hybrid Light-Emitting Diodes Using CsPbBr3 Green Quantum Dots.

To address the increasing demand for multicolor light-emitting diodes (LEDs), a monolithic multicolor LED with a simple process and high reliability is desirable. In this study, organic-inorganic hybrid LEDs with violet and green wavelengths were fabricated by depositing CsPbBr3 perovskite green quantum dots (QDs) as the light-converting material on InGaN-based violet LEDs. As the injection current was increased, the total electroluminescence (EL) intensities of the hybrid LEDs increased, whereas the light-converted green emission efficiency of the CsPbBr3 QDs decreased. The maximum green-to-violet EL spectral intensity ratio of the hybrid LEDs with CsPbBr3 QDs was achieved with the injection current of <10 mA. Moreover, the EL spectral ratio of the green-to-violet emission decreased at an injection current of 100 mA. The light-conversion intensity of the CsPbBr3 QDs decreased linearly as the junction temperature of the hybrid LEDs was increased with increasing injection current, similar to the temperature-dependent photoluminescence degradation of CsPbBr3 QDs. In addition, the junction temperature of the hybrid LED was minimized by pulse injection to suppress the thermal degradation of QDs and increase the light conversion efficiency to green emission. Therefore, the overall emission spectrum color coordinates of the hybrid LEDs exhibited a red shift from violet to blue in the low-current region and a blue shift toward violet as the green emission of the QDs was decreased above 10 mA.

High-efficiency light-emitting diode with air voids embedded in lateral epitaxially overgrown GaN using a metal mask.

We report high-efficiency blue light-emitting diodes (LEDs) with air voids embedded in GaN. The air void structures were created by the lateral epitaxial overgrowth (LEO) of GaN using a tungsten mask. The optical output power was increased by 60% at an injection current of 20 mA compared with that of conventional LEDs without air voids. The enhancement is attributed to improved internal quantum efficiency because the air voids reduce the threading dislocation and strain in the LEO GaN epilayer. A ray-tracing simulation revealed that the path length of light escaping from the LED with air voids is much shorter because the air voids efficiently change the light path toward the top direction to improve the light extraction of the LED.

Churros-like Polyvinylidene Fluoride Nanofibers for Enhancing Output Performance of Triboelectric Nanogenerators.

Triboelectric nanogenerators (TENGs) have emerged as a next-generation sustainable power source for Internet of Things technology. Polyvinylidene fluoride (PVDF) nanofibers (NFs) have been investigated widely to enhance the TENG performance by controlling their polarity; however, controlling the surface morphology of the PVDF NFs has rarely been studied. Here, surface-roughened, churros-like PVDF NFs were fabricated by controlling the solvent evaporation kinetics. The solvent evaporation rate was modulated by varying the relative humidity (RH) during the electrospinning process. With increasing RH, the fraction of polar ß-phase in the PVDF NFs increased, the specific surface area of the PVDF NFs increased gradually and the surface morphology changed from smooth to rough, finally resulting in a churros-like structure. Therefore, the output performance of the TENG devices was enhanced with increasing RH, because of the combined effects of the enlarged surface area and the increased fraction of the polar phase in the PVDF NFs. The TENG device with the churros-like PVDF NFs showed an output voltage of 234 V, current of 11 µA, and power density up to 1738 µW/cm2, giving it the capability to turn on 60 series-connected commercial light-emitting diodes without using an external charge storage circuit.

Flexible Visible-Blind Ultraviolet Photodetectors Based on ZnAl-Layered Double Hydroxide Nanosheet Scroll.

Visible-blind ultraviolet (UV) photodetectors have received a great deal of attention for realizing Internet of Things technologies as well as for monitoring the level of UV exposure to humans. Realizing next-generation flexible and visible-blind UV photodetectors requires development of new functional material systems with easy fabrication, selectively strong UV light absorption, environmental friendliness, and high stability regardless of ambient conditions. Herein, flexible visible-blind UV photodetectors are successfully fabricated on the basis of two-dimensional ZnAl-layered double hydroxide (LDH) nanosheets with scroll structures grown on flexible substrates. The ZnAl-LDH nanosheet scrolls exhibit highly resistive semiconducting properties with a band gap of 3.2 eV and work function of 3.64 eV. The photodetector based on the ZnAl-LDH shows photoresponse in the UV spectral range below 420 nm, indicating visible-blind spectral response. In addition, the UV photodetector shows a maximum responsivity of 17 mA/W under illumination with 365 nm light. Moreover, the flexible photodetector shows reproducible photoresponse even after 1000 bending cycles, which indicates the acceptable stability of the ZnAl-LDH nanosheet scrolls.

Surface-diffusion-limited growth of atomically thin WS2 crystals from core-shell nuclei.

Atomically thin transition metal dichalcogenides (TMDs) have recently attracted great attention since the unique and fascinating physical properties have been found in various TMDs, implying potential applications in next-generation devices. The progress towards developing new functional and high-performance devices based on TMDs, however, is limited by the difficulty in producing large-area monolayer TMDs due to a lack of knowledge of the growth processes of monolayer TMDs. In this work, we have investigated the growth processes of monolayer WS2 crystals using a thermal chemical vapor deposition method, in which the growth conditions were adjusted in a systematic manner. It was found that, after forming WO3-WS2 core-shell nanoparticles as nucleation sites on a substrate, the growth of three-dimensional WS2 islands proceeds by ripening and crystallization processes. Lateral growth of monolayer WS2 crystals subsequently occurs by the surface diffusion process of adatoms toward the step edge of the three-dimensional WS2 islands. Our results provide understanding of the growth processes of monolayer WS2 by using chemical vapor deposition methods.

Mechanically Robust Magnetic Fe3O4 Nanoparticle/Polyvinylidene Fluoride Composite Nanofiber and Its Application in a Triboelectric Nanogenerator.

Mechanically robust composite nanofibers (NFs) with enhanced magnetic properties were made from polyvinylidene fluoride (PVDF) and Fe3O4 nanoparticles (NPs) by an electrospinning method. At up to 11.3 wt %, Fe3O4 NPs were embedded randomly in the PVDF NFs, but when the content exceeded 17 wt %, the NPs aggregated on the NF surfaces. Magnetization of the composite NFs consistently increased with the increasing Fe3O4 NP content. The mechanical strength of the Fe3O4 NP/PVDF composite NF was enhanced by a dispersion strengthening mechanism. A triboelectric nanogenerator was made from the composite, which showed enhanced output performance with the Fe3O4 NP content less than 11.3 wt %, but the performance degraded at higher content. These results were attributed to the electret doping effect and surface aggregation of the Fe3O4 NPs on the NFs, respectively.

Vacuum-Assisted Closure (VAC) Using Multiple Foam Pieces for Hidden Space Drainage through Less Exposure in Musculoskeletal Infections.

BACKGROUND: Purulent musculoskeletal infections often require surgical debridement and drainage. However, when the infection is extensive or involving multiple layers of tissues, maintaining drainage of the involved spaces can be difficult, even with the application of vacuum-assisted closure (VAC) therapy. Wide exposure and aggressive debridement is often required for such cases, which in turn may complicate wound coverage. METHODS: A retrospective review was performed for 16 patients with musculoskeletal infections treated surgically. The diagnosis for the patients consisted of necrotizing fasciitis, large soft tissue abscess, peri-hardware abscess, infected compartment syndrome, emphysematous osteomyelitis, and gas gangrene of diabetic foot. We minimized the incision and resection for debridement and drainage, and instead we placed multiple foam pieces between the tissues involved with VAC, to maintain drainage of the hidden spaces with negative pressure. RESULTS: Infection was successfully controlled in all cases. The mean duration of VAC treatment was 16.1 days (range, 5-36) and the mean number of VAC changes was 5.1 (range, 1-13). Primary wound closure was achieved in 11 cases, while skin grafts were used to cover the remaining five cases, which consisted of necrotizing fasciitis, infected compartment syndrome, and diabetic foot gas gangrene. No complications specifically associated with VAC therapy were observed. CONCLUSIONS: VAC using multiple foam pieces for hidden space drainage appears to be effective for infection control. It is helpful for minimizing exposure and resection for drainage and debridement, although subsequent reduction of the necessity or the level of wound coverage should further be investigated.

In vitro and in vivo characteristics of PCL scaffolds with pore size gradient fabricated by a centrifugation method.

Polycaprolactone (PCL) cylindrical scaffolds with gradually increasing pore size along the longitudinal direction were fabricated by a novel centrifugation method to investigate pore size effect on cell and tissue interactions. The scaffold was fabricated by the centrifugation of a cylindrical mold containing fibril-like PCL and the following fibril bonding by heat treatment. The scaffold showed gradually increasing pore size (from approximately 88 to approximately 405 microm) and porosity (from approximately 80% to approximately 94%) along the cylindrical axis by applying the centrifugal speed, 3000 rpm. The scaffold sections were examined for their in vitro cell interactions using different kinds of cells (chondrocytes, osteoblasts, and fibroblasts) and in vivo tissue interactions using a rabbit model (skull bone defects) in terms of scaffold pore sizes. It was observed that different kinds of cells and bone tissue were shown to have different pore size ranges in the scaffold for effective cell growth and tissue regeneration. The scaffold section with 380-405 microm pore size showed better cell growth for chondrocytes and osteoblasts, while the scaffold section with 186-200 microm pore size was better for fibroblasts growth. Also the scaffold section with 290-310 microm pore size showed faster new bone formation than those of other pore sizes. The pore size gradient scaffolds fabricated by the centrifugation method can be a good tool for the systematic studies of the interactions between cells or tissues and scaffolds with different pore size.