Phased peristaltic micropumping for continuous sampling and hardcoded droplet generation.

Droplet microfluidics has recently emerged as a new engineering tool for biochemical analysis of small sample volumes. Droplet generation is most commonly achieved by introducing aqueous and oil phases into a T-junction or a flow focusing channel geometry. This method produces droplets that are sensitive to changes in flow conditions and fluid composition. Here, we present an alternative approach using a simple peristaltic micropump to deliver the aqueous and oil phases in antiphase pulses resulting in a robust "chopping"-like method of droplet generation. This method offers controllable droplet dynamics, with droplet volumes solely determined by the pump design, and is insensitive to liquid properties and flow rates. Importantly, sequences of droplets with controlled composition can be hardcoded into the pump, allowing chemical operations such as titrations and dilutions to be easily achieved. The push-pull pump is compact and can continuously collect samples, generating droplets close to the sampling site and with short stabilisation time. We envisage that this robust droplet generation method is highly suited for continuous in situ sampling and chemical measurement, allowing droplet microfluidics to step out of the lab and into field-deployable applications.

Successful Treatment of Infectious Scleritis by Pseudomonas aeruginosa with Autologous Perichondrium Graft of Conchal Cartilage.

Infectious scleritis by Pseudomonas aeruginosa is a well-known vision-threatening disease. In particular, scleral trauma following pterygium surgery may increase the risk of sclera inflammation. Surgical debridement and repair is necessary in patients who do not respond to medical treatments, such as topical and intravenous antibiotics. We reports herein the effectiveness of an autologous perichondrium conchal cartilage graft for infectious scleritis caused by Pseudomonas aeruginosa. This procedure was performed on four eyes of four patients with infectious scleritis who had previously undergone pterygium surgery at Gyeongsang National University Hospital (GNUH), Jinju, Korea from December 2011 to May 2012. Pseudomonas aeruginosa was identified in cultures of necrotic scleral lesion before surgery. The conchal cartilage perichondrium graft was transplanted, and a conjunctival flap was created on the scleral lesion. The autologous perichondrium conchal cartilage graft was successful and visual outcome was stable in all patients, with no reports of graft failure or infection recurrence. In conclusion, autologous perichondrium conchal cartilage graft may be effective in surgical management of Pseudomonal infectious scleritis when non-surgical medical treatment is ineffective. Further studies in larger, diverse populations are warranted to establish the effectiveness of the procedure.

Single CdTe microwire photodetectors grown by close-spaced sublimation method.

We demonstrate single CdTe microwire field-effect transistors (FETs) that are highly sensitive to ultraviolet (UV) light. Dense CdTe microwires were catalytically grown using a close-spaced sublimation system. Structural, morphological and transport properties in conjunction with the optoelectronic properties were systemically investigated. CdTe microwire FETs exhibited p-type behaviors with field-effect mobilities up to 1.1 × 10(-3) cm2 V(-1) s(-1). Optoelectronic properties of our CdTe microwire FETs were studied under dark and UV-illumination conditions, where photoresponse was highly dependent on the back-gate bias conditions. Our CdTe microwire FET-based photodetectors are promising for high-performance micro-optoelectronic applications.

Effect of nozzle tip configuration on the micro-droplet formation.

Micro-droplet formation is an emerging area of research due to its wide-ranging applications in micro-fluidic based devices. For high resolution patterning and coating processes in various industrial fields, the formation of micro-droplets should be controlled according to the rheological properties of the working fluids. However, the physical properties of the some of working fluids are limited to meet the industrial applications. In this paper, the effect of the nozzle tip configuration on the micro-droplet formation process was numerically observed. A two-phase level-set modeling method was employed for simulations, and the results for various nozzle shapes were compared. In order to validate the numerical results of ink-jet printing with various operating conditions, we introduced a dimensionless parameter Z which is the factor of correlation of dynamic viscosity with surface tension of a working fluid on the microfluidics of drop-on-demand (DOD) jets, and obtained reasonable values of Z. Also, the numerical results such as velocity and shear rate distributions, etc. were graphically depicted in two-dimensional coordinates.

Mean platelet volume reflect hematopoietic potency and correlated blood group o in cord blood from healthy newborn.

We evaluated the relationship between mean platelet volume (MPV) and characteristics of 10,577 cord blood (CB) units in a public CB bank in Korea. Blood group O has the highest MPV (P = 0.002). MPV correlated with CB volume (r = 0.121), Hb (r = 0.377), WBC (r = 0.111), TNCs (r = 0.110), CD34+ cell (r = 0.174), CD34+ cells/TNCs (r = 0.157), gestational age (r = -0.102), and birth weight (r = 0.023); (P < 0.001 in all). MPV may be one of the useful decision parameters of process priority in CB bank.

GaN-based ultraviolet light-emitting diodes with AuCl3-doped graphene electrodes.

We demonstrate AuCl3-doped graphene transparent conductive electrodes integrated in GaN-based ultraviolet (UV) light-emitting diodes (LEDs) with an emission peak of 363 nm. AuCl3 doping was accomplished by dipping the graphene electrodes in 5, 10 and 20 mM concentrations of AuCl3 solutions. The effects of AuCl3 doping on graphene electrodes were investigated by current-voltage characteristics, sheet resistance, scanning electron microscope, optical transmittance, micro-Raman scattering and electroluminescence images. The optical transmittance was decreased with increasing the AuCl3 concentrations. However, the forward currents of UV LEDs with p-doped (5, 10 and 20 mM of AuCl3 solutions) graphene transparent conductive electrodes at a forward bias of 8 V were increased by ~48, 63 and 73%, respectively, which can be attributed to the reduction of sheet resistance and the increase of work function of the graphene. The performance of UV LEDs was drastically improved by AuCl3 doping of graphene transparent conductive electrodes.

Electroluminescence from InGaN/GaN multi-quantum-wells nanorods light-emitting diodes positioned by non-uniform electric fields.

We report that the nanorod light-emitting diodes (LEDs) with InGaN/GaN multi-quantum-wells (MQWs) emitted bright electroluminescence (EL) after they were positioned and aligned by non-uniform electric fields. Firstly, thin film LED structures with MQWs on sapphire substrate were coated with SiO(2) nanospheres, followed by inductively-coupled plasma etch to create nanorod-shapes with MQWs, which were transferred to the pre-patterned SiO(2)/Si wafer. This method allowed us to obtain nanorod LEDs with uniform length, diameter and qualities. Dielectrophoretic force created by non-uniform electric field was very effective at positioning the processed nanorods on the pre-patterned contacts. After aligned by non-uniform electric field, we observed bright EL from many nanorods, which had both cases (p-GaN/MQWs/n-GaN or n-GaN/MQWs/p-GaN). Therefore, bright ELs at different locations were observed under the various bias conditions.

Increased numbers of total nucleated and CD34+ cells in blood group O cord blood: an analysis of neonatal innate factors in the Korean population.

BACKGROUND: We analyzed neonatal factors that could affect hematopoietic variables of cord blood (CB) donated from Korean neonates. STUDY DESIGN AND METHODS: The numbers of total nucleated cells (TNCs), CD34+ cells, and CD34+ cells/TNCs of CB in neonates were compared according to sex, gestational age, birth weight, birth weight centile for gestational age, and ABO blood group. RESULTS: With 11,098 CB units analyzed, blood group O CB showed an increased number of TNCs, CD34+ cells, and CD34+ cells/TNCs compared with other blood groups. Although TNC counts were lower in males, no difference in the number of CD34+ cells was demonstrated because the number of CD34+ cells/TNCs was higher in males. An increase in the gestational age resulted in an increase in the number of TNCs and decreases in the number of CD34+ cells and CD34+ cells/TNCs. The numbers of TNCs, CD34+ cells, and CD34+ cells/TNCs increased according to increased birth weight centile as well as birth weight. CONCLUSION: CB with blood group O has unique hematologic variables in this large-scale analysis of Korean neonates, although the impact on the storage policies of CB banks or the clinical outcome of transplantation remains to be determined.

Three-dimensional multilayered nanostructures with controlled orientation of microdomains from cross-linkable block copolymers.

Three-dimensional (3D) nanostructures were obtained by the directed formation of multilayer block copolymer (BCP) thin films. The initial step in this strategy involves the assembly and cross-linking of cylinder-forming polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) BCP, in which 1.5 mol % of reactive azido (-N(3)) groups were randomly incorporated along the styrene backbone. Significantly, assembly of thin films of lamellar-forming BCPs on top of the underlying cross-linked cylindrical layer exhibited perpendicular orientations of microdomains between lamellae and cylinder layers. From the theoretical calculation of free energy in the multilayers, it was found that the nematic interactions between polymer chains at the interface play a critical role in the perpendicular orientation of lamellae on the cross-linked cylinder layers. Removal of the PMMA domains then affords nonsymmetrical nanostructures which illustrate the promise of this strategy for the design of well-defined 3D nanotemplates. It was also demonstrated that this structure can be effectively used to enhance the light extraction efficiency of GaN light-emitting diodes. Furthermore, we anticipate that such 3D nanotemplates can be applied to various areas, including advanced BCP nanolithography and responsive surface coating.

Fabrication of GaAs subwavelength structure (SWS) for solar cell applications.

We developed a novel GaAs subwavelength structure (SWS) as an antireflective layer for solar cell applications. The GaAs SWS patterns were fabricated by a combination of nanosphere lithography (NSL) and reactive ion etching (RIE). The shape and height of the GaAs SWS were controlled by the diameter of the SiO2 nanospheres and the etching time. Various GaAs SWS were characterized by the reflectance spectra. The average reflectance of the polished GaAs substrate from 200nm to 800nm was 35.1%. However, the average reflectance of the tapered GaAs SWS was reduced to 0.6% due to scattering and moth-eye effects.

Transparent conductive graphene electrode in GaN-based ultra-violet light emitting diodes.

We report a graphene-based transparent conductive electrode for use in ultraviolet (UV) GaN light emitting diodes (LEDs). A few-layer graphene (FLG) layer was mechanically deposited. UV light at a peak wavelength of 368 nm was successfully emitted by the FLG layer as transparent contact to p-GaN. The emission of UV light through the thin graphene layer was brighter than through the thick graphene layer. The thickness of the graphene layer was characterized by micro-Raman spectroscopy. Our results indicate that this novel graphene-based transparent conductive electrode holds great promise for use in UV optoelectronics for which conventional ITO is less transparent than graphene.