Home About us Contact
|
Home About us Contact | ||
|
|
||
Single Device (single + device)
Selected AbstractsSpectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device.ELECTROANALYSIS, Issue 5 2007Abstract Quaternized poly(4-vinylpyridine) (QPVP) has been incorporated as an anion exchanger into sol-gel derived silica films for use in a spectroelectrochemical sensor. The preparation, characteristics and performance of these films are described. The films, which are spin-coated onto the surface of a planar optically transparent electrode, are optically transparent and uniform. Scanning electron microscopy and spectroscopic ellipsometry have been used to examine film structure, thickness and optical properties. These films have been shown both spectroscopically and electrochemically to preconcentrate ferrocyanide, a model analyte for the sensor. The films can be regenerated for multiple measurements by exposure to 1,M KNO3. The effects of polymer molecular weight and storage conditions on film performance are described. The overall response of this film is comparable to the poly(dimethyldiallylammonium chloride)-silica films previously used for this sensor. [source] On-line cell lysis and DNA extraction on a microfluidic biochip fabricated by microelectromechanical system technologyELECTROPHORESIS, Issue 9 2008Xing Chen Dr. Abstract Integrating cell lysis and DNA purification process into a micrototal analytical system (,TAS) is one critical step for the analysis of nucleic acids. On-chip cell lysis based on a chemical method is realized by sufficient blend of blood sample and the lyzing reagent. In this paper two mixing models, T-type mixing model and sandwich-type mixing model, are proposed and simulation of those models is conducted. Result of simulation shows that the sandwich-type mixing model with coiled channel performs best and this model is further used to construct the microfluidic biochip for on-line cell lysis and DNA extraction. The result of simulation is further verified by experiments. It asserts that more than 80% mixing of blood sample and lyzing reagent which guarantees that completed cell lysis can be achieved near the inlet location when the cell/buffer velocity ratio is less than 1:5. After cell lysis, DNA extraction by means of a solid-phase method is implemented by using porous silicon matrix which is integrated in the biochip. During continuous flow process in the microchip, rapid cell lysis and PCR-amplifiable genomic DNA purification can be achieved within 20,min. The potential of this microfluidic biochip is illustrated by pretreating a whole blood sample, which shows the possibility of integration of sample preparation, PCR, and separation on a single device to work as portable point-of-care medical diagnostic system. [source] Organic Electronics: High Tg Cyclic Olefin Copolymer Gate Dielectrics for N,N,-Ditridecyl Perylene Diimide Based Field-Effect Transistors: Improving Performance and Stability with Thermal Treatment (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Mater. Abstract A novel application of ethylene-norbornene cyclic olefin copolymers (COC) as gate dielectric layers in organic field-effect transistors (OFETs) that require thermal annealing as a strategy for improving the OFET performance and stability is reported. The thermally-treated N,N, -ditridecyl perylene diimide (PTCDI-C13)-based n-type FETs using a COC/SiO2 gate dielectric show remarkably enhanced atmospheric performance and stability. The COC gate dielectric layer displays a hydrophobic surface (water contact angle = 95° ± 1°) and high thermal stability (glass transition temperature = 181 °C) without producing crosslinking. After thermal annealing, the crystallinity improves and the grain size of PTCDI-C13 domains grown on the COC/SiO2 gate dielectric increases significantly. The resulting n-type FETs exhibit high atmospheric field-effect mobilities, up to 0.90 cm2 V,1 s,1 in the 20 V saturation regime and long-term stability with respect to H2O/O2 degradation, hysteresis, or sweep-stress over 110 days. By integrating the n-type FETs with p-type pentacene-based FETs in a single device, high performance organic complementary inverters that exhibit high gain (exceeding 45 in ambient air) are realized. [source] High Tg Cyclic Olefin Copolymer Gate Dielectrics for N,N,-Ditridecyl Perylene Diimide Based Field-Effect Transistors: Improving Performance and Stability with Thermal TreatmentADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Jaeyoung Jang Abstract A novel application of ethylene-norbornene cyclic olefin copolymers (COC) as gate dielectric layers in organic field-effect transistors (OFETs) that require thermal annealing as a strategy for improving the OFET performance and stability is reported. The thermally-treated N,N, -ditridecyl perylene diimide (PTCDI-C13)-based n-type FETs using a COC/SiO2 gate dielectric show remarkably enhanced atmospheric performance and stability. The COC gate dielectric layer displays a hydrophobic surface (water contact angle = 95° ± 1°) and high thermal stability (glass transition temperature = 181 °C) without producing crosslinking. After thermal annealing, the crystallinity improves and the grain size of PTCDI-C13 domains grown on the COC/SiO2 gate dielectric increases significantly. The resulting n-type FETs exhibit high atmospheric field-effect mobilities, up to 0.90 cm2 V,1 s,1 in the 20 V saturation regime and long-term stability with respect to H2O/O2 degradation, hysteresis, or sweep-stress over 110 days. By integrating the n-type FETs with p-type pentacene-based FETs in a single device, high performance organic complementary inverters that exhibit high gain (exceeding 45 in ambient air) are realized. [source] A terminal-controlled vertical handover decision scheme in IEEE 802.21-enabled heterogeneous wireless networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2009Jung-Shyr Wu Abstract The seamless internetworking among heterogeneous networks is in great demand to provide ,always-on' connectivity services with quality of service (QoS) provision, anywhere at anytime. The integration of wireless-fidelity (Wi-Fi) and wireless metropolitan area networks (WiMAX) networks can combine their best features to provide ubiquitous access, while mediating the weakness of both networks. While it is challenging to obtain optimized handover decision-based dynamic QoS information, users can improve their perceived QoS by using the terminal-controlled handover decision in a single device equipped with multiple radio interfaces. The IEEE 802.21 aims at providing a framework that defines media-independent handover (MIH) mechanism that supports seamless handover across heterogeneous networks. In this paper, an multiple attributes decision making-based terminal-controlled vertical handover decision scheme using MIH services is proposed in the integrated Wi-Fi and WiMAX networks to provide ,always-on' connectivity QoS services. The simulation results show that the proposed scheme provides smaller handover times and lower dropping rate than the RSS-based and cost function-based vertical handover schemes. Copyright © 2009 John Wiley & Sons, Ltd. [source] The Aachen MiniHLM,A Miniaturized Heart-Lung Machine for Neonates With an Integrated Rotary Blood PumpARTIFICIAL ORGANS, Issue 9 2010Jutta Arens Abstract The operation of congenital heart defects in neonates often requires the use of heart-lung machines (HLMs) to provide perfusion and oxygenation. This is prevalently followed by serious complications inter alia caused by hemodilution and extrinsic blood contact surfaces. Thus, one goal of developing a HLM for neonates is the reduction of priming volume and contact surface. The currently available systems offer reasonable priming volumes for oxygenators, reservoirs, etc. However, the necessary tubing system contains the highest volumes within the whole system. This is due to the use of roller pumps; hence, the resulting placement of the complete HLM is between 1 and 2 m away from the operating table due to connective tubing between the components. Therefore, we pursued a novel approach for a miniaturized HLM (MiniHLM) by integrating all major system components in one single device. In particular, the MiniHLM is a HLM with the rotary blood pump centrically integrated into the oxygenator and a heat exchanger integrated into the cardiotomy reservoir which is directly connected to the pump inlet. Thus, tubing is only necessary between the patient and MiniHLM. A total priming volume of 102 mL (including arterial filter and a/v line) could be achieved. To validate the overall concept and the specific design we conducted several in vitro and in vivo test series. All tests confirm the novel concept of the MiniHLM. Its low priming volume and blood contact surface may significantly reduce known complications related to cardiopulmonary bypass in neonates (e.g., inflammatory reaction and capillary leak syndrome). [source] Immunoaffinity removal of xenoreactive antibodies using modified dialysis or microfiltration membranesBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2003Sujatha Karoor Abstract Hyperacute rejection following xenogeneic transplantation in primates is mediated by naturally occurring IgM antibodies, which are specifically directed to ,-Galactosyl residues on many nonprimate mammalian cells. Current approaches to remove these anti-,Gal IgM include plasmapheresis followed by immunoaffinity adsorption on bead columns using synthetic Gal epitopes, which requires two pieces of complex equipment. In this study, we explored the use of immunoaffinity adsorption with hollow fiber microporous or dialysis membranes to which a synthetic ,Gal trisaccharide ligand is bound. Covalent attachment of ligand directly to the surface produced negligible binding, but use of long-chain polyamines as reactive spacers yielded binding densities for anti-,Gal IgM as high as 89 mg/mL membrane volume in breakthrough curve experiments with microporous nylon membranes having an internal surface area of 4.2 m2/mL membrane volume. A crossflow microfilter fabricated from the membranes described in this study and having about 0.4 m2 luminal surface area would be able to carry out plasma separation and immunoadsorption in a single device with a large excess of binding capacity to ensure that all plasma that filters across the device and is returned to a human patient is essentially free of anti-,Gal IgM. We conclude that immunoaffinity removal of xenoreactive antibodies using microfiltration hollow fiber membranes is feasible and has potential advantages of efficiency and simplicity for clinical application. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 134,148, 2003. [source] Transcatheter closure of high-risk muscular ventricular septal defects with the CardioSEAL occluder: Initial report from the CardioSEAL VSD RegistryCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 5 2007D. Scott Lim MD Abstract Objectives: The CardioSEAL VSD registry was created to track safety of the device to close high-risk Ventricular Septal Defect (VSD). Background: This is the first report from the multi-centered CardioSEAL VSD registry reviewing demographics and initial results. Methods: Centers recruited patients with VSD who were high-risk for surgery due to medical condition or anatomic features. Results: 18 centers contributed data on 55 high-risk patients who had 61 VSD-occlusion procedures, with age of range of 5 days to 65 years and using one to six devices. Implantation approach was transvenous in 48, perventricular in five, and by combined approach in two patients. Ninety-two percent of intended VSD device implants were judged successful. Twenty-two patients had single VSD closed by single device in 18 and by two devices in four patients. All patients <8 kg underwent perventricular device implantation. Thirty-three patients had multiple VSDs which were closed by a single device in 23, and multiple devices in 10. At discharge echocardiography showed total residual flow through all VSDs in which devices were used was classified as "Small" or less in 74%, "More than small" in 11%, and "Uncertain" in 15%. Eight major adverse events occurred in 5/61 cases (8% event rate), with 3/81 devices embolized (4% embolization rate), 5/81 devices surgically explanted (6% explant rate), and no deaths judged to be procedure-related. Conclusion: This initial report from the multi-centered CardioSEAL VSD registry demonstrates the safety of the device to close high-risk VSDs. © 2007 Wiley-Liss, Inc. [source] Transcatheter closure of coronary artery fistulae using the Amplatzer duct occluderCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 2 2006Sarina K. Behera MD Abstract Objective: The aim of this study is to report our experience using the Amplatzer Duct Occluder (ADO) for occlusion of significant coronary artery fistulae (CAF). Background: Transcatheter closure of CAF with coils is well described. Use of newer devices may offer advantages such as improved control of device placement, use of a single instead of multiple devices, and high rates of occlusion. Methods: A retrospective review of all patients catheterized for CAF from July 2002 through August 2005 was performed. Results: Thirteen patients with CAF underwent cardiac catheterization, of which a total of 6 patients had ADO placement in CAF (age, 21 days to 56 years; median age, 4.3 years and weight, 3.8 kg to 74.6 kg; median weight, 13.3 kg). An arteriovenous wire loop was used to advance a long sheath antegrade to deploy the ADO in the CAF. Immediate and short-term outcomes (follow-up, 3 months to 14 months; median follow-up, 8.5 months) demonstrated complete CAF occlusion in 5 patients and minimal residual shunt in 1 patient (who had resolution of right atrial and right ventricular enlargement). On follow-up clinical evaluation, all 6 patients had absence of fistula-related murmurs, and 2 previously symptomatic patients had resolution of congestive heart failure symptoms. Early complications included transient palpitations and atrial arrhythmia in the 2 oldest patients (52 and 56 years old). Conclusions: Use of the ADO is applicable for transcatheter closure of significant CAF. Advantages of using the ADO include the antegrade approach, use of a single device, and effective CAF occlusion. © 2006 Wiley-Liss, Inc. [source] Evaluation of an Inexpensive Small-Diameter Temperature Logger for Documenting Ground Water,River InteractionsGROUND WATER MONITORING & REMEDIATION, Issue 4 2005Adam N. Johnson Increasing numbers of studies are recording detailed temperature data for characterization of ground water,stream exchange. We examined laboratory and field operation of a small-diameter, stand-alone and inexpensive temperature logger capable of investigating stream,ground water exchange was examined. The Thermochron iButton is a 17.35-mm-diameter by 6-mm-thick instrument that costs <$10 when ordered in quantity. Testing of the loggers in a controlled temperature bath revealed a precision of ±0.4°C and an accuracy of ±0.5°C for a group of 201. More than 500 loggers have been installed in channels and in subchannel and floodplain ground water environments in two gravel-bedded rivers in the western United States. Loggers were placed as single devices and in vertical arrays in monitoring wells with diameters of 10.16, 5.08, 2.54, and 1.9 cm. We determined that the loggers have four principal advantages over more commonly used wired and currently available stand-alone logging devices: (1) the wireless nature does not require the instrument location to be associated with a control-recording system; (2) the small size allows for installation in small hand-driven or direct-push monitoring wells and thus intimate contact of the instruments with the hydrologic environment; (3) multiple loggers are easily suspended in a single fully perforated monitoring well, allowing for the collection of high-resolution temperature profile data; and (4) the low cost of the loggers allows for the deployment of large numbers, thus improving spatial resolution in shallow ground water floodplain scale studies. [source] | ||||||||||||||||