• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 305
  • 70
  • 44
  • 27
  • 27
  • 18
  • 16
  • 14
  • 10
  • 6
  • 5
  • 3
  • 2
  • 2
  • 2
  • Tagged with
  • 664
  • 257
  • 139
  • 117
  • 61
  • 59
  • 49
  • 45
  • 45
  • 44
  • 43
  • 42
  • 41
  • 41
  • 40
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Cell Manipulations with Dielectrophoresis

Lin, James Ting-Yu January 2007 (has links)
Biological sample analysis is a costly and time-consuming process. It involves highly trained technicians operating large and expensive instruments in a temperature and dust controlled environment. In the world of rising healthcare cost, the drive towards a more cost-effective solution calls for a point-of-care device that performs accurate analyses of human blood samples. To achieve this goal, today's bulky laboratory instruments need to be scaled down and integrated on a single microchip of only a few square centimeters or millimeters in size. Dielectrophoresis (DEP), a phenomenon where small particles such as human blood cells are manipulated by non-uniform electric fields, stands to feature prominently in the point-of-care device. An original device that enhances DEP effect through novel geometry of the electrodes is presented. When activated with two inverting sinusoidal waveforms, the novel-shaped electrodes generate horizontal bands of increasing electric fields on the surface of the microchip. With these bands of electric fields, particles can be manipulated to form a straight horizontal line at a predictable location. Experimental results showing the collection, separation, and transportation of mammalian cells are presented. A strategy for simultaneous processing of two or more types of particles is also demonstrated. With capabilities for an accurate position control and an increased throughput by parallel processing, the novel microchip device delivers substantial improvements over the existing DEP designs. The research presented here explores the effects of novel electrode geometries in cell manipulations and contributes to the overall progress of an automated blood analysis system.
92

Microfabricated Multi-Analysis System for Electrophysiological Studies of Single Cells

Han, Arum 14 July 2005 (has links)
A micro-electrophysiological analysis system (-EPAS) using various microfabrication techniques for single cell study was developed. Conventional microfabrication techniques combined with plastic and polymer microfabrication techniques have been used to realize the system. The system is capable of performing patch clamp recording and whole cell electrical impedance spectroscopy (EIS) on a single cell. Methodologies for single cell manipulation were developed. The ion channel activities of primary cultured bovine chromaffin cells were measured in both the patch clamping mode and the whole cell EIS mode. Membrane capacitance of the chromaffin cell was calculated from these measurements. Increases in the capacitances were observed when certain ion channels were blocked using toxins. The dielectric properties of human breast cancer cell lines from different pathological stages were measured and compared to a normal human breast cell line in the whole cell EIS mode. The measured properties were correlated to the pathological stages of the breast cancer cell lines. Decreases in the membrane capacitances were observed for the more pathologically progressed cancer cell lines.
93

Application of Lab VIEW in Smart Home Surveillance Systems

Chen, Kun-Wei 23 June 2011 (has links)
The objective of this research is to study smart home network systems and the application of Lab VIEW to develop man machine interface (MMI) so that traditional instrument panels can be replaced with virtual panels to reduce the consumption of hardware resources. For energy efficiency, the focus is on using MATLAB¡¦s fuzzy toolbox as the computing center and applying it to both lighting and air-conditioning systems. This thesis also looks into the use of Lab VIEW¡¦s CGI tools to develop remote monitoring functions as well as embedding the network related syntax into the Web pages. The user not only can use his/her computer equipment, but also their mobile devices (cell phone, PDA, pad, etc.) to link up to the networks and conduct remote monitoring, which enhances convenience and security. Hardware using wired control (PCI, Ethernet) and wireless control (ZigBee) could monitor the information from the components and transmit it to the computer for processing using the aforementioned method, and finally send it to the control end to complete the monitoring process. Choosing ZigBee wireless control is because it is more energy saving and network friendly than other wireless devices.It will have were opportunities to be used in home applications in the future. This thesis also integrates a fuzzy control for the power consumption. Test results show that adding fuzzy control can reduce power consumption. Besides using computers for remote monitoring functions, cell phones and pads were used as well.
94

Energy Savings Analysis and Full Scale Experimental Validation on VRV Air-Conditioning Systems

Ying, Jau 04 July 2007 (has links)
Keywords: EAC, full-scale experimental Validation, ABRI Lab, VRV The VRV air-conditioning system has been gaining overwhelming popularity in recent years due to its superb merits such as high energy efficiency, lower power consumption, low noise and increasing thermal comfort. During last phase of study, computer simulation using the DOE 2.1 as a tool has been performed systematically to establish a calculation equation for the EAC for Green Building Evaluation Indexes, in replacing the currently adapted fixed constant of 0.8. It is the goal of this year¡¦s project to further validate this equation by conducting a series of full-scale experiments at the ABRI Tainan Laboratory. The experimental result will be organized as a model to revise the equations established during last phase of study with good accuracy. Various different VRV systems which were commercially available on the local air-conditioning market will be adapted so that comparative study can be performed among them. The IPLV curves, which are the essential performance curve of each specific VRV system will then be obtained under local weather conditions. It is expected that through the execution of this project, the calculation equation of the VRV system to be adapted in the Green Building EAC evaluation index will be finalized and validated by the full-scale experiments. The test facilities established during this phase of study will then become the most suitable location of similar tests when building energy conservation is concerned.
95

none

Chien, Lien-yin 25 July 2008 (has links)
This article is about building a dynamic model of an Italian food restaurant in Kaohsiung, Taiwan. The model contains six sectors, including human resource sector, kitchen sector, quality sector, training sector, market sector and the financial sector. Depending on these six sectors we build a computer simulation model. With this computer simulation model can help people get better understanding of the real operational system and can have better insights of the restaurant management. In this article, we found out that the restaurant manager needs to emphasize the quality and training of their employees. If the restaurant grows without enough qualified employees, the growth will meet its limit and has problems like quality decline, working overtime, high turnover rate, customer base decline and may cause the restaurant to close up. In this article, we also found out that the training must both emphasize the professional training and ethic training and it is better to emphasize a little more on the ethic training. If the restaurant managers focus only on the professional training, it will bring serious problems. Since it has many conflicts during the work, the ethic training can help employees having more stable, social emotions for better customer service and build a trust and harmonious working atmosphere. Otherwise, the conflicts between the coworkers may cause service delay, service mistakes, increasing cost and high turnover rate. All these problems will affect the operation of the restaurant management in long term. In this article, the dynamic model contains many soft variables of the restaurant management. It can provide the learner of dynamic model building to learn about the soft variables modeling.
96

Programmable bio-nano-chip immunosensor for multiplexed detection of ovarian cancer biomarkers

Raamanathan, Archana 03 July 2013 (has links)
Ovarian cancer is a high mortality disease where early stage detection may have significant survival benefits. Promising next-generation non-invasive, biomarker-based screening modalities involve longitudinal monitoring of serum biomarkers and multi-marker panel detection. Here, rapid, sensitive, precise and multiplexable diagnostic platforms can facilitate biomarker validation along with early detection and screening, and this work attempts to exploit the programmable bio-nano-chip (p-BNC) immunosensor to address these specific translational needs in ovarian cancer. First, the p-BNC was adapted for Cancer Antigen 125 (CA125) quantitation, the current FDA standard, with prominent implications in novel early detection and screening modalities. Antibody pairs binding to distinct epitopes on CA125 were identified and the p-BNC operating variables (incubation times, flow rates and reagent concentrations) were attuned to deliver optimal analytical performance (inter- and intra-assay precision of 1.2% and 1.9% and Limit-of-Detection (LOD) 1.0 U/mL), competitive with current gold standards, but with a short analysis time of 43 minutes. Further validation of the system with advanced stage patient sera (n=20) demonstrated good correlation with 'gold standard' ELISA (R² = 0.97). Next, the p-BNC was adapted for concomitant analysis of CA125 and Human Epididymis Protein 4 (HE4), a novel multiplexed biomarker panel for early detection and screening. The HE4 immunoassay was developed to perform optimally with the 'rate determining' CA125 assay. Cross-reactivity analysis demonstrated high specificity multiplexing. The dose-response curves for the multiplexed CA125 and HE4 immunoassays were congruous with their singleplex counterparts with respective LODs of 0.51 U/mL and 4.18 pM and a total analysis time of 44 minutes. A small pilot scale clinical study was conducted to discriminate between surgically confirmed patient sera (n=8) and corresponding age-matched healthy controls (n=8) utilizing the multiplexed p-BNC, interpreted with a risk of ovarian malignancy algorithm. Successful discrimination was achieved between the groups with Receiver Operating Characteristic (ROC) curve AUC (Area Under the Curve) values of 1.00, 0.984 and 1.00 respectively for CA125, HE4 and the composite marker combination. Taken together, the analytical and clinical performance, multiplexing capabilities and the short turn-around times on the p-BNC offer methodological advancements over current gold standard techniques, indicating strong promise for ovarian cancer diagnostics. / text
97

Development of a multi-measurement confined free-free resonant column device and initial studies

Pucci, Martin Joseph 20 December 2010 (has links)
This study is comprised of three major parts. The first part involved the development of a multi-measurement, confined, free-free resonant column device. This device was developed to improve upon traditional manually excited, vacuum-confined, free-free methods. The device is capable of testing specimens with diameters up to 6-in., under confinements upwards of 50 psi. The device is composed of a seismic-source system, a data acquisition system and a specimen support and confinement system. The seismic source system is used to induce small-strain constrained compression waves, and longitudinal and torsional stress waves in the specimen. The data acquisition system is used to measure: (1) direct travel time of constrained compression waves, (2) longitudinal resonance in unconstrained compression, and (3) torsional resonance. From these measurements, constrained compression wave velocity, Vp, unconstrained compression wave velocity, Vc, and shear wave velocity, Vs, can be determined. With these wave velocities, small-strain, constrained modulus, Mmax, Young’s modulus, Emax, and shear modulus, Gmax can be determined. Poisson’s ratio is also calculated with the wave velocities. Finally, from the resonance measurements, small-strain material damping in unconstrained compression, DCmin, and in shear, DSmin, can be evaluated. The second part of this study involved verification tests with materials of known dynamic properties. The tests were performed with a manufactured aluminum specimen, ASTM graded Ottawa sand, and crushed rock aggregate base. The results compared well with previous results from similar tests. The third part of this study involved testing artificially cemented ASTM graded Ottawa sand. Cement contents (by weight) of 0.0, 0.5, 1.0 and 2.0%, were used to observe the effect of cementation with curing time at a constant confining pressure of 5 psi. The overall effect of cementation was: (1) a large increase in stiffness, and (2) an increase in material damping. The key effects related to cementation versus curing time are: (1) the increase in wave velocities are reasonably proportional to an increase in cement content up to a curing time of about 5 to 7 days, and (2) after a curing time of 5 to 7 days time the velocity increase with time seems to be similar for all cemented specimens. Additionally, the 2% cemented specimen was tested to observe the effect of confining pressure. The stiffness of this specimen was quite insensitive to confining pressure as was the material damping. / text
98

Development of Microfluidic Chips for High Performance Electrophoresis Separations in Biochemical Applications

Shameli, Seyed Mostafa 15 August 2013 (has links)
Electrophoresis separation corresponds to the motion and separation of dispersed particles under the influence of a constant electric field. In molecular biology, electrophoresis separation plays a major role in identifying, quantifying and studying different biological samples such as proteins, peptides, RNA acids, and DNA. In electrophoresis separation, different characteristics of particles, such as charge to mass ratio, size, and pI, can be used to separate and isolate those particles. For very complex samples, two or more characteristics can be combined to form a multi-dimensional electrophoresis separation system, significantly improving separation efficiency. Much effort has been devoted in recent years to performing electrophoresis separations in microfluidic format. Employing microfluidic technology for this purpose provides several benefits, such as improved transport control, reduced sample volumes, simplicity of operation, portability, greater accessibility, and reduced cost. The aim of this study is to develop microfluidic systems for high-performance separation of biochemical samples using electrophoresis methods. The first part of the thesis concerns the development of a fully integrated microfluidic chip for isoelectric focusing separation of proteins with whole-channel imaging detection. All the challenges posed in fabricating and integrating the chip were addressed. The chip was tested by performing protein and pI marker separations, and the separation results obtained from the chip were compared with those obtained from commercial cartridges. Side-by-side comparison of the results validated the developed chip and fabrication techniques. The research also focuses on improving the peak capacity and separation resolution of two counter-flow gradient electrofocusing methods: Temperature Gradient Focusing (TGF) and Micellar Affinity Gradient Focusing (MAGF). In these techniques, a temperature gradient across a microchannel or capillary is used to separate analytes. With an appropriate buffer, the temperature gradient creates a gradient in the electrophoretic velocity (TGF) or affinity (MAGF) of analytes and, if combined with a bulk counter-flow, ionic species concentrate at unique points where their total velocity is zero, and separate from each other. A bilinear temperature gradient is used along the separation channel to improve both peak capacity and separation resolution simultaneously. The temperature profile along the channel consists of a very sharp gradient used to pre-concentrate the sample, followed by a shallow gradient that increases separation resolution. A simple numerical model was applied to predict the improvement in resolution when using a bilinear gradient. A hybrid PDMS/glass chip integrated with planar micro-heaters for generating bilinear temperature gradients was fabricated using conventional sputtering and soft lithography techniques. A specialized design was developed for the heaters to achieve the desired bilinear profiles using both analytical and numerical modeling. To confirm the temperature profile along the channel, a two-color thermometry technique was also developed for measuring the temperature inside the chip. Separation performance was characterized by separating several different dyes, amino acids and peptides. Experiments showed a dramatic improvement in peak capacity and resolution of both techniques over the standard linear temperature gradients. Next, an analytical model was developed to investigate the effect of bilinear gradients in counter-flow gradient electrofocusing methods. The model provides a general equation for calculating the resolution for different gradients, diffusion coefficients and bulk flow scan rates. The results indicate that a bilinear gradient provides up to 100% improvement in separation resolution over the linear case. Additionally, for some scanning rates, an optimum bilinear gradient can be found that maximizes separation resolution. Numerical modeling was also developed to validate some of the results. The final part of the thesis describes the development of a two-dimensional separation system for protein separation, combining temperature gradient focusing (TGF) and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) in a PDMS/glass microfluidic chip. An experimental study was performed on separating a mixture of proteins using two characteristics: charge to mass ratio, and size. Experimental results showed a dramatic improvement in peak capacity over each of the one-dimensional separation techniques.
99

Towards a portable and inexpensive lab-on-a-chip device for point of care applications

Olanrewaju, Ayokunle Oluwafemi Unknown Date
No description available.
100

High voltage CMOS devices and systems for lab-on-a-chip applications

Al-Haddad, Wesam Ahmed Unknown Date
No description available.

Page generated in 0.0761 seconds