An Electrokinetically Controlled DNA Hybridization Chip

2004 ◽  
Author(s):  
David Erickson ◽  
Xuezhu Liu ◽  
Ulrich Krull ◽  
Dongqing Li
Keyword(s):  
Dna Hybridization ◽  
Mass Transfer Rate ◽  
Channel Structure ◽  
Nucleic Acid Hybridization ◽  
Recognition Element ◽  
Delivery Technique ◽  
Biological Recognition ◽  
Long Time ◽  
On Line ◽  
Time Required

Biosensors and more specifically biochips exploit the interactions between a target analyte and an immobilized biological recognition element to produce a measurable signal. Systems based on surface phase nucleic acid hybridization, such as modern microarrays, are particularly attractive due to the high degree of selectivity in the binding interactions. One drawback of this reaction is the relatively long time required for complete hybridization to occur, as a result of the diffusion limited reaction kinetics. In this work an electrokinetically controlled DNA hybridization microfluidic chip will be introduced. The electrokinetic delivery technique provides the ability to dispense controlled sample sizes to the hybridization array while serving to increase the mass transfer rate and therefore the reaction speed. The focus of this paper will be on the design and microfabrication of the chip, the unique H-type channel structure and electrokinetic sample delivery and washing technique, and development of the on-line hybridization scanning. Initial hybridization results presented here demonstrate that less than 5 minutes and 4.9nL of 0.5μM ssDNA sample was required (35s dispensing period followed by a 4 minute wash) for complete hybridization.

A DNA Hybridization Chip With Electrokinetically-Based Single Nucleotide Polymorphism (SNP) Discrimination

2004 ◽  
Author(s):  
David Erickson ◽  
Xuezhu Liu ◽  
Roberto Venditti ◽  
Ulrich Krull ◽  
Dongqing Li
Keyword(s):  
Single Nucleotide Polymorphism ◽  
Dna Hybridization ◽  
Muscular Atrophy ◽  
Mass Transfer Rate ◽  
Nucleic Acid Hybridization ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide ◽  
Recognition Element ◽  
Delivery Technique ◽  
Biological Recognition

Biosensors and more specifically biochips exploit the interactions between a target analyte and an immobilized biological recognition element to produce a measurable signal. Systems based on surface phase nucleic acid hybridization, such as modern microarrays, are particularly attractive due to the high degree of selectivity in the binding interactions. In this work an electrokinetically controlled poly(dimethylsiloxane) based DNA hybridization microfluidic chip is presented. The electrokinetic delivery technique provides the ability to dispense controlled sample sizes to the hybridization array for quantitative analysis while serving to increase the mass transfer rate and therefore reduce the overall analysis time. An automatic, electrokinetically based, single-nucleotide polymorphism (SNP) discrimination technique (that takes advantage of the combined effects of joule heating, applied potential field and the shear gradients within the double layer field on the thermodynamic stability of the target: probe complex) will also be described for the first time. The clinical utility of the technique will be demonstrated through the detection of genetic markers associated with spinal muscular atrophy, specifically the common C←T mutation in the SMN1 gene.

On-line image readout in CTEM

1994 ◽  
Vol 52 ◽  
pp. 400-401
Author(s):  
K.-H. Herrmann ◽  
W. D. Rau ◽  
R. Sikeler
Keyword(s):  
Primary Electron ◽  
Digital Information ◽  
Electron Hole ◽  
Detection Technology ◽  
Long Time ◽  
On Line ◽  
Electron Image ◽  
Optical Transfer ◽  
Detection Quantum Efficiency ◽  
Technical Solutions

Quantitative recording of electron patterns and their rapid conversion into digital information is an outstanding goal which the photoplate fails to solve satisfactorily. For a long time, LLL-TV cameras have been used for EM adjustment but due to their inferior pixel number they were never a real alternative to the photoplate. This situation has changed with the availability of scientific grade slow-scan charged coupled devices (CCD) with pixel numbers exceeding 106, photometric accuracy and, by Peltier cooling, both excellent storage and noise figures previously inaccessible in image detection technology. Again the electron image is converted into a photon image fed to the CCD by some light optical transfer link. Subsequently, some technical solutions are discussed using the detection quantum efficiency (DQE), resolution, pixel number and exposure range as figures of merit.A key quantity is the number of electron-hole pairs released in the CCD sensor by a single primary electron (PE) which can be estimated from the energy deposit ΔE in the scintillator,

Effect of Vial shaking on Loading Time of Epirubicin into Drug-Eluting Bead

2015 ◽  
Vol 5 (3) ◽  
Author(s):  
Kenji Ikeda ◽  
Yusuke Kawamura ◽  
Masahiro Kobayashi ◽  
Taito Fukushima ◽  
Yushi Sorin ◽  
...  
Keyword(s):  
Antitumor Agent ◽  
Loading Rates ◽  
Vortex Mixer ◽  
Long Time ◽  
Group A ◽  
Drug Eluting ◽  
Large Hepatocellular Carcinoma ◽  
Group B ◽  
Time Required ◽  
Short Time

Background: Although DC Bead has been useful in treatment of multiple and large hepatocellular carcinoma, loading time of doxorubicin into the DC Bead takes a long time of 30-120 minutes. Epirubicin is also used as an antitumor agent together with DC Bead, but its loading efficiency was not sufficiently elucidated. Methods: To shorten loading time of epirubicin into DC Bead (100-300µm, 300-500µm, 500-700µm), we examined the following three methods after mixing the drug: (a) let stand in room temperature, (b) agitated for 30 seconds with Vortex mixer, and (c) sonicated for 30 seconds with ultrasonic cleaner. After loading of epirubicin by each method, supernatant concentration for epirubicin was assayed at 5, 10, 30, 60, and 120 minutes. Results: Epirubicin loading rates for small bead (100-300µm) at 5 minutes were 82.9 % in group a, 93.8% in group b, and 79.9 % in group c. Similarly, medium bead (300-500µm), 40.1% in group a, 65.7% in group b and 45.5% in group c, respectively. In large-sized bead (500-700µm), loaded rates of epirubicin were 38.8% in group a, 59.0% in group b and 48.0% in group c. Agitation of mixture of epirubicin and DC Bead with Vortex mixer significantly shortened the loading time, but sonication did not affect the time required. Microscopic examination did not lead to any morphological change of microspheres in all the methods. Conclusions: Short time of agitation with Vortex mixer reduced the necessary time for loading of epirubicin in every standard of DC Bead.

scholarly journals A Stochastic Model to Describe the Scattering in the Response of Polysilicon MEMS

2021 ◽  
Vol 2 (1) ◽  
pp. 95
Author(s):  
Luca Dassi ◽  
Marco Merola ◽  
Eleonora Riva ◽  
Angelo Santalucia ◽  
Andrea Venturelli ◽  
...  
Keyword(s):  
Silicon Film ◽  
Micro Fabrication ◽  
Micro Electro Mechanical Systems ◽  
Local Fluctuations ◽  
Stochastic Framework ◽  
On Line ◽  
Chip Testing ◽  
On Chip ◽  
Time Required ◽  
Polycrystalline Silicon Film

The current miniaturization trend in the market of inertial microsystems is leading to movable device parts with sizes comparable to the characteristic length-scale of the polycrystalline silicon film morphology. The relevant output of micro electro-mechanical systems (MEMS) is thus more and more affected by a scattering, induced by features resulting from the micro-fabrication process. We recently proposed an on-chip testing device, specifically designed to enhance the aforementioned scattering in compliance with fabrication constraints. We proved that the experimentally measured scattering cannot be described by allowing only for the morphology-affected mechanical properties of the silicon films, and etch defects must be properly accounted for too. In this work, we discuss a fully stochastic framework allowing for the local fluctuations of the stiffness and of the etch-affected geometry of the silicon film. The provided semi-analytical solution is shown to catch efficiently the measured scattering in the C-V plots collected through the test structure. This approach opens up the possibility to learn on-line specific features of the devices, and to reduce the time required for their calibration.

scholarly journals Patients' anxiety before cardiac catheterization

2010 ◽  
Vol 8 (4) ◽  
pp. 483-487 ◽  
Author(s):  
Leandro Loureiro Buzatto ◽  
Suely Sueko Viski Zanei
Keyword(s):  
Cardiac Catheterization ◽  
Patient Information ◽  
Scientific Publications ◽  
Patient Understanding ◽  
Post Procedure ◽  
Long Time ◽  
On Line ◽  
First Time ◽  
Multiprofessional Approach ◽  
Pharmacologic Therapies

ABSTRACT Objective: To identify researches related to anxiety and strategies to reduce it in patients who are in the pre-cardiac catheterization period. Methods: A bibliographic research was carried out in the on line databases of PubMed, MedLine, CINAHL, LILACS and SciELO, from 1997 to 2009 in MedLine and from 1999 to 2009 in the others databases. The boolean expressions “and” and “or” has been used with the descriptors in Portuguese and in English. The inclusion of discerning was related about the presence, level and workable of the anxiety from the period of pre-cardiac catheterization. Results: Coping most of 17 researches selected were in American scientific publications, with experimental-descriptive studies. The possibilities of intercurrence and/or complications during and post-procedure, diagnostic, possibility of bad prognostic, being alone during the waiting, the first time submission the procedure, lost information and/or orientation and long time waiting could cause anxiety in pre-cardiac catheterization. Maintenance of escort and family alongside the patient, information adapted to the patient understanding level, overcoming traumas and difficulties with a multiprofessional approach, pharmacologic and non pharmacologic therapies were strategies to reduce the anxiety. Conclusions: The nurses are responsible to provide a humanized assistance to offer a fast recuperation, minimize traumas of the hospitalization and the procedure. The knowledge of the causes and the strategies are fundamental to reduce the level of anxiety in pre-catheterization cardiac.

Long Time Coming: Prospects for Democracy in Iraq

2009 ◽  
Vol 33 (4) ◽  
pp. 115-148 ◽  
Author(s):  
Bruce E. Moon
Keyword(s):  
Nineteenth Century ◽  
The Other ◽  
Democratic Transitions ◽  
Quarter Century ◽  
The Past ◽  
Political Experience ◽  
Long Time ◽  
Time Required ◽  
Established Democracies

Prospects for democracy in Iraq should be assessed in light of the historical precedents of nations with comparable political experiences. Saddam Hussein's Iraq was an unusually extreme autocracy, which lasted an unusually long time. Since the end of the nineteenth century, only thirty nations have experienced an autocracy as extreme as Iraq's for a period exceeding two decades. The subsequent political experience of those nations offers a pessimistic forecast for Iraq and similar nations. Only seven of the thirty are now democratic, and only two of them have become established democracies; the democratic experiments in the other five are still in progress. Among the seven, the average time required to transit the path from extreme autocracy to coherent, albeit precarious, democracy has been fifty years, and only two have managed this transition in fewer than twenty-five years. Even this sober assessment is probably too optimistic, because Iraq lacks the structural conditions that theory and evidence indicate have been necessary for successful democratic transitions in the past. Thus, the odds of Iraq achieving democracy in the next quarter century are close to zero, at best about two in thirty, but probably far less.

A Study of Polymers. II. Dynamic Method of Studying Elastic Materials

1940 ◽  
Vol 13 (4) ◽  
pp. 898-904 ◽  
Author(s):  
Yu S. Lazurkin
Keyword(s):  
Elastic Deformation ◽  
Dynamic Tests ◽  
Elastic Materials ◽  
General Picture ◽  
High Frequencies ◽  
Dynamic Conditions ◽  
Automobile Tire ◽  
General Law ◽  
Long Time ◽  
Time Required

Abstract Most articles made from elastic substances are intended for service under dynamic conditions. Static methods of investigation are clearly insufficient for determining the behavior of elastic substances under dynamic conditions and therefore there has for a long time been a need for dynamic tests. In recent years several dynamic tests have been developed, and a number of investigations of elastic properties under dynamic conditions have been published. The works of Frumkin, Roelig, Kosten, Naunton and Waring and other investigators have established a series of relations in the behavior of elastic substances under dynamic conditions. However, the limited intervals of frequency and temperature in these experiments gave relations of peculiar character and even led to contradictions. Thus Naunton and Waring showed that, under dynamic conditions (at high frequencies), automobile tire casings act as solid hoops and, according to Roelig and Kosten, the relation between modulus and frequency, though still existing, is of relatively little importance. The development of a concept of the mechanism of highly elastic deformation, and in particular the disclosure of relaxation made it possible for Kornfel'd and Poznyak and Mikhai˘lov and Kirilina to demonstrate experimentally the existence of a more general law relating the phenomena. However, in their experiments, the frequency in both cases changed within narrow limits, and consequently these investigations too do not give a general picture of the behavior of elastic materials in relation to the frequency of deformation and temperature. The idea of highly elastic deformation, as well as that of relaxation, comes down to the fact that the magnitudes of the deformations observed depend on the relation between the time of action of the force and the time required for regrouping of the particles in the substance during the deformation.

scholarly journals Design of multilayer microfluidic paper chip and its visual detection of pesticide residues

2020 ◽  
Vol 11 ◽  
pp. 170-182
Author(s):  
Li zhi Li ◽  
Han Ping Mao
Keyword(s):  
Pesticide Residues ◽  
Visual Detection ◽  
Channel Structure ◽  
Test Results ◽  
Mixed Effect ◽  
Detection Range ◽  
Long Time ◽  
Paper Chip ◽  
Channel Structures ◽  
High Repeatability

With the increase of China's grain production, the use of pesticides is gradually increasing. Traditional pesticide detection takes a long time and requires expensive experimental instruments, which is not conducive to the rapid and accurate detection of pesticide residues in the field. To solve this problem, this paper proposes a visual detection method of pesticide residues based on multi-layer microfluidic paper chips. The internal channel structure of paper chip is designed from the perspective of efficient mixing. Through the simulation of the mixed effect of three kinds of staggered channel structures, which are arc type, triangle type, and ladder type, the "ladder-type h-0.3, s-2.6" is selected as the best-staggered structure, and the mixing strength is 0.91534. The best simulation structure was tested by a colored reagent, and the image processing of 15 test results was carried out with MATLAB. The average mixing strength was 0.84, and the and the standard deviation was 0.022. The visual detection experiment of acetamiprid and profenofos in cabbage samples was carried out by using the device，The detection range of acetamiprid was 4~72 μg/kg, and the detection range of profenofos was 3~54 μg/kg . The recovery of acetamiprid was 75%~85%, and the recovery of profenofos was 80%~90%. The detection range and recovery rate indicate that the device has high repeatability and accuracy in the actual sample detection

Time- and age-dependent effects of serotonin on gasping and autoresuscitation in neonatal mice

2013 ◽  
Vol 114 (12) ◽  
pp. 1668-1676 ◽  
Author(s):  
Jianping Chen ◽  
Jennifer Magnusson ◽  
Gerard Karsenty ◽  
Kevin J. Cummings
Keyword(s):  
Heart Rate ◽  
Tryptophan Hydroxylase ◽  
Single Injection ◽  
Heart Rate Recovery ◽  
Wild Type ◽  
Tryptophan Hydroxylase 2 ◽  
Age Dependent ◽  
Long Time ◽  
Time Required

The role of brain stem serotonin (5-hydroxytryptamine, 5-HT) in autoresuscitation in neonatal life is unclear. We hypothesized that a specific loss of 5-HT would compromise gasping and autoresuscitation mainly in the second postnatal week and that acute restoration of 5-HT would reverse the defects. We exposed postnatal day (P)4–5, P8–9, and P11–12 tryptophan-hydroxylase-2 knockout ( TPH2−/−) and wild-type littermates (WT) to 10 episodes of anoxia (97% N2, 3% CO2), measuring survival, gasp latency, gasp frequency ( fB), and the time required to restore eupnea and heart rate. We also tested P8–9 TPH2−/− mice after restoring 5-HT with a single injection of 5-hydroxytryptophan (5-HTP) 1–2 h before testing or with multiple injections beginning 24 h before testing. At P4–5 and P8–9, but not at P11–12, gasp latency and the recovery of eupnea were delayed ∼2- to 3-fold in TPH2−/− pups compared with WT ( P < 0.001). At all ages, TPH2−/− pups displayed reduced gasp fB (∼20–30%; P < 0.001) and delayed heart rate recovery (∼60%; P = 0.002) compared with WT littermates. TPH2−/− survival was reduced compared with WT ( P < 0.001), especially at P8–9 and P11–12 ( P = 0.004). Whereas 1–2 h of 5-HTP treatment improved the gasp latency and fB of P8–9 TPH2−/− pups, improved cardiorespiratory recovery and survival required 24 h of treatment. Our data suggest that 5-HT operates over a long time span (∼24 h) to improve survival during episodic severe hypoxia. Early in development (P4–9), 5-HT is critical for both respiratory and cardiovascular components of autoresuscitation; later (P11–12), it is critical mainly for cardiovascular components. Nevertheless, the effect of 5-HT deficiency on survival is most striking from P8 to P12.

Rapid Measurement of Nutation NQR Spectra in Powders Using an RF Pulse Train

1996 ◽  
Vol 51 (5-6) ◽  
pp. 363-367 ◽  
Author(s):  
Nicolai Sinyavsky ◽  
Michał Ostafin ◽  
Mariusz Maćkowiak
Keyword(s):  
Asymmetry Parameter ◽  
Pulse Train ◽  
Pulse Action ◽  
Rf Pulses ◽  
Time Saving ◽  
Long Time ◽  
The Asymmetry ◽  
Rf Pulse ◽  
Time Required

Abstract The method of two-dimensional nutation NQR spectroscopy, introduced by Harbison in 1989, has been successfully used for determining of the asymmetry parameter of the EFG tensor for spin-3/2 nuclei in both powdered and monocrystal samples in the absence of an external magnetic field. The inconvenience inherent in the method, however, is the long time required, because data acquisition must be repeated for various RF pulse lengths. We discuss a method to reduce the time of the nutation experiment by using a sequence of identical short RF pulses of length r w and distance τ. It is shown that for an NQR frequency ω0 , frequency offset Δω, and pulse parameters satisfying the relation ω0τ + Δωtw = 2πk (k = 1, 2, 3,..., n) a synchronism of pulse action takes place and the nutation interferogram can be measured "stroboscopically" between the pulses. The maximum time saving factor that can be obtained as compared to the conventional nutation experiment is of the order of the number of pulses used in a pulse train. The method has been successfully applied for determination of the asymmetry parameter for one of the two 3 5 Cl sites in polycrystalline 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride).

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