device optimization
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We have developed a new microextraction technique for equilibrium, non-exhaustive analyte preconcentration from aqueous solutions into organic solvents lighter than water. The key point of the method is application of specially designed and optimized bell-shaped extraction device, BSED. The technique has been tested and applied to the preconcentration of selected volatile and semi volatile compounds which were determined by gas chromatography/mass spectrometry in spiked water samples. The significant parameters of the extraction have been found using chemometric procedures and these parameters were optimized using the central composite design (CCD) for two solvents. The analyte preconcentration factors were in a range from 8.3 to 161.8 (repeatability from 7 to 14%) for heptane, and 50.0-105.0 (repeatability from 0 to 5%) for tert-butyl acetate. The reproducibility of the technique was within 1-8%. The values of limits of detection and determination were 0.1-3.3 ng mL(-1) for heptane and 0.3-10.7 ng mL(-1) for tert-butyl acetate. The new microextraction technique has been found to be a cheap, simple and flexible alternative to the common procedures, such as SPME or LLME. This BSED-LLME technique can also be combined with other separation methods, e.g., HPLC or CE.
- MeSH
- chemické látky znečišťující vodu analýza izolace a purifikace MeSH
- design vybavení MeSH
- mikroextrakce kapalné fáze přístrojové vybavení metody MeSH
- minerální vody analýza MeSH
- pitná voda analýza MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí metody MeSH
- reprodukovatelnost výsledků MeSH
- voda analýza MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
BACKGROUND: Device-based algorithms offer the potential for automated optimization of cardiac resynchronization therapy (CRT), but the process for accepting them into clinical use is currently still ad-hoc, rather than based on pre-clinical and clinical testing of specific features of validity. We investigated how the QuickOpt-guided VV delay (VVD) programming performs against the clinical and engineering heuristic of QRS complex shortening by CRT. METHODS: A prospective, 2-center study enrolled 37 consecutive patients with CRT. QRS complex duration (QRSd) was assessed during intrinsic atrioventricular conduction, synchronous biventricular pacing, and biventricular pacing with QuickOpt-proposed VVD. The measurements were done manually by electronic calipers in signal-averaged and magnified 12-lead QRS complexes. RESULTS: Native QRSd was 174 ± 22 ms. Biventricular pacing with empiric AVD and synchronous VVD resulted in QRSd 156 ± 20 ms, a significant narrowing from the baseline QRSd by 17 ± 27 ms, P = 0.0003. In 36 of 37 patients, the QuickOpt algorithm recommended left ventricular preexcitation with VVD of 42 ± 18 ms (median 40 ms; interquartile range 30-55 ms, P <0.00001). QRSd in biventricular pacing with QuickOpt-based VVD was significantly longer compared with synchronous biventricular pacing (168 ± 25 ms vs. 156 ± 20 ms; difference 12 ± 11ms; P <0.00001). This prolongation correlated with the absolute VVD value (R = 0.66, P <0.00001). CONCLUSIONS: QuickOpt algorithm systematically favours a left-preexcitation VVD which translates into a significant prolongation of the QRSd compared to synchronous biventricular pacing. There is no reason to believe that a manipulation that systematically widens QRSd should be considered to optimize physiology. Device-based CRT optimization algorithms should undergo systematic mechanistic pre-clinical evaluation in various scenarios before they are tested in large clinical studies.
A device with four parallel channels was designed and manufactured by 3D printing in titanium. A simple experimental setup allowed splitting of the mobile phase in four parallel streams, such that a single sample could be analysed four times simultaneously. The four capillary channels were filled with a monolithic stationary phase, prepared using a zwitterionic functional monomer in combination with various dimethacrylate cross-linkers. The resulting stationary phases were applicable in both reversed-phase and hydrophilic-interaction retention mechanisms. The mobile-phase composition was optimized by means of a window diagram so as to obtain the highest possible resolution of dopamine precursors and metabolites on all columns. Miniaturized electrochemical detectors with carbon fibres as working electrodes and silver micro-wires as reference electrodes were integrated in the device at the end of each column. Experimental separations were successfully compared with those predicted by a three-parameter retention model. Finally, dopamine was determined in human urine to further confirm applicability of the developed device.
There is a constant need for the development of easy-to-operate systems for the rapid and unambiguous identification of bacterial pathogens in drinking water without the requirement for time-consuming culture processes. In this study, we present a disposable and low-cost lab-on-a-chip device utilizing a nanoporous membrane, which connects two stacked perpendicular microfluidic channels. Whereas one of the channels supplies the sample, the second one attracts it by potential-driven forces. Surface-enhanced Raman spectrometry (SERS) is employed as a reliable detection method for bacteria identification. To gain the effect of surface enhancement, silver nanoparticles were added to the sample. The pores of the membrane act as a filter trapping the bodies of microorganisms as well as clusters of nanoparticles creating suitable conditions for sensitive SERS detection. Therein, we focused on the construction and characterization of the device performance. To demonstrate the functionality of the microfluidic chip, we analyzed common pathogens (Escherichia coli DH5α and Pseudomonas taiwanensis VLB120) from spiked tap water using the optimized experimental parameters. The obtained results confirmed our system to be promising for the construction of a disposable optical platform for reliable and rapid pathogen detection which couples their electrokinetic concentration on the integrated nanoporous membrane with SERS detection.
- MeSH
- design vybavení MeSH
- kovové nanočástice chemie MeSH
- laboratoř na čipu * MeSH
- mikrofluidní analytické techniky přístrojové vybavení MeSH
- pitná voda mikrobiologie MeSH
- Ramanova spektroskopie přístrojové vybavení MeSH
- stříbro chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Liver resection is the standard treatment for any liver lesion. Laparoscopic liver resection is associated with lower intra-operative blood loss and fewer complications than open resection. Access to the posterior part of the right liver lobe is very uncomfortable and difficult for surgeons due the anatomic position, especially when employing laparoscopic surgery. Based on these experiences, a new laparoscopic device was developed that is capable of bending its long axis and allowing the application of radiofrequency energy in areas that were not technically accessible. The device is equipped with four telescopic needle electrodes that cause tissue coagulation after the delivery of radiofrequency energy. Ex vivo testing was performed in 2012 and 2014 at the University Hospital, Ostrava, on a porcine liver tissue. The main goal of this testing was to verify if the newly proposed electrode layout was suitable for sufficient tissue coagulation and creating a safety zone around lesions. During the ex vivo testing, the material of needle electrodes was improved to achieve the lowest possibility of adhesion. The power supply was adjusted from 20 to 120 W and the ablation time, which varied from 10 to 110 s, was monitored. Subsequently, optimal power delivery and time for coagulation was determined. This experimental study demonstrated the feasibility and safety of the newly developed device. Based on the ex vivo testing, LARA-K1 can create a safety zone of coagulation. For further assessment of the new device, an in vivo study should be performed.
- MeSH
- design vybavení * MeSH
- hemostáza chirurgická přístrojové vybavení MeSH
- hepatektomie přístrojové vybavení metody MeSH
- játra chirurgie MeSH
- katetrizační ablace přístrojové vybavení MeSH
- laparoskopie přístrojové vybavení metody MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Optical trapping of particles has become a powerful non-mechanical and non-destructive technique for precise particle positioning. The manipulation of particles in the evanescent field of a channel waveguide potentially allows for sorting and trapping of several particles and cells simultaneously. Channel waveguide designs can be further optimized to increase evanescent field prior to the fabrication process. This is crucial in order to make sure that the surface intensity is sufficient for optical trapping. Simulation configurations are explained in detail with specific simulation flow. Discussion on parameters optimization; physical geometry, optical polarization and wavelength is included in this paper. The effect of physical, optical parameters and beam spot size on evanescent field has been thoroughly discussed. These studies will continue toward the development of a novel copper ion-exchanged waveguide as a method of particle sorting, with biological cell propulsion studies presently underway.
- MeSH
- analýza selhání vybavení MeSH
- design s pomocí počítače MeSH
- design vybavení MeSH
- ionty chemie MeSH
- měď chemie MeSH
- optická pinzeta * MeSH
- počítačová simulace MeSH
- povrchová plasmonová rezonance přístrojové vybavení MeSH
- radiační rozptyl MeSH
- světlo MeSH
- teoretické modely * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
The article presents a new concept of preparative solution IEF where time requirements and efficiency are similar to gel-based IEF whereas simple fraction handling as well as quick and complete protein recovery typical for solution-based IEF methods are maintained. The presented method is based on the IEF in separation medium soaked in a segmented strip of nonwoven fabric. The strip is positioned in an open horizontal V-shaped trough. Suggested focusing method combines free solution IEF under continuous evaporation and whole channel dispensing. Separation medium based on ethylene glycol/water mixture enhances viscosity enough to reduce electroosmosis and prevents the medium from completely drying out. Generation of pH gradient and final local pH is visually traced by colored low-molecular pI markers added to input mixture, which enables an optimization of focusing process and collection of individual fractions at desired pH range. The proposed method was tested by fractionation of the proteins and bioactive peptides originating from raw whey. Moreover, subsequent HPLC analysis of the individually collected solution IEF fractions was used for identification of whey components. We confirmed that the method is capable to process directly few tenths of milliliters of raw samples including the salty ones.
Optimalizace radiační ochrany byla vždy prioritou, zejména v pediatrii. Vzhledem ke stále rostoucímu počtu vyšetření je nutné se zaměřit na základní principy radiační ochrany - zdůvodnění a optimalizaci. Užitečným nástrojem optimalizace je stanovení místních diagnostických referenčních úrovní (MDRÚ). Další klíčovou roli v optimalizaci hraje nastavení a přizpůsobení radiologických přístrojů dětskému pacientovi. I když je každá modalita specifická, lze dodržet několik obecných pravidel. Zásadní je úprava expozičního nastavení, orgánové automatiky, případně použití manuálního režimu. U CT dávku významně ovlivňuje volba správného vyšetřovacího protokolu specifického podle věku, váhy nebo diagnózy. Optimalizace v radiační ochraně představuje komplex vzájemně na sebe navazujících kroků. I v pediatrii optimalizace neznamená, že dávka musí být minimální za každou cenu. Optimalizace znamená, že dávka musí být minimální pro získání kvalitní diagnostické informace.
Optimization of radiation protection has always been a priority, especially in pediatrics. Due to the growing number of examinations it is necessary to focus on the basic principles of radiation protection - justification and optimization. A useful tool for optimaliza-tion is establishing local diagnostic reference levels (DRL). Another key role is the setting and adjustment of the radiological device used for children. Although each modality is specific, some general rules exist. The adjustment of exposure settings, automatic exposure control, or using the manual mode. In CT, the dose is significantly affected by the choice of the right examination protocol according to patient age, bodymass or diagnosis. Optimization of radiation protection is a complex of many interconnected steps. Optimization, also in pediatrics does not mean that the dose must be at minimum at all costs. Optimization means that the dose must be minimal for
- Klíčová slova
- optimalizace radiační ochrany, expoziční nastavení, diagnostické referenční úrovně (DRÚ),
- MeSH
- dávka záření MeSH
- diagnostické techniky a postupy * normy přístrojové vybavení využití MeSH
- dítě MeSH
- lidé MeSH
- pediatrie * MeSH
- počítačová rentgenová tomografie metody přístrojové vybavení využití MeSH
- radiační ochrana metody normy přístrojové vybavení MeSH
- radiografie metody využití MeSH
- referenční standardy MeSH
- statistika jako téma MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- Publikační typ
- přehledy MeSH
BACKGROUND: The HeartMate 3 (HM3) is a Conformiteé Européenne (CE) mark-approved left ventricular assist device (LVAD) with a fully magnetically levitated rotor with features consisting of a wide range of operational speeds, wide flow paths and an artificial pulse. We performed a hemodynamic and echocardiographic evaluation of patients implanted with the HM3 LVAD to assess the speed range for optimal hemodynamic support. METHODS: Sixteen HM3 patients underwent pump speed ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP] and blood pressure [BP]) and 3-dimensional echocardiography (3DE). Data were recorded at up to 13 speed settings. Speed changes were in steps of 100 revolutions per minute (rpm), starting at 4,600 rpm and ramping up to 6,200 rpm. RESULTS: Mean original speed was 5,306 ± 148 rpm, with a majority of patients (10 of 16, 62.5%) having normal CVPs and PCWPs at their original rpm settings. Going from lowest to highest speeds, cardiac output improved at the rate of 0.08 ± 0.08 liter/min per 100 rpm (total change 1.25 ± 1.20 liters/min) and PCWP decreased at the rate of -0.48 ± 0.27 mm Hg per 100 rpm (total change -6.13 ± 3.72 mm Hg). CVP and systolic BP did not change significantly with changes in rpm. Left ventricular end-diastolic dimension (LVEDD) decreased at a rate of -0.15 ± 0.09 cm per 100 rpm. Number of rpm was adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in 13 (81.3%) patients. For the remaining 3 patients, medical management was pursued to optimize hemodynamic support. CONCLUSION: Hemodynamic normalization of pressures was achieved in the majority of patients implanted with the HM3 pump within a narrow speed range.
- MeSH
- časové faktory MeSH
- design vybavení MeSH
- funkce levé komory srdeční fyziologie MeSH
- hemodynamika fyziologie MeSH
- lidé MeSH
- magnetismus přístrojové vybavení MeSH
- následné studie MeSH
- podpůrné srdeční systémy * MeSH
- prospektivní studie MeSH
- senioři MeSH
- srdeční selhání patofyziologie chirurgie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
A simple sample pretreatment device was developed employing extractions across supported liquid membranes (SLMs) and in-line coupling to a commercial CE instrument. The device consisted of two polypropylene conical units interspaced with a polypropylene planar SLM, which were impregnated with 1-ethyl-2-nitrobenzene. The two units and the SLM were pressed against each other, donor unit was filled with 40 μL of an untreated body fluid and acceptor unit with 40 μL of DI water. The device was then placed into conventional CE vial fitted with a soft spring, which was depressed during injection into CE capillary and ensured that the SLM was not ruptured. Position of separation capillary injection end and high-voltage electrode in the CE instrument was optimized in order to ensure efficient injection of pretreated body fluids. The device can be easily assembled/disassembled and SLMs can be replaced after each extraction thus minimizing sample carry-over, avoiding tedious SLM regeneration, and reducing total pretreatment time and costs. The pretreatment device was examined by direct injection of human urine and serum spiked with nortriptyline, haloperidol, and loperamide. The basic drugs were diffusionaly transported across the SLM within 10 min and were injected into the separation capillary directly from the SLM surface in the acceptor unit, whereas matrix components were retained by the SLM. The in-line SLM-CE method showed good repeatability of peak areas (3.8-11.0%) and migration times (below 1.4%), linear relationship (r(2) = 0.990-0.999), and low LODs (12-100 μg/L).
