Injection Apparatus Research Articles

High performance liquid chromatography hydride generation in situ trapping graphite furnace atomic absorption spectrometry: A new way of performing speciation analysis using GFAAS as detector

A new procedure for the speciation analysis of hydride forming elements using GFAAS as detector is proposed. The separation of the species is performed by HPLC and the eluent flow is merged with HCl and NaBH 4 solutions moved by peristaltic pumps controlled by a flow injection apparatus. As the species emerges from the column, its respective hydride is formed and carried through the autosampler capillary to an Ir treated graphite tube pre-heated at 300 °C, where it is trapped. After the hydride collection, the autosampler arm is moved from the tube and atomization takes place. The sequence is repeated for the next emerging species. The feasibility of the system was evaluated for the speciation of As (III) and As (V) in waste water samples. The retention times were previously determined using a more concentrated mixed analytical solution and a quartz tube as atomizer. The analytical curves obtained by the proposed procedure showed similar slopes for both species as well as coefficient of regression better than 0.99. Limits of detection were 0.2 ng/mL for both species, 50 times better then the same assembly using a quartz tube atomizer. In the analysis of certified reference materials the sum of the As (III) and As (V) species concentrations were in close agreement with the arsenic concentration certified for total arsenic.

Reformulation of a new vancomycin analog: An example of the importance of buffer species and strength.

The purpose of this research was to use our previously validated dynamic injection apparatus as a rapid method for screening pH-adjusted formulations of a new vancomycin analog, Van-An, for their potential to precipitate upon dilution. In 1 vial, Van-An was reconstituted according to the manufacturer's instructions. In a separate vial, the Van-An formulation's existing phosphate buffer species was supplemented with acetate buffer, which has a pKa in the desired range: between the pH values of the formulation (pH 3.9) and blood (pH 7.4). The formulations were injected using the dynamic injection apparatus into a flowing stream of isotonic Sorensen's phosphate buffer at rates of 0.25, 0.5, 1, and 2 mL/min. The peaks obtained with the spectrophotometer were reproducible for each injection rate/formulation combination. For the phosphate-buffered formulation, the least amount of precipitation was obtained at the 0.25 mL/min injection rate. Acetate buffer was able to substantially reduce such precipitation, even at the highest injection rate. The opacity peaks for the formulation with the acetate addition were significantly smaller (P<.05) than those obtained for the unaltered formulation at all 4 injection rates. The results suggest that acetate is a better buffer species than phosphate for the pH range defined. Furthermore, we present evidence to support a generally applicable approach to screening new formulations of drug products that may be clinically useful for reducing the incidence of phlebitis in humans.

Drip Injection of Chemical Grouts: A New Apparatus

Abstract The tip structure of conventionally used drip injection apparatus for chemical grouting has the defect that the chemical grouts flow upwards to the ground surface frequently, which reduces the accuracy and efficiency of injection significantly. Normally, cement and bentonite are used for sealing the gap between injection tube and drill hole, the performance of which is not satisfactory. In this study, a balloon cover injection tip (called BCIT) has been developed. The special tip structure of the injection tube prohibits the chemical grout flowing upward to the ground surface. In particular, BCIT can implement down-to-up chemical grouting due to its soft and tight attachment with the drill hole sides. The main advantage of the BCIT is its simplicity, portability, adaptability, and accurate injection quantity management. Further, this can be used effectively for small-scale strengthening and preservation of historical remains with complicated geographic features without spoiling their appearance. In the laboratory, the feasibility of BCIT apparatus has been verified by chemical grouting in model ground, which simulates the practical condition of Funasako kiln sites. A soil hardness tester was used to evaluate the strength of the solidified body.

Mass-Production of Pigment Nanocrystals by the Reprecipitation Method and their Encapsulation

ABSTRACT Quinacridone nanocrystals with controlled size and morphology were readily fabricated by using a pump as an injection apparatus of the reprecipitation method for mass-production and injecting concentrated N-methyl-2-pyrrolidinone solution. Encapsulation of quinacridone nanocrystals using polymer was achieved and quite improved dispersibility was confirmed for the encapsulated nanocrystals.

Electron-beam induced deposition of a nanotip within a nano-aperture structure

This work details the electron-beam induced deposition of a nanotip with apical radius <10 nm within the nano-aperture structure present in the nanopentode vacuum nanoelectronic device. Simple vapour priming of the substrate is used to provide the precursor for the deposition, enabling the consistent fabrication of nanotips using conventional electron beam systems without gas precursor injection apparatus. When these tips are grown through nano-apertures with radii ∼50 nm, SEM observations and electrical characterization show that material is deposited on the apertures, which can make contact with the centrally positioned nanotip. While this degrades the electrical isolation between the electrodes in nanopentode devices, it permits the estimation of the deposited material resistivity to be of the order 1 Ωm. Isotropic plasma etching is suggested as a method to improve the inter-electrode electrical isolation.

Medium Throughput pK a Determination of Drugs and Chemicals Using an HPLC Equipped with a DAD as a Flow Injection Apparatus

A semi‐automated method to determine pK a values of drugs and chemicals spectrophotometrically is described. The method uses the capabilities of a HPLC with a diode array detector (DAD) as a flow injection apparatus and a binary solvent delivery system. The advantages of this method are low sample consumption (less than 0.1 mg compound needed), high sample throughput, easy set up, high sensitivity, and low cost, precision within a 0.2 unit. Experimental pK a values obtained for over thirty model compounds are consistent with literature values.

An analytical application of the electrocatalysis of the iodate reduction at tungsten oxide films

Films of non-stoichiometric tungsten oxides have been deposited onto glassy carbon surfaces by electrodeposition from acidic W(VI) solutions and the chemical stability of these oxides was investigated by using the electrochemical quartz crystal microbalance. At these modified surfaces, rotating disc electrode voltammetric experiments indicated that iodate is electrocatalytically reduced in a mass-transport controlled process. The influence of the film thickness on the response to iodate was investigated and the results indicated a linear relationship between catalytic current and film thickness for relatively thin oxide layers. The modified electrode was employed successfully as an amperometric sensor for iodate in a flow injection apparatus. The linear response of the developed method is extended from 5 μmol L −1 to 5 mmol L −1 iodate with a limit of detection (signal-to-noise = 3) of 1.2 μmol L −1. The repeatability of the method for 41 injections of a 1 mmol L −1 iodate solution was 0.8% and the throughput was determined as 123 h −1. Interference from other oxidant anions such as nitrate and nitrite was not noticeable, whereas bromate and chlorate interfere at slight levels. The method was used in the determination of the iodate content in table salt samples.

Fast screening of total flavonols in wines, tea-infusions and tomato juice by flow injection/adsorptive stripping voltammetry

A novel approach for a fast screening of total flavonols (quercetin, kaempferol, myricetin) in wines, tea-infusions and tomato juice using adsorptive stripping voltammetry in a flow injection system is described. The proposed method is based on the property of flavonols to be pre-concentrated on carbon paste electrodes where diphenylether is used as the pasting liquid. The samples are subjected to an acid hydrolysis step and 1 mL sample of the diluted hydrolysate is injected in the flow injection apparatus. After 2 min pre-concentration period (under reciprocated flow) the electrode is washed with Britton–Robinson buffer, pH 5 solution and an anodic voltammetric scan is applied to produce an anodic current peak (analytical signal). The lower determination limits for kaempferol, quercetin and myricetin in pure aqueous solutions were 20, 9 and 25 μg L −1. Mixtures of flavonols resulted into a single anodic peak, which can be used for the calculation of the total flavonols concentration expressed in terms of “quercetin equivalent”. The measurement throughput was about 13 h −1 and the overall reproducibility of measurements was 3–6%. The total concentration of quercetin equivalent in eight tested samples was found in the range 3–60 mg L −1 and the results compare favorably with those obtained by an LC procedure.

Type-III effectors: Sophisticated bacterial virulence factors

Bacterial pathogens cause a wide spectrum of diseases in human and other animals. Some virulence factors, which are referred to as effectors, are directly translocated into the host cell via an injection apparatus, i.e., the type-III secretion system. Most effectors mimic host molecules, and translocated effectors are thereby able to perturb or modulate host cell signaling, cytoskeletal rearrangement, vesicular traffic, and autophagy, thus eliciting disease. Effectors are roughly classified among exotoxins, but in most cases, their functions are exerted focally when they are translocated into the host cell. To cite this article: A. Abe et al., C. R. Biologies 328 (2005).

Novel Polymeric Thin Film Deposition System: Injector‐Apparatus/PECVD Reactor#

A monomer injection apparatus has been developed to be used with a plasma enhanced chemical vapor deposition (PECVD) reactor to deposit polymeric thin films from precursor monomers with boiling points ranging from low to very high. The system (PECVD reactor–injection apparatus) allows deposition of layered, as well as doped, polymeric thin films. Thin film deposition from a mixture of two monomers with very different boiling points—thiophene and 2,3‐dihydrothieno [3,4‐b]‐1,4‐dioxin (EDOT)—and other monomers like dicyclopentadiene (DCPD) and 2‐chloro‐p‐xylene has been performed to demonstrate the capabilities of the deposition system. Thermal analysis of the deposited thin film using microthermal analysis (µTA™) and differential scanning calorimetry performed on deposited films is also presented. The injection apparatus associated with a PECVD reactor proved to be a very versatile tool for novel polymeric thin film deposition. #Dedicated to the Memory of Professor Sukant K. Tripathy.

Acoplamento de cela de difusão gasosa a sistema de análise por injeção seqüencial visando a determinação espectrofotométrica de sulfeto

A new configuration for coupling a gas diffusion cell to a sequential injection system is presented. The matrix exchange is made without the need for additional rotary injection valves or peristaltic pumps, keeping the original mechanical components of the sequential injection apparatus: one syringe pump (or peristaltic pump) and one selection valve. The system was tested constructing analytical curves for sulfide exploring the formation of the methylene blue dye. The proposed method has a detection limit of 60 µg L-1 S2-, with a linear dynamic range between 0.10 and 4.0 mg L-1 S2- concentrations, with a sampling frequency of 20 h-1.

Electrochemical modulation of antigen–antibody binding

The label-free amperometric detection of a rabbit IgG antigen by an anti-rabbit IgG antibody is achieved by observing the electrochemistry at a glassy carbon electrode modified with antibody entrapped in an electrodeposited polypyrrole membrane. In a flow injection apparatus the electrode is pulsed between −0.2 and +0.4 V versus Ag/AgCl. The pulsing of the electrode switches the polypyrrole membrane between the oxidised and reduced states. When antigen is injected into the flow stream a change in current is observed at the electrode despite the antigen or antibody being redox inactive at the potentials employed. It is proposed that this current is due to a change in the flux of ions into and out of the polypyrrole matrix during a pulse when the poly-anionic antigen is present. The immunoreaction was reversible because the 200 ms pulse at each potential was too short to allow secondary bonding forces (hydrogen bonding and hydrophobic forces) which are responsible for the strength of the antibody–antigen complex to be established. The consequence of the reversibility of the antigen–antibody binding is a low apparent affinity constant but an easily regenerated recognition interface.

Bacterial Contamination of Recirculating Brine Used in the Commercial Production of Moisture-Enhanced Pork

In a commercial process for the production of moisture-enhanced pork, boneless pork loins were conveyed through a recirculating injection apparatus, and brine (sodium phosphate, sodium chloride, and lemon juice solids) was pumped into the meat through banks of needles inserted automatically into the upper surfaces of cuts. Brine samples were collected at intervals during the production process and analyzed to determine the total plate count and the numbers of lactic acid bacteria, pseudomonads, Brochothrix thermosphacta, and Enterobacteriaceae. Listeria monocytogenes numbers in the brine were determined using a PCR with primers for the hemolysin gene in combination with a most probable numbers determination. Maximum numbers of bacteria (log CFU/ml) recovered from the brine after 2.5 h of recirculation were as follows: total plate count, 4.50; lactic acid bacteria, 2.99; pseudomonads, 3.95; B. thermosphacta, 2.79; and enterics, 3.01. There was an increase in the number of L. monocytogenes in the recirculating brine with time, reaching a maximum of 2.34 log CFU/100 ml after 2.5 h of moisture-enhanced pork production. Thus, recirculating brines can harbor large populations of spoilage bacteria and L. monocytogenes and are an important source of contamination for moisture-enhanced pork.

Prediction of Precipitation-Induced Phlebitis: A Statistical Validation of an In Vitro Model

To avoid phlebitis, new intravenous (IV) parenterals are often screened by injection into animals. This method is not only expensive and time consuming, it is also detrimental to the animals. An alternate method, focusing on precipitation as the cause, uses an in vitro dynamic injection model that requires less money and time and reduces the need for live models. Validation of the dynamic injection apparatus, for predicting mechanical phlebitis, is established. Twenty-one currently marketed IV products were injected into isotonic Sorenson's phosphate buffer flowing at 5 mL/min. The resulting opacities, produced by precipitation, are measured in an ultraviolet flow cell. These opacity data, coupled with literature reports on phlebitis occurrence, were used to generate a logistic regression that indicates the probability of phlebitis given an opacity value measured by the apparatus. Regression results are supported by a receiver operator characteristic curve that establishes the most ideal cut-off opacity value. This opacity value provides the highest combined sensitivity (statistical power) and specificity while minimizing false-positive and false-negative results. Both analyses show that an opacity value of 0.003 best delineates phlebitic and nonphlebitic products. Measures of sensitivity (0.83), specificity (0.93), positive predictive value (0.93), and negative predictive value (0.78) indicate the model's predictive accuracy and reliability. These results support the use of the dynamic model in place of animals for preliminary phlebitis testing of new IV injectables.

Static resistivity image of a cubic saline phantom in magnetic resonance electrical impedance tomography (MREIT)

In magnetic resonance electrical impedance tomography (MREIT) we inject currents through electrodes placed on the surface of a subject and try to reconstruct cross-sectional resistivity (or conductivity) images using internal magnetic flux density as well as boundary voltage measurements. In this paper we present a static resistivity image of a cubic saline phantom (50 × 50 × 50 mm3) containing a cylindrical sausage object with an average resistivity value of 123.7 Ω cm. Our current MREIT system is based on an experimental 0.3 T MRI scanner and a current injection apparatus. We captured MR phase images of the phantom while injecting currents of 28 mA through two pairs of surface electrodes. We computed current density images from magnetic flux density images that are proportional to the MR phase images. From the current density images and boundary voltage data we reconstructed a cross-sectional resistivity image within a central region of 38.5 × 38.5 mm2 at the middle of the phantom using the J-substitution algorithm. The spatial resolution of the reconstructed image was 64 × 64 and the reconstructed average resistivity of the sausage was 117.7 Ω cm. Even though the error in the reconstructed average resistivity value was small, the relative L2-error of the reconstructed image was 25.5% due to the noise in measured MR phase images. We expect improvements in the accuracy by utilizing an MRI scanner with higher SNR and increasing the size of voxels scarifying the spatial resolution.

Automated affinity capture-release of biotin-containing conjugates using a lab-on-valve apparatus coupled to UV/visible and electrospray ionization mass spectrometry.

We report a new method for automated affinity capture and release of biotin-containing conjugates on immobilized streptavidin using a lab-on-valve (LOV) bead injection apparatus. The apparatus is also coupled to UV/visible and electrospray ionization mass spectrometry (ESI-MS) for monitoring the captured and released biotin-containing conjugates. Dissociation rate constants for release from streptavidin of two chromophore-tagged biotin conjugates were measured by UV/visible spectrometry and the dissociation was simultaneously monitored by ESI-MS. The LOV-ESI-MS instrument was also used for repetitive assays of lysosomal beta-galactosidase in human cell homogenates. Fast analysis in 4.5 min/full cycle and robust operation in 60 repetitive analyses are demonstrated that are promising for transfer of the LOV-ESI-MS technology into clinical practice.

Laryngeal collagen injection as an adjunct to medialization laryngoplasty.

Dysphonia associated with laryngeal paralysis may be identified in the short term postoperatively or may develop years after successful medialization laryngoplasty. In selected cases, laryngeal collagen injection permits further medialization of one or both vocal folds by small increments to improve phonation after medialization thyroplasty. The study seeks to determine whether collagen injections result in measurable improvements in voice quality and vocal function when offered to select patients who have received medialization thyroplasty. Retrospective review of patient charts and voice database. Seven patients were treated with Zyderm II collagen using indirect mirror laryngoscopy and a curved injection apparatus. Changes in voice quality and function were assessed by comparing measures obtained before treatment (mean period, 5.6 d), shortly after treatment (mean period, 38.1 d), and in the long term after treatment (mean period, 226 d). Mean self-ratings of the patient, clinician's ratings, and objective measures demonstrated measurable improvement in vocal function after collagen injection. The office-based procedure offers a simple, efficient adjunct to open techniques of medialization laryngoplasty. Techniques of anesthesia, injection, and patient selection are discussed.

Anti-coking air injection apparatus for an internal combustion engine

Ceramic thermal barrier coatings (TBCs) used in gas-turbine engines afford higher operating temperatures, resulting in enhanced efficiencies and performance. However, in the case of syngas-fired engines, fly ash particulate impurities that may be present in syngas can melt on the hotter TBC surfaces and form glassy deposits. These deposits can penetrate the TBCs leading to their failure. In experiments using lignite fly ash to simulate these conditions we show that conventional TBCs of composition 93 wt% ZrO2 + 7 wt% Y2O3 (7YSZ) fabricated using the air plasma spray (APS) process are completely destroyed by the molten fly ash. The molten fly ash is found to penetrate the full thickness of the TBC. The mechanisms by which this occurs appear to be similar to those observed in degradation of 7YSZ TBCs by molten calcium–magnesium–alumino–silicate (CMAS) sand and by molten volcanic ash in aircraft engines. In contrast, APS TBCs of Gd2Zr2O7 composition are highly resistant to attack by molten lignite fly ash under identical conditions, where the molten ash penetrates ∼25% of TBC thickness. This damage mitigation appears to be due to the formation of an impervious, stable crystalline layer at the fly ash/Gd2Zr2O7 TBC interface arresting the penetrating molten-fly-ash front.

Droplet Size and Velocity Distributions of a Transient Hollow-Cone Spray for GDI Engines

An experimental investigation of a gasoline direct injection (GDI) spray, emerging from an electronically controlled swirl-type injector, was carried out at an injection pressure and duration of 7.0 MPa and 3.0 ms, respectively, in an optically accessible vessel, at atmospheric pressure and ambient temperature. The temporal and spatial spray evolution was investigated in terms of global spray structure, interaction with the external gas, time-resolved droplet size and velocity distribution. The measurements were carried out with an AVL Engine Video System with a CCD camera, a frame grabber and a strobe flash triggered by the injection apparatus. Digital image processing software for the study of the global parameters of the spray was used. A particle Doppler analyzer (PDA) system was used to estimate the local droplet size and velocity as function of the radial coordinate and distance from the nozzle. A laser light extinction technique was applied to investigate the region close to the nozzle up to 5 mm. The spray emerging from the nozzle, at an early time, showed a hollow-cone type of structure because of the swirl motion of the fuel in the orifice that produces a rotational momentum at the nozzle exit. The spray starts with a central pre-injection phase followed, later, by the main body characterized by a large cone angle. The interaction of the fuel with the gas in the spray chamber was evidenced; curls on the external boundary and re-filling of the central part of the cone, during the second part of the injection, were observed. Measurements at different locations within the spray showed high values of the droplet velocity close to the nozzle exit at an early time. These high values were found downstream in the final stage of injection. Radial velocities were present along the entire injection process with an outer direction in the first stage, while an inner direction was observed in the second part. The droplet size distribution showed increasing values along the injector axis and towards the periphery of the spray.

99/03132 Rapid injection process and apparatus for producing synthesis gas

99/03132 Rapid injection process and apparatus for producing synthesis gas