Measurement Of Oxygen Content Research Articles

Cardiac Output Technologies with Special Reference to the Horse

Critical illness, anesthesia, primary cardiovascular disease, and exercise may result in marked hemodynamic alterations. Measuring cardiac output (CO) is central to defining these alterations for both clinician and researcher. In the past 10 years, several new methods of measuring CO have been developed for the human medical market. Some of these methods are now validated in the horse and are in clinical use. The Fick method has been used in equine research for more than a century. It depends on simultaneous measurement of mixed venous (pulmonary arterial) and peripheral arterial oxygen content and oxygen uptake by the lungs. The technique is technically demanding, which restricts its clinical use. Indicator dilution techniques, with indocyanine green, cold (thermodilution), or lithium as the marker, have also been widely used in the horse. The indocyanine technique is cumbersome, and thermodilution requires right heart catheterization, which is not a benign procedure, making both of these methods less than ideal for clinical use. Lithium dilution requires catheterization of a peripheral artery and a jugular vein. It has recently been validated in anesthetized adult horses and neonatal foals. Doppler echocardiography is a noninvasive ultrasound-based technique. More accurate measurements are obtained with transesophageal than with transthoracic measurements; however, both methods require considerable technical expertise. Bioimpedance and pulse contour analysis are 2 new methods that have yet to be validated in the horse. With the currently available technology, lithium dilution appears to be the method of measuring CO best suited to the equine clinic.

Scientific and technological aspects of oxygen-sensitive electrodes for measurements of oxygen partial pressure in patch-clamp experiments

Anoxia/hypoxia induces dramatic changes in brain activity leading to the damages in brain structure. Several minutes of decrease in environmental oxygen partial pressure ( P O 2 ) can irreversibly destroy nerve cells. Therefore, investigations of intracellular mechanisms responsible for hypoxia-induced changes of mammalian nerve system are very important. On-line adjustment and measurements of P O 2 in bath solution during patch-clamp experiments are especially topical. At the recent time, a special interest on the on-line measurements of oxygen contents in bath solution has appeared as a result of application of old approaches previously used for polarographic measurements of oxygen contents in the blood and tissues. Here we describe the simple method of manufacturing oxygen-sensitive microelectrodes, which can be used with standard patch-clamp amplifier. We also describe the main principles of polarographic method and properties of oxygen-sensitive electrodes used in patch-clamp experiments.

Plasma sprayed coatings for RF wave absorption

High requirements for fusion reactor materials and for experimental fusion devices have led within the fusion community to the development and testing of various coatings of the surfaces of in-vessel components and biological shields for microwave heating systems. Based on contacts with ITER, W7X and the Spanish Stellarator TJ-II, IPP Prague has initiated a development, production and test program on various low- Z materials. This paper reports on the production, development and properties of B 4C, Si and Al 2O 3 coatings sprayed by water stabilized plasma. Main focus is on their radio frequency wave reflection properties. Further characterization includes the coating structure by microscopy, phase composition by X-ray diffraction and oxygen content measurement by atomic absorption spectroscopy. The results are discussed with respect to processing conditions as well as potential application.

Increased blood oxygen affinity during digestion in the snake Python molurus.

Many snakes exhibit large increases in metabolic rate during digestion that place extensive demands on efficient oxygen transport. In the present study, we describe blood oxygen affinity following three weeks of fasting and 48 h after feeding in the Burmese python (Python molurus). We also report simultaneous measurements of arterial blood gases and haematological parameters. Arterial blood was obtained from chronically implanted catheters, and blood oxygen-dissociation curves were constructed from oxygen content measurements at known oxygen partial pressure (P(O(2))) values at 2% and 5% CO(2). Arterial pH remained constant at approximately 7.6 after feeding, but digestion was associated with an approximately 6 mmol l(-1) increase in [HCO(3)(-)], while CO(2) partial pressure (P(CO(2))) increased from 2.21+/-0.13 kPa in fasted animals to 2.89+/-0.17 kPa at 48 h after feeding. Blood oxygen affinity in vivo was predicted on the basis of pH in vivo and the blood oxygen-dissociation curves obtained in vitro. The blood oxygen affinity in vivo increased during digestion, with P(50) values decreasing from 4.58+/-0.11 kPa to 3.53+/-0.24 kPa. This increase was associated with a significant decrease in the red blood cell [NTP]/[Hb(4)] ratio (relationship between the concentrations of organic phosphates and total haemoglobin) and a significant decrease in mean cellular haemoglobin content, which is indicative of swelling of the red blood cells. Our data for blood oxygen affinity and arterial oxygen levels, together with previously published values of oxygen uptake and blood flows, allow for a quantitative evaluation of oxygen transport during digestion. This analysis shows that a large part of the increased metabolism during digestion is supported by an increased venous extraction, while arterial P(O(2)) (Pa(O(2))) and haemoglobin saturation do not vary with digestive status. Thus, we predict that venous P(O(2)) (Pv(O(2))) is reduced from a fasting value of 5.2 kPa to 1.6 kPa during digestion.

Nondestructive Measurement of Oxygen in Modified Atmosphere Packaged Hams Using a Phase‐Fluorimetric Sensor System

ABSTRACT: The phase‐fluorimetric oxygen sensing system recently developed by our team was used for nondestructive measurement of oxygen content in the heasdspace of 4 types of ham slice products. The system allowed accurate measurement of oxygen levels in all types of ham packs in a contact‐less nondestructive fashion; it worked satisfactorily under ambient light and in conditions of direct contact with packaged cooked ham slices and variation of sample temperature. A primary screening for oxygen content of the modified atmosphere packs revealed that a significant proportion of packs contained elevated levels of oxygen. The sensor demonstrated minor changes in calibration as a result of direct physical contact with food and prolonged exposure.

Developmental and neurologic outcomes late after neonatal corrective surgery

J Thorac Cardiovasc Surg 2002;124:425-7

Palladseite and its oxidation: evidence from Au-Pd vein-type mineralization (jacutinga), Cauê iron-ore mine, Quadrilátero Ferrífero, Minas Gerais, Brazil

AbstractPalladseite (palladium selenide) and palladian gold occur as euhedral inclusions in specularite and as infill of microfractures and interstices in magnetite aggregates (host rock fragments) within specularite-rich auriferous veins (jacutinga). Palladseite has minor amounts of Pt (0.6–3.5 wt.%), Cu (2.9–3.5 wt.%), Hg (0.9–1.9 wt.%), and Ag (0.3–0.5 wt.%). The palladian gold contains up to 6 wt.% Pd, and minor Cu and Ag. Isomertieite (Pd11Sb2As2) and sudovikovite (PtSe2) are also recorded. The veins cross-cut the main tectonic foliation of the wallrock (itabirite). The feature of fracture infill and the Se-Sb-As-Hg-Cu-Ag geochemical/mineralogical signature of the Au-Pd mineralization point to a post-ductile deformation and possibly low-temperature (epithermal) origin of the jacutinga mineralization style.Palladseite is replaced locally by a Pd-rich oxidation phase. Electron microprobe analysis of alteration halos around palladseite yields 76–80 wt.% Pd. Oxygen calculated by stoichiometry accords with a monoxide compound of the type PdO. However, the measured oxygen content is lower than expected for the PdO stoichiometry, suggesting loss of volatile species, and a more ‘hydrated’ compound, such as an oxyhydroxide.

Optimisation of colour stability of cured ham during packaging and retail display by a multifactorial design

A multifactorial design, including (1) percent residual oxygen, (2) oxygen transmission rate of packaging film (OTR), (3) product to headspace volume ratio, (4) illuminance level and (5) nitrite level during curing, was established to investigate factors affecting light-induced oxidative discoloration of cured ham (packaged in modified atmosphere of 20% carbon dioxide and balanced with nitrogen) during 14 days of chill storage. Univariate statistical analysis found significant effects of all main factors on the redness (tristimulus a-value) of the ham. Subsequently, Response Surface Modelling of the data further proved that the interactions between packaging and storage conditions are important when optimising colour stability. The measured content of oxygen in the headspace was incorporated in the model and the interaction between measured oxygen content in the headspace and the product to headspace volume ratio was found to be crucial. Thus, it is not enough to keep the headspace oxygen level low, if the headspace volume at the same time is large, there will still be sufficient oxygen for colour deteriorating processes to take place.

Deuteron induced gamma-ray emission method applied at a nuclear microprobe for carbon and oxygen content measurements

The deuteron induced gamma-ray emission (DIGE) method is not usually used for analytical purposes at nuclear microprobes; therefore we show here its capabilities at the microprobe facility of the Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI). In this paper the compositional analysis of magnetic spherules carried out earlier [Nucl. Instr. and Meth B 181 (2001) 557] is combined with the determination of their carbon and oxygen contents, elements which (beside nitrogen and hydrogen) play a relevant role in the study of planetary evolution and in the elucidation of the composition of cosmic parent bodies.

Discussion

Discussion

Structural studies of the superconducting La2.5Y0.5CaBa3(Cu1-xFex)7Oz(0 ≤ x ≤ 0.1) perovskite system by neutron diffraction

We have investigated the effect of Fe substitution on the structural and superconducting properties of La2.5Y0.5CaBa3(Cu1−x Fe x )7O z system by Rietveld refinement of the neutron diffraction patterns of three samples with x = 0.02 (labelled B1), x = 0.06 (B2), and x = 0.10 (B3) along with X-ray diffraction, resistivity, AC susceptibility, and oxygen-content measurements. Samples B1, B2, and B3 are superconducting with T c R=0 values of 73, 62, and 41 K, respectively. Neutron diffraction studies confirm (i) the formation of a single phase tetragonal structure (space group P4/mmm) for all three samples, (ii) Ca and Y ions substitution at the La site concomitantly displaces La onto Ba sites, and (iii) increasing x from 0.02 to 0.10 increases oxygen content (the amount of oxygen per unit cell), as well as Cu(1)— O(4) and Cu(1)— O(1) bond lengths whereas Cu(2)— O(4) bond length decreases with corresponding decrease in T c to 41 K due to increasing occupancy of Fe ions at Cu(2) site. The change in bond lengths with oxygen content are essentially the same as those of Fe content (x). Present studies establish a correlation between the bond lengths (Cu(1)— O(1), Cu(1)— O(4), and Cu(2)— O(4)) and the measured T c values of three samples.

Oximetry with a multiple wavelength SLO.

Oximetry may be useful for understanding pathologies of the eye. We use a prototype scanning laser ophthalmoscope capable of simultaneous multiple wavelength imaging to record fundus images. The system is run under non-confocal conditions in using slit apertures with a width of up to 600 microm. The laser lines launched into the SLO were the 633 nm line of a HeNe-laser, and the 815 nm line from a tunable (700 to 900 nm) cw Ti:Sapphire-laser. These wavelengths were selected because of their availability and absorption characteristics. The difference in absorption at these two wavelengths is used to assess blood oxygen content. Images were averaged to improve the signal to noise ratio. This simultaneous method of measuring oxygen content may be preferred to other techniques such as sequential SLO imaging at different wavelengths, or spot analysis using a modified fundus camera. The advantages of this technique are that image registration is not required, and a large area of the retina can be assessed concurrently.

Effect of hole filling by Co and hole doping by Ca on the superconductivity of GdBa2Cu3O7−δ

The structural and superconducting properties of Cu–Co and coupled Gd–Ca/Cu–Co substitution in GdBa2Cu3O7−δ have been studied by X-ray diffraction for crystal structure determination, resistivity, a.c. susceptibility for Tc determination and iodometry for oxygen content measurements. The oxides (Gd1−yCay)Ba2(Cu1−xCox)3O7−δ have been synthesised for 0.0≤x≤0.15 and 0.0≤y≤0.45. The effect of increasing Co-concentration in GdBa2(Cu1−xCox)3O7−δ for 0.0≤x≤0.15 is to lower the carrier concentration and decrease Tc which is attributed to the hole filling by Co. This suppression in Tc has been compensated for by appropriate hole doping with Ca, in (Gd1−yCay)Ba2(Cu1−xCox)3O7−δ which shows that for a fixed Co-content Tc increases dramatically as the Ca-content increases leading for instance to the oxides x=0.1, y=0.3; x=0.12, y=0.36 and x=0.15, y=0.45 with respective Tc’s of 83 K, 68 K and 63 K whereas the nonsubstituted phases x=0.1, 0.12, 0.15, y=0.0 don’t superconduct.

Effect of Cu-Ga and coupled Nd-Ca/Cu-Ga substitution on thesuperconductivity of NdBa2Cu3O7-δ

The structural and superconducting properties of(Nd1-yCay)Ba2(Cu1-xGax)3Oz samples have been studiedby x-ray diffraction, resistivity, ac susceptibility and oxygen contentmeasurements. The effect of increasing the Ga concentration inNdBa2(Cu1-xGax)3Oz reduces the orthorhombicity without muchdisturbing the oxygen-vacancy order. This is accompanied by an increase in thenormal state resistivity and decreases in both the carrier concentration andTc, which is attributed to hole filling by Ga. This suppression of Tchas been compensated by appropriate hole doping with Ca in(Nd1-yCay)Ba2(Cu1-xGax)3Oz, which shows that for afixed Ga content Tc increases dramatically as the Ca content increases. Forinstance, in the oxide(Nd1-yCay)Ba2(Cu0.94Ga0.06)3Oz, the Tc increasesfrom 0 K (y = 0.0, semiconductor) to 76 K (y = 0.36, compensated oxide) as thehole filling by Ga is nearly balanced by hole doping from Ca.

Correlation between Tc and hole concentration in superconducting NdBa 2(Cu 1− xGa x) 3O z system

The structural and superconducting properties of Ga substituted for Cu in NdBa 2Cu 3O 7− δ samples have been studied by X-ray diffraction, resistivity, AC susceptibility and oxygen content measurements. The effect of increasing Ga concentration in NdBa 2(Cu 1− x Ga x ) 3O z reduces orthorhombicity very fast displaying the destruction of oxygen vacancy order (OVO) for x⩾0.03 accompanied by an increase in the normal state resistivity and decreases both carrier concentration and T c, which is attributed to hole filling by Ga. The calculated hole concentration from oxygen content data and T c display a strong correlation between the two.

Monitorage du traumatisé crânien grave durant les 24 premières heures

Monitoring of severely head-injured patients during the first 24 hours. Monitoring of severely head-injured patients is essential to optimize cerebral haemodynamics and thus to limit intracranial hypertension and to prevent the occurrence of secondary systemic cerebral injuries. It includes continuous measurement of intracranial pressure, mean arterial pressure and venous jugular oxygen saturation. Assessment of circulatory velocity in the arteries of the polygon of Willis allows identification of intracranial hypertension, and later, a vasospasm in case of subarachnoid haemorrage. Near infrared spectroscopy is an indirect indicator of cerebral oxygenation. This technique has not yet been validated. Direct tissue measurement of cerebral oxygen content is the most recently developed monitoring tool. Its clinical range of application has still to be specified. These basic monitoring techniques are a standard. They are essential for an undelayed and efficient treatment of complications occurring in head trauma patients.

INTRODUCTION TO MONITORING IN THE NEUROLOGICAL INTENSIVE CARE UNIT AND ITS FUTURE IMPACT

BACKGROUND- Effective management of the medical and surgical aspects of patients who are treated in neurological intensive care units (NICUs) depends on periodic neurological assessment of brain function. This assessment can be aided by application of various monitoring tools on a periodic or continuous basis. REVIEW SUMMARY- Intracranial pressure monitoring is standard in NICUs and allows for the continuous measurement of cerebral perfusion pressure. Transcranial Doppler can provide information about pending cerebral vasospasm after subarachnoid hemorrhage and can measure cerebral vasoreactivity. Jugular venous oximetry monitoring has been applied to patients with head injury. Paired measurement of both intracranial pressure and jugular venous oxygen content provides useful information to manage blood pressure, ventilation, and osmotherapy in patients with head injury. Continuous EEG may identify unsuspected nonconvulsive status epilepticus and when applied to all NICU patients may provide important information for medical decision making. Evoked potentials are useful in establishing prognosis for both adults and neonates. CONCLUSIONS- The continuous measure of brain function of patients in NICUs is technologically feasible and devices that provide this information in real time are now commercially available. It is hoped that these devices can improve patient outcome and hospital efficiency. (THE NEUROLOGIST 6:83-97, 2000)

Role of calcium in the evolution of superconductivity in a (La2-xRx)Ba2(CayCu4+y)Oz (R = Y, Er, Gd) system

It has been reported that, by adding equal amounts of CaO and CuO to non superconducting La3Ba3Cu6O z (La-336), a series of superconductors with nominal compositions La3Ca y Ba3Cu6+yO z were prepared with maximum Tonc ∼ 80K. Similar studies on addition of CaO and CuO in nonsuperconducting LaBaCu2O z (La-112) resulted into superconducting LaCaBaCu3O z (La-1113). To date no attempt has been made to synthesize La2CaBa2Cu5O z (La-2125) superconducting phase by addition of CaO and CuO to non superconducting La2Ba2Cu4O z (La-224) system. Also no reports are published to study the effect of replacing larger La3+-ions (1.01A) by smaller rare earth ions viz Y3+(0.89A), Er3+(0.91A), Gd3+(0.91A) on the structural and superconducting properties of (La2−xR x )Ba2(Ca y Cu4+y)O z (LRBCaC); 0.0 ≤ x ≤ 0.5; y=2x system. In this paper, we report the method of synthesis, structural and superconducting property characterization using X-ray diffraction, oxygen content measurements using iodometry, resistivity measurements using d.c. four probe technique and a.c. susceptibility measurements in the temperature range RT to 15K. Also a comparative study, on the evolution of superconducting phase with Ca-concentration for different rare earth substitutions for LRBCaC system in the context of hole doping mechanism, is carried out.

Activity of Ga<SUB>2</SUB>O<SUB>3</SUB> in B<SUB>2</SUB>O<SUB>3</SUB> Flux and Standard Free Energies of Formation of GaBO<SUB>3</SUB> and InBO<SUB>3</SUB>

The equilibrium between liquid III group metal and B2O3 flux was investigated thermodynamically as a fundamental study on impurity control in single crystal growth of III–V group compound semiconductors. The oxygen distribution ratio between gallium melt and B2O3 flux and the activity of Ga2O3 in B2O3 flux were clarified at 1373 and 1273 K by measuring oxygen contents in gallium melt and Ga2O3 contents in B2O3 flux. The standard free energies of formation of GaBO3 and InBO3 were determined by measuring oxygen content of liquid III group metal (gallium or indium) equilibrated with B2O3 flux and GaBO3 or InBO3:ΔGGaBO3°=−1.14×106+251T (J) (T: 1123∼1173 K)ΔGInBO3°=−1.02×106+220T (J) (T: 1223∼1373 K)

Oximetric and capnometric studies--aspects of natural and artificial ventilation.

Methods and instrumentation of own design and their application to the measurement of oxygen and CO2 content in blood and respiration gases are discussed. Spectrophotometry, particularly double wavelength colorimetry using red light and IR light, applied to the measurement of oxygen blood saturation for in vitro examination and through an intravascular catheter for invasive in vivo study and by means of pulse oximetry for non-invasive in vivo examination are presented. The electrochemical methods applied to in vitro and in vivo measurement of oxygen in blood (amperometric method) and in respiration gases (amperometric and fuel cell methods) are discussed. The electrochemical Stow-Severinghaus method of CO2 tension measurement in blood and CO2 partial pressure in respiratory gases as well as the selective IR light (4.26 microm) absorption method and instruments of own design for CO2 measurements in respiratory gases are also discussed. The methods and instrumentation described are very important for monitoring respiratory and circulatory function, particularly during artificial ventilation and circulatory support.