Gas Partial Pressure Research Articles

Ab-initio calculation of point defect equilibria during heat treatment: Nitrogen, hydrogen, and silicon doped diamond

Point defects in diamond are responsible for a wide range of optoelectronic properties, making it crucial to engineer defect concentrations for novel applications. However, considering the plethora of defects in co-doped semiconducting and dielectric materials and the dependence of defect formation energies on heat treatment parameters, process-design based on an experimental trial and error approach is not an efficient strategy. This makes it necessary to explore computational pathways for predicting defect equilibria during heat treatments. By considering nitrogen, hydrogen, and silicon doped diamond, we have investigated the pressure dependence of defect formation energies and calculated the defect equilibria during heat treatment of diamond through ab-initio calculations. We have plotted monolithic-Kröger-Vink diagrams for various defects, representing defect concentrations based on process parameters, such as temperature and partial pressure of gases used during heat treatments of diamond. The method demonstrated predicts the majority of experimental data, such as nitrogen aggregation path leading towards the formation of the B center, annealing of the B, H3, N3, and NVHx centers at ultra high temperatures, the thermal stability of the SiV center, and temperature dependence of NV concentration. We demonstrate the possibility of designing heat treatments for diamond and other semiconducting or dielectric materials through ab-initio modeling of defect equilibria.

Experimental determination of N2 solubility in silicate melts and implications for N2–Ar–CO2 fractionation in magmas

The solubility of nitrogen in magmatic melts is key for understanding the degassing of Earth’s interior and formation of Earth’s N-rich atmosphere. We performed high-pressure experiments to determine the solubility of nitrogen at N2-saturation in basaltic to granitic melts at pressures of 0.3–8 GPa, temperatures of 1200–1600 °C, and oxygen fugacities between the Fe–FeO and Ni–NiO oxygen buffers. The solubility and speciation of nitrogen in the quench silicate melts were quantified by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), electron probe microanalyzer (EPMA), and Nano-scale secondary ion mass spectrometry (NanoSIMS). The results show that the predominant N-species in our silicate melts is N2, which dissolves physically by filling the interstitial sites of the silicate melt network. The measured N-solubilities in silicate melts (SN2melt) by using different approaches agree with each other, and they vary from 200 to 17,000 ppm by weight. The SN2melt increases with increasing pressure and/or decreasing silicate melt NBO/T (the ratio of non-bridging oxygens to tetrahedrally coordinated cations), but it is temperature-independent. Using our newly obtained SN2melt and previous SN2melt and SArmelt data, we develop an empirical model that describes the physical dissolution of N2 and Ar in silicate melts as a function of gas partial pressure and silicate melt composition, and this model can be used to predict SN2melt and SArmelt in magmatic melts of Earth’s mantle and crust. The comparison of our SN2melt data with previous SArmelt and SCO2melt data shows that the solubility in granitic melts is in the order of SArmelt >SCO2melt >SN2melt, but in basaltic melts it is in the order of SCO2melt >SArmelt > SN2melt. The lower SN2melt than SArmelt at Earth’s mantle and crustal conditions suggests N2–Ar fractionation during degassing of mid-ocean ridge basalts and arc magmas. Therefore, the N2/Ar ratios in degassed magmas may not fully represent those in their mantle source regions. The solubility-controlled, preferential degassing of N2 relative to CO2 in Earth’s oxidized shallow magma ocean, in conjunction with collision-induced atmospheric loss, can explain the superchondritic C/N ratio in the bulk silicate Earth. However, the two orders of magnitude higher N2/36Ar ratio in Earth’s mantle than in atmosphere could have resulted from preferential retention of reduced N-species in Earth’s reduced silicate magma ocean or preferential deep subduction of nitrogen.

Ceiling-controlled versus staged decompression: comparison between decompression duration and tissue tensions.

In dissolved gas decompression algorithms, the ceiling is the depth at which the dissolved gas pressure in at least one tissue equals the maximum tolerated value defined by the algorithm. Staged decompression prescribes stationary stops in three-metre intervals so as to never exceed this maximum tolerated value. This keeps the diver deeper than the ceiling until the ceiling itself decreases to coincide with the next, three-metre shallower stage. Ceiling-controlled decompression follows the ceiling in a continuous ascent. Mathematical simulations using the ZH-L16C decompression algorithm and gradient factors were carried out for several dive profiles to compare patterns of tissue gas supersaturation and overall decompression times for decompressions based on these approaches. During a stationary staged decompression stop the available pressure gradient for inert gas washout diminished as inert gas is washed out while inhaled inert gas partial pressure remained unchanged. Ceiling-controlled decompression, on the other hand, maintained the available pressure gradient for inert gas washout at its maximum tolerated level. Decompressions were 4-12% shorter using ceiling-controlled approaches but at the cost of exposing tissues with faster half times to higher levels of supersaturation than they would experience during staged decompression. Ceiling controlled approaches accelerate decompression but the effect of this on the risk of decompression sickness is unknown.

Charge transfer mechanism in KNbO3 dispersed composites of monovalent alkali carbonate

The ferroelectric phase KNbO3 dispersed composites of Na2CO3 were prepared and studied for its applicability as an electrolyte/sensing electrode in electrochemical sensors. The composites were characterized with in-situ impedance measurements under different CO2 gas partial pressures and transport number measurements. The dispersoid was found modifying the conduction mechanism of ions as revealed from impedance spectroscopy. The electrolyte showed variation in the electrical conductivities in presence of the test gas. Significant improvement in the response time of the electrochemical CO2 gas sensor was observed while using this composite as an electrolyte cum sensing electrode.

A computationally efficient jaya optimization for fuel cell maximum power tracking

ABSTRACT Fuel cells typically exhibit non-linear, convex P − I characteristics with a single peak power-point for a constant temperature, membrane water content (MWC), hydrogen gas, and oxygen partial pressure. In this paper, a Jaya algorithm-based maximum power point tracking (MPPT) is developed for fast and accurate peak power tracking of a proton exchange membrane fuel cell (PEMFC). Most of the conventional MPPT algorithms are prone to continual steady-state oscillations. Further, most meta-heuristic MPPT algorithms use a PID controller to track the peak power-point. The use of combined meta-heuristic and PID controller affects the efficiency of MPPT since it is strongly dependent on PID controller gains and meta-heuristic optimization parameters. In this paper, a Jaya algorithm-based MPPT tracking approach without a PID controller is developed to fulfill the MPP of a PEMFC. The Jaya algorithm-based MPPT solution ensures a global maximum peak power-point solution that is independent of solver parameters. The efficacy of the proposed Jaya MPPT is evaluated by performing various simulation studies under various operating conditions with different perturbations and compared against widely accepted particle swarm optimization (PSO), conventional perturb and observe (P&O)-based MPPT techniques. The proposed method can track a maximum power of 1411.02 W within two iterations as compared to method particle swarm optimization (PSO), conventional perturb and observe (P&O), which could track a maximum power of 1376.11 W and 1370.4 W, respectively. Thus, giving an additional increase in power efficiency 2.53% Jaya algorithm. Furthermore, the proposed approach delivered an improved output power efficiency of 11.28% compared to the fuel cell operation without MPPT. Further, the real-time feasibility of the proposed algorithm is also validated by developing a hardware prototype and performing various case studies to track MPPT under different operating conditions and perturbations.

A study of the gas interference effects in quadrupole mass spectrometer

In most applications, it is significant to understand how the composition and total pressure of the gas affect the sensitivity of a mass spectrometer for a specific composition of the gas. This work reports on the interference effects of the QMG700 quadrupole mass spectrometer (QMS) with the use of the ultrahigh vacuum partial pressure standard apparatus and standard leaks. Six combinations for Ar–H2, Ar–He, N2–H2, He–H2, He–N2 and CH4–N2–Ar–He–H2 gas mixtures were selected for the study of the instrument–gas interaction. The partial pressures of the interference gases varied in the range of 2.2 × 10−7–8.3 × 10−3Pa, and the total pressures of the calibration chamber ranged from 1.2 × 10−5Pa to 9.9 × 10−3 Pa. The detector of the QMS utilized only a Faraday cup, and the results demonstrated that the sensitivity of the trace gas was significantly affected by the interfering gas when the total pressure exceeded about 10−5 Pa. This study was also performed according to ISO TS 20175:2018.

Effects of Using Epidural Analgesia during Delivery on Maternal and Infant Outcomes

Objectives: The aim of the study was to estimate the impact of epidural analgesia (EA) during delivery on maternal and infant outcomes. Design: This was a prospective cohort study. Participants: In total, 159 pregnant multiparas in Women and Children’s Hospital, School of Medicine, Xiamen University from November 2019 to May 2020 were enrolled. Patients were divided into the EA group (n = 80) and no analgesia group (n = 79) based on the choice of the parturients. Methods: The duration of labor, levels of umbilical arterial blood gas (pH and partial pressure oxygen), visual analog score (VAS), and adverse events were evaluated to compare differences between the EA group and no analgesia group, respectively. Results: The duration of labor was prolonged in the entire labor (p = 0.002), and the first stage (p = 0.001) in the EA group compared with the no analgesia group. The second stage of labor and third stage of labor, levels of umbilical arterial blood gas, and 1-min Apgar score in neonates were similar in EA and no analgesia groups (All p > 0.05). After adjusting age, prepregnancy body mass index, and past and present medical history, the VAS was low in the EA group compared with the no analgesia group when the uterine orifice was completely open (odds ratio [OR] = 0.001, 95% confidence interval [CI]: 0.001–0.002), 8 h postdelivery (OR = 0.508, 95% CI: 0.264–0.977), and 24 h postdelivery (OR = 0.321, 95% CI: 0.167–0.617). EA increased the proportion of adverse events occurring 5 min postdelivery (χ2 = 10.137, p = 0.001), while decreased the proportion of adverse events occurring 24 h postdelivery (χ2 = 4.750, p = 0.029). Limitations: In terms of the effects of EA on neonates, we only measured the 1-min Apgar score of neonates. Conclusions: EA might be a reliable pain relief method for pregnant women. The results of our study might give a reference for the use of EA during delivery in clinic.

Wholebody Simulator Connected With Lung Simulator for Educational Purposes

The modern trend is to include the novel equipment into the education. The ASL 5000 is a precise simulator of lung mechanics with possible settings of a large amount of intrapulmonary parameters. The ECS simulator can simulate gas diffusion from the lungs to the blood and vice versa, and computes blood pH, partial pressures of blood gases, oxygen saturation etc. This study describes a connection between these two simulators with regard to the optimal use of the properties of both simulators. This connection enables monitoring of lung mechanics and gas diffusion at the same time. The aim of the study is to describe the connection of the systems for the education of the practically oriented students.

Main control factors and prediction model of flow-accelerated CO2/H2S synergistic corrosion for X65 steel

As an important infrastructure for offshore petroleum development, submarine pipelines are the lifeline of offshore petroleum resources development. However, the medium flow containing H2S and CO2 threatens the normal production of oil fields. Based on 18 groups of orthogonal experiments, considering CO2 partial pressure, H2S partial pressure, temperature, pH, chloride concentration and liquid flow rate, the general and local corrosion rate were obtained. The corrosion products were characterized with SEM/EDS and XRD. The main controlling factors and corrosion mechanism were explored. Under the experimental conditions, CO2 and H2S were the main controlling factors of general and local corrosion. With the increase of gas partial pressure, the corrosion rate increaseed gradually. Flow accelerated the synergistic corrosion mechanism and model were established. Within the working condition range, the prediction error was less than 20%, which was better than ECE prediction model. The results can improve the integrity management of submarine pipelines.

Thermodynamic calculation and microstructure characterization of spinel formation in MgO–Al2O3–C refractories

In this paper, by simulating the gas phase conditions inside the MgO–Al2O3–C refractories during continuous casting process and combining with thermodynamic analysis, as well as SEM analysis, the gas-gas and gas-solid formation of MA spinel were clarified in carbon containing refractories. Thermodynamic calculations showed that gas partial pressure of CO, O2 and Mg could meet the formation and stable existence conditions of MA spinel in MgO–Al2O3–C refractories under service environment, and nitrogen could not affect the formation of MA spinel at 1550 °C in the thermodynamic condition. The formation processes of MA spinel were analyzed experimentally under embedding carbon atmosphere. The carbon-coated alumina powders in MgO–Al2O3–C refractories prevented the direct contact between magnesia and alumina. Mg gas was formed by carbon thermal reaction, then reacted with alumina (gas-solid) and gas containing aluminum (gas-gas) to generate MA spinel. Through gas-gas or gas-solid reaction, the formation of MA spinel was effectively controlled. By means of SEM analysis, a two-layer structure with dense outer spinel layer and loose inner layer was formed in MgO–Al2O3–C refractories.

High Mobility and Photo‐Bias Stable Metal Oxide Thin‐Film Transistors Engineered by Gradient Doping

AbstractDoping of oxygen‐deficient binder is an efficient way to alleviate the photo‐bias instability issue of oxide thin‐film transistors (TFTs). However, almost all dopants are working as electron suppressors and degrading mobility. Here we report an effective three‐level O‐anti|O|O‐N (OI|OII|N) gradient doping solution to overcome the adverse mobility‐stability trade‐off in N‐doped InGaZnO (IGZO:N) TFTs. 100 nm‐thick IGZO:OI|IGZO:OII|IGZO:N (IGZO:OI|OII|N) junctionless channel layers are fabricated by varying the partial pressures of oxygen and nitrogen doping gases. Best balance between improved performance and negligible degraded stability is first engineered by reducing the back‐channel IGZO:N depth close to the theoretical diffusion length of photo‐excited holes and forming two‐level graded IGZO:OII|N (40 nm|60 nm) TFTs. Much improved performance and comparable stability are further induced by incorporating ~1.5 nm percolation conduct IGZO:OI at the front‐channel to enhance accumulation. The three‐level graded IGZO:OI|OII|N TFTs exhibit high mobility (34.25 cm2 V−1 s−1) and good photo‐bias stability (∆Vth = −0.85 V@10 000 cd m−2, 3.0 h), which are 2~5‐fold superior to those of the controlled two‐level graded IGZO:OI|N TFTs, IGZO:OII|N TFTs, and homogeneous IGZO:OII TFTs, IGZO:N TFTs. The fabrication of high mobility and photo‐bias stable IGZO TFTs paves the way to future high‐performance oxide electronics.

Field emission energy distribution studies of single multi-walled carbon nanotube emitter with gas adsorptions

The field emission electron energy distribution (FEED) investigation on the individual carbon nanotube (CNT) is a powerful approach to study the intrinsic electronic properties, including the work function and field emission energy level, for CNT devices. We fabricated the single multi-walled carbon nanotube (MWNT) emitter by the solution evaporation dielectrophoretic process after the chemical vapor deposition (CVD) synthesis of the MWNT film. The FEED properties of the MWNT emitter in hydrogen and nitrogen environments were investigated. The FEED peaks shifted up gradually in both hydrogen and nitrogen ambiences, indicating the effective work function reduction effect with gas adsorptions. The amounts of spectrum displacements increased with raising gas partial pressures, with larger displacements of up to 0.65 eV for hydrogen between 10−7 Pa and 10−4 Pa. The double peak spectra imply that emission electrons could be from the hexagonal and the pentagonal carbons. Meanwhile, high carbon content was detected in the ultimate vacuum, attributed highly to the MWNT etching from the emission. This investigation suggests that the work function variation plays key role for the field emission instability and the pressure sensing effect of CNT emitters.

Competitive adsorption characteristics based on partial pressure and adsorption mechanism of CO2/CH4 mixture in shale pores

• Gas partial pressure is the decisive factor under certain temperature and pore size. • Each adsorption layer of mixture gas can be explained by monolayer adsorption theory. • Appropriate timing and amount of CO 2 injection were proposed for CS-EGR technology. In the context that CS-EGR technology has received more and more attention, molecular dynamics simulation method was used to analyze the competitive adsorption characteristics and mechanism of CO 2 /CH 4 mixture in graphene-MMT heterogeneous surface pores. In the case of certain temperature and pore size, the gas partial pressure of mixture is found to be the decisive factor of the competitive adsorption behavior. It’s better to describe the competitive adsorption behavior by gas partial pressure. Langmuir equation was applied to fitting adsorption isotherm in the first adsorption layer and the second adsorption layer. The good fitting results indicate that although the competitive adsorption mechanism of CO 2 /CH 4 mixture can’t be considered as monolayer adsorption due to the existence of multiple adsorption layers, each adsorption layer can be explained by Langmuir adsorption theory. To enhance the CH 4 recovery and CO 2 storage, the appropriate timing and amount of CO 2 injection were proposed. The pressure should be reduced to as low as possible in the first pressure drawdown process, because the first pressure drawdown is obviously beneficial to CH 4 production. The Ratio should be controlled not to exceed 1.11 ∼ 1.21 when injecting CO 2 . The operation recommendations can effectively enhance the shale gas recovery and CO 2 storage and may help to optimize the design of CS-EGR technology.

Thermodynamics and kinetics of in situ synthesized In-P melt by the phosphorus injection and its solidification behavior

In the study, the thermodynamics and kinetics of phosphorus injected into indium melt has been investigated. The partial pressures of the phosphorus gases, P(g), P2(g) and P4(g), in equilibrium with the In-P melt with different concentrations is calculated from 1345 to 1700 K. Based on the thermodynamic analysis, the kinetic process of phosphorus injection synthesis has been studied in details, which involves the relationship among the absorption rate, synthesis efficiency, bubble diameter, rising distance of bubble, bubbling rate, injection rate, environmental pressure and melt concentration. The calculated absorption rate is in good agreement with the experimental data. Based on the kinetic analysis, 20 kg InP polycrystals are synthesized in 3 h by optimizing the synthesis parameters. It is found that local indium and phosphorus separation occurs near the bottom of the ingot during solidification from the P-rich melt. The phosphorus depositions present the radioactivity round rod, columnar polyhedron and fibrous characteristics. The formation mechanism of the separation phenomenon is analyzed. Finally, the methods of obtaining stoichiometric and P-rich polycrystals are put forward.

Origin of Enhanced Ammonia Synthesis on Ru–Co Catalysts Unraveled by Density Functional Theory

Bimetallic Ru–Co catalysts have been reported as promising NH3 production catalysts that are better than various Ru–X alloys, including RuFe and pure Ru, under mild conditions; however, a systematic understanding of their superior activity is still lacking. Here, we report a comprehensive theoretical study on NH3 synthesis of Ru–Co catalysts using density functional theory and microkinetic modeling. Indeed, the RuCo surface enables more facile N2 dissociation than the Ru surface, which results from the manifested Co-induced spin symmetry breaking of Ru. We also investigated the surface phase diagram of RuCo(0001) with partial pressures of H2 and N2 gases and found that the most stable phase of the RuCo surface consists of a fraction of both N and H atoms under experimental Haber–Bosch pressure conditions; however, NH3 can be readily produced on the surfaces without severe surface poisoning issues. Furthermore, this study shows that the spin-symmetry breaking of nonmagnetic surfaces can enhance the catalytic activity for NH3 synthesis, which provides an alternative strategy to catalyst design.

Effects of temperature and pressure on chemical vapour deposition in micro-nano porous structure in char layer of polymer composites

The char layer is an important barrier that resists ablation. During chemical vapour deposition (CVD), hydrocarbons from pyrolysis gas densify the porosity of the char layer, which can enhance the char layer by improving its mechanical properties, and its ability to resist mechanical erosion by gases and particulate erosion. The conditions for depositing gaseous hydrocarbons in the porous structure of the char layer differ from those under circumfluence and large-scale deposition in the pores. Therefore, investigating the deposition characteristics of pyrolysis gases in the char layer is of great significance for establishing a strength model of the char layer and an ablation model of the polymer composites. In this study, the effects of the deposition temperature and gas partial pressure on the CVD characteristics of propylene at 1000–1400 °C were studied by simulating the deposition mode in the porous structure of the char layer based on a high-temperature reaction platform. The experimental results show that the deposition rate in the char layer is much higher than that under circumfluence and large-scale deposition in the pores. Moreover, in contrast with the exponential relationship between the deposition rate and reaction temperature under circumfluence and large-scale pore deposition, there is a well-established linear relationship between these variables during deposition of the char layer. Based on these results, it can be inferred that the micro-nano and honeycomb porous structure of the char layer increased the reaction area, affected the flow state, and changed the kinetics of the depositional reaction.

УЛЬТРАФИОЛЕТОВАЯ ФОТОМОДИФИКАЦИЯ КРОВИ У ПАЦИЕНТОВ С ОСТРЫМ КОРОНАРНЫМ СИНДРОМОМ БЕЗ ПОДЬЕМА СЕГМЕНТА ST (ЧАСТЬ 1). ФОТОХИМИЧЕСКИЕ РЕАКЦИИ

Objective. To specify photochemical reactions, occurring in the blood of patients with non-ST elevation acute coronary syndrome (NSTE-ACS), followed by the study of the mechanisms of alterations of ultraviolet blood modification (UVBM) into biological reactions. Methods. We studied 90 blood samples from patients with NSTE-ACS, receiving complex treatment that included UVBM by mercury lamp radiation with blood taken from the ulnar vein (device "Nadezhda"), the course of treatment consisted of 5 procedures conducted daily. We compared absorption spectra of blood and erythrocytes, results of optical oximetry, spectrophotometry, data of general blood analysis before UVBM, during individual procedures and 20-30 minutes after the end of the course. Results. We have studied the effect of UVBM on patients with NSTE-ACS. Based on the results of spectral and clinical studies of blood, patterns of its photomodification under the influence of ultraviolet (UV) radiation were found. The spectra of blood absorption and blood oxygenation were evaluated in patients whose complex treatment included five courses of UVBM along with traditional drug therapy. It is noted that UV radiation leads to photomodification of blood, changes in the partial pressure of blood gases, changes in the level of oxyhemoglobin and the degree of hemoglobin oxygen saturation. UVBM is proven as an effective method of non-drug treatment of patients with NSTE-ACS. Conclusion. UVBM, influencing the oxygen metabolism in patients with NSTE-ACS, increases the oxygen capacity of the blood, reduces the oxygen demand by the tissues. Photoinduced changes in the degree of hemoglobin oxygen saturation are determined by the individual sensitivity of patients to UV radiation and can be controlled by venous blood oxygenation as the best way to individualize therapy.

Switching of N- and P-Type Doping with Partial Pressure of Oxygen Gas on Few Layers Mos2-Field Effect Transistor

Switching of N- and P-Type Doping with Partial Pressure of Oxygen Gas on Few Layers Mos2-Field Effect Transistor

Influence of protective lung ventilation on arterial-to-end tidal carbon dioxide gradient during one lung ventilation: A prospective observational study

Background: One lung ventilation (OLV) results in a ventilation-perfusion (V/Q) mismatch. Protective lung ventilation (PLV) reduces postoperative pulmonary complications following OLV. However, PLV predisposes to areas of atelectasis in the ventilated lung and worsens the V/Q mismatch. Aim of Study: To evaluate the gradient between arterial carbon dioxide tension (PaCO2) and partial pressure of end-tidal carbon dioxide gas (ETCO2) during OLV using PLV. The second objective was to see if a high gradient could be predicted based on preoperative pulmonary function tests (PFTs), American Society of Anesthesiologists Physical Status (ASA-PS) or intraoperative haemodynamic changes. Patients and Methods: The PaCO2 and ETCO2 during two lung ventilation (TLV) and OLV were noted with patient in the lateral position. The PaCO2-ETCO2 gradients during TLV and OLV were calculated. The mean values of PaCO2, ETCO2 and PaCO2-ETCO2 gradient were compared for OLV and TLV. For gradients above 8 mm Hg, PFT, ASA-PS grade and blood pressure were assessed to identify any clinical association. Results: Sixty patients were enrolled in the study. The mean values of PaCO2 were 38.17 and 44.02 mm Hg during TLV and OLV respectively. The mean values of ETCO2 were 31.31 and 34.53 mm Hg during TLV and OLV respectively. The mean PaCO2-ETCO2 gradient was 6.74 and 9.71 mm Hg during TLV and OLV respectively. These values were significantly lower during TLV than OLV. Conclusion: ETCO2 does not correspond with PaCO2 during OLV using PLV. It is not possible to predict which patients will show a higher PaCO2-ETCO2 gradient. This study could not find any clinical association between the preoperative PFT, ASA-PS grade or intraoperative haemodynamics when PaCO2-ETCO2 gradient was greater than 8 mm Hg.

Effect of intravenous butorphanol infusion on the minimum alveolar concentration of isoflurane in cats

ObjectiveTo determine the effect of butorphanol, administered by intravenous (IV) infusion, on the minimum alveolar concentration of isoflurane (MACISO) in cats and to examine the dosage dependence of this effect. Study designRandomized, placebo-controlled, crossover experimental study. AnimalsA group of six healthy adult male neutered cats. MethodsCats were anesthetized with isoflurane in oxygen. A venous catheter was placed for fluid and drug administration, and an arterial catheter was placed for measurement of arterial pressure and blood sampling. Four treatments were administered at random with at least 2 week interval between treatments: saline (control), butorphanol low dosage (treatment LD; 0.25 mg kg–1 IV bolus followed by 85 μg kg–1 minute–1 for 20 minutes, then 43 μg kg–1 minute–1 for 40 minutes, then 19 μg kg–1 minute–1), medium dosage (treatment MD, double the dosages in LD) and high dosage (treatment HD, quadruple the dosages in LD). MACISO was determined in duplicate using the bracketing technique and tail clamping. Pulse rate, arterial pressure, hemoglobin oxygen saturation, end-tidal partial pressure of carbon dioxide and arterial blood gas and pH were measured. ResultsButorphanol reduced MACISO in a dosage-dependent manner, by 23 ± 8%, 37 ± 12% and 68 ± 10% (mean ± standard deviation) in treatments LD, MD and HD, respectively. The main cardiopulmonary effect observed was a decrease in pulse rate, significant in treatment HD compared with control. Conclusions and clinical relevanceButorphanol caused a dosage-dependent MACISO reduction in cats. IV infusion of butorphanol may be of interest for partial IV anesthesia in cats.