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Using Newton's gravitational equation, we have been able to calculate the orbital data of the planets in the solar system more accurately, but there are deviations between these data and astronomical observations. For example, the precession of Mercury's orbit has a deviation of 43" per century. There are two important gravitational theories in modern physics: general relativity (GR) and quantum mechanics, of which GR has given an explanation for the precession deviation of Mercury, so from the perspective of quantum mechanics, can the quantum gravity equation also be derived? Can it be verified in the calculation of planetary orbits in the solar system? This paper will explore these questions.

Background Ridge preservation is performed by placing a biocompatible product, following tooth extraction, to maintain bone volume. However, current ridge preservation therapies do not always maintain the volume required for future implant placement. Variations in surgical technique and material selection contribute to determining clinical outcomes. The wide variety of grafting materials available and conflicting efficacy reports make selecting the appropriate graft materials challenging. To investigate how different commercially available ridge preservation products might perform clinically: Helistat¶ (collagen control) (Material 1), OsteoGen# Plug (Material 2), Bio-Oss Collagen** (Material 3), and J-Bone†† (native bone) (Material 4) were evaluated. Methods These products underwent field emission scanning electron microscopy, microcomputed tomography, helium pycnometry, and infrared spectra analysis. Human osteosarcomas were incubated on products and proliferation was monitored with CCK-8 and visualized with confocal microscopy. Scaffold osteoconductivity was evaluated cellular production of osteocalcin, osteonectin, and osteopontin. Results Results indicated that products varied in porosity and pore interconnectivity. Although Material 3 was chemically similar to Material 4, Material 2 demonstrated significantly better biocompatibility. Functionally, Material 1 and Material 2 elicited higher osteonectin release than Material 3 and Material 4 which suggests the latter products suppress endogenous osteonectin secretion. Furthermore, osteopontin secretion was minimal for all products, while osteocalcin was elevated. This seems to suggest that high levels of mineralization might be deleterious for bone regeneration. Conclusions Although all products are marketed as effective preservation products, the results demonstrated high variability in physical, chemical, and biological effects; however this study suggests a product with higher ratio of collagen to mineral component may have the most desirable effects for the use in alveolar ridge preservation. This article is protected by copyright. All rights reserved.

Since last year, I have conducted in-depth discussions with a physics professor in Austin, Texas, on gravitational fields, gravitational waves, and gravity. At the beginning of this year, I summarized the gravitational equation under the influence of gravitational waves. I applied the new gravitational equation to planetary orbit calculations, and all planetary precession data are basically the same as GR except for Venus, which is 240" vs 8.6" per century. GR does not consider the angle between the planet’s orbital plane and the sun’s vertical plane and also does not consider the eccentricity of the orbit when calculating the planetary precession. However, we need to consider them and consider them as the main factor. This may be the biggest difference between the two. Let’s look at the characteristics of Venus: Venus’s eccentricity is abnormally low (e = 0.0068), which makes its perihelion extremely sensitive to small disturbances. But the angle between its orbit and the vertical plane of the sun is very large 3.39°, so we have reason to believe that gravitational waves will have a great influence on the orbital precession of Venus. I hope my discovery can add a new idea to the development of general relativity. TonyYuan tony1807559167@gmail.com

Background The COVID-19 pandemic has led to an increase in the use of and demand for telehealth services. Objective Here, we describe the utilization of telehealth services provided by Doctor On Demand, Inc., a well-known telehealth company in the United States, before and during the COVID-19 pandemic. We also explore how the number of virtual visits, reasons for visits, and patients served changed over time. Methods We reported data as a percentage change from the baseline week during 2 distinct time periods: February-June 2019 and February-June 2020 based on 4 categories of visits: respiratory illness, unscheduled behavioral health, scheduled behavioral health, and chronic illness. Results In 2020, the total visit volume increased considerably from March through April 7, 2020 (59% above the baseline) and then declined through the week of June 2 (15% above the baseline). Visits for respiratory illnesses increased through the week of March 24 (30% above the baseline) and then steadily declined through the week of June 2 (65% below the baseline). Higher relative increases were observed for unscheduled behavioral health and chronic illness visits through April (109% and 131% above the baseline, respectively) before a decline through the week of June 2 (69% and 37% above the baseline, respectively). Increases in visit volume among rural residents were slightly higher than those among urban residents (peak at 64% vs 58% above the baseline, respectively). Conclusions Although this telehealth service provider observed a substantial increase in the volume of visits during the COVID-19 pandemic, it is interesting to note that this growth was not fueled by COVID-19 concerns but by visits for behavioral health and chronic illness. Telehealth services may play a role as a “safety valve” for patients who have difficulty accessing care during a public health emergency.

BACKGROUND The COVID-19 pandemic has led to an increase in the use of and demand for telehealth services. OBJECTIVE Here, we describe the utilization of telehealth services provided by Doctor On Demand, Inc., a well-known telehealth company in the United States, before and during the COVID-19 pandemic. We also explore how the number of virtual visits, reasons for visits, and patients served changed over time. METHODS We reported data as a percentage change from the baseline week during 2 distinct time periods: February-June 2019 and February-June 2020 based on 4 categories of visits: respiratory illness, unscheduled behavioral health, scheduled behavioral health, and chronic illness. RESULTS In 2020, the total visit volume increased considerably from March through April 7, 2020 (59% above the baseline) and then declined through the week of June 2 (15% above the baseline). Visits for respiratory illnesses increased through the week of March 24 (30% above the baseline) and then steadily declined through the week of June 2 (65% below the baseline). Higher relative increases were observed for unscheduled behavioral health and chronic illness visits through April (109% and 131% above the baseline, respectively) before a decline through the week of June 2 (69% and 37% above the baseline, respectively). Increases in visit volume among rural residents were slightly higher than those among urban residents (peak at 64% vs 58% above the baseline, respectively). CONCLUSIONS Although this telehealth service provider observed a substantial increase in the volume of visits during the COVID-19 pandemic, it is interesting to note that this growth was not fueled by COVID-19 concerns but by visits for behavioral health and chronic illness. Telehealth services may play a role as a “safety valve” for patients who have difficulty accessing care during a public health emergency.

This paper presents a review of the literature, including government legislations, policies, guidelines, and recommendations available in the European Union, the United States of America, and Australia pertaining to the availability, development, and distribution of written medicine information (WMI) for prescription medicines. The online databases searched were Embase, International Pharmaceutical Abstracts, Medline, and PubMed, together with Google as the Internet search engine. The design and content of WMI documents have similarities and differences across all the 3 geographical regions. All the 3 regions have legislations in place to evaluate and regulate WMI documents for health care professionals (HCPs) and, to some degree, for patients; however, the degree of regulation varies between the 3 regions. The regulations around the content and information design of WMI impacts how well the WMI performs and consequently influences patients’ knowledge and medication-taking behavior. Legislation in certain areas could be seen as more beneficial and can be implemented across the 3 regions. Furthermore, the required legislation on the evaluation of the content of WMIs can be seen in some areas to be more stringent and comprehensive, which when taken onboard across the 3 regions can be valuable when creating WMIs for both patients and HCPs.

Widespread prevalence of multidrug and pandrug-resistant bacteria has prompted substantial concern over the global dissemination of antibiotic resistance genes (ARGs). Environmental compartments can behave as genetic reservoirs and hotspots, wherein resistance genes can accumulate and be laterally transferred to clinically relevant pathogens. In this work, we explore the ARG copy quantities in three environmental media distributed across four cities in California and demonstrate that there exist city-to-city disparities in soil and drinking water ARGs. Statistically significant differences in ARGs were identified in soil, where differences in blaSHV gene copies were the most striking; the highest copy numbers were observed in Bakersfield (6.0 × 10–2 copies/16S-rRNA gene copies and 2.6 × 106 copies/g of soil), followed by San Diego (1.8 × 10–3 copies/16S-rRNA gene copies and 3.0 × 104 copies/g of soil), Fresno (1.8 × 10–5 copies/16S-rRNA gene copies and 8.5 × 102 copies/g of soil), and Los Angeles (5.8 × 10–6 copies/16S-rRNA gene copies and 5.6 × 102 copies/g of soil). In addition, ARG copy numbers in the air, water, and soil of each city are contextualized in relation to globally reported quantities and illustrate that individual genes are not necessarily predictors for the environmental resistome as a whole.

T HE miniaturization of space systems, such as microsatellites, has become an important development trend. Using a cluster of microspacecraft with a constellational architecture to replace a traditional spacecraft can greatly reduce the costs of production and launch, increase flexibility, and disperse the risks of a mission. Miniaturized spacecraft are classified based on mass, power, and dimensions. Spacecraft with amass of less than 20 kg are classified as class I microspacecraft [1] and require millinewton-level thrusts for spacecraft control. For microspacecraft, the onboard thrusters must be extremely small and lightweight; microelectromechanical systems (MEMS) are thus employed in microthruster design and fabrication [2]. A number ofmicropropulsion systems have been proposed.Micro cold-gas systems have been constructed and used in practice [3,4]; however, a rather low specific impulse (60–80 s) limits their usage. Micro electric-type thrusters provide a high specific impulse [5], but the requirement of high power for operation limits them to larger spacecraft. Miniaturized solid-propellant thrusters have a simple structure and a high specific impulse [6], but their relatively high thrust level (10–10 mN) and single use restrict their application. Monopropellant thrusters are appropriate for miniaturization due to their simplicity and acceptable working temperatures [7]. The catalytic reaction of monopropellant systems mitigates the constraints of radical quenching and mixing prohibition found in the microcombustion of bipropellant systems. Although hydrogen peroxide/silver systems have been tested and effectively reacted in microreactors, hydrazine is considered a better monopropellant for actual microthruster design and operation [7]. A millinewton hydrazine (N2H4) monopropellant thruster is presented in this work. MEMS technologies are employed in the design. The design considerations and component fabrication are discussed. The vacuum thrust of the designed thruster was measured and its propulsive performance was analyzed.

The combustion phenomena of doublet impingements of nitrogen tetroxide and monomethylhydrazine were observed in this research. The total flow rates of the propellants were controlled at 8:00 g=s to simulate the operation of a 5 lbf rocket, and the ratios of the mass flow rates (O=F) of nitrogen tetroxide and monomethylhydrazine were varied from 1.0 to 2.5. With a two-axis translation module, a C-type thermocouple was used to measure the two-dimensional temperature distributions of the flames at 20 mm downstream of their impinging points. The observations showed that induction distances always appeared from the positions of propellants’ impingement to ignition, and the ignition was induced by the local concentrations of gaseous monomethylhydrazine.Themaximum flamelengthof80 mmappearedatthebestmixingconditionofO=F 1:2, and diffusion-type flames at higher O=F showed shorter flame lengths for poor mixing after the flames had been ignited. Comparing to the previous cold-flow observations by the planar laser induced fluorescence technique with simulants of water- and chloroform-based solutions to match the densities, viscosities, and surface tensions of monomethylhydrazine and nitrogen tetroxide, the locations of high-temperature zones in hot-fire experiments were adequately described by the calculated two-dimensional temperature distributions from the observed local mixture ratio data at the corresponding ignition positions in the cold-flow experiments. These results inferred that the mixture ratio profile was almost conserved after ignition. That is, by properly analyzing the mass distribution of the cold-flow observation with simulants, the temperature distribution of the impinging combustion of nitrogen tetroxide/monomethylhydrazine can be predicted.

Quantitative measurements of radical concentrations are important in studies of the structure of flames. In this research, a quantitative analysis was performed using laser-induced predissociative fluorescence of OH radicals (OH-LIPF) in high-pressure (1–5 atm) premixed methane-air and propane-air flat flames (ϕ = 0.7–1.3). OH was excited (A2Σ+, ν′ = 3 − X2Π, ν″=0, and P28) using a KrF excimer laser and (3,2) band fluorescence was observed. OH fluorescence intensities were calibrated against the OH concentrations calculated from flame simulation results in the postflame zone using the CHEMKIN premix flame code in conjunction with the GRI-Mech 3.0 reaction mechanism. The accuracy and spatial resolution of temperature measurements are important factors for the correctness of the corresponding flame simulations, especially in the reaction zone near the burner surface. In this work, a carefully constructed thermocouple (R-type, 50 µm) positioning system was used to identify the temperatures above the burner surface. With careful evaluations of quenching rates, Voigt profiles, and normalization against room-air N2 Raman scattering intensity, a universal calibration constant [CT = (1.076 ± 0.174) · 1016 molecules/cm3] was determined. The OH concentrations obtained by flame simulations showed good agreement with the quantitative OH-LIPF measurements in all methane-air flames and fuel lean (ϕ = 0.7−0.8) propane-air flames. However, a 2-fold to 5-fold discrepancy was obtained in propane flames at ϕ > 0.9. This may be caused by the lack of C3 reaction paths in the GRI mechanism and/or the inaccuracy of the thermochemical data for large molecules.

Green (low toxicity) liquid rocket propellants have become attractive in recent years due to the features of the low cost and less environmental impact. However, the green propellants, such as kerosene/H2O2, usually have different operational conditions (i.e. relatively high O/F ratio) compared to conventional propellants because of their chemical properties. In this research, a new concept of the two-stage impinging type injector (O-F-F-O) is adopted for investigating the spray mixing at high O/F ratios between 3.75 and 6.25. The impinging distance, jet velocity and impinging angle for the two-stage impinging type injector are design parameters examined, where the impinging angle is more effective at spray atomization and droplet distribution. The PLIF technique is used to measure the droplet distribution so as to identify the spray characteristics. In order to simplify the development process of the injector, the predicted mixture ratio distribution from the individual fuel (F-F) and oxidizer (O-O) sprays by overlapping their averaged images is used to compare with the actual distribution from the two-stage impinging spray (O-F-F-O). At a constant total mass flow rate, results indicate that tendencies towards the variations of the average characteristic velocity (C) with increasing O/F ratios are similar for outcomes of the prediction and actual measurement. Also, there is obvious flow fields interaction between the fuel and oxidizer sprays and coordinating their relative intensities of sprays well can optimize the mixture ratio distribution of the two-stage impinging spray. Better mixing occurs when the fuel and oxidizer sprays have more similar and uniform distributions.

The spray phenomena of doublet and triplet impingements of nitrogen tetroxide (NTO) and monomethylhydrazine (MMH) simulants were studied by the planar laser induced fluorescence technique. The total flow rates of the simulants were controlled at ∼8.00 g/s to simulate the operations of a 5-lb f rocket, and the ratios of the mass flow rates (O/F) of NTO and MMH simulants were varied from 1.0 to 2.4. Statistical analysis was employed to examine the probability distributions of the mass of individual simulants at 10 mm downstream from the impinging point. The distributions of local mixture ratios and flame temperatures were deduced, and the estimation of characteristic exhaust velocity was performed. The results revealed that the breakup and mixing of the impinging jets were closely related to the momentum flux ratio of the jets and the surface tension of the liquids. The triplet impingement was superior in symmetry and uniformity of the spray than that of the doublet impingement, and its mixing was less sensitive to the momentum flux ratio and showed a better mixing effect than doublet impingement at higher O/F ratio conditions. With the detailed distribution information provided by the optical technique, the optimum C* occurred at O/F = 1.18 with doublet impingements for the operation of a 5-lb f NTO/MMH rocket.

Time-averaged, spatially resolved point measurements of temperature, major species concentrations (O 2 , N 2 , H 2 O, H 2 ), and hydroxyl radical concentration (OH) in laminar hydrogen jet diffusion flames ( Re = 30 and 330) are performed using nonintrusive UV Raman scattering coupled with the laser-induced predissociative fluorescence (LIPF) technique for assessment of combustion models. Effects of thermal diffusion and chemical kinetics on the flame structure are investigated by comparing computed results with experimental data. Comparisons of the computed temperature and species concentration profiles with experimental measurements are in good agreement for both flames. The numerical simulations, using the Miller and Bowman mechanism, indicate that thermal diffusion affects the flame structure for the Re = 330 flame, whereas its influence becomes minor for the Re = 30 flame. Effects of chemical kinetics on the flame structure are investigated in the Re = 30 flame using five different H 2 /air reaction mechanisms. Comparisons of the measured and calculated data reveal that this low stretched flame is not very sensitive to the mechanisms used and it may not be suitable for examining the effects of chemical kinetics on the flame structure. Effects of burner wall and coflow boundary conditions on the computed flame structures are also examined in detailed to clarify the importance of boundary conditions in simulating these flames.

The complicated flame stabilization mechanisms and flame/flow interactions in the blowout of turbulent nonpremixed jet flames are experimentally studied using phenomenological observation, 2D Rayleigh scattering, 2D laser-induced predissociative fluorescence (LIPF) images of OH, and particle image velocimetry (PIV) techniques. The blowout process may be categorized into four characteristic regions: pulsating, onset of receding, receding, and extinction. Based on experimental findings, a blowout mechanism is proposed. The maximum “waistline” point of the stoichiometric contour, defined as the point where the radial distance between the elliptic stoichiometric contour and the jet axis reaches a maximum value, can be regarded as the dividing point separating the unstable and stable regions for the lifted flame in the blowout process. If the flame base is pushed beyond the maximum “waistline” point, the flame will step into the pulsating region and become unstable, triggering the blowout process. The triple flame structure is identified and found to play an important role in flame stabilization within the stable liftoff and pulsating regions. In the pulsating region, the stabilization point of the triple flame moves along the stoichiometric contour, stabilizing the flame where the flame base is bounded by the contours of lean and rich limits. If the flame is pushed beyond the tip of the stoichiometric contour, the stabilization point and triple flame structure vanish and the flame becomes lean. The flame then recedes downstream continuously and finally extinguishes.

Ultraviolet (UV) spontaneous vibrational Raman scattering is used for temperature measurements in premixed methane/air flat flames burning at 1-5 bar. The measured spectra indicate that the peak and integrated intensities of the O 2 and N 2 Stokes Raman signals are linearly proportional to pressure at room temperature. Temperature measurements are made by spectral-fit of the theoretical spectra to the measured N 2 Q-branch spectra. The Raman-measured temperatures agree well with the thermocouple-measured temperatures. The line widths (full width at half maximum; FWHM) of the trapezoidal slit function in flames at 1-5 bar are used to extrapolate the line widths for pressures up to 30 bar. The calculated theoretical spectra indicate that the spectral-fit method can be used to determine flame temperature at conditions close to adiabatic and 30 bar with an adequate accuracy.

Acoustically tuned lift-off flame with good repetition of the global flame stabilization process is used for detailed measurements and analysis using the line Raman spectroscopy and laser-induced f...

Experimental measurements of visible flame heights, temperatures, and pollutant emission indices in partially premixed swirling flames with a broad range of central fuel tube equivalence ratios (Φ F ) are reported. Two cases of partially premixed swirling flames are studied; one with a constant fuel tube exit velocity and the other with an increased exit velocity. With increasing partial premixing, the visible flame height decreases and the overall flame color changes from yellow to blue. Temperature measurements indicate that the flame structures become thinner and temperatures increase continuously with increasing partial premixing. Emission index, EINO x and EICO, values decrease with increasing levels of partial premixing and reach a minimum value at Φ F ≈ 3, followed by an increase as Φ F approaches the blowoff limits. The reduction in EINO x and EICO at optimum partial premixing (Φ F ≈ 3), as compared with that for the non-premixed swirling flame is at least 23% and 77%, respectively. The emission index for NO x scales very well with the fuel mass fraction and the fuel-air momentum flux ratio. Good agreement is achieved between the predictions and measured results.

A spontaneous vibrational Raman scattering technique is developed for simultaneous measurements of temperature and multi-species (CO 2 , O 2 , CO. N 2 , CH 4 , H 2 O, H 2 , and OH) concentrations in premixed methane- air flames. The Raman spectra and spectral background are obtained using a narrowband tunable KrF excimer laser working at 248 nm and a spectrometer combined with an intensified CCD camera. Optimal tuning of the narrowband KrF excimer laser (248.632 nm) for minimization of OH A 2 Σ-X 2 II and O 2 B 3 Σ - u - X 3 Σ - g fluorescence interference is determined from fluorescence excitation spectra. Laser emission spectra are made to ensure that the optimum wavelength of the laser is within a good locking region. Natural fluorescence spectra (without laser excitation) are used to determine the gate time of the ICCD camera. Measured Raman spectra demonstrate that single-pulse concentration and temperature measurements, with only minimal fluorescence interference, are possible for turbulent premixed methane-air flames. A time-averaged temperature measurement technique is presented that matches the theoretical spectra to the measured N 2 Stokes Raman spectrum. Methodologies for simultaneous temperature, major species, and OH concentration measurements in turbulent premixed flames are discussed.

The effect of the combustion fluid dynamics of a lifted jet flame with and without acoustic excitation on the control of NOx formation in the flame is investigated. A partially premixed jet was used, operated under lift-off flame bifurcation condition in the hysteresis region. Results show that flame lifting and acoustic excitation are effective in reducing the emission index of NOx (EINOx). A lean premixed condition, achieved by the strong upstream mixing of the lifted flame base, can further reduce NOx formation without increasing CO emissions. The prompt NO mechanisms of super-equilibrium OH concentrations and three-body recombination through N20 intermediates dominate in the initial region close to the flame base of the lean premixed, lifted flame. A lower initial prompt NOx and shorter flame length with reduced flame temperature, caused by the enhanced upstream mixing due to flame lifting and acoustic excitation, result in the low NOx and CO emissions in the present lean premixed jet flame.

By the PLIF optical technique, this study focused on the development of the impinging type injector design of the 100-lbf level monomethylhydrazine/nitrogen tetroxide liquid rocket. The design of the multi-pair impinging injector plate is based on the cold flow and hot fire observations of unlike-doublet impinging jets of monomethylhydrazine/nitrogen tetroxide and their simulants. The mass distributions of the impinging jets from the cold flow observations are used to arrange the paired orifices of the impinging unit on the injector plate through a image projection method. For the most uniform distribution and the best overall estimated C* of the overall spray, the orifice size of the impinging element and the configuration of the paired orifices of an injector plate was determined for the prototype injector plate design. Static tests of the ground-test liquid rocket engine with the designed injector plate are performed. The measured sea-level thrust of the engine was 62.1 lb, and the characteristic exhaust velocity reached 1429.2 m/s at a total propellant mass flow rate of 153.4 g/s. The estimated vacuum thrust was 99.8 lb, and the vacuum Isp was 295.8 s as well. The combustor pressure of the liquid rocket engine was 153.2 psi and remained stable during operation. During the 17 seconds of the hot fire test, the highest wall temperature was measured at the nozzle throat, which was about 1000K.

The turbulence and concentration characteristics in the stabilization zone of a lifted jet flame with and without acoustic excitation are measured by a time-resolved Rayleigh scattering, a LDV, and a hot vire anemometry system together with other probes. Both amplification and suppression of the flow can be achieved by acoustic excitation. By careful comparison of the turbulence and concentration characteristics in the stabilization zone for the natural, amplification and suppression cases, it is found that the key parameters of lifted flame stabilization in the stabilization zone are the integral length scale, the F probability of the presence of a flammable premixture, and the G probability of the presence of a fluid with a temperature reaching the ignition temperature. Amplification excitation enhances the large-scale coherent vortices and the vortical entrainment, thus enhancing the length scale, theF probability, and the G probability of having a combustibltoe premixture in the stabilization zone. In this case, the flame shifts upstream to a higher gas speed location and restabilizes there. Suppression excitation shows the opposite results. Practical need calls for a new model capable of predicting the stabilization zone structure of excited lifted flames where the large length scale, theF andG probabilities are suggested to be important parameters.

A MEMS-based millinewton level hydrazine thruster was designed and tested in this research. The microthruster was composed of a microvalve, a microreactor, and a micronozzle. The detailed considerations of system and component designs were presented. For the microreactor, iridium coated micro catalytic bed was fabricated with a high flow path surface to volume ratio of 84mm/mm. The microreactor successfully proceeded hydrazine dissociation reactions and achieved desired ammonia dissociations over 90% at the hydrazine flow rates of interest. Bonded with the micronozzle, the microreactor/nozzle assembly produced an optimum performance at the hydrazine flow rate of 0.625mg/s, where a vacuum thrust of 0.99 mN was observed with a specific impulse close to 162s. A deficiency of 35% was estimated and considered mainly from the heat loss and viscous loss in microchannels. More effective thermal management should be developed in the future design. In addition, research on ICP etching control would be necessary to produce smoother surface to reduce the friction loss. This preliminary test result demonstrated the feasibility of utilizing hydrazine on MENS-based microthruster’s operations.

[Abstract] The combustion phenomena of doublet impingements of nitrogen tetroxide (NTO) and monomethylhydrazine (MMH) were studied in this research. The total flow rates of the propellants were controlled at ~8.00 g/s to simulate the operation of a 5-lbf rocket, and the ratios of the mass flow rates (O/F) of NTO and MMH were varied from 1.0 to 2.4. With a 2-axis translation module, the thermocouple array measured the 2-D temperature distributions in the hot-fire experiments at the 20mm downstream of the impinging point. The results showed that the temperature distribution was strongly affected by O/F and mixing effect. Comparing to the previous PLIF cold-flow studies in the same conditions, the results demonstrated that the cold-flow analyses could adequately predict the position and shape of the high temperature zone in hot-fire situation. In views of the combustion phenomena, an induction period (length) to reach intensive reactions always exists, and it can be correlated to the MMH droplet size distribution or the uniformity of the MMH spray. And, a maximum length of ∼80mm of the intensive reaction zone was shown for the conditions investigated. This may be caused by the diffusion-controlled combustion in the downstream reactions.

Endotoxin depresses left ventricular (LV) contractility independently of alterations in loading conditions, acidosis, or hypoxia (Hung and Lew, 1993a). We evaluated if endotoxin-induced LV depression is associated with a decrease in functional L-type calcium channels, as reflected by the number of dihydropyridine receptors measured by [3H]-PN200-110 binding. New Zealand white rabbits were instrumented with sonomicrometers to measure the end-systolic pressure-volume relationship after i.v. saline (group 1, n = 6), 5 micrograms/kg endotoxin (group II, n = 6), or 10 micrograms/kg endotoxin (group III, n = 6). The end-systolic volume (ESV) measured at a matched end-systolic pressure did not change significantly over 6 h in group I (ESV changed by5 +/- 2% S.E.) and group II (ESV changed by3 +/- 2%), but increased markedly in group III (ESV increased 70 +/- 24%, P0.05), indicating LV systolic depression. We measured [3H]-PN200-110 binding in crude membrane homogenates from the left ventricle. There was a dose-dependent decrease in Bmax: 75 +/- 5 fmol/mg protein in group I, 62 +/- 3 fmol/mg in group II, and 56 +/- 5 fmol/mg in group III (P = 0.02 by ANOVA). Since the majority of dihydropyridine receptors are functional L-type calcium channels in rabbits (Lew et al., 1991), we conclude that a decreased number of dihydropyridine receptors contributes to endotoxin-induced LV depression.