The drug loading in the SMPs was enhanced in the presence of Crysmeb. The in vitro drug release was found to be enhanced with SMPs prepared using higher concentrations of Crysmeb.
These results indicate that SMPs formed from chitosan chlorhydrate and Crysmeb are promising submicron carriers for enhancing the dissolution of meloxicam and aceclofenac. Precipitation of sparingly soluble salts in packed sandbeds. One of the main problems encountered by the oil extraction industry, is the reduction of the local permeability of the rock formation near the extraction wells because of salt deposition in the pores of the rocks during the injection of brine water to displace the trapped oil ganglia within the oil formations.
This phenomenon makes the oil recovery less efficient and under extreme cases the well is abandoned with a large amount of oil entrapped. Several detailed studies have been conducted in the past concerning sand bed consolidation using sparingly soluble salts for varying conditions e.
Nevertheless, salt precipitation in the rock formation pores under the presence of other miscible or immiscible substances with water has not been investigated in details yet.
In the present study, salt CaCO3 precipitation experiments were performed in small beds packed with sea sand mixed with a low amount of CaCO3 seed grains. Additionally, precipitation experiments were performed using pure solutions in sand beds saturated with oil phase n-dodecane for a wide range of solution supersaturation. During the experiments the ionic strength was kept constant. At the end of each experiment Scanning Electron Microscope SEM was conducted using a sample of the precipitated sand to identify the morphology of the precipitated crystals and their cohesion with sand grains.
These data in turn were extrapolated to the critical point of water, thus providing a complete set of Henry's law constants from to ?? K when combined with the existing literature data.
Equations describing the behavior of the Henry's law constants over this temperature range are also given. The data do not confirm extrapolations of empirical correlations based on low-temperature solubility data. The solubility data of apolar gases in light and heavy water over the temperature range covered experimentally have been evaluated, laying particular emphasis to the region above the normal boiling points of the solvents.
The systems that have been included in this work are the inert gases and CH4 in light water and heavy water, H2, O2, N2, and C2H6 in light water and D2 in heavy water. Data in the original sources have been brought to the same footing by calculating from the raw experimental data P, T, and x when they were not reported by the author. This step is considered necessary to assess critically the available sets of data. The temperature dependence of Henry's constants for all the binary systems have been expressed in terms of two different polynomial equations.
The formulations presented are discussed and the limits of application given. Noble gases solubility models of hydrocarbon charge mechanism in the Sleipner Vest gas field. Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways and mechanisms, as well as reservoir storage conditions.
Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. Here, we present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea.
Sleipner Vest gases are generated from primary cracking of kerogen and the thermal cracking of oil. Gas was emplaced into the Sleipner Vest from the south and subsequently migrated to the east, filling and spilling into the Sleipner Ost fields. Air-derived noble gas isotopes 20Ne, 36Ar, 84Kr, Xe are introduced into the hydrocarbon system by direct exchange with air-saturated water ASW. The distribution of air-derived noble gas species are controlled by phase partitioning processes; in that they preferentially partition into the gas i.
Therefore, the extent of exchange between hydrocarbon phases and formation waters - that have previously equilibrated with the atmosphere - can be determined by investigating air-derived noble gas species. We utilize both elemental ratios to address process i. Methods for calculation of engineering parameters for gas separation.
A group additivity method is generated which allows estimation, from the structural formulas alone, of the energy of vaporization and the molar volume at 25 C of many nonpolar organic liquids. Using these two parameters and appropriate thermodynamic relations, the vapor pressure of the liquid phase and the solubility of various gases in nonpolar organic liquids are predicted. It is also possible to use the data to evaluate organic and some inorganic liquids for use in gas separation stages or liquids as heat exchange fluids in prospective thermochemical cycles for hydrogen production.
Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring.
The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array FPGA platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible. Automatic carbon dioxide-methane gas sensor based on the solubility of gases in water. A molecular study of gas solubility in nitrile rubber. One of the most important uses of elastomers in the oil industry is for seals to encase and protect sensitive monitoring equipment from contamination by gases and liquids at the high pressures and temperatures in the well.
Failure of such seals sometimes occurs on decompression when they are returned to the surface. The conditions in the well lead to gases being absorbed by Nitrile rubber NBR seals. NBR exhibits a strong permselectivity towards CO2 compared to other gases ; something attributed experimentally to the enhanced solubility of CO2. In this study an explanation is sought at the molecular level for this phenomenon.
A series of molecular mechanics calculations are performed to compute solubilities of different gases in NBR. The effect of acrylonitrile content on their solubilities is studied for the first time by simulation, and we discuss the important issue of convergence with respect to the sampling of different elastomer configurations.
It is observed that the presence of cyano groups has a marked impact on the solubility of CO2 and an explanation is offered. Design of biodegradable nanoparticles: a novel approach to encapsulating poorly soluble phytochemical ellagic acid.
Nanosizing of poorly water soluble drugs or incorporating them into nanoparticles to increase their solubility and thereby the bioavailability has become a favoured approach today. Molecular simulation is used to compute the solubility of small gases in nitrile butadiene rubber NBR with a Widom particle-insertion technique biased by local free volume. The convergence of the method is examined as a function of the number of snapshots upon which the insertions are performed and the number of insertions per snapshot and is compared to the convergence of the unbiased Widom insertion technique.
The effect of varying the definition of local free volume is also investigated. The acrylonitrile content of the polymer is altered to examine its influence on the solubility of helium, CO 2 , and H 2 O, and the solubilities of polar gases are found to be enhanced relative to those of nonpolar gases , in qualitative agreement with experiment.
To probe this phenomenon further, the solubilities are decomposed into contributions from the neighborhoods of different atoms, using a Voronoi cell construction, and a strong bias is found for CO 2 and H 2 O in particular to be situated near nitrogen sites in the elastomer.
Temperature is shown to suppress the solubility of CO 2 and H 2 O but to increase that of helium. Increasing pressure is found to suppress the solubility of all gases but at different rates, according to a balance between their molecular sizes and electrostatic interactions with the polymer.
These results are relevant to the use of NBR seals at elevated temperatures and pressures, such as in oil and gas wells. Rhizospheric pH changes, redesigned root architecture and pi-uptake kinetics. Non-mycorrhizal Brassica does not produce specialized root structures such as cluster or dauciform roots but is an effective user of P compared with other crops.
To visualize the dissolution of sparingly soluble Ca-phosphate Ca-P , newly formed Ca-P was suspended in agar containing other essential nutrients. To observe in situ rhizospheric pH changes, images were recorded after embedding the roots in agar containing bromocresol purple as a pH indicator. P-tolerant cultivar showed a greater decrease in pH than the sensitive cultivar in the culture media the appearance of typical patterns of various colors of pH indicator in the root vicinity , and at stress P-level this acidification was more prominent.
To elucidate P-stress-induced remodeling and redesigning in a root architectural system, cultivars were grown in rhizoboxes in experiment 3. The elongation rates of primary roots increased as P-supply increased, but the elongation rates of the branched zones of primary roots decreased. The length of the lateral roots and topological index values increased when cultivars were exposed to a P-stress environment. To elucidate Pi-uptake kinetics, parameters. We examine wet scavenging of soluble trace gases in storms observed during the Deep Convective Clouds and Chemistry DC3 field campaign.
The model represents well the storm location, size, and structure as compared with Next Generation Weather Radar reflectivity, and simulated CO transport is consistent with aircraft observations. Scavenging efficiencies SEs between inflow and outflow of soluble species are calculated from aircraft measurements and model simulations. Using a simple wet scavenging scheme, we simulate the SE of each soluble speciesmore » within the error bars of the observations.
The simulated SEs of all species except nitric acid HNO3 are highly sensitive to the values specified for the fractions retained in ice when cloud water freezes. To reproduce the observations, we must assume zero ice retention for formaldehyde CH2O and hydrogen peroxide H2O2 and complete retention for methyl hydrogen peroxide CH3OOH and sulfur dioxide SO2 , likely to compensate for the lack of aqueous chemistry in the model.
We then compare scavenging efficiencies among storms that formed in Alabama and northeast Colorado and the Oklahoma storm. Significant differences in SEs are seen among storms and species. Biofiltration of Volatile Pollutants: Solubility Effects. This project investigates and collects fundamental partitioning data for a variety of sparingly soluble subsurface contaminants e.
Due to the difficulty of obtaining these measurements, environmental models have generally used solubility constants of chemicals in pure water or, in a few rare cases, simple linear models. Our prior EMSP work has shown that the presence of biological material can increase effective solubilities by an order of magnitude for sparingly soluble organics; therefore, the previous simple approaches are not valid and are extremely poor predictorsmore » of actual bio-influenced partitioning.
It is likely that environmental contaminants will partition in a similar manner into high-biomass phases e. Biological material in the subsurface can include lipids, fatty acids, humic materials, as well a s the lumped and difficult to estimate 'biomass'.
Our measurements include partition into these biological materials to allow better estimation. Fundamental data collected will be used in mathematical models predicting transport and sorption in subsurface environments, with the impacts on bioremediation being evaluated based on this new information.
Biological material in the subsurface can include lipids, fatty acids, humic materials, as well as the lumped and difficult-to-estimate 'biomass'. Method for enhancing microbial utilization rates of gases using perfluorocarbons. A method of enhancing the bacterial reduction of industrial gases using perfluorocarbons PFCs is disclosed. Because perfluorocarbons PFCs allow for a much greater solubility of gases than water does, PFCs have the potential to deliver gases in higher concentrations to microorganisms when used as an additive to microbial growth media thereby increasing the rate of the industrial gas conversion to economically viable chemicals and gases.
Transport of dissolved gases through unsaturated porous media. The natural porous media e. The saturation of soil depends on hydrostatic pressure which is linearly increased with depth.
Often some gases e. The solubility of gases is very small because of that two assumptions is applied: I. The concentration of gas is equal to solubility , II. Solubility depends only on pressure for isothermal systems. In this way some part of dissolved gas transfers from the solution to the bubble phase. The gas bubbles are immovably trapped in a porous matrix by surface-tension forces and the dominant mechanism of transport of gas mass becomes the diffusion of gas molecules through the liquid.
If the value of water content is small then the transport of gas becomes slow and gas accumulates into bubble phase. The presence of bubble phase additionally decreases the water content and slows down the transport. As result the significant mass of gas should be accumulated into the massif of porous media. We derive the transport equations and find the solution which is demonstrated the accumulation of gases.
The influence of saturation, porosity and filtration velocity to accumulation process is investigated and discussed. The solvation radius of silicate melts based on the solubility of noble gases and scaled particle theory. The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model PCM.
The solubility calculations were then extended to He, Ne, and Kr, whose dispersive and repulsive coefficients are available from theory and we have shown that their ab initio Henry's constants at high T reproduce the observed increase with the static polarizability of the series element with reasonable accuracy. The present investigation opens new perspectives on a wider application of PCM theory which can be extended to materials of great industrial interest at the core of.
The lithium-sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur. However, even state-of-the-art lithium-sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte.
The use of sparingly solvating electrolytes in lithium-sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach.
Herein, we demonstrate that sparingly solvating electrolytes based on compact, polar molecules with a ratio of a functional group to lithium salt can fundamentally redirect the lithium-sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. In contrast to the standard catholyte sulfur electrochemistry, sparingly solvating electrolytes promote intermediate- and short-chain polysulfide formation during the first third of discharge, before disproportionation results in crystalline lithium sulfide and a restricted fraction of soluble polysulfides which are further reduced during the remaining discharge.
Moreover, operation at intermediate temperatures ca. This discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation-dissolution chemistries, lithium-sulfur and beyond.
Incorporating single-side sparing in models for predicting parotid dose sparing in head and neck IMRT. Purpose: Sparing of single-side parotid gland is a common practice in head-and-neck HN intensity modulated radiation therapy IMRT planning. It is a special case of dose sparing tradeoff between different organs-at-risk. The authors describe an improved mathematical model for predicting achievable dose sparing in parotid glands in HN IMRT planning that incorporates single-side sparing considerations based on patient anatomy and learning from prior plan data.
Methods: Among 68 HN cases analyzed retrospectively, 35 cases had physician prescribed single-side parotid sparing preferences. The single-side sparing model was trained with cases which had single-side sparing preferences, while the standard model was trainedmore » with the remainder of cases. A receiver operating characteristics ROC analysis was performed to determine the best criterion that separates the two case groups using the physician's single-side sparing prescription as ground truth.
The final predictive model combined model takes into account the single-side sparing by switching between the standard and single-side sparing models according to the single-side sparing criterion. The models were tested with 20 additional cases.
The significance of the improvement of prediction accuracy by the combined model over the standard model was evaluated using the Wilcoxon rank-sum test. Results: Using the ROC analysis, the best single-side sparing criterion is 1 the predicted median dose of one parotid is higher than 24 Gy; and 2 that of the other is higher than 7 Gy. This criterion gives a true positive rate of 0. For the bilateral sparing cases, the combined and the standard models performed equally well, with the median of the prediction errors for parotid median dose being 0.
For the single-side sparing cases, the standard model overestimates the median dose by 7. Equivalent survival after nipple- sparing compared to non-nipple- sparing mastectomy: data from California, Nipple- sparing mastectomy, which may improve cosmesis, body image, and sexual function in comparison to non-nipple- sparing mastectomy, is increasingly used to treat early-stage breast cancer; however, long-term survival data are lacking.
We evaluated survival after nipple- sparing mastectomy versus non-nipple- sparing mastectomy in a population-based cancer registry. We conducted an observational study using the California Cancer Registry, considering all stage 0-III breast cancers diagnosed in California from to We compared breast cancer-specific and overall survival time after nipple- sparing versus non-nipple- sparing mastectomy, using multivariable analysis. Among , stage 0-III female breast cancer patients treated with unilateral mastectomy from , 0.
The proportion of mastectomies that were nipple- sparing increased over time , 0. On multivariable analysis, nipple- sparing mastectomy was associated with a lower risk of breast cancer-specific mortality compared to non-nipple- sparing mastectomy [hazard ratio HR 0. However, when restricting to diagnoses or later and adjusting for a larger set of covariates, risk was attenuated HR 0. Among California breast cancer patients diagnosed from , nipple- sparing mastectomy was not associated with worse survival than non-nipple- sparing mastectomy.
These results may inform the decisions of patients and doctors deliberating between these surgical approaches for breast cancer treatment. An Introduction to the Understanding of Solubility. Explores different solubility processes and related issues, including the second law of thermodynamics and ideal mixtures, real liquids, intermolecular forces, and solids in liquids or gases in liquids.
Contains 22 references. A study of gas solubilities and transport properties in fuel cell electrolytes. An analysis of the rate of heat generation on the dissolution of sparingly soluble gas in electrolytes was made, and it leads to the conclusion that the temperature changes to be expected are much too small to be measured with precision owing to the slowness of the gas dissolution. It appears that more accurate gas solubility measurements are the only real hope of improved precision in heats of solution and other thermodynamic properties.
Molecular simulations and experimental studies of solubility and diffusivity for pure and mixed gases of H2, CO2, and Ar absorbed in the ionic liquid 1-n-hexylmethylimidazolium bis trifluoromethylsulfonyl amide [hmim][Tf2N]. Classical molecular dynamics and Monte Carlo simulations are used to calculate the self-diffusivity and solubility of pure and mixed CO 2 , H 2 , and Ar gases absorbed in the ionic liquid 1-n-hexylmethylimidazolium bis trifluoromethylsulfonyl amide [hmim][Tf 2 N].
Overall, the computed absorption isotherms, Henry's law constants, and partial molar enthalpies for pure H 2 agree well with the experimental data obtained by Maurer et al. Data , 51, ] and the experimental values determined in this work. However, the agreement is poor between the simulations and the experimental data by Noble et al.
Data , 52, ] at high temperatures. The computed H 2 permeability values are in good agreement with the experimental data at K obtained by Luebke et al. Our computed H 2 solubilities using different H 2 potential models have similar values and solute polarizations were found to have a negligible effect on the predicted gas solubilities for both the H 2 and Ar.
The interaction between H 2 and the ionic liquid is weak, about three times smaller than between the ionic liquid and Ar and six times smaller than that of CO 2 with the ionic liquid, results that are consistent with a decreasing solubility from CO 2 to Ar and to H 2.
The molar volume of the ionic liquid was found to be the determining factor for the H 2 solubility. For mixed H 2 and Ar gases , the solubilities for both solutes decrease compared to the respective pure gas solubilities.
To understand changes in blood gases results with core temperature. Analysis from two case reports. Hypothermia induces a decrease in PaCO 2 with a related increase in pH, thus a physiologic alkalosis. Decrease in PaCO 2 is due to an increase of gas solubility and a decrease of peripheral consumption that can be estimated from comparison between corrected and non-corrected for temperature blood gases.
For O 2 , variations of temperature induce variations of solubility but also of haemoglobin affinity for O 2. During hyperthermia, haemoglobin affinity for O 2 is decreased with a decreased SvO 2 for a same PvO 2.
SvO 2 ischemic or therapeutic thresholds are thus modified with core temperature. Blood gases cannot be understood without patient core temperature. Physiologic variations of PaCO 2 and pH must probably be tolerated. Ischemic threshold should be estimated on PvO 2 , not only on PvO 2. The lithium—sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur.
However, even state-of-the-art lithium—sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte.
The use of sparingly solvating electrolytes in lithium—sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach.
Herein, we demonstrate that sparingly solvating electrolytes based on compact, polar molecules with a ratio of a functional group to lithium salt can fundamentally redirect the lithium—sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. This discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation—dissolution chemistries, lithium—sulfur and beyond.
Spare antenna. A spare transmitting antenna completely assembled for immediate erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a Solubility of single gases carbon dioxide and hydrogen sulfide in aqueous solutions of N-methyldiethanolamine in the temperature range K at pressures up to 5 MPa.
A model taking into account chemical reactions as well as physical interactions is used to correlate the new data. The correlation is also used to compare the new experimental data with literature data. Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids. This study focuses on the solubility behaviors of CO2, CH4, and N2 gases in binary mixtures of imidazolium-based room-temperature ionic liquids RTILs using 1-ethylmethylimidazolium bis trifluoromethylsulfonyl imide [C2mim][Tf2N] and 1-ethylmethylimidazolium tetrafluoroborate [C2mim][BF4] at 40 degrees C and low pressures approximately 1 atm.
Results show that regular solution theory RST can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Physiological and morphological adaptations of herbaceous perennial legumes allow differential access to sources of varyingly soluble phosphate. The aim of this study was to investigate the capacity of three perennial legume species to access sources of varyingly soluble phosphorus P and their associated morphological and physiological adaptations.
Two Australian native legumes with pasture potential Cullen australasicum and Kennedia prostrata and Medicago sativa cv. All species grew well with soluble P. In contrast, K. These findings provide strong indications that there are opportunities to utilize local Australian legumes in low P pasture systems to access sparingly soluble soil P and increase perennial legume productivity, diversity and sustainability.
Late-stage optimization of a tercyclic class of S1P3- sparing , S1P1 receptor agonists. Poor solubility and cationic amphiphilic drug-likeness were liabilities identified for a lead series of S1P3- sparing , S1P1 agonists originally developed from a high-throughput screening campaign.
This work describes the subsequent optimization of these leads by balancing potency, selectivity, solubility and overall molecular charge. Focused SAR studies revealed favorable structural modifications that, when combined, produced compounds with overall balanced profiles.
The low brain exposure observed in rat suggests that these compounds would be best suited for the potential treatment of peripheral autoimmune disorders.
Skin sparing mastectomy, a surgical procedure sparing a large portion of the overlying skin of the breast, and nipple- sparing mastectomy, sparing the whole nipple-areolar complex, are increasingly used, although their oncologic efficacy remains unclear. The aim of this study was to assess the radiation oncologists' opinions regarding the indications of radiation therapy RT after skin- sparing mastectomy and nipple- sparing mastectomy.
Radiation oncology members of four national and international societies were invited to complete a questionnaire comprising of 22 questions to assess their opinions regarding RT indications in the context of skin- sparing and nipple- sparing mastectomy. A total of radiation oncologists answered the questionnaire. The majority declared that post-mastectomy RT is indicated for early-stage stages I and II breast cancer patients who present with risk factors for recurrence after skin- sparing or nipple- sparing mastectomy All suggested risk factors tumor size, lymph node involvement, extracapsular extension, lymphovascular space invasion, positive surgical margins, triple negative tumor, multicentric tumor, and age were considered as major elements important or very important.
There is no consensus regarding the necessity of evaluating residual breast tissue or the definition of residual breast tissue after mastectomy. All classic factors were considered as major elements, potentially influencing the decision to advice or not postoperative RT. Many uncertainties remain about the indications for RT after skin- sparing mastectomy or nipple- sparing mastectomy. Volatile elements are transported from Earth's surface reservoirs back into the mantle during subduction of oceanic lithosphere [e.
Here, we investigate the degree to which the fate of slab-bound noble gases and water are linked through the subduction process. Both water and noble gases are soluble in ring-structured minerals, such as amphibole, that are common constituents of subducted oceanic lithosphere.
Heating and burial during subduction liberates noble gases and water from minerals through a combination of diffusion and dissolution.
Combining a kinetic model, parameterized for noble gas fractionation in amphibole [2], with thermodynamic phase equilibria calculations, we quantify the effect of subduction dehydration on the elemental composition of slab-bound noble gases.
Results show that post-arc slab water and noble gas fluxes are highly correlated. Hot subduction zones, which likely dominate over geologic history, efficiently remove noble gases and water from the down-going slab; furthermore, kinetic fractionation of noble gases is predicted to occur beneath the forearc.
Conversely, hydrated portions of slab mantle in cold subduction zones transport noble gases and water to depths exceeding km. Preservation of seawater-like abundances of Ar, Kr and Xe in the convecting mantle [1] implies that recycling of noble gases and water occurred during cold subduction and that the subduction efficiency of these volatile elements has increased over geological time, driven by secular cooling of the mantle.
Nature , Solubility correlations. Part 1. Simultaneous fitting of both solute and solvent properties. A method is described for estimating solubility by fitting both solute and solvent properties in a single equation. Generally, the correlation R 2 values of the fits achieved were significantly better than 0.
It is suggested that similar methods can be used for estimating other physico-chemical properties such as excess molar volumes and enthalpies of solution.
MRI using hyperpolarized noble gases. The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status of preclinical and clinical applications. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal vapors spin exchange or metastable atoms metastability exchange. Hyperpolarization results in a non-equilibrium polarization five orders of magnitude higher than the Boltzmann equilibrium compensating for the several times lower density of noble gases as compared with liquid state hydrogen concentrations in tissue and allows for short imaging times.
Hyperpolarization can be stored sufficiently long 3 h to 6 days to allow for transport and application. Magnetic resonance systems require a broadband radio-frequency system - which is generally available for MR spectroscopy - and dedicated coils. The hyperpolarized gases are administered as inhalative "contrast agents" allowing for imaging of the airways and airspaces. Besides the known anesthetic effect of xenon, no adverse effects are observed in volunteers or patients.
Since helium is not absorbed in considerable amounts, its application is restricted to the lung. Xe is also under investigation for imaging of white matter disease and functional studies of cerebral perfusion. Magnetic resonance imaging using hyperpolarized gases is emerging as a technical challenge and opportunity for the MR community. Preliminary experience suggests potential for functional imaging of pulmonary ventilation and cerebral perfusion.
Cost analysis of medical device spare parts. Objective: To establish estimation method on budget management of medical device spare parts and to evaluate the cost of medical device spare parts in affiliated hospitals of Istanbul Public Hospital Unions PHUs. Methods: While this evaluation was performed, the relationship between paid cost for spare parts according to technological development level of device groups and total inventory value was used.
Spare part cost analysis was carried out by using the normalized weighted arithmetic average method. Cost analysis of medical equipment spare parts of Istanbul PHUs was performed by using the data retrieved from Ministry of Health Business Intelligence Decision Support System for spending of spare parts in Results: The medical device spare part groups were categorized based on technological development.
Among 1 to 6 PHUs, the cost ratios were acquired for high, middle, low and simple technology group as The ratio between the spare part and total inventory costs for PHUs were calculated as 1. Expected rates based on normalized weighted method were obtained as follows; 5. Conclusion: The expenditure analysis and budget planning for medical device spare parts in PHU could be predicted more accurately by taking into consideration the expected rate calculated by the normal weight method.
It's obvious that oxygen does dissolve, or else fish could not survive, but I'm confused on how it does so. That explains in part why you and fish require dedicated oxygen carriers in your blood to transfer sufficient oxygen around your body. That oxygen is weakly soluble can be explained, as you point out, on the basis of the hydrophobic effect, which amounts to saying that water likes to hydrogen bond, and an oxygen molecule is not very good at that compared to another water molecule.
That oxygen is soluble at all can be explained on two grounds. First, statistics, just the random mixing of matter. Some oxygen molecules will happen to find their way into water and not find their way out for a while. The other explanation is that oxygen is not entirely nonpolar: it lacks a permanent dipole moment, but it is polarizable. Even molecules that we think of as highly water repellent can exist as liquids oxygen is a gas at room temperature but can be cooled into a liquid state , which means something must be keeping them together, and that is dispersion forces due to the polarizability of all atoms and molecules.
Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Like the solubility of carbon dioxide in water, the solubility of oxygen decreases as the temperature increases.
If you are willing to do this demonstration, it must be done outside. Mentos and Diet Coke work in the same way. On the microscopic level, the surface of the mint is rough with many tiny bumps and pits. When the candy is added to the soda pop, carbon dioxide molecules adhere to these tiny spots called nucleation points. More carbon dioxide molecules collect in these areas, forming bubbles. The bubbles of carbon dioxide form quickly and grow in all directions but can only escape from the top of the bottle.
The American Chemical Society is dedicated to improving lives through Chemistry. Skip Navigation. Lesson 5. Engage Show students the bubbles that appear when a new bottle of soda is opened. Ask students: Do you think that gases can dissolve in water? The idea of a gas dissolving may seem strange to students, but this demonstration will help them realize that gases can dissolve in water.
Materials Unopened 1-liter bottle of club soda Teacher Preparation Remove the label from a 1-liter bottle of carbonated water. Ask students: How is a bottle of carbonated water different from a regular bottle of water? Students will probably say that carbonated water has bubbles. Do you see any bubbles in the carbonated water? Procedure Very slowly unscrew the bottle cap. Wait a few seconds to allow students to observe the bubbles.
Tighten the cap on the bottle. Expected Results When the cap is loosened, many bubbles will appear throughout the soda and rise up through the water to the surface, where they pop. Ask students: What did you observe when I opened and then closed the bottle of soda?
Bubbles appeared only when the bottle was opened. The bubbles stopped forming when the bottle cap was tightened. What is the gas that makes these bubbles? The carbon dioxide was dissolved in the water.
Explain that carbonated water is made of carbon dioxide gas dissolved in water. Give each student an activity sheet. Explore Have students add objects to carbonated water to see if they can get carbon dioxide gas to come out of solution. Ask students: Aside from shaking soda, or leaving it uncovered, are there other ways to make carbon dioxide gas come out of carbonated water?
Tell students that objects can be placed in the soda that can cause the carbon dioxide to bubble out of the soda. Question to Investigate How can you make carbon dioxide gas come out of solution?
Procedure Evenly divide the club soda among the 3 clear plastic cups. Push two of these cups aside to use later.
Place a pipe cleaner in the soda and observe. Expected Results Bubbles form on the pipe cleaner. Ask students: Where did the gas bubbles that you observed come from?
There were molecules of carbon dioxide dissolved in the water. Where did the carbon dioxide gas that was dissolved in the water go? The carbon dioxide bubbles rose to the surface and popped, releasing carbon dioxide into the air. Ask students: While drinking soda pop with a straw, you may have noticed that bubbles form on the outside of the straw. Now that you have done this activity, why do you think these bubbles form on the straw?
Even though the straw looks smooth, it also has tiny bumpy areas, where molecules of carbon dioxide collect. When enough of them collect in an area, they become a bubble of carbon dioxide gas.
Discuss how to find out whether temperature affects how quickly gas escapes from carbonated water. Ask students: Would you expect carbon dioxide to stay dissolved better in hot or cold water?
Hint: Soda pop is kept in the refrigerator after it is opened. Students will discover the answer to this question as they do the following activity. How could you set up an experiment to find out whether carbon dioxide stays dissolved better in water that is warmed or water that is cooled?
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