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Abstract Background Limited literature exists on the feasibility and effectiveness of integrating stereotactic ablative radiotherapy (SABR) techniques with hyperfractionated regimens for patients with lung cancer. This study aims to assess whether the SABR technique with hyperfractionation can potentially reduce lung toxicity. Methods We utilized the linear‐quadratic model to find the optimal fraction to maximize the tumor biological equivalent dose (BED) to normal‐tissue BED ratio. Validation was performed by comparing the SABR plans with 50 Gy/5 fractions and hyperfractionationed plans with 88.8 Gy/74 fractions with the same tumor BED and planning criteria for 10 patients with early‐stage lung cancer. Mean lung BED, Lyman–Kutcher–Burman (LKB) normal tissue complication probability (NTCP), critical volume (CV) criteria (volume below BED of 22.92 and 25.65 Gy, and mean BED for lowest 1000 and 1500 cc) and the percentage of the lung receiving 20Gy or more (V20) were compared using the Wilcoxon signed‐rank test. Results The transition point occurs when the tumor‐to‐normal tissue ratio (TNR) of the physical dose equals the TNR of α/β in the BED dose‐volume histogram of the lung. Compared with the hypofractionated regimen, the hyperfractionated regimen is superior in the dose range above but inferior below the transition point. The hyperfractionated regimen showed a lower mean lung BED (6.40 Gy vs. 7.73 Gy) and NTCP (3.50% vs. 4.21%), with inferior results concerning CV criteria and higher V20 (7.37% vs. 7.03%) in comparison with the hypofractionated regimen (p

Background: Limited literature exists on the feasibility and effectiveness of integrating stereotactic ablative radiotherapy (SABR) techniques with hyperfractionated regimens for patients with lung cancer. This study aims to assess whether the SABR technique with hyperfractionation can potentially reduce lung toxicity. Methods: We utilized the linear‐quadratic model to find the optimal fraction to maximize the tumor biological equivalent dose (BED) to normal‐tissue BED ratio. Validation was performed by comparing the SABR plans with 50 Gy/5 fractions and hyperfractionationed plans with 88.8 Gy/74 fractions with the same tumor BED and planning criteria for 10 patients with early‐stage lung cancer. Mean lung BED, Lyman–Kutcher–Burman (LKB) normal tissue complication probability (NTCP), critical volume (CV) criteria (volume below BED of 22.92 and 25.65 Gy, and mean BED for lowest 1000 and 1500 cc) and the percentage of the lung receiving 20Gy or more (V20) were compared using the Wilcoxon signed‐rank test. Results: The transition point occurs when the tumor‐to‐normal tissue ratio (TNR) of the physical dose equals the TNR of α/β in the BED dose‐volume histogram of the lung. Compared with the hypofractionated regimen, the hyperfractionated regimen is superior in the dose range above but inferior below the transition point. The hyperfractionated regimen showed a lower mean lung BED (6.40 Gy vs. 7.73 Gy) and NTCP (3.50% vs. 4.21%), with inferior results concerning CV criteria and higher V20 (7.37% vs. 7.03%) in comparison with the hypofractionated regimen (p < 0.01 for all). Conclusions: The hyperfractionated regimen has an advantage in the high‐dose region of the lung but a disadvantage in the low‐dose region. Further research is needed to determine the superiority between hypo‐ and hyperfractionation. [ABSTRACT FROM AUTHOR]

100 years ago, two scientists M.N. Saha and S.N. Basu tried to give an equation of state for real gas system by taking into consideration the probabilistic theory of finite volume of gas molecules as well as the influence of cohesive force. As compared to experimental observation, their theoretical prediction elucidates very close agreement of critical coefficient value. However, this unusual equation of state gets very little attention from the scientific community. In this study, the Saha-Basu equation is revisited. Critical coefficients as well as critical exponents corresponding to Saha-Basu equation are critically explored. Furthermore, interactions among the gas particles obeying Saha-Basu equation is still an open problem which we try to discuss in this article. [ABSTRACT FROM AUTHOR]

Algorithms used to generate Monte Carlo input decks and to analyze the output over a range of uranium mass, water volume, and particle size in a regular lattice are described. The algorithms produce input decks for both homogeneous and heterogeneous, regular-lattice systems of 20% enriched uranium metal and water and then analyze the results to determine the minimum critical mass over a range of input mass and particle size. The output is presented and analyzed for a 20% enriched uranium metal and water system, and comparisons to existing technical reports and safety guides are discussed. Two particular existing recommendations are tested and compared with new results: the boundary between a homogeneous system and a heterogeneous system, and the recommended margins of safety that can be applied to account for the effects of heterogeneity. [ABSTRACT FROM AUTHOR]

The importance, yet scarcity of the critical constants of thermally unstable fluids warrants the development of reliable methods for the estimation of these essential thermodynamic properties. A thorough investigation undertaken in this study on 1,589 compounds belonging to 83 chemical classes, indicated that the ratio of critical temperature to critical pressure TcPc of both low and high molecular weight compounds could be well expressed in terms of their volumetric properties. In addition, two new methodologies are presented for estimating Vc, as well as an indirect approach for prediction of Tc from surface tension data, altogether allowing the calculation of Zc. Moreover, comparative studies are made with five group contribution methods. It is also demonstrated that by employing the Peng‐Robinson EOS, and without prior knowledge of the critical properties, it is possible to calculate various thermophysical properties including Psat., Tb, ρliq.sat., ∆Hvap., Cp, and even the Tc and Pc themselves. [ABSTRACT FROM AUTHOR]

A new second order group contribution method for the estimation of critical constants of organic compounds is developed. The functional groups of Joback and Reid method are employed with some changes as first order functional groups and some second order functional groups are also defined and added to them. A set of experimental data for the critical temperature of 969 compounds, the critical pressure of 715 compounds and the critical volume of 539 compounds are collected in this study. The group contribution values of 122 functional groups have been optimized using the experimental data of organic compounds, including complex and heavy polycyclic aromatic components. The critical constants of most structural isomers and stereoisomers are distinguished in this method by considering the second order functional groups. The hydrocarbons and hydrocarbon derivatives considered in this research include carbon, hydrogen, oxygen, nitrogen, sulfur, fluorine, chlorine, bromine, and iodine atoms. Development of the new models and optimizing the values for the group contributions have been performed by the fminsearch algorithm in MATLAB software. The results of the new method are compared to three well known group contribution methods. The percentage of the average absolute relative deviations are 1.12% for critical temperature, 2.69% for critical pressure, and 2.67% for critical volume. • A new group contribution method is developed for critical constants of organic compounds. • Precise estimations for isomers are presented. • This method can estimate 25 chemical families including complex and polycyclic components. • A large set of experimental data for critical constants are used to develop new models. • The new method yields a better accuracy compared to three well-known methods. [ABSTRACT FROM AUTHOR]

Studies have been taken into the breakdown voltage jitter of corona-stabilized switch at high repetition rate up to several kHz. It is thought that the gas recovery affect the jitter of breakdown voltage directly at high repetition rate, because the gas switch will breakdown at a low voltage if the gas cannot fully recover. The breakdown voltage jitter is called voltage jitter in the following paper. However, based on the experimental results, the voltage jitter still exists at low repetition rate, even at single-shot mode. This is not explained by the previous studies. In this paper, voltage jitter below 100 Hz of a corona-stabilized switch is investigated experimentally. A corona-stabilized switch is introduced, using a cylindrical electrode as the cathode and a plane electrode as the anode. The gas used between the electrodes is SF6. A negative pulse with a maximum width of 30~\mu \texts is used to charge this switch. The tested factors include gas pressure, gap space, repetition rate, and switch geometry. Experimental results show that voltage jitter is mainly affected by the gas pressure and switch geometry. It is seen that voltage jitter decreases as gas pressure increases and a suitable cathode geometry presents a low voltage jitter. Critical volume is a region close to the highly stressed electrode, where the presence of an electron will lead to an electron avalanche which attains a critical size and hence leads to a stabilizing corona. Critical volume is introduced to explain the experimental results. It is found that less voltage jitter can be achieved with a smaller and more concentrated critical volume, as well as efficient corona stabilization. The results indicate that voltage jitter may be reduced by optimize the critical volume at low repetition rate. [ABSTRACT FROM PUBLISHER]

The deformation of viscoelastic droplets rising in non-Newtonian fluids is examined experimentally. Similarly to the case of bubbles and Newtonian droplets traveling in viscoelastic fluids, a critical volume exists but there is no jump in velocity nor a drastic change in droplet geometry. Nevertheless, a tail appears as well as a negative wake. For large-enough volumes, the thickness of the tail is much larger than that for the Newtonian droplets; this is also true for the magnitude of the negative wake and for the extension of the tail. The head of the droplet is subjected to a bi-axial elongation which deforms the spherical part of the droplet converting it into an elongated shape. This elongated shape blends into a tail and the droplet is converted into a viscous elongated teardrop. The tail is then subjected to a uniaxial extensional flow under the action of elongational stresses along the length of the tail. This extensional flow is counteracted by the shear stresses acting on the interface between the tail and the outer surrounding fluid. This interaction will determine the tail breakup. The influence of the elastic properties of the surrounding fluid and the extensional viscosity of the droplet will be responsible for the length and thickness of the tail as well as for its breakup mechanism. [ABSTRACT FROM AUTHOR]

A vacuum chamber is used as a new method to suppress gas explosion. Explosion propagation characteristics were studied in a system composed of rectangular pipes and a vacuum chamber. The volume of the vacuum chamber was adjusted by inserting PVC sheets into it. Two groups of explosion suppression experiments were conducted. In one group, the distance between the vacuum chamber and the explosive source point was 3 m and in the other group, this distance was 4 m. The results demonstrated that the effect of explosion suppression of the vacuum chamber is related to the vacuum chamber's critical volume. When the volume of the vacuum chamber was greater than the critical volume, the chamber exhibited a good explosion suppression effect. When the volume of the vacuum chamber was less than the critical volume, it could not suppress the explosion, and the explosive pressure and flame were stronger than those measured in the absence of the vacuum chamber. On the basis of the experimental results, we further analyzed the suppression mechanism of the vacuum chamber and concluded that stretching of the explosion flame front as well as alteration of the composition of the explosive gas led to the explosive flame being extinguished. [ABSTRACT FROM AUTHOR]

A new approach to structure-property problems using new invariants of fully weighted graphs to provide a quantitative description of the critical properties of freons is proposed. A general principle for constructing topological invariants of fully weighted graphs for structure-property correlations is formulated. Two new invariants are proposed and used to calculate critical properties of freons of the methane, ethane, and propane series. It is shown that unlike all other known incremental methods, the proposed approach does not require the use of experimental data or calibrations to calculate critical properties. It ensures a statistically reliable linear dependence of all critical properties of freons on the value of the matching index for our corresponding molecular graph. Over 2.5 thousand previously unknown values of the critical properties of lower freons are calculated. [ABSTRACT FROM AUTHOR]

Abstract: Ignition behavior of bituminous coal dust deposited between two hot surfaces forming wedges of 60°, and 90° is experimentally studied. Three thermocouples placed along the symmetry plane of the wedge cross-section at various heights from the apex (lowermost, middle and top) are used to record the transient temperature data. Results show that ignition always occurs around the region surrounding the top thermocouple in the case of 60° wedge and both the top and the middle regions in the case of 90° wedge. The trends are explained by investigating three parameters affecting the ignition behavior, namely, the heat transfer from the hot plate to the coal dust, the subsequent chemical heat release, and the heat transfer between different regions within the coal dust. Furthermore, an experimental setup, similar to the standard ASTM E 2021 test, is used to determine the minimum ignition temperatures of coal layers of various thicknesses and to assess the ignition scenario in the wedge configuration using an effective length scale. Measured quantities such as minimum hot plate temperature that causes ignition and the ignition time, as well as the transient heat release rate and heat conducted between various zones, calculated based on the temperature data are used to quantify the three parameters and their effects on ignition behavior. [Copyright &y& Elsevier]

Eleven types of the equation of state (EOS) are compared and classified into two groups, linear EOS and exponential EOS. The qualities of these two EOS groups are then verified with the data of 50 alloys. Through the comparison, it is found that the exponential Li equation gives a more reliable result when the fitting energy versus volume points are scattered in a wide scale or have a large number of data to fit. However, when the fitting data concentrate is in a small area near the equilibrium point, the linear four-parameter Birch-Murnaghan EOS has a better fitting result. Moreover, it is found that the Li equation has the best performance among these exponential EOSs with the smallest fitting errors. Additionally, there is a correlation found to be (PC/B0)/[(VC/V0)/V0] ≈ 0.3087 between ultimate strength PC and critical volume VC for the stable phases among the studied alloys. [ABSTRACT FROM AUTHOR]

The specific heat of solid elements (Cv) varies at lower temperatures, which means that there is some causes as to why it happens. Hence finding out that cause, presently a new theory has been proposed to explain the variation of their specific heat. The cause is that out of heat energy, subjected to increase the temperature of the substance, some part is drawn by the orbiting electrons of the atoms of the substance to furnish work against their binding force in order to excite them from their energy state E1 to energy state E2. Consequently, the temperature of the substance is not being increased to the amount to which it would have increased if no heat energy was drawn by the orbiting electrons. The emission of energy hν(=E2-E1) in the form of a photon from an excited orbiting electron, before its transition from energy state E2 to E1, confirms that the orbiting electrons draw some heat energy for their excitations. In order to verify the truth of this cause, evidence has also been given from a well-established existing knowledge. The present theory explains the so far unexplained variation of critical coefficient and critical volume of gases from gas to gas too. Using the present theory, the equation of state proposed by van der Waals has been modified, and critical coefficients and critical volumes have been calculated for some of the gases, which vary from gas to gas in accordance with the experimentally observed values. [ABSTRACT FROM AUTHOR]

Abstract: A new group contribution method for the estimation of critical property data has been developed. The method is based on structural group definitions, with minor modifications, of a method recently published for the estimation of the normal boiling point by Nannoolal et al. [Y. Nannoolal, J. Rarey, D. Ramjugernath, W. Cordes, Fluid Phase Equilib. 226 (2004) 45–63]. Special care was taken to ensure physically meaningful extrapolation to large and multifunctional compounds, as it could be shown that such extrapolation may lead to very improbable or unrealistic results in the case of some methods published earlier. Regression of group increments was not performed simultaneously but with great care one group at a time. With all other group increments fixed, all data for components with a specific group led to approximately the same group increment. This allowed one to determine group increments for cases where only one reliable experimental value was available. For the case of more than one strongly associating group, a group interaction contribution was required as these groups do not observe simple additivity. The estimation of the critical temperature requires knowledge of the normal boiling point. Critical pressure and volume can be estimated from chemical structure alone. The performance of the new model has been compared with 10 well-known estimation methods from literature and the results indicate that the new model is significantly more reliable. To enable comparison, chemical family definitions have been developed that allow one to automatically classify new components and thus, inform the user about the expected reliability of the different methods for a component of interest. Chemical family definitions are based on the kind and frequency of the different structural groups in the molecule. In addition to these advantages, the range of applicability of the new method is larger than that of comparable methods. [Copyright &y& Elsevier]

Abstract: Positron annihilation lifetime spectroscopy (PALS) and impedance spectroscopy (IS) have been employed to study the effect of temperature and pressure on the DC conductivity (σ DC) and the mean hole volume (V h) of a NaPF6 ethylene oxide based polyurethane electrolyte. The DC conductivity of the polymer electrolyte displayed a characteristic non-Arrhenius temperature dependence yielding acceptable values for both the “pseudo-activation energy” (B) and the “zero mobility temperature” (T 0) from a VTF fit. V h(T) showed a linear increase of 0.53cm3 (molK)−1. When extrapolating V h(T) to 0K a temperature very close to T 0 from the VTF fit was obtained, which suggests a free volume mediated conductivity mechanism. This suggestion is further supported by the linear dependence of ln(σ DC(T)) on . Conductivity was measured as a function of pressure (σ DC(P)) with ln(σ DC(P)) showing a characteristic decrease with increasing pressure. The activation volumes (V A) calculated from these measurements ranged from 45 to 20cm3 mol−1 over a temperature from 304 to 365K. Critical volumes calculated from two current free-volume models were found to be unrealistic. Combining the extra volume required for ionic motion (V A) with the available free volume (V h) at the same temperature poses a realistic and ‘model-free’ figure of 117cm3 mol−1 for the critical volume at 304K. This equates roughly to the volume of 3–4 EO units. The pressure dependence of free volume (V h(P)) for a polymer electrolyte has been measured for the first time, and yielded a linear decrease in V h with increasing pressure. A linear dependence of σ DC(P) on was also found. A comparison of the isothermal and isobaric dependence of σ DC on illustrates the contribution of factors other than free volume have on charge carrier number and mobility. This comparison shows that the variation of V h with temperature and the variation of V h with pressure affect the conductivity in very different ways. These results clearly show that free volume cannot be considered the sole factor responsible for conductivity in polymer electrolytes. [Copyright &y& Elsevier]

A new technique for predicting saturated liquid densities of alkanes at 25°C as a function of reduced temperature, acentric factor, critical volume, and molecular weight has been suggested. This new model shows good results in data fitness with an average absolute error (AAE) of 2.6% for 27 data point. [ABSTRACT FROM AUTHOR]

A new equation to predict critical volume for hydrocarbon compounds has been developed. The proposed new equation is based on molecular weight and boiling temperature, and it shows a significantly better correlation with the average absolute deviation (AAD) of 0.3% and 4.8% for two groups of hydrocarbon. [ABSTRACT FROM AUTHOR]

The critical volume (CV) normal tissue complication probability (NTCP) model was used to fit experimental data on radiation pneumonitis in mice to test the model and determine the values of the model parameters characterizing the lung structure: relative critical volume and cell radiosensitivity. The entire lungs of mice from ten different strains were irradiated acutely and homogeneously to different doses. The experimental animals from the different strains expressed different radiation sensitivities, forming ten well-defined dose?–?response curves. The most widely accepted biological NTCP model (the individual CV NTCP) readily applicable to cases of acute uniform irradiation was used to fit all the individual dose?–?response curves simultaneously. To account for the apparent difference in the response of the different strains, it was assumed that the strains differed in their (cell) radiosensitivity. The maximum likelihood method of fitting was used. The obtained fit was statistically highly acceptable. The best-fit value of the relative critical volume, µ, was 78%, which is extremely close to the histologically observed value of around 72%. The values of radiosensitivity, a, ranged between 0.26 and 0.37?Gy ?–?1 for the different strains. The best-fit numbers of functional subunits (FSU) constituting the lung, N, and the number of cells in an FSU, No, were implausibly low: N?=?9 and No?=?23, respectively. The best-fit value of NoN was a very small number that was unlikely to correspond to the total number of cells comprising the lung, suggesting that a different interpretation of N and No was required. The individual CV model provided a simultaneous description of the individual responses of different mouse strains through assumed interindividual variability in a only. A new interpretation is given to the entities corresponding to No and N. NoN is interpreted as the number of certain elementary structures. These structures are considered to be equivalent to the classical functional subunit, which is much larger than a cell and plays a fundamental role in determining the radiation response of the organ. N is identified as the number of the few large subdivisions of the lungs, M?=?µN is the number that have to be damaged for the lung to fail. No is interpreted as the mean number of elementary structures (FSU) per large subdivision. This imposes a picture of damage to large, contiguous subdivisions containing many FSU, which is consistent with the histological appearance of the lungs of mice in respiratory distress. This picture is in marked contrast to the random distribution of small areas of damage expected for the small size of an FSU. This random distribution is characteristic of earlier stages of the development of radiation pneumonitis, suggesting that some additional process spreads injury from damaged FSU to adjacent, undamaged FSU during the terminal phase. [ABSTRACT FROM AUTHOR]

The mass-transfer coefficient of a free-fall cascade-aerator unit of 15 million litres per day was evaluated for its efficiency in the removal of a class of volatile organics, the trihalomethanes (THMs). These compounds are carcinogenic and occur as a result of chlorination of natural waters. Due to the volatile nature of the THMs, the efficiency of aeration as a potential technique for their removal has been studied. The principle behind aeration is gas-transfer, according to which the gas-liquid interface is hypothesized to consist of a gas and liquid film through which gas is transferred by molecular diffusion until equilibrium is attained. The overall mass transfer coefficient (KL) of the aerator considering oxygen as the reference compound, was found to be 29.3 hr-1 for THMs. [ABSTRACT FROM AUTHOR]

• A unique method combining size and stress distribution effects is developed. • It is assessed on 34 different multiaxial load cases with various specimen designs. • Seven multiaxial fatigue strength methods are assessed. • PCRN method reaches the best output, the MMP method is only slightly worse. • The McDiarmid criterion provides good output despite its two-parametric character. This paper attempts to describe the effect of a non-constant stress distribution on the fatigue strength of unnotched hollow specimens of various sizes and loaded by different load combinations. The chosen solution evaluates the critical volume, which decides the level of fatigue damage. It relates dimensions of these critical entities to component fatigue strengths, which replace the material parameters in multiaxial fatigue strength criteria. The output shows that the proposed critical volume method is a promising solution. The PCRN and MMP multiaxial fatigue strength methods result in the best prediction outputs from the seven methods assessed here. [ABSTRACT FROM AUTHOR]

The predictive capability of the Peng–Robinson–Stryjek–Vera (PRSV-2) equation of state (1986) for critical properties of binary mixtures was investigated. The procedure adopted by Heidemann and Khalil (1980) and discussed by Abu-Eishah et al. (1998) was followed. An optimized value for the binary interaction parameter based on minimization of error between experimental and predicted critical temperatures was used. The standard and the average of the absolute relative deviations in critical properties are included. The predicted critical temperature and pressure for several nonpolar and polar systems agree well with experimental data and are always better than those predicted by the group-contribution method. A correction is introduced here to modify the predicted critical volume by the PRSV-2 equation of state, which makes the average deviations between predicted and experimental values very close to or even better than those predicted by the group-contribution method. [ABSTRACT FROM AUTHOR]

We have developed an endoscopic instrument that will allow a surgeon to safely, dependably and accurately place intramuscular (IM) electrodes in the diaphragm. This instrument has been used to implant 28 IM electrodes in the diaphragms of eleven acute and four chronic dogs. All electrodes achieved full activation of the diaphragm muscle, producing tidal volumes up to 130% VTCRIT, the critical volume necessary for basal ventilatory support, with unilateral stimulation. The surgeon is able to control the angle of the IM electrode insertion needle, which enables the needle to approach the diaphragm at an angle that is parallel to the surface of the muscle. This insures good control over the depth of needle penetration into the muscle, which greatly reduces the risk of accidentally passing the needle through the diaphragm and entering the thorax. Endoscopic placement of IM electrodes into the diaphragm opens opportunities to provide cost effective negative pressure ventilation to patients who are unable to effect sufficient ventilation by central nervous system (CNS) control of respiration [ABSTRACT FROM PUBLISHER]

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