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PubMed1990

[The effect of energy-rich and energy-reduced rations with n-alkane yeast portions on the fatty acid composition of fat stores of swine].

In 3 test groups (11 pigs in each group), rations with an identical fatty acid pattern of the fat in the fodder (except C 17 acids) with a high energy level (energy concentrations = 131%), medium energy level (energy concentrations = 100%) and low energy level (energy concentrations 90 or 82%, resp.) were used. In the course of the investigation the fatty acid spectrum was studied by analyzing spinal fat biopsy specimen. An interrelation was found to exist between the energy supply and the fatty acid spectrum in the depot fat. When identical quantities of heptadecenoic and heptadecanoic acids were added to the fodder, a high energy level resulted in a reduced C17 acid content in the spinal fat, whereas a low energy level led to an increased C17 acid content in the spinal fat. Different energy concentrations caused a change in the contents of oleic acid, linoleic acid and linolenic acid in the spinal fat. With changed energy concentrations, the C16 and C18 acid content showed variations compared with the group given standard fodder. The myristin acid content showed almost no change.

Adipose Tissue↗
PubMed2004

Salad and satiety: energy density and portion size of a first-course salad affect energy intake at lunch.

OBJECTIVE: We tested the effect on meal intake of varying the energy density and portion size of a compulsory first-course salad. DESIGN: The study used a randomized crossover design. SUBJECTS/SETTING: Forty-two women from the State College, PA, university community ate lunch in the laboratory once per week for 7 weeks. INTERVENTION: Lunch comprised one of six first-course salads, or no salad in the control condition, followed by a main course of pasta. Subjects were required to consume the entire salad, but ate as much pasta as they wanted. The salads varied in energy density (0.33, 0.67, or 1.33 kcal/g) and portion size (150 or 300 g). The energy density of the salad was reduced by changing the amount and type of dressing and cheese. MAIN OUTCOME MEASURES: Energy intake and ratings of hunger, satiety, and food characteristics were measured. STATISTICAL ANALYSES PERFORMED: Outcomes were analyzed using a linear mixed model with repeated measures. RESULTS: Compared with having no first course, consuming the low-energy-dense salads reduced meal energy intake (by 7% for the small portion and 12% for the large), and consuming the high-energy-dense salads increased intake (by 8% for the small portion and 17% for the large). When two salads with the same number of calories were compared, meal intake was decreased when the large portion of the lower-energy-dense salad was consumed. CONCLUSIONS: Eating a low-energy-dense first course enhances satiety and reduces meal energy intake. Consuming a large portion of a low-energy-dense food at the start of a meal may be an effective strategy for weight management.

Adult↗
PubMed1998

Dual-energy CT in the diagnosis and quantification of fatty liver: limited clinical value in comparison to ultrasound scan and single-energy CT, with special reference to iron overload.

BACKGROUND/AIMS: It has been suggested that dual-energy CT could differentiate irregular fatty liver from other hypodense lesions. We compared dual-energy CT to ultrasound scan and single-energy CT in the diagnosis and quantification of fatty liver, with special reference to iron overload. METHODS: Twenty-seven patients were included according to ultrasound: fatty liver (n=16) and normal liver (n=11). Single and dual-energy CT were performed. Attenuation measurements of hepatic lobes and control tissues were taken at 140 kV and 80 kV CT-guided liver biopsy was done in fatty liver patients, the degree of infiltration was estimated, and the histologic iron overload determined (iron overload, n=11; iron-free, n=5). RESULTS: The mean changes in attenuation for the right hepatic lobe were: normal liver: -0.8 (ns); iron overloaded fatty liver: 1.5 (ns); and iron-free fatty liver: 7.7 (p<0.0053). A spleen-liver attenuation differential threshold of 12H (140 kV, single-energy CT) and a right hepatic lobe 140 kV to 80 kV attenuation differential threshold of 9 H (dual-energy CT) were specific for fatty liver. Histology confirmed all cases of fatty liver diagnosed by ultrasound, independently of iron overload. Ultrasound did not differentiate cases of irregular from diffuse fatty liver detected on CT. Iron overload produced a masking effect in CT, decreasing its sensitivity: fatty liver was diagnosed in 67% of cases by single-energy CT and in 20% by dual-energy CT. Degree of fatty infiltration correlated with single-energy CT. CONCLUSIONS: Ultrasound diagnosed fatty liver best. Single-energy CT quantifies fatty infiltration, and best differentiates the irregular from the diffuse forms. Dual-energy CT is limited by poor sensitivity, especially in iron overload.

Adult↗
PubMed2003

Primary cortical neuronal cultures reduce cellular energy utilization during anoxic energy deprivation.

It has been widely hypothesized that neurons reduce cellular energy use in response to periods of energy deprivation. To test this hypothesis, we measured rates of energy use under normoxia and anoxia in immature (6 days in vitro) and mature (13 days in vitro) neuronal cultures. During anoxic incubation immature and mature cultures reduced cellular energy use by 80% and 45%, respectively. Reduced cellular energy use dramatically affected ATP depletion in neuronal cultures under anoxia. Intracellular ATP stores were expected to deplete within 3 min of anoxia. However, ATP was maintained at decreased but stabilized concentrations for at least 3 h. The capacity of neuronal cultures to reduce cellular energy use during anoxia correlated with their sensitivity towards simulated ischemia. Immature cultures, with the largest capacity to reduce cellular energy use, survived simulated ischemia 2.5 times longer than mature cultures. The addition of glutamate receptor antagonists to mature cultures further decreased cellular energy use during anoxia and significantly extended their survival time under simulated ischemia. This study verifies that primary cortical neuronal cultures reduce cellular energy use during energy deprivation. Additionally, we show that maturation of glutamate receptor activity increases non-depressible energy demand in neuronal cultures.

Adenosine Triphosphate↗
PubMed1988

[Energy requirements of young female cattle. 6. Energy requirements].

Results taken from 6 experiments with young female cattle comprising 477 metabolism periods served the derivation of the animals energy requirement in the development range greater than 125 kg live weight according to the factorial method. The energy requirement per kg LW0.75 and day, calculated from metabolism data, was independent of the stage of development and the intensity of feeding. It averaged 455 +/- 66 kJ metabolizable energy/kg LW0.75.d and 250 +/- 37 kJ NEFcattle/kg LW0.75.d respectively. The partial energy requirement for live weight gain, expressed in net energy fat, was equivalent to the energy content of the live weight gain. Energy retention and thus energy requirement per kg live weight gain increased with the live weight and reached a maximum of 26 MJ. Energy retention per kg live weight gain largely depended on the intensity of feeding and the stage of gravidity. Restrictive energy supply and progressing gravidity decreased energy content in the weight gain. The influences mentioned were taken into consideration on the derivation of the partial requirement for live weight gain. Equations were developed for the estimation of the energy requirement of young female cattle, which can be applied to both gravid and non-gravid cattle.

Animals↗
PubMed1997

Effect of high-fat and low-fat diets on voluntary energy intake and substrate oxidation: studies in identical twins consuming diets matched for energy density, fiber, and palatability.

There remains controversy over the effects of dietary fat content on voluntary energy intake. Additionally, the question of whether there is a genetic susceptibility to overeating high-fat diets has not been resolved. To address these issues, we designed two diets: a low-fat diet providing approximately 20% of energy as fat and a high-fat diet with approximately 40% of energy as fat. The diets were matched for energy density, fiber, and palatability. In a two-phase, 18-d intervention study, voluntary energy intakes and macronutrient oxidation rates during the fasting and fed states were determined in seven pairs of identical male twins. In contrast with results of previous intervention studies, in which low-fat and high-fat diets were not matched for energy density and other associated variables, we observed no significant difference in voluntary energy intake between the low-fat and high-fat phases, and mean daily intakes were similar (10.3 and 10.7 MJ/d, respectively). Postprandial rates of fat oxidation tended to reflect fat intakes in the two dietary phases, thus helping to explain the lack of a difference in mean energy intakes. There was also a significant twin-pair similarity in differences in energy intakes between dietary phases (P = 0.013). These results suggest that dietary fat content does not have a major influence on voluntary energy intake when dietary variables usually associated with fat are controlled for and that there may be a familial influence on the effects of dietary fat content on energy intake.

Adult↗
PubMed1979

Maintenance energy requirements, energy retention and heat production of young obese (ob/ob) and lean mice fed a high-fat or a high-carbohydrate diet.

Female obese (ob/ob) and lean mice were weaned at 21 days of age, placed in wire-mesh cages maintained at 25 to 30 degrees, and fed a high-fat or a high-carbohydrate diet for 21 days. The body energy balance procedure was utilized to determine the maintenance energy requirements, and the efficiency of dietary energy utilization, above maintenance, in these mice. Heat production of each mouse was measured weekly in a gradient-layer calorimeter. Regressions of changes in body energy per kg3/4 on metabolizable energy intake per kg3/4 indicated that the maintenance energy requirement averaged 72 kcal/kg3/4/day for obese mice and 124 kcal/kg3/4/day for lean mice. Diet composition did not influence the maintenance energy requirements, but utilization of energy, above maintenance, in obese mice fed the high-fat diet was 41% more efficient than observed in obese mice fed the high-carbohydrate diet and 38 to 71% more efficient than observed in lean mice. Heat production, per unit body weight was lower in obese mice than in lean mice. The lowest heat production was observed in obese mice fed the high-fat diet. The 40% lower maintenance energy requirement of the obese mice is a major factor contributing to the high efficiency of energy retention in these mice. Consumption of a high-fat diet further improved the ability of the obese mice to retain dietary energy.

Animals↗
PubMed1991

Energy restriction and the partitioning of energy among the costs of reproduction in rats in relation to growth of the progeny.

Compared with well-nourished controls, progeny of energy-restricted females are smaller and grow less well. The mechanisms behind these effects are frequently studied in rats but interpretation of such studies requires knowledge about the partitioning of dietary energy among the costs of reproduction and maternal needs. Energy partitioning was studied in rats fed ad libitum or 70% of ad libitum intake from 24-34 d before conception until d 14 of lactation and in virginal controls. Body composition was estimated for adult rats on d 1 of gestation, for adult rats and litters on d 1, 9 and 14 of lactation and for virginal controls after 65 d of dietary treatment. Milk production and composition were also studied. Dams in the two groups retained similar amounts of energy during pregnancy. Mobilized body energy corresponded to only 6 and 12% of the energy in milk for ad libitum-fed and restricted rats, respectively. Adult energy-restricted rats were smaller than their ad libitum-fed counterparts and thus needed less energy for maintenance. During lactation, energy-restricted rats used less energy per unit body size than ad libitum-fed rats. Pups of restricted dams were not only smaller, they also utilized milk energy less efficiently than did pups of well-fed dams.

Aging↗
PubMed1995

The role of energy expenditure in energy regulation: findings from a decade of research.

The role of energy expenditure in energy regulation remains a subject of continuing controversy. New data have emerged from studies conducted over the last decade demonstrating that energy expenditure is a critical factor contributing to successful energy regulation in normal individuals, as well as to the disregulation of energy balance that characterizes obesity. Reduced energy expenditure appears to facilitate weight gain in individuals susceptible to obesity and also appears to reduce the extent of body energy loss during undereating in both lean and obese individuals. The magnitude of the reduction in energy expenditure during, and perhaps after, weight loss is greater than expected on the basis of the reduction in body weight and appears to occur in response to undefined underlying determinants of energy regulation. In addition, exercise intervention studies and cross-sectional investigations of the relationship between energy expenditure for physical activity and body composition demonstrate an apparent equilibration between physical activity and body fat content. This equilibration is suggestive of a direct influence of physical activity on the underlying metabolic determinants of energy balance.

Body Mass Index↗
PubMed1982

Dietary energy requirements of broilers reared in low and moderate environmental temperatures. 1. Adjusting dietary energy to compensate for abnormal environmental temperatures.

Four trials were conducted to determine the feasibility of replacing fossil fuel energy with dietary energy to meet the 23- to 48-day-old broiler chicken's energy requirements during abnormal cold exposure. Sexed broilers were fed 3250 or 3500 kcal metabolizable energy (ME)/kg in a 21.1 C environment (a normal management situation), and 3250 or 3125 kal ME/kg in a 26.7 C environment. Body weights and feed utilizations increased when broilers were exposed to a 15.6 C environmental temperature and fed 3375 kcal ME/kg dietary energy as compared to feeding a 3250 kcal ME/kg dietary energy in the same environment. When broilers were reared in a 10.0 C environment, maximum body weights were not obtained by increasing the dietary energy from 3250 to 3500 kcal/kg dietary energy. Broiler males, fed 3250 kcal ME/kg and reared in either a 21.1 or a 26.7 C environment, were larger than males reared in 10.0 C environment. No significant differences were found in broiler female weights reared in a 10.0, 15.6, or 21.1 C environment and fed 3250 kcal ME/kg in each temperature regimen. Feed utilizations were the same broilers were reared in a 15.6 C environment and fed 3375 kcal ME/kg compared to broilers reared in a 21.1 C environment and fed 3250 kcal ME/kg. These results indicate that maximum performance of 23- to 48-day-old broilers may be achieved in a 15.6 C environment by feeding a high energy diet (3375 kcal/kg). Results also showed that dietary energy may replace fossil fuel energy that would normally be supplied in a 21.1 C environment.

Adipose Tissue↗
PubMedDate not supplied

Smaller but energy and protein-enriched meals improve energy and nutrient intakes in elderly patients.

UNLABELLED: The purpose of the present study was to investigate if smaller but energy and protein enriched meals could improve energy and nutrient intakes in elderly geriatric patients. Ten patients, between 77 and 87 years of age were included in the study, performed at a Geriatric rehabilitation ward. The first week after inclusion, the patients were offered a three days' standard hospital menu and the second week, a three days' energy and protein-enriched menu. The consumption of food and the fluid intake were recorded using a pre-coded food record book during both the menus and analysed by the Swedish National Food Administration. The patients' energy requirements were calculated according to the Nordic Nutrition Recommendation for elderly subjects. When the standard hospital menu was offered, six patients had lower energy intake, -67 to -674 kcal/day, than the calculated energy requirements. The daily energy intake increased by 37 %, with the energy and protein-enriched menu compared with the standard hospital menu. Furthermore, the daily intake of protein, fat, carbohydrate, certain vitamins and minerals was significantly higher with the energy and protein-enriched menu compared with the standard hospital menu. CONCLUSION: This study showed that the intake of energy and nutrients increased with the energy and protein-enriched menu in elderly patients on a geriatric rehabilitation ward.

Aged↗
PubMed1990

Comparison of energy expenditure estimated in healthy infants using the doubly labelled water and energy balance methods.

The doubly labelled water method was used to estimate energy expenditure in 20 formula-fed infants (10 aged 1 month and 10 aged 4 months). We then compared the energy expenditure values with energy balance values calculated from energy intake and energy cost of growth. Our purpose was to compare various published equations for calculating CO2 expiration rates (and thus energy expenditure values) from the isotopic data. Those equations in which we used measured values for 18O and 2H isotope dilution spaces and estimated or measured values for insensible water losses yielded energy expenditure values (69.7 +/- 8.4 kcal/kg/d) that agreed most closely with energy balance data (70.3 +/- 11.9 kcal/kg/d). Equations in which we used a constant ratio of 1.03 between the 2H and 18O isotope dilution spaces resulted in energy expenditure values (66.3 +/- 10.2 kcal/kg/d) lower than those predicted by the energy balance data. Data analysis by nonlinear curve fitting compared to logarithmic transformation did not alter the estimates of energy expenditure obtained in these infants.

Child Development↗
PubMed1996

[Effect of energy density and fat level of milk formulas on subsequent food and energy intake in preschool children].

The aim of this study was to examine the effects of two levels of energy intakes and two levels of fat at breakfast, on the food and energy intakes in subsequent meal (lunch). The study was performed in 51 children both genders, with ages ranging from 24 to 48 months, attending a day care center. The children selected had normal nutritional status (weight/height index) according to the NCHS standards. The food intake was determined by differential weighing and energy intake was calculated from proximal analysis. The energy densities of the cow's milk formula used were 0.8 and 1.2 kcal/g, resulting in a total energy offer (breakfast) of 267.5 and 367.5 kcal respectively, the fat levels were 6.3 and 0.9 g/250 g of formula, using the design 2 x 2 factorial. In the study, 720 observations of food intake were conducted in those children consuming higher than 75% of the total food offered at breakfast. In the lunch-time were offered in alternated form two preparations with an 0.97 kcal/g of energy density. The results demonstrated that the children consumed significantly higher energy amounts in the subsequent meal, after being fed the high fat and lower energy-content breakfast. When the total energy intake (breakfast + lunch) was compared these results show that the caloric difference of breakfast was reduced and the degree of reduction was influenced by the fat level. These results show evidence for partial caloric compensation of 67% in the higher-fat level, and only 34% for the children with the lower of fat-level. It is conclude that the energy intake and fat intake at breakfast influences the energy intake at the subsequent meal. These findings are important to the preschool children's feeding with risk of malnutrition.

Animals↗
PubMed2005

Continuous energy variation during the seizure cycle: towards an on-line accumulated energy.

OBJECTIVE: Increases in accumulated energy on intracranial EEG are associated with oncoming seizures in retrospective studies, supporting the idea that seizures are generated over time. Published seizure prediction methods require comparison to 'baseline' data, sleep staging, and selecting seizures that are not clustered closely in time. In this study, we attempt to remove these constraints by using a continuously adapting energy threshold, and to identify stereotyped energy variations through the seizure cycle (inter-, pre-, post- and ictal periods). METHODS: Accumulated energy was approximated by using moving averages of signal energy, computed for window lengths of 1 and 20 min, and an adaptive decision threshold. Predictions occurred when energy within the shorter running window exceeded the decision threshold. RESULTS: Predictions for time horizons of less than 3h did not achieve statistical significance in the data sets analyzed that had an average inter-seizure interval ranging from 2.9 to 8.6h. 51.6% of seizures across all patients exhibited stereotyped pre-ictal energy bursting and quiet periods. CONCLUSIONS: Accumulating energy alone is not sufficient for predicting seizures using a 20 min running baseline for comparison. Stereotyped energy patterns through the seizure cycle may provide clues to mechanisms underlying seizure generation. SIGNIFICANCE: Energy-based seizure prediction will require fusion of multiple complimentary features and perhaps longer running averages to compensate for post-ictal and sleep-induced energy changes.

Algorithms↗
PubMed2003

Insights into protein-protein binding by binding free energy calculation and free energy decomposition for the Ras-Raf and Ras-RalGDS complexes.

Absolute binding free energy calculations and free energy decompositions are presented for the protein-protein complexes H-Ras/C-Raf1 and H-Ras/RalGDS. Ras is a central switch in the regulation of cell proliferation and differentiation. In our study, we investigate the capability of the molecular mechanics (MM)-generalized Born surface area (GBSA) approach to estimate absolute binding free energies for the protein-protein complexes. Averaging gas-phase energies, solvation free energies, and entropic contributions over snapshots extracted from trajectories of the unbound proteins and the complexes, calculated binding free energies (Ras-Raf: -15.0(+/-6.3)kcal mol(-1); Ras-RalGDS: -19.5(+/-5.9)kcal mol(-1)) are in fair agreement with experimentally determined values (-9.6 kcal mol(-1); -8.4 kcal mol(-1)), if appropriate ionic strength is taken into account. Structural determinants of the binding affinity of Ras-Raf and Ras-RalGDS are identified by means of free energy decomposition. For the first time, computationally inexpensive generalized Born (GB) calculations are applied in this context to partition solvation free energies along with gas-phase energies between residues of both binding partners. For selected residues, in addition, entropic contributions are estimated by classical statistical mechanics. Comparison of the decomposition results with experimentally determined binding free energy differences for alanine mutants of interface residues yielded correlations with r(2)=0.55 and 0.46 for Ras-Raf and Ras-RalGDS, respectively. Extension of the decomposition reveals residues as far apart as 25A from the binding epitope that can contribute significantly to binding free energy. These "hotspots" are found to show large atomic fluctuations in the unbound proteins, indicating that they reside in structurally less stable regions. Furthermore, hotspot residues experience a significantly larger-than-average decrease in local fluctuations upon complex formation. Finally, by calculating a pair-wise decomposition of interactions, interaction pathways originating in the binding epitope of Raf are found that protrude through the protein structure towards the loop L1. This explains the finding of a conformational change in this region upon complex formation with Ras, and it may trigger a larger structural change in Raf, which is considered to be necessary for activation of the effector by Ras.

Biophysical Phenomena↗
PubMed2001

Dual-coil vs single-coil active pectoral implantable defibrillator lead systems: defibrillation energy requirements and probability of defibrillation success at multiples of the defibrillation energy requirements.

AIMS: The aim of the study was to compare the defibrillation energy requirements and the probability of successful defibrillation at multiples of the minimum defibrillation energy requirements in active pectoral implantable defibrillators with single- and dual-coil lead systems. METHODS AND RESULTS: Eighty-three consecutive patients undergoing implantation of an active pectoral cardioverter-defibrillator were randomized to receive a dual- or single-coil lead system. Defibrillators of two manufacturers with a fixed tilt biphasic defibrillation waveform were used. Defibrillation energy requirements were determined using a step-down defibrillation testing protocol. According to the randomization protocol, the patients were assigned to three additional consecutive defibrillation attempts during device implantation and during pre-discharge testing of either 1.0, 1.5 or 2.0 times the determined defibrillation energy requirement. Patients presenting defibrillation energy requirements > 15 J were excluded from analysis. Eighty of 83 patients (96%) completed the study protocol. Three patients were excluded due to elevated defibrillation energy requirements. The defibrillation energy requirements in the dual- and single-coil patient groups were 8.0 +/- 3.6 J and 8.4 +/- 3.7 J (ns), respectively. A comparable percentage of study patients showed defibrillation energy requirements <10 J (dual-coil: 88% vs single-coil: 83%). Defibrillation impedance was significantly different (dual-coil: 50 +/- 5.8 Ohm; single-coil: 39.8 +/- 4.2 Ohm). Regarding the probabilities of successful defibrillation, there were no significant differences between the two patient groups. The probabilities of defibrillation at the three multiples of the defibrillation energy requirement using a dual- and single-coil lead system were 82, 89.7 and 93.6 and 77.8, 94.1 and 95.8%, respectively (P=0.88, P=0.42, P=0.62, respectively). CONCLUSIONS: Dual- and single-coil active pectoral defibrillator systems show no difference in defibrillation energy requirements and no difference in the probability of successful defibrillation at multiples of the minimum defibrillation energy requirement. The use of more simplified defibrillator lead systems may contribute to a future lead design focusing on improvement in lead durability.

Aged↗
PubMed2005

Recoil energy distributions for dissociation of the van der Waals molecule p-difluorobenzene-Ar with 450-3000 cm(-1) excess energy.

Velocity map imaging has been used to measure the distributions of translational energy released in the dissociation of p-difluorobenzene-Ar van der Waals complexes from the 5(1), 3(1), 5(2), 3(1)5(1), 5(3), 3(2), and 3(2)5(1) states. These states span 818-3317 cm(-1) of vibrational energy and correspond to a range of energies above dissociation of 451-2950 cm(-1). The translational energy release (recoil energy) distributions are remarkably similar, peaking at very low energy (10-20 cm(-1)) and decaying in an exponential fashion to approach zero near 300 cm(-1). The average translational energy released is small, shows no dependence on the initial vibrational energy, and spans the range 58-72 cm(-1) for the vibrational levels probed. The average value for the seven levels studied is 63 cm(-1). The low fraction of transfer to translation is qualitatively in accord with Ewing's momentum gap model [G. E. Ewing, Faraday Discuss. 73, 325 (1982)]. No evidence is found in the distributions for a high energy tail, although it is likely that the experiment is not sufficiently sensitive to detect a low fraction of transfer at high translational energies. The average translational energy released is lower than has been seen in comparable systems dissociating from triplet and cation states.

Journal Article↗
PubMed2006

New exchange-Coulomb N2-Ar potential-energy surface and its comparison with other recent N2-Ar potential-energy surfaces.

The reliability of five N2-Ar potential-energy surfaces in representing the N2-Ar interaction has been investigated by comparing their abilities to reproduce a variety of experimental results, including interaction second viral coefficients, bulk transport properties, relaxation phenomena, differential scattering cross sections, and the microwave and infrared spectra of the van der Waals complexes. Four of the surfaces are the result of high-level ab initio quantal calculations; one of them utilized fine tuning by fitting to microwave data. To date, these four potential-energy surfaces have only been tested against experimental microwave data. The fifth potential-energy surface, based upon the exchange-Coulomb potential-energy model for the interaction of closed-shell species, is developed herein: it is a combination of a damped dispersion energy series and ab initio calculations of the Heitler-London interaction energy, and has adjustable parameters determined by requiring essentially simultaneous agreement with selected quality interaction second viral coefficient and microwave data. Comparisons are also made with the predictions of three other very good literature potential-energy surfaces, including the precursor of the new exchange-Coulomb potential-energy surface developed here. Based upon an analysis of a large body of information, the new exchange-Coulomb and microwave-tuned ab initio potential-energy surfaces provide the best representations of the N2-Ar interaction; nevertheless, the other potential-energy surfaces examined still have considerable merit with respect to the prediction of specific properties of the N2-Ar van der Waals complex. Of the two recommended surfaces, the new exchange-Coulomb surface is preferred on balance due to its superior predictions of the effective cross sections related to various relaxation phenomena, and to its reliable, and relatively simple, representation of the long-range part of the potential-energy surface. Moreover, the flexibility still inherent in the exchange-Coulomb potential form can be further exploited, if required, in future studies of the N2-Ar interaction.

Journal Article↗