Varying Energy Content Research Articles

Co-Valorisation Energy Potential of Wastewater Treatment Sludge and Agroforestry Waste

The growing demand for sustainable and environment-friendly energy sources resulted in extensive research in the field of renewable energy. Biomass, derived from organic materials such as agricultural waste, forestry products, and wastewater treatment plant (WWTP) sludge, holds great potential as a renewable energy resource that can reduce greenhouse gas emissions and offer sustainable solutions for energy production. This study focused on diverse biomass materials, including sludge from WWTPs, forest biomass, swine waste, cork powder, and biochar. Chemical and physicochemical characterizations were performed to understand their energy potential, highlighting their elemental composition, proximate analysis, and calorific values. Results showed that different biomasses have varying energy content, with biochar and cork powder emerging as high-energy materials with net heating values of 32.56 MJ/kg and 25.73 MJ/kg, respectively. WWTP sludge also demonstrated considerable potential with net heating values of around 14.87 MJ/kg to 17.44 MJ/kg. The relationships between biomass compositions and their heating values were explored, indicating the significance of low nitrogen and sulphur content and favourable carbon, hydrogen, and moisture balances for energy production. Additionally, this study looked into the possibility of mixing different biomasses to optimize their use and overcome limitations like high ash and moisture contents. Mixtures, such as “75% Santo Emilião WWTP Sludge + 25% Biochar,” showed impressive net heating values of approximately 21.032 MJ/kg and demonstrated reduced emissions during combustion. The study’s findings contribute to renewable energy research, offering insights into efficient and sustainable energy production processes and emphasizing the environmental benefits of biomass energy sources with low nitrogen and sulphur content.

Targeted dietary approaches for the management of obesity and severe obesity in children and adolescents: A systematic review and meta-analysis.

There is a need for a detailed understanding of effective dietary interventions for children with obesity. This systematic review examined the effectiveness of diets of varying energy content as a component of weight treatment in children and adolescents with obesity, severe obesity and obesity-related comorbidity. A systematic search of six databases, from 2000 to 2021, for intervention studies of targeted dietary treatment for obesity in children aged 2-18 years identified 125 studies. Dietary interventions were grouped according to diet type and energy target. Risk of bias was assessed using the Effective Public Healthcare Panacea Project assessment tool. Meta-analysis examined change in body mass index (BMI) at intervention end. A broad array of diet types were effective at reducing BMI in children with obesity. When dietary types were considered by energy target, a gradient effect was observed. Very-low energy diets were most effective with a - 4.40 kg/m2 (n=3; 95% CI -7.01 to -1.79). While dietary interventions with no specified energy target were ineffective, resulting in a BMI gain of +0.17 kg/m2 (n=22; 95% CI 0.05 to 0.40). Practical definitions of dietary energy target in the management of obesity and severe obesity are urgently required to ensure treatment seeking children have timely access to efficacious interventions.

Can oceanic prey effects on growth and time to fledging mediate terrestrial predator limitation of an at‐risk seabird?

AbstractMost seabird species nest colonially on cliffs or islands with limited terrestrial predation, so that oceanic effects on the quality or quantity of prey fed to chicks more often determine nest success. However, when predator access increases, impacts can be dramatic, especially when exposure to predators is extended due to slow growth from inadequate food. Kittlitz’s Murrelet (Brachyramphus brevirostris), a rare seabird having experienced serious declines, nests solitarily on the ground in barren, often alpine areas where exposure to predators is generally low. Nestling growth rates are exceptionally high and nestling periods very short relative to other Alcidae. This strategy reduces duration of exposure to predators, but demands adequate deliveries of high‐energy prey. In an area where foxes can access nests, we investigated whether varying energy content of prey fed to chicks could alter growth rates and resulting duration of predator exposure, and whether prolonged exposure appreciably reduced nest success. From 2009 to 2016, we monitored 139 nests; 49% were depredated (almost all by foxes) and 25% fledged. Prey fed to nestlings were 80% Pacific sand lance (Ammodytes personatus) and 19% capelin (Mallotus villosus), with capelin having 2.3× higher energy content per fish. In a year of slow chick growth, increased sand lance energy density of 31% (4.29–5.64 kJ/g, within published values), or increased proportion of capelin in the diet from 5.6% to 27.2%, would have allowed maximum chick growth. Maximum growth rates were attainable by delivering only 1.9 capelin/d versus 5.5 sand lance/d. Slow growth increased time to fledging by up to 5 d, decreasing survival by 7.7% (0.142–0.131). Breeding propensity of Kittlitz’s Murrelet averages only 20%, so even small changes in nest success could affect populations. Although nest success was limited mainly by predation, oceanic effects on prey quantity and quality had overriding impacts in one year (2015 heat wave), and small but substantive effects in other years by mediating exposure to predation. Climate warming that decreases availability of high‐energy forage fish, or increases expansion of predators into nesting habitats, may disproportionately affect this sensitive species and others with predator‐accessible nests and demands for energy‐rich prey.

Impact of dose-response calorie reduction or supplementation of a covertly manipulated lunchtime meal on energy compensation

Numerous studies have examined energy compensation following overfeeding regimes whereas much less is known about the impact of acute underfeeding on energy compensation and fewer still have compared energy reduction and addition in the same group of individuals. This study compared the effects of consuming lunches with varying energy content (7.2-fold difference) on subsequent energy intake. A total of 27 healthy males took part in this randomized, crossover study with five treatments: 163kcal (very low energy meal, VLEM), 302kcal (low energy meal, LEM), 605kcal (control), 889kcal (high energy meal, HEM), and 1176kcal (very high energy meal, VHEM) served as a noodle soup. Participants were instructed to consume a standardized breakfast in the morning and they were provided with one of the five treatments for lunch on non-consecutive test day. Test lunches were matched for palatability, sensory properties, and volume. Participants were provided with an afternoon snack and ad libitum dinner on each test day and recorded food intake for the rest of the day. Appetite ratings were measured at regular intervals. As the energy content of treatments increased, participants' hunger, desire to eat, and prospective consumption decreased significantly whereas fullness increased significantly. However, no significant difference in subsequent meal intake was found between the treatments (P=0.458): 1003kcal VLEM, 1010kcal LEM, 1011kcal control, 940kcal HEM, and 919kcal VHEM. Total daily energy intake was statistically significantly different between the treatments (P<0.001) and was varied directly with the energy content of the lunchtime meal. Despite the large difference in energy content between the treatments, participants did not compensate for the “missing calories” or “additional calories” at subsequent meals. These results suggest that covertly manipulated, equally palatable, sensory and volume matched meals have the potential to promote either positive or negative energy balance if the effects seen in this single meal study are sustained.

Effects of Guanidinoacetic Acid Supplementation to Broiler Diets With Varying Energy Content

An experiment was conducted to determine the response of broiler chickens to guanidinoacetic acid (GAA) added to diets with different energy levels during fattening to 35 days of age. Ross 308 male chicks were allotted to 10 treatments, each consisting of six replicates of 140 birds/pen. Five maize-soyabean meal isonitrogenous diets with decreasing AMEn levels (100, 99, 98, 97 and 96% of requirement) with or without supplements of 0.6 g/kg CreAMINO® containing a minimum of 96% GAA were formulated. The criteria of response were feed intake, body weight gains, feed conversion ratio and carcass, breast meat, leg meat and abdominal fat yields. Supplementation of broiler diets with 0.06% GAA resulted in a significant (P < 0.05) decrease in voluntary feed intake. With decreasing AMEn level, voluntary feed intake and consequently protein and amino acid intakes increased which was manifested by improved growth performance (P < 0.01). GAA supplements significantly (P < 0.001) improved feed conversion ratio and efficiency of AMEn utilization and significantly (P < 0.01) increased breast meat yield. With decreasing AMEn level, the effects of GAA supplementation tended to diminish.

Early optical emission from the gamma-ray burst of 4 October 2002.

Observations of the long-lived emission--or 'afterglow'--of long-duration gamma-ray bursts place them at cosmological distances, but the origin of these energetic explosions remains a mystery. Observations of optical emission contemporaneous with the burst of gamma-rays should provide insight into the details of the explosion, as well as into the structure of the surrounding environment. One bright optical flash was detected during a burst, but other efforts have produced negative results. Here we report the discovery of the optical counterpart of GRB021004 only 193 seconds after the event. The initial decline is unexpectedly slow and requires varying energy content in the gamma-ray burst blastwave over the course of the first hour. Further analysis of the X-ray and optical afterglow suggests additional energy variations over the first few days.

Energy content of the evening meal alters nocturnal body temperature but not sleep

Meals of varying energy content and episodes of sleep influence body temperature. We compared the effect of an evening meal, varying from high-energy (11.91 ± 0.86 MJ) to average (5.74 ± 0.88 MJ) and a 10-h fast (no evening meal), on nocturnal body temperature and sleep. Seven healthy men (20–24 years, mean body mass index of 23.4 ± 2.6 kg/m 2) reported to the laboratory for an evening meal at 2000 h having consumed similar amounts of food before 1300 h. After completing the meal, subjective hunger ratings were assessed, and a venous blood sample taken. The subjects spent 4 nonconsecutive nights (an adaptation night, followed by either of the two meal conditions or the fast in random order) in the sleep laboratory when polysomnographic recordings were made from 2300 to 0700 h. Meal energy content and serum concentrations of insulin, triglyceride, and low-density lipoproteins (LDL) varied significantly. Lower rectal temperatures were measured during the fast than following the meals. Over the 8-h recording period, thermal response indices (TRI) varied with higher body temperatures following the higher energy meal. Similar rectal temperatures were attained by the end of the sleep periods. There were no significant differences in any of the subjective or objective sleep measures. The physiological responses associated with the transient dietary changes of an evening meal or a 10-h fast altered nocturnal body temperature but did not significantly affect sleep of good sleepers when sleep was initiated 2 to 3 h after finishing the meal.

Short-term effects of different amounts of sweet and nonsweet carbohydrates on satiety and energy intake

If a sweet taste sensation increases appetite it can be hypothesized that sweet carbohydrates (CHOs) are less satiating than nonsweet CHOs. We studied this hypothesis in two experiments. In two within-subjects repeated measures experiments, subjects ( n = 28 in study 1, n = 29 in study 2) got lunches of varying energy content. There were five energy levels (250, 350, 450, 550, and 650 kcal) in the first experiment, and three energy levels (250, 500, and 750 kcal) in the second experiment. Within each energy level there was one lunch with sweet, and one lunch with nonsweet CHOs. The weight, protein, fat, carbohydrate, and fibre level was kept constant within each energy level. The results of the first study confirmed the hypothesis that sweet CHOs were less satiating than nonsweet CHOs. The results of the second study did not show a difference between the satiating effect of sweet and nonsweet CHOs. There was a strong sensory specific effect in both studies. Sweet CHOs had a suppressing effect on appetite for something sweet, whereas nonsweet CHOs suppressed appetite for something savoury. In the second study, sweet CHOs suppressed the intake of sweet food items in a test meal 2 h later in a dose-response manner. Nonsweet CHOs suppressed the intake of nonsweet food items, also in a dose-response manner. It is concluded that energy (or a food property related to energy) has a strong effect on appetite. The taste had a sensory specific effect on subsequent appetite and food selection.

Consumer/professional

Numerous studies have examined energy compensation following overfeeding regimes whereas much less is known about the impact of acute underfeeding on energy compensation and fewer still have compared energy reduction and addition in the same group of individuals. This study compared the effects of consuming lunches with varying energy content (7.2-fold difference) on subsequent energy intake. A total of 27 healthy males took part in this randomized, crossover study with five treatments: 163 kcal (very low energy meal, VLEM), 302 kcal (low energy meal, LEM), 605 kcal (control), 889 kcal (high energy meal, HEM), and 1176 kcal (very high energy meal, VHEM) served as a noodle soup. Participants were instructed to consume a standardized breakfast in the morning and they were provided with one of the five treatments for lunch on non-consecutive test day. Test lunches were matched for palatability, sensory properties, and volume. Participants were provided with an afternoon snack and ad libitum dinner on each test day and recorded food intake for the rest of the day. Appetite ratings were measured at regular intervals. As the energy content of treatments increased, participants' hunger, desire to eat, and prospective consumption decreased significantly whereas fullness increased significantly. However, no significant difference in subsequent meal intake was found between the treatments (P = 0.458): 1003 kcal VLEM, 1010 kcal LEM, 1011 kcal control, 940 kcal HEM, and 919 kcal VHEM. Total daily energy intake was statistically significantly different between the treatments (P < 0.001) and was varied directly with the energy content of the lunchtime meal. Despite the large difference in energy content between the treatments, participants did not compensate for the “missing calories” or “additional calories” at subsequent meals. These results suggest that covertly manipulated, equally palatable, sensory and volume matched meals have the potential to promote either positive or negative energy balance if the effects seen in this single meal study are sustained.

Robust optimal control theory for selective vibrational excitation in molecules: A worst case analysis

Recent research has demonstrated that optimal electromagnetic fields capable of producing selective vibrational excitation in molecules can be designed employing linear quadratic control methods using a cost functional that balances the energy distribution in the molecule, the fluence of the optical field, and a final cost to insure the desired excitation. Practical computations of molecular control theory for large molecules especially with anharmonic potentials become difficult to obtain due to the increased dimensionality and the accompanying uncertainty in the Hamiltonian. In this paper we reduce the complexity of the problem by treating a portion of the molecule including the target and optical dipoles in full detail, while the remainder of the molecule is modeled as an external disturbance of bounded energy. The optimal control field now minimizes the cost functional which is simultaneously maximized with respect to the energy constrained external disturbance to assure robustness. This optimal design process is commensurate with taking the most pessimistic view of the disturbance. This conservative view was born out in the numerical calculations such that practical laboratory studies should reach results much improved over the worst case design. As an illustration we investigate disturbances of varying energy content for a truncated 20 atom molecular chain where the uncontrolled remainder of the chain is the source of the system disturbance. The sensitivity of the system with respect to the disturbance was found to be strongly dependent on the distance of the disturbance to the target bond and the dipole arrangement. In addition, in the range of physically reasonable disturbance energy the optimal field could be accurately predicted from an asymptotic expansion involving only the reference undisturbed case. Although the present paper takes advantage of linear system techniques, the same robust optimal control procedure can be generalized to nonlinear systems by a variety of means.

Effect of guar gum on gastric emptying of test meals of varying energy content in growing pigs.

1. Existing information on whether the action of guar gum in decreasing postprandial blood glucose concentrations is due, at least in part, to a reduced rate of gastric emptying is conflicting, possibly because three types of test meals have been used. In order to test whether the type of test meal used influences the action of guar gum, these three types of meal were compared, either without or with guar gum, in growing pigs. The meals were: a high-energy meal (HEM), a low-energy milky drink (LEMD) and a glucose drink (GD). 2. Six pigs were prepared with a simple gastric cannula which allowed complete removal of the stomach contents just before or 0.5, 1, 2 or 4 h after feeding. 3. The three types of test meal without guar gum gave rise to very different postprandial profiles of gastric pH and of digesta and dry matter (DM) emptying from the stomach. 4. Addition of guar gum to the GD significantly raised gastric pH at 0.5 and 1 h after feeding but, when it was added to HEM, gastric pH was only significantly raised 4 h after feeding. No significant effect on gastric pH was seen when guar gum was added to LEMD. 5. Although addition of guar gum to GD had no significant effect on the emptying of digesta from the stomach, when added to HEM the rate of emptying of digesta was significantly reduced 1, 2 and 4 h after feeding. Addition of guar gum to LEMD only significantly increased the amount of digesta remaining in the stomach 2 h after feeding. 6. There was no significant effect on the emptying of DM from the stomach when guar gum was added to either HEM or LEMD. However, addition of guar gum to GD significantly reduced the mean rate of emptying of DM 0.5 h after feeding. 7. Addition of guar gum to either LEMD or GD had no significant effect on the DM concentration of the evacuated gastric digesta. However, addition of guar gum to HEM significantly lowered the DM concentration of the evacuated gastric digesta 1, 2 and 4 h after feeding. 8. It was concluded that differences in test meal composition and also in the methods used to measure gastric emptying could account for the discrepancies previously reported. The results suggest that although guar gum may reduce the rate of gastric emptying under some conditions, this is unlikely to be the only mechanism by which it acts.

The effect of restricted access to food on the voluntary food intake of pigs

SUMMARYTwo experiments were carried out to examine the effects of restricted food access on the voluntary food intake of pigs given diets of varying energy content or palatability. Where pigs were offered access to food for a restricted time period each day, the voluntary food intake was reduced in relation to the length of access allowed. Compensation was slow, particularly where a low-energy diet was fed. Younger pigs (35–45 kg) compensated faster than heavier pigs (100–110 kg). The responses of the heavier pigs appeared to be similar to those reported for genetically obese rats in their strong reaction to diets of different energy content or palatability.

Influence of Metabolizable Energy on Condition and Reproduction of Pheasants

Influence of Metabolizable Energy on Condition and Reproduction of Pheasants

Blast furnace operation at high blast temperatures

The problems of operating blast furnaces at temperatures in the 1900°–2100°F range—handling air at these temperatures, maintaining such temperatures with gas of low and varying energy content, and controlling the furnace for efficiency and quality—are discussed. The steps taken to overcome these problems at the Fairless Works of U.S. Steel Corp. are described. The effect of increasing the casting schedule, lengthening the tap hole, and improving the consistency of the hearth heat level are reported. The methods developed for utilizing top gas analysis for better furnace control are discussed.