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Obesity is caused by a prolonged positive energy balance1,2. Whether reduced energy expenditure stemming from reduced activity levels contributes is debated3,4. Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased over time. We use the International Atomic Energy Agency Doubly Labelled Water database on energy expenditure of adults in the United States and Europe (n = 4,799) to explore patterns in total (TEE: n = 4,799), basal (BEE: n = 1,432) and physical activity energy expenditure (n = 1,432) over time. In males, adjusted BEE decreased significantly, but in females this did not reach significance. A larger dataset of basal metabolic rate (equivalent to BEE) measurements of 9,912 adults across 163 studies spanning 100 years replicates the decline in BEE in both sexes. We conclude that increasing obesity in the United States/Europe has probably not been fuelled by reduced physical activity leading to lowered TEE. We identify here a decline in adjusted BEE as a previously unrecognized factor.

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction. (C) 2022 The Author(s). Published by Elsevier Ltd.

Publisher Copyright: © 2021 The Authors Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1–3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response—energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to find that energy compensation by a typical human averages 28% due to reduced BEE; this suggests that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day. Moreover, the degree of energy compensation varied considerably between people of different body compositions. This association between compensation and adiposity could be due to among-individual differences in compensation: people who compensate more may be more likely to accumulate body fat. Alternatively, the process might occur within individuals: as we get fatter, our body might compensate more strongly for the calories burned during activity, making losing fat progressively more difficult. Determining the causality of the relationship between energy compensation and adiposity will be key to improving public health strategies regarding obesity.

The significant advancement and growth of organic and flexible electronic applications demand materials with enhanced properties. This paper reports the fabrication of a nonsynthetic polymer thin film using radio frequency plasma polymerisation of 3,7-dimethyl-1,6-octadien-3-ol. The fabricated optically transparent thin film exhibited refractive index of approximately 1.55 at 500 nm and rate of deposition was estimated to be 40 nm/min. The surface morphology and chemical properties of the thin films were also reported in this paper. The optical band gap of the material is around 2.8 eV. The force of adhesion and Young's modulus of the linalool polymer thin films were measured using force-displacement curves obtained from a scanning probe microscope. The friction coefficient of linalool polymer thin films was measured using the nanoscratch test. The calculated Young's modulus increased linearly with increase in input power while the friction coefficient decreased.

Amongst alternative energy sources, photovoltaics hold a considerable promise for it is a plentiful, easily accessible and renewable source of power. Yet, the overall cost of generating electricity using the most advanced silicon based solar cells remains high compared to both traditional and other renewable power generation approaches. Organic thin film photovoltaics are an emerging economically competitive photovoltaic technology that combines manufacturing adaptability, low-cost processing and a lightweight, flexible device end-product. At present, however, commercial use of organic photovoltaics is hindered by low conversion efficiency and poor overall stability of the devices. Encapsulation with high barrier performance materials and structures is one of the key ways to address these issues and improve device lifetime. This paper will briefly outline the current understanding of the major degradation mechanisms, their interrelation and the internal and external factors that initiate these processes. Then, the paper will provide an overview of currently available encapsulant materials, their utility in limiting chemical (water vapor and oxygen penetration) and mechanical degradation within individual layers and device as a whole, and potential drawbacks to their application in organic photovoltaic devices.

Electrical impedance spectroscopy measurements were performed on metal–insulator–metal structures using recently developed plasma deposited thin films of linalyl acetate as the insulating layer between frequencies of 10 Hz and 100 kHz in order to better understand this material's dielectric and structural properties. Furthermore, measurements were performed on samples fabricated under various input energy conditions to determine whether effects induced by these conditions influence the dielectric properties. The plasma deposited linalyl acetate thin films were found to be low dielectric constant across a wide range of frequencies, with primary contributions from electronic factors. Neither α- nor β-relaxation peaks were observed in the frequency range investigated at room temperature and no significant dependence of dielectric properties on input energy was observed. Samples were then investigated under heated conditions at four temperatures, where a single relaxation peak was found. This peak was quite broad, indicative of the contribution of multiple relaxations to the dielectric response. The distribution of these relaxation times was determined through regularisation methods. The breakdown field was investigated for samples at three thicknesses, and found to be approximately 1.8 MV/cm.

Contact angle and temperature-dependent variable angle spectroscopic ellipsometry measurements have been performed on plasma-deposited linalyl acetate thin films in order to provide insight into the compatibility of the material with current organic electronic fabrication techniques. XPS data on several substrates confirmed that the chemical properties of the thin films were substrate independent. The plasma-deposited layers were found to be insoluble in many solvents commonly used in the deposition of organic semiconducting layers, including chloroform and dichlorobenzene, and the wetting envelope for the surfaces presented. Thermal degradation was found to begin at ~200 °C, and up until this temperature the material’s thickness, refractive index and transparency in the visible region were constant. The exhibited properties show plasma-deposited linalyl acetate thin films to be compatible with state of the art organic electronic processing techniques.

Thin films of plasma polymerised linalyl acetate (PLA) were fabricated and their electrical properties investigated. The high frequency dielectric constant was determined using the split post dielectric resonator (SPDR) technique at frequencies of 10 GHz and 20 GHz and compared with the low frequency dielectric constant found from capacitive measurements of metal–insulator–metal (MIM) structures. Dielectric constants of 2.39 and 2.43 resulted from each of the respective techniques, in good agreement with each other. The J – V characteristics of MIM structures fabricated at various RF power levels were then investigated in order to determine the resistivity and DC conduction mechanism of the PLA thin films. From these data, the predominate mechanism of charge transport in the high voltage region was found to be consistent with Richardson–Schottky conduction, and the resistivity of the thin films found to increase with increasing RF power.

Thin films of the n-type, organic semiconductor PDI-8CN2 were thermally evaporated on two different dielectric surfaces and their optical and morphological properties investigated using Variable Angle Spectroscopic Ellipsometry (VASE) and Atomic Force Microscopy (AFM), respectively. The two dielectric surfaces used were SiO2 and a plasma polymer derived from the non-synthetic monomer linalyl acetate. The characterisations were performed in order to assess the viability of plasma polymerised linalyl acetate (PLA) thin films as dielectric layers in future Organic Field-Effect Transistor (OFET) devices. These studies resulted in determination of the optical profiles (refractive index and extinction coefficient) in the UV-Vis band of PDI-8CN2 grown on SiO2 and an observation of uniaxial anisotropy in the organic semiconductor. This information is useful for the design of opto-electronic devices using PDI-8CN2 layers. Variations in morphological properties and small variations optical properties were found when the PDI-8CN2 films were grown on PLA layers, and attributed to the change in surface chemistry between dielectrics.

The optical properties of thermally evaporated PDI-8CN2 thin films have been investigated using Variable Angle Spectroscopic Ellipsometry (VASE). These layers were deposited on SiO2 dielectric layers as a means of measuring their properties on a standard interface. Regression analysis was used to determine the optical constants (refractive index and extinction coefficient) across a bandwidth of 300 – 900nm. Anisotropy of the films was investigated, as well as the thickness dependence of the optical constants. This paper presents the results of these investigations.

Polymerized Linalyl Acetate (PLA) thin films were fabricated using RF plasma polymerization. The dielectric properties of the PLA thin films have been investigated using the split post dielectric resonance technique, which consists of a silver coated copper cavity and two precisely machined identical dielectric materials. The measurements have been carried out at resonance frequencies of 10GHz and 20GHz, with good agreement between results. The dielectric properties were also investigated at low frequencies using capacitive measurements of MIM structures. All methodologies place the dielectric constant of the PLA material at approximately 2.4, indicating the material is suitable for use in electronics as an insulating layer.

Thin films derived from linalyl acetate were fabricated using the Radio Frequency (RF) plasma polymerisation technique between RF power levels of 10 and 75 W. The optical properties of the films were investigated using spectroscopic ellipsometry and UV–vis spectroscopy between 200 and 1000 nm. An optical band gap of approximately 3 eV for all power levels was determined from Tauc plots. The surface morphology and hardness of the material were studied using AFM and nano-indentation respectively to determine the effect of RF power on the thin film properties. Smooth surfaces with an average roughness of approximately 0.2 nm with consistent morphology were obtained across all power levels, while hardness demonstrated a linearly increasing dependence on RF deposition power, with values ranging between 0.29 and 0.44 GPa. These studies indicate the ability to tailor film characteristics by varying the RF deposition power, and the potential for the films to be used within electronic devices as encapsulation layers, insulating layers, or as semiconducting layers with the introduction of charge carriers to the chemical structure of the material.

Deep ultraviolet light emitting diodes (DUVLEDs) are fabricated using plasma assisted molecular beam epitaxy (PA-MBE) AlGaN films grown on 6-inch c-plane sapphire substrates with focus on yield and external quantum efficiency (EQE).

Plasma polymerisation is an effective tool for fabrication of thin films from volatile organic monomers. RF plasma assisted deposition is used for one-step, chemical-free polymerisation of nonsynthetic materials derived directly from agricultural produces. By varying the deposition parameters, especially the input RF power, the film properties can be tailored for a range of uses, including electronics or biomedical applications. The fabricated thin films are optically transparent with refractive index close to that of glass. Given the diversity of essential oils, this paper compares the chemical and physical properties of thin films fabricated from several commercially exploited essential oils and their components. It is interesting to note that some of the properties can be tailored for various applications even though the chemical structure of the derived polymer is very similar. The obtained material properties also show that the synthesised materials are suitable as encapsulating layers for biodegradable implantable metals.