Low-energy Approach Research Articles

Low energy nanoemulsions as carriers of thyme and lemon balm essential oils

The aim of this work was to produce monomodal and stable thyme and lemon balm-loaded nanoemulsions (NE), through a low energy approach. NEs were prepared by the emulsion phase inversion method using sunflower oil as carrier and Tween 80 as surfactant. Different surfactant-to-oil ratios (SOR) and essential oil (EO) loadings were evaluated. Nanoemulsions presented a monomodal diameter distribution below 200 nm and high negative zeta potential (>−40 mV). Nanoemulsions loaded with EOs were physically stable for 3 months at 4 °C and 20 °C. Nanoemulsions with thyme EO presented the highest radical scavenging activity by DPPH and ABTS tests. Loaded nanoemulsions were not effective against Escherichia coli but could inhibit Staphylococcus aureus. Cytotoxicity studies using cell counting kit-8 and resazurin assays revealed a dose-responsive effect of nanoemulsions on Caco-2 cells after incubation for 24 h. A concentration of 100 μg oil/mL of NE for unloaded and thyme loaded and 50 μg oil/mL of NE for lemon balm loaded showed to be safe to use.

Graphene Flake Self-Assembly Enhancement via Stretchable Platforms and External Mechanical Stimuli.

While the green production and application of 2D functional nanomaterials, such as graphene flakes, in films for stretchable and wearable technologies is a promising platform for advanced technologies, there are still challenges involved in the processing of the deposited material to improve properties such as electrical conductivity. In applications such as wearable biomedical and flexible energy devices, the widely used flexible and stretchable substrate materials are incompatible with high-temperature processing traditionally employed to improve the electrical properties, which necessitates alternative manufacturing approaches and new steps for enhancing the film functionality. We hypothesize that a mechanical stimulus, in the form of substrate straining, may provide such a low-energy approach for modifying deposited film properties through increased flake packing and reorientation. To this end, graphene flakes were exfoliated using an unexplored combination of ethanol and cellulose acetate butyrate for morphological and percolative electrical characterization prior to application on polydimethylsiloxane (PDMS) substrates as a flexible and stretchable electrically conductive platform. The deposited percolative free-standing films on PDMS were characterized via in situ resistance strain monitoring and surface morphology measurements over numerous strain cycles, with parameters extracted describing the dynamic modulation of the film’s electrical properties. A reduction in the film resistance and strain gauge factor was found to correlate with the surface roughness and densification of a sample’s (sub)surface and the applied strain. High surface roughness samples exhibited enhanced reduction in resistance as well as increased sensitivity to strain compared to samples with low surface roughness, corresponding to surface smoothing, which is related to the dynamic settling of graphene flakes on the substrate surface. This procedure of incorporating strain as a mechanical stimulus may find application as a manufacturing tool/step for the routine fabrication of stretchable and wearable devices, as a low energy and compatible approach, for enhancing the properties of such devices for either high sensitivity or low sensitivity of electrical resistance to substrate strain.

Insight into the effect of OH modification on the piezo-photocatalytic hydrogen production activity of SrTiO3

Surface modification by hydrophilic functional group have a tremendous influence on the catalytic activity of photocatalyst, however, there are few reports on improving piezoelectric catalytic performance through surface functionalization. Herein, OH-modified SrTiO3 was successfully obtained via a novel low-temperature solid-state precursor method and employed as a catalyst for photocatalytic, piezocatalytic and piezo-photocatalytic hydrogen production. Thanks to the super hydrophilic that is facilitating the contact of catalyst and water molecular and the more oxygen vacancies that can promote electron-hole separation, the photocatalytic, piezocatalytic and piezo-photocatalytic hydrogen generation of OH-modified SrTiO3 (OH-STO) is about two times higher than pristine SrTiO3 (STO). It is worth mentioning that the optimal piezo-photocatalytic hydrogen evolution rate of OH-STO (701.2 µmol h−1 g−1) is 5.3 times higher than the photocatalytic hydrogen evolution process of STO. This study presents a low-energy approach to the rational design of functional group modification nanomaterials that possess excellent piezo-photocatalytic performance.

Advances in Implantable Optogenetic Technology for Cardiovascular Research and Medicine.

Optogenetic technology provides researchers with spatiotemporally precise tools for stimulation, sensing, and analysis of function in cells, tissues, and organs. These tools can offer low-energy and localized approaches due to the use of the transgenically expressed light gated cation channel Channelrhodopsin-2 (ChR2). While the field began with many neurobiological accomplishments it has also evolved exceptionally well in animal cardiac research, both in vitro and in vivo. Implantable optical devices are being extensively developed to study particular electrophysiological phenomena with the precise control that optogenetics provides. In this review, we highlight recent advances in novel implantable optogenetic devices and their feasibility in cardiac research. Furthermore, we also emphasize the difficulties in translating this technology toward clinical applications and discuss potential solutions for successful clinical translation.

A Low Energy Approach for the Preparation of Nano-Emulsions with a High Citral-Content Essential Oil.

Pectis elongata is found in the northern and northeastern regions of Brazil. It is considered a lemongrass due to its citric scent. The remarkable citral content and the wide antimicrobial properties and bioactive features of this terpene make this essential oil (EO) eligible for several industrial purposes, especially in cosmetics and phytotherapics. However, to address the problems regarding citral solubility, nano-emulsification is considered a promising strategy thanks to its improved dispersability. Thus, in this paper we propose a low-energy approach for the development of citral-based nano-emulsions prepared with P. elongata EO. The plant was hydrodistillated to produce the EO, which was characterized with a gas chromatograph coupled to mass spectrometry. The nano-emulsion prepared by a non-heated water titrating (low-energy) method was composed of 5% (w/w) EO, 5% (w/w) non-ionic surfactants and 90% (w/w) deionized water and was analyzed by dynamic light scattering. Levels of citral of around 90% (neral:geranial—4:5) were detected in the EO and no major alteration in the ratio of citral was observed after the nano-emulsification. The nano-emulsion was stable until the 14th day (size around 115 nm and polydispersity index around 0.2) and no major alteration in droplet size was observed within 30 days of storage. Understanding the droplet size distribution as a function of time and correlating it to concepts of compositional ripening, as opposing forces to the conventional Ostwald ripening destabilization mechanism, may open interesting approaches for further industrial application of novel, low-energy, ecofriendly approaches to high citral essential oil-based nano-emulsions based on lemongrass plants.

Constructing the frustrated Lewis pairs within N,S-codoped carbon to reveal the role of adjacent heteroatom sites for highly effective removal of heavy metal ions

Heteroatom doping is a promising strategy for improving adsorption performance of cost-effective carbon materials for heavy-metal ions from wastewater. However, the lack of theoretical research restricts its development. Herein, theoretical simulations successfully predict that the short distance between the N and S sites is a key factor for the N,S-codoped carbon with a higher adsorption capacity than that of the single doping carbon. Inspired by this interesting finding, a low-energy and ultrafast approach is proposed to prepare N,S-codoped carbon within only 10 s from ternary deep eutectic solvents. Benefiting from the unique dual-doped architecture, the adsorption capacity of the N,S-codoped carbon for Cr(VI) is significantly enhanced to 564.7 mg/g in comparison with single doped carbon (396.2 mg/g) and pristine carbon (186.4 mg/g). The further calculations of energy and electronic structure reveal that adjacent –NH3+ and –SO2– groups can generate frustrated Lewis pairs (FLPs). Such FLP-type sites can promote the adsorption and reduction of Cr(VI) ions due to enhanced electron transfer between functional groups and Cr(VI) ions. This work provides an in-depth comprehension and guidance for synthesis of heteroatom-codoped carbon-based materials with excellent separation performance for heavy metal ions.

Vertebrate Life, 10th edition

Vertebrate Life, 10th edition

Neutrino masses and mixing in models with large extra dimensions and localized fermions

Using a low-energy effective field theory approach, we study some properties of models with large extra dimensions, in which quarks and leptons have localized wave functions in the extra dimensions. We consider models with two types of gauge groups: (i) the Standard-Model gauge group, and (ii) the left-right symmetric (LRS) gauge group. Our main focus is on the lepton sector of models with $n=2$ extra dimensions, in particular, neutrino masses and mixing. We analyze the requisite conditions that the models must satisfy to be in accord with data and present a solution for lepton wave functions in the extra dimensions that fulfills these conditions. As part of our work, we also present a new solution for quark wave function centers. Issues with flavor-changing neutral current effects are assessed. Finally, we remark on baryogenesis and dark matter in these models.

Assembly of propylene glycol alginate/β-lactoglobulin composite hydrogels induced by ethanol for co-delivery of probiotics and curcumin

Probiotics and curcumin can exhibit synergistic biological activities on the basis of a gut-brain axis, but are sensitive to environmental conditions, making it a challenge for their co-utilization. To meet the demand for high efficiency and convenience, both probiotics and curcumin were encapsulated within a propylene glycol alginate-based hydrogel delivery system, which was assembled using an ethanol-induced approach. The composite hydrogel was effective at sustaining the release of curcumin and protecting LGG cells in simulated gastrointestinal tract conditions. Moreover, it could also largely reduce the chemical degradation of curcumin and increase the survival of LGG during light exposure and long-term storage: up to 91.3 % of curcumin and 9.72 log CFU cm−3 remained present throughout 4 weeks of storage. Results in this work demonstrate a low-energy and green approach to assemble a composite hydrogel with remarkable biocompatibility, which is considered as a desired delivery vehicle for co-delivery of probiotics and curcumin.

Low Energy Architecture and Low Carbon Cities: Exploring Links, Scales, and Environmental Impacts

Projected population growth and urbanization rates will create a huge demand for new buildings and put an unprecedented pressure on the natural environment and its limited resources. Architectural design has often focused on passive or low-energy approaches to reduce the energy consumption of buildings but it is evident that a more holistic, whole-life based mindset is imperative. On another scale, the movement for, and global initiatives around, low carbon cities promise to deliver the built environment of tomorrow, in harmony with the natural boundary of our planet, the societal needs of its human habitants, and the required growth for economic prosperity. However, cities are made up of individual buildings and this intimate relationship is often poorly understood and under-researched. This multi-scale problem (materials, buildings, and cities) requires plural, trans-disciplinary, and creative ways to develop a range of viable solutions. The unknown about our built environment is vast: the articles in this special issue aim to contribute to the ongoing global efforts to ensure our built environments will be fit for the challenges of our time.

Ethylcellulose nanoparticles prepared from nano-emulsion templates as new folate binding haemocompatible platforms

Ethylcellulose is a biocompatible polymer attracting increasing interest for biomedical applications. In the present work, the formation of folate-ethylcellulose nanoparticle complexes from nano-emulsion templates prepared by a low-energy approach, using aqueous components suitable for biomedical applications has been investigated. The composition of the aqueous component is shown to be crucial for the formation of stable nano-emulsions and influences the zeta potential values. The ethylcellulose nanoparticles with mean sizes around 100 nm were obtained from the nano-emulsions by solvent evaporation and showed positive zeta potential values above +20 mV due to the presence of the cationic surfactant. The nanoparticles were successfully complexed with folate, as evidenced by both particle size and zeta potential measurements. The complexes prepared with HEPES buffered glucose solution showed excellent haemocompatibility, which make them promising for parenteral therapeutic applications and also for those in which easy access to systemic circulation may occur, like in lungs.

Problems encountered during the start-up of up flow anaerobic sludge blanket reactors (UASB) at 20 ⁰C & 15 ⁰C

UASB technology has been widely adopted for the treatment wastewaters in warm climates. Operation at low temperature wastewaters still present some challenges. When working at lower temperatures a number of operational problems were experienced associated with the accumulation of biogas and wastewater solids in or below the sludge bed. Physical entrapment of the biogas produced formed a buoyant plug, which had a tendency to float the sludge bed. An operational solution to this problem was found which involved fluidising the bed once a day to ensure better distribution of organic solids and allow the release of any trapped biogas. This was achieved by pumping biogas directly from the reactor headspace back up through the bed for a period of ~4 minutes, then allowing the bed to settle for a short period (< 10 minutes) before allowing the effluent to discharge. This mode of operation has not been previously been reported and represents a valuable low-energy approach to dealing with high solids wastewaters of this type at low operating temperatures. The results confirmed that full flow treatment under ambient conditions, without heating of the UASB reactor, was feasible.

Quantum anomalies in string-inspired running vacuum universe: Inflation and axion dark matter

In this letter, we elaborate further on a Cosmological “Running-Vacuum” type model for the Universe, suggested previously by the authors [1,2], within the context of a string-inspired effective theory in the presence of a Kalb-Ramond (KR) gravitational axion field which descends from the antisymmetric tensor of the massless gravitational string multiplet. In the presence of this field, which has anomalous CP violating interactions with the gravitons, primordial gravitational waves induce gravitational anomalies, which in turn are responsible for the appearance of H2 and H4 contributions to the vacuum energy density, these terms being characteristic of generic “running-vacuum-model (RVM) type”, where H is the Hubble parameter. In this work we prove in detail the appearance of the H4 terms due to gravitational-anomaly-induced condensates in the energy density of the primordial Universe, which can self-consistently induce inflation, and subsequent exit from it, according to the generic features of RVM. We also argue in favour of the robustness of our results, which were derived within an effective low-energy field theory approach, against Ultra Violet completion of the theory. During the radiation and matter-dominated eras, gravitational anomalies cancel, as required for the consistency of the quantum matter/radiation field theory. However, chiral and QCD-axion-type anomalies survive and have important consequences for both cosmic magnetogenesis and axionic dark matter in the Universe. Finally, the stringy RVM scenario presented here predicts quintessence-like dynamical dark energy for the current Universe, which is compatible with the existing fitting analyses of such model against observations.

A scalable Bluetooth Low Energy approach to identify occupancy patterns and profiles in office spaces

Building occupants are often assumed to follow deterministic schedules in building performance simulation programs. Therefore, to accurately capture the dynamic nature of the occupants' movement patterns, researchers have proposed various indoor localisation technologies to infer occupancy information with varying degrees of accuracy and resolution. Among these technologies, the Bluetooth Low Energy (BLE) technology emerged as a popular alternative due to its availability in smartphone devices, as well as its low cost and power demand. In this study, we proposed a scalable and less intrusive occupancy detection method that leverages existing BLE technologies found in smartphone devices to perform zone-level occupancy localisation, without the need for a mobile application. The proposed method uses a network of BLE beacons for data collection before passing the pre-processed data into a machine learning model to infer the occupants' zone-level location. A supervised ensemble model and a semi-supervised clustering model were proposed and evaluated to identify the best performing model. The feasibility of the proposed method is demonstrated during a five-week case study involving two office spaces in an academic building in Singapore. While the supervised ensemble model produced the best performance in terms of accuracy and macro-average f1-score, the semi-supervised model was able to produce a reasonable performance while using a fraction of the training data (<4%) and time needed by the supervised model. By analysing the occupancy information obtained through the best performing model, we further identified a set of occupancy profiles to represent the diverse occupancy patterns observed in the study area.

Nanoemulsions and Their Potential Applications in Food Industry

Nanoemulsions have small droplet size and are kinetically stable colloidal systems. They have enhanced functional properties in comparison to conventional emulsions. The composition and structure of the nanoemulsions can be controlled for the encapsulation and effective delivery of bioactive lipophilic compounds. Nanoemulsions have potential application in the food industry for the delivery of nutraceuticals, coloring and flavoring agents, and antimicrobials. The nanoemulsion formulations of active ingredients can be used for developing biodegradable coating and packaging films to enhance the quality, functional properties, nutritional value and shelf life of foods. This review focuses on preparation of food grade nanoemulsions using high-energy methods and low-energy approaches and their characterization for physical properties, stability and microstructure. The application of nanoemulsion formulations for sustainable food processing and improving the delivery of functional compounds, such as colorants, flavouring agents, nutraceuticals and preservatives or antimicrobial agents in foods has been discussed.

Preparation of Food Flavor Nanoemulsions by High- and Low-Energy Emulsification Approaches

Flavor ingredients are major contributors to the profile of food products. As these components are mostly volatile and hydrophobic, achieving their enhanced bioaccessibility and controlled release during processing is of utmost concern to food manufacturers. Emulsions prepared at nanoscale (2–200 nm) not only give the opportunity to protect the flavor ingredients but also enable achieving higher homogeneity in the emulsion system through produced smaller droplet size. Among developed approaches of high and low energy for preparation of flavor nanoemulsions, low-energy approaches give the possibility to develop nanoemulsions in absence of high shear and pressure, and are suitable selections for preparation of nanoemulsions for thermal-sensitive flavor components with the requirement of consuming less energy in comparison to high-energy methods. However, limitation of using synthetic surfactants might limit their applications for food systems and high amount of surfactant might be necessary to produce stable nanoemulsions with small droplet sizes. Preparation of nanoemulsions for encapsulation of food flavors applying low-energy methods is considered as a new emerging approach with potential for further research for development of ingredients applicable in food formulations and production of stable nanoemulsions at large scale. Considering the growing demand for food flavors, this review aims to highlight recent advancements in the application of high- and low-energy approaches for preparation of flavor nanoemulsions with the focus on discussing the main factors influencing stability and particle size of prepared nanoemulsions during development and storage and can provide insights on further production of nanoemulsions at an industrial large scale.

Destruction of dioxin and furan pollutants via electrophilic attack of singlet oxygen

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) remain of particular concern owing to their extensive toxicity towards health and accumulation in the environment. Atmospheric oxidation (by ambient oxygen molecules) of this class of persistent environmental pollutants has little to no kinetic feasibility due to very sizable activation energies in the entrance channel. The current control measures involve energy-intensive source incineration of contaminated materials at high temperatures as high as 850 °C. This study finds an alternative low-energy approach of destroying dioxin-like compounds, proposing that advanced oxidation by highly reactive singlet oxygen (O21Δg, originated from chemical, surface-mediated and photochemical processes) can initiate low-temperature remediation of these pollutants. This contribution completes the first milestone in mapping out the mechanisms of the electrophilic addition of singlet oxygen to unsubstituted and chlorinated dibenzo-p-dioxin (DBD) and dibenzofuran (DBF) structures, according to density functional theory DFT-B3LYP method in conjunction with the 6–311+g(d,p) basis set, as well as energy refinements based on the approximate spin-projection scheme. The [2+2]-cycloaddition mechanism appears dominant for singlet oxidation of dibenzo-p-dioxin with a fitted rate constant of k(T) = 5.01 × 10−14 exp(-98000/RT). On the other hand, the addition of singlet oxygen to the aromatic ring of dibenzofuran primarily transpires via [4+2]-cycloaddition channel with a fitted rate constant of k(T) = 2.16 × 10−13 exp(-119000/RT). The results suggest that application of singlet oxygen can reduce the energy cost of recycling halogenated and flame retarded materials.

Modulation of the electronic states of perovskite SrCrO3 thin films through protonation via low-energy hydrogen plasma implantation approaches

Hydrogenation of transition metal oxides offers a powerful platform to tailor physical functionalities as well as for potential applications in modern electronic technologies. An ideal nondestructive and efficient hydrogen incorporation approach is important for the realistic technological applications. We demonstrate the proton injection on SrCrO3 thin films via an efficient low-energy hydrogen plasma implantation experiments, without destroying the original lattice framework. Hydrogen ions accumulate largely at the interfacial regions with amorphous character which extend about one-third of the total thickness. The HxSrCrO3 (HSCO) thin films appear like exfoliated layers which however retain the fully strained state with distorted perovskite structure. Proton doping induces the change of Cr oxidation state from Cr4+ to Cr3+ in HSCO thin films and a transition from metallic to insulating phase. Our investigations suggest an attractive platform in manipulating the electronic phases in proton-based approaches and may offer a potential peeling off strategy for nanoscale devices through low-energy hydrogen plasma implantation approaches.

Waveguide-Imprinted Slim Polymer Films: Beam Steering Coatings for Solar Cells

We report that transparent polymer coatings imprinted with tilted planar waveguides significantly reduce optical loss caused by the scattering of incident light by front metal contacts of solar cells. A periodic array of planar waveguides oriented at specific angles with respect to the film’s surface normal efficiently captures and steers incident light away from contacts and, in this way, suppresses scattering. These beam steering films are fabricated in a single, room temperature step by self-trapped incandescent beams. The beams inscribe multimode planar waveguides oriented at angles ranging from 0° to 2.7° inphotopolymerizable epoxide resin. We characterized the microstructural and optical properties of the films and demonstrated their ability to deflect incident white light, comparable to sunlight, by as much as 180 μm. Solar cells coated with beam steering films showed significant enhancements in external quantum efficiency (EQE) of up to 4.42% relative to unstructured films. This first demonstration of waveguide-based deflection of light from metal contacts represents a facile, inexpensive, low energy approach to EQE enhancement, which can be integrated without disrupting well-established solar cell manufacturing technologies.

Non-Volatile Spintronic Flip-Flop Design for Energy-Efficient SEU and DNU Resilience

In this paper, low-energy radiation-hardening approaches are proposed to develop non-volatile (NV) flip-flop (FF) circuits using spintronic devices. In particular, spin Hall effect magnetic tunnel junctions are used to design a radiation-hardened NV-latch that is proposed to be utilized as a shadow latch to maintain the data during the standby mode when the circuit is power-gated. Moreover, soft-error resilient complementary metal–oxide–semiconductor-based latching circuits are designed to be leveraged as master and slave latches in the NVFF structure. The proposed hardening techniques are based on using feedback loops and clock-gating Muller C-elements, as well as increasing the charge capacity of the vulnerable nodes. The circuit simulations indicate that the proposed single-event upset and double node upset resilient latching circuits can achieve at least 81% and 24% power-delay product improvement, respectively, while incurring comparable area overhead compared to the previous energy-efficient radiation-hardened latch designs. Finally, the proposed latching circuits are combined to develop four radiation-hardened NVFF designs. The results obtained show that, using the proposed NV latching circuit as a shadow latch can result in two orders of magnitude reduction in energy consumption compared to the FF circuits with an NV master latch. In addition, the proposed latches achieve favorable tradeoffs in terms of minimized performance overheads and maximized robustness (100%) of soft fault coverage to single and double upsets. Thus, the proposed NVFFs can be employed within logic datapaths to ensure data integrity as a potential mainstream solution for aerospace and avionic nanoelectronics.