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In a highly competitive market, word-of-mouth (WOM) has become one of the most effective ways to attract new customers, as consumer opinions are seen as reliable and have a direct impact on their consumption habits. Based on this premise, the present study aimed to analyze the factors that influence fast-food restaurant consumers in Chile in their intention to share word-of-mouth information. A quantitative approach was adopted for this analysis, using a cross-sectional and correlational design, which included 739 Chilean fast-food consumers, who were given a 25-item questionnaire. This questionnaire was developed from previous research in the field and validated by a panel of experts in marketing and research. The data analysis was conducted using the statistical software Smart PLS 4, allowing for the evaluation of the model’s convergent and discriminant validity, as well as facilitating hypothesis testing through structural equation modeling. The results showed that the physical atmosphere of the restaurants generates both hedonic and utilitarian value for consumers, which increases their satisfaction and reinforces their intention to recommend these restaurants. In conclusion, this study provides valuable insights into consumer behavior, offering a solid foundation for strategic decision making that could enhance the positioning of restaurants in the market and create a loyalty cycle among customers.

Microplastics contamination is growing globally, being a risk for different environmental compartments including animals and humans. At present, some Spanish beaches and coasts have been affected by discharges of these pollutants, which have caused a serious environmental problem. Therefore, efficient strategies to remove microplastics (MPs) from environmental samples are needed. In this study, the application of three magnetic materials, namely iron oxide (Fe3O4) and the composites Fe3O4@Ag and Fe3O4@Ag@L-Cysteine, to remove MPs, specifically polystyrene (PS), from water samples has been assessed. The magnetic nanoparticles were synthesized and characterized by field effect scanning electron microscopy with energy dispersive X-ray spectroscopy detection (FESEM-EDX). Experimental conditions such as temperature, time, and pH during the removal process were assessed for the different adsorbent materials. The removal rate was calculated by filtering the treated water samples and counting the remaining MPs in the water using ImageJ software. The strongest removal efficiency (100%) was shown using Fe3O4@Ag@L-Cysteine for PS at 50 mg L−1 within 15 min of the separation process at room temperature and a neutral pH. A thermodynamic study demonstrated that the developed MPs elimination strategy was a spontaneous and physisorption process. Coated Fe3O4 magnetic nanoparticles were demonstrated to be an efficient adsorbent for MP removal in aquatic environments and their use a promising technique for the control of MPs contamination.

Long non-coding RNAs (lncRNAs) are involved in numerous biological processes and serve crucial regulatory functions in both animals and plants. Nevertheless, there is limited understanding of lncRNAs and their patterns of expression and roles in sharks. In the current study, we systematically identified and characterized lncRNAs in the blue shark (Prionace glauca) from four tissues (liver, spleen, muscle, and kidney) using high-throughput sequencing and bioinformatics tools. A total of 21,932 high-confidence lncRNAs were identified, with 8984 and 3067 stably and tissue-specific expressed lncRNAs, respectively. In addition, a total of 45,007 differentially expressed (DE) lncRNAs were obtained among tissues, with kidney versus muscle having the largest numbers across tissues. DE lncRNAs trans target protein-coding genes were predicted, and functional gene ontology enrichment of these genes showed GO terms such as muscle system processes, cellular/metabolic processes, and stress and immune responses, all of which correspond with the specific biological functions of each tissue analyzed. These results advance our knowledge of lncRNAs in sharks and present novel data on tissue-specific lncRNAs, providing key information to support future functional shark investigations.

The emergence of prosumers, who actively participate in designing and producing goods, has generated a growing interest in homemade products. Factors such as design methods, component reuse, or digital fabrication empower prosumer designers to realize their ideas. Although there are cases of bioinspired products manufactured by prosumers, the interactions between bioinspired design methods in the prosumer field have not been addressed from an academic point of view. This article presents a case that combines bioinspired design methods with prosumer characteristics from the perspective of a designer who uses biological research results whilst acting as a prosumer. The proposal is to see whether working on a small scale, without the need for biomimetics experts, and independently, as a prosumer, is feasible and valuable. As a result, a bicycle flashlight is designed with a microgenerator bioinspired by the geometry of samara seeds, and is tested in a wind tunnel. This case shows that the integration of a bioinspired design in prosumer contexts poses unique challenges and requires a multidisciplinary approach. Furthermore, the application of a bioinspired approach in this case has not only provided a certain level of novelty to the final product, but has also improved its efficiency and reduced its financial expenditure.

The increasing contamination of soil with heavy metals poses a problem to environmental sustainability. Among these pollutants, lead is particularly concerning due to its persistence in the environment, with harmful effects on human health and ecosystems. Various strategies that combine phytoremediation techniques with soil amendments have emerged to mitigate lead contamination. In this context, biochar has gained significant attention for its potential to enhance soil quality and remediate metal-contaminated environments. This study aims to investigate the combined effect of biochar amendments on the phytoremediation of lead-contaminated shooting range soils. A series of experiments were conducted to determine the impact of the amount and distribution of biochar on lead removal from soil. Soil samples were incubated with biochar for one week, after which two types of seeds (Brassica rapa and Lolium perenne) were planted. Plant and root lengths, as well as the number of germinated seeds, were measured, and a statistical analysis was conducted to determine the influence of the amendments. After one month, the Pb concentration decreased by more than 70%. Our results demonstrate that seed germination and plant growth were significantly better in soil samples where biochar was mixed rather than applied superficially, with the optimal performance observed at a 10% wt. biochar amendment. Additionally, the combined use of biochar and phytoremediation proved highly effective in immobilizing lead and reducing its bioavailability. These findings suggest that the combination of biochar, particularly when mixed at appropriate concentrations, and Brassica rapa significantly improved lead removal efficiency.

A reliable, rapid, and low-cost procedure for determining very low concentrations of hexavalent chromium (Cr) in water is discussed. The procedure is based in the classical reaction of Cr6+ with diphenylcarbazide. Once this reaction has taken place, sodium dodecylsulfate is added to obtain an ion-pair, and Triton X-114 is incorporated. Next, the heating of the mixture allows two phases that can be separated by centrifugation to be obtained in a cloud point microextraction (CPE) process. The coacervate contains all the Cr6+ originally present in the water sample, so that the measurement by molecular absorption spectrophotometry allows the concentration of the metal to be calculated. No harmful organic solvents are required. The discrimination of hexavalent and trivalent forms is achieved by including an oxidation stage with Ce4+. To take full advantage of the pre-concentration effect inherent to the coacervation process, as well as to minimize reagent consumption and waste generation, a portable mini-spectrophotometer which is compatible with microvolumes of liquid samples is used. The preconcentration factor is 415 and a chromium concentration as low as 0.02 µg L−1 can be detected. The procedure shows a good reproducibility (relative standard deviation close to 3%).

Extended Reality (XR) is an emerging technology that enables enhanced interaction between the real world and virtual environments. In this study, we conduct a scoping review of XR engines for developing gamified apps and serious games. Our study revolves around four aspects: (1) existing XR game engines, (2) their primary features, (3) supported serious game attributes, and (4) supported learning activities. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model to conduct the scoping review, which included 40 primary studies published between 2019 and 2023. Our findings help us understand how current XR engines support the development of XR-enriched serious games and gamified apps for specific learning activities. Additionally, based on our findings, we suggest a set of pre-established game attributes that could be commonly supported by all XR game engines across the different game categories proposed by Lameras. Hence, this scoping review can help developers (1) select important game attributes for their new games and (2) choose the game engine that provides the most support to these attributes.

The increase in the production and use of disinfectants containing silver atoms (in both its ionic and nanomeric forms) in their formulation, due to the global pandemic situation caused by COVID-19, has increased the presence of silver species in wastewater. Moreover, silver atoms are now considered as emerging pollutants in water. In this work, we propose a novel method for the instantaneous and simultaneous removal of ionic and nanomeric silver in water samples, using a previously unpublished methodology consisting of the in situ formation of magnetic nanoparticles in the aqueous samples to be treated. While the nanoparticle precursors react to form them, the silver atoms present in the sample are adsorbed onto them due to a strong electrostatic interaction. As the final nanoparticles are magnetic, they can be easily removed from the aqueous medium using a magnet, leaving the samples free of silver species. The innovative feature of the method is that the adsorbent is synthesized in situ, within the sample to be treated, making the approach a low-cost, easy-to-perform solution. Temperature, contact time, dose of Fe3O4, and concentration of nanomeric and ionic silver were investigated. The results showed that at 50 °C, 100% of both silver species were removed from the water samples simultaneously. The surface of Fe3O4 was characterized before and after the application of the removal process using energy-dispersive X-ray spectroscopy and Field Emission scanning electron microscopy. Adsorption kinetics and equilibrium isotherms studied reveal a Langmuir-type physicochemical process. The procedure has been applied to different water samples (river and drinking water) with excellent results, making the method a new standard for the removal of ionic and nanomeric silver. In addition, the nanoparticles formed could be recycled and reused for other analytical and decontamination purposes.

In this work, we present the operation of a femtosecond-laser-written diode-pumped visible waveguide laser based on praseodymium-doped lithium lutetium fluoride. The refractive index modification induced by the femtosecond laser in the crystal exhibits an anisotropic behavior, thus enabling the fabrication of different types of waveguides from single-track structures to stress-induced waveguides and depressed cladding structures. All the waveguides were characterized by realizing transmission measurements and the waveguide design was optimized to obtain extremely low propagation losses, equal to 0.12 dB/cm. Lasing has been achieved at 604 nm and 721 nm from different waveguides. In addition, stable continuous-wave lasing at 698 nm has been obtained in a depressed cladding waveguide. This wavelength corresponds to the one needed for the transition of the atomic clock based on the neutral strontium atom. In the end, we report the observation of laser emission at 645 nm from a depressed cladding waveguide.

A solid-phase dispersive microextraction procedure has been developed using ferrite (Fe3O4), an inexpensive magnetic material, as an adsorbent for the separation and subsequent determination of Ga(III) and In(III). The ions were removed from an aqueous solution by adsorption on Fe3O4, which was next easily collected from the medium by the action of a magnet. The analytes were then desorbed using 50 µL of 2 M NaOH or 50 µL of a 4:1 mixture of 0.1 M EDTA and 2 M HNO3 for the determination of Ga(III) or In(III), respectively. The level of the elements in the desorption phase was measured by electrothermal atomic absorption spectrometry (ETAAS) by injecting 10 µL of this phase into the atomizer. The enrichment factor was 163, and detection limits of 0.02 and 0.01 µg L−1 were achieved for Ga(III) and In(III), respectively. The reliability of the procedure has been verified by means of standard reference materials and by means of standard additions. Results are given for waters, soils and samples obtained from various electronic devices. It is of note that the procedure could be the basis for a useful way of recovering these valuable elements from different matrices for reuse.

The toxicity of all species of mercury makes it necessary to implement analytical procedures capable of quantifying the different forms this element presents in the environment, even at very low concentrations. In addition, due to the assorted environmental and health consequences caused by each mercury species, it is desirable that the procedures are able to distinguish these forms. In nature, mercury is mainly found as Hg0, Hg2+ and methylmercury (MeHg), with the latter being rapidly assimilated by living organisms in the aquatic environment and biomagnified through the food chain. In this work, a dispersive solid-phase microextraction of Hg2+ and MeHg is proposed using as the adsorbent a magnetic hybrid material formed by graphene oxide and ferrite (Fe3O4@GO), along with a subsequent determination by electrothermal atomic absorption spectrometry (ETAAS). On the one hand, when dithizone at a pH = 5 is used as an auxiliary agent, both Hg(II) and MeHg are retained on the adsorbent. Next, for the determination of both species, the solid collected by the means of a magnet is suspended in a mixture of 50 µL of HNO3 (8% v/v) and 50 µL of H2O2 at 30% v/v by heating for 10 min in an ultrasound thermostatic bath at 80 °C. On the other hand, when the sample is set at a pH = 9, Hg(II) and MeHg are also retained, but if the solid collected is washed with N-acetyl-L-cysteine only, then the Hg(II) remains on the adsorbent, and can be determined as indicated above. The proposed procedure exhibits an enrichment factor of 49 and the determination presents a linear range between 0.1 and 10 µg L−1 of mercury. The procedure has been applied to the determination of mercury in water samples from different sources.

Modular design is the design based on independent and connectable modules to achieve product variety. It is an ideal tool that could facilitate the inclusion of prosumers in the creative process. However, its evolution has focused on product development and not on end users. The creation of a new modular design model for prosumers could respond to their needs while exploiting the advantages of modularity. The present work analyzes the applicability of modular design in the prosumer scope and defines a guideline for the creation of the new model. To this end, prosumer and modular design methods are collected and analyzed throughout the previously defined design process. The intersection between both terms is analyzed through a series of real cases and design methods that show what the objectives of prosumers are and if the present products and methods meet their needs. These results will establish the current and potential link between modular design and prosumers. Finally, the objectives and stages to develop the design model based on previous results are presented. The paper presents relevant findings such as the lack of methods in the conceptual design phases and a guideline to ensure that the prosumer benefits from modular design.

Nitrosamines (NAs), which are catalogued as carcinogenic compounds, may be present in meat products due to the conversion of nitrites and as result of migration from elastic rubber nettings used. A method based on ultrasonic assisted extraction coupled with dispersive liquid–liquid microextraction as sample treatment and gas chromatography-mass spectrometry as separation and detection technique was proposed for the determination of twelve NAs in cooked ham samples. The method was validated by evaluating linearity (0.5–1000 ng g−1), matrix effect, sensitivity (detection limits were between 0.15 and 1.4 ng g−1) and precision, which was below 12%. Five NAs were found in the samples with levels ranging from not quantifiable to 40 ng g−1. The effect of the elastic rubber nettings on the nitrosamine content of meat was evaluated by comparing the levels found in products made with several plastics or thread in the presence of additives.

Mobile learning (mLearning) is now being increasingly used in university education, with positive impacts on the motivation and predisposition of students when learning. The aim of this study was to evaluate the impact of the use of mobile applications as a learning resource in applied biomechanics, with regard to attitudinal variables (interest, motivation, applicability and learning experience) and its efficacy in the learning of general physics contents. A quasi-experimental design was proposed, with the random assignment of participants to experimental and control groups, with the post-trial measurement of a sample of 76 university students studying Applied Biomechanics, who were given an ad-hoc questionnaire in order to evaluate attitudinal aspects, as well as a test of knowledge. With regard to attitudinal aspects, higher scores were observed among the group which used the applications as learning instruments (the experimental group) when evaluating their interest in biomechanics (t = 2.79; p < 0.05; d = −0.641), the applicability of the applications in real life (t = 7.34; p < 0.001; d = −1.687) and the general evaluation of the practical sessions (t = 6.45; p < 0.001; d = −1.481). At the conceptual level, significant differences were observed in the contents worked on with the KinematicLab Jump© application. Our results show the positive effect of the use of applications on important attitudinal aspects in the learning of university students, without any relevant effect on the acquisition of conceptual learning.

In this work, an evaluation and quantification of the impact of using mixtures based on supercritical carbon dioxide “s-CO2” (s-CO2/COS, s-CO2/H2S, s-CO2/NH3, s-CO2/SO2) are made as a working fluid in simple and complex recompression Brayton s-CO2 power cycle configurations that have pressure drops in their components. These cycles are coupled with a solar thermal plant with parabolic-trough collector (PTC) technology. The methodology used in the calculation performance is to establish values of the heat recuperator total conductance (UAtotal) between 5 and 25 MW/K. The main conclusion of this work is that the cycle’s efficiency has improved due to using s-CO2 mixtures as working fluid; this is significant compared to the results obtained using the standard fluid (pure s-CO2). Furthermore, a techno-economic analysis is carried out that compares each configuration’s costs using pure s-CO2 and a mixture of s-CO2/COS with a molar fraction (70/30), respectively, as working fluid where relevant results are obtained. These results show that the best configuration in terms of thermal efficiency and cost is the RCC-RH for pure sCO2 with values of 41.25% and 2811 $/kWe, while for the mixture sCO2/COS, the RCC-2RH configuration with values of 45.05% and 2621 $/kWe is optimal. Using the mixture costs 6.75% less than if it is used the standard fluid (s-CO2).

Dry-cured Iberian ham is officially classified into different commercial categories according to the pig’s breed and feeding regime. These reach very different prices, thus promoting labelling fraud and causing great damage to the food sector. In this work, a method based on Raman spectroscopy was explored as a rapid in situ screening tool for Iberian ham samples. A total of 110 samples were analyzed to assess the potential of this technique to differentiate purebred, crossbred, acorn-fed and feed-fed dry-cured Iberian ham. A continuous signal probably due to sample fluorescence was obtained, which hid the Raman scattering signal. Therefore, chemometric treatment was applied in order to extract non-apparent information. High validated classification rates were obtained for feeding regime (83.3%) and breed (86.7%). In addition, an interlaboratory study was carried out to confirm the applicability of the method with 52 samples, obtaining a validated rate above 80%.

After the International Agency for Research on Cancer (IARC) classified ingested nitrites and nitrates as “probably carcinogenic to humans” under conditions favoring endogenous nitrosation, several meat products labeled as “made without nitrite” were launched. In order to distinguish uncured products truly made without nitrite from cured products made with any nitrite source (vegetal or mineral), this article presents an approach to detect and quantify nitrite from different origins added to meat. The method consists on the determination of nitrous oxide as a target compound using headspace gas chromatography–mass spectrometry (HS-GC–MS). Nitrous oxide (N2O) is formed after two reduction steps: from nitrite to nitric oxide (NO) and then to N2O. The NO is bound to myoglobin (Mb) or metmyoglobin (Met-Mb), forming a complex, which is subsequently released using sulfuric acid, which also favors the reduction to N2O. The HS-GC–MS conditions were split ratio 1:10; injection temperature at 70 °C; incubation temperature at 30 °C and time 45 min; and injection volume 1 mL. As a result, a relationship was established between the concentration of nitrite in cooked ham samples and the area of the N2O peak generated, meaning that this method allows the quantification of added nitrite within a concentration range of 10 to 100 mg kg−1.

Introduction: This study describes the theoretical foundations of the development of an equation that allows for the estimation of the mobilized load when training with suspension devices (type TRX®) and presents a mobile application as a means for its use. Methods: Systems of equations are proposed of which the terms depend on the angulation of the device with respect to the vertical (angle α), the relationship between the height of grip, the height of the center of mass and the weight of the subject, which are recorded from a photo. Results: Based on the photo and the subject’s standing height, the application allows the user to measure the angle α, providing the values of applied force (in N) and mobilized load in relation to the percentage of body mass, applying the calculations described in our equations. The equation also provides the estimated value of the load mobilized during a push up on the floor (68% of the subject’s body mass) and the equation for the calculation of the mobilized load when the suspension device is fixed to the feet. Conclusions: It is possible to use equations to estimate the load mobilized in each repetition during training using suspension devices and to implement this algorithm in a mobile application.

The p53 and Mouse double minute 2 (MDM2) proteins are hubs in extensive networks of interactions with multiple partners and functions. Intrinsically disordered regions help to adopt function-specific structural conformations in response to ligand binding and post-translational modifications. Different techniques have been used to dissect interactions of the p53-MDM2 pathway, in vitro, in vivo, and in situ each having its own advantages and disadvantages. This review uses the p53-MDM2 to show how different techniques can be employed, illustrating how a combination of in vitro and in vivo techniques is highly recommended to study the spatio-temporal location and dynamics of interactions, and to address their regulation mechanisms and functions. By using well-established techniques in combination with more recent advances, it is possible to rapidly decipher complex mechanisms, such as the p53 regulatory pathway, and to demonstrate how protein and nucleotide ligands in combination with post-translational modifications, result in inter-allosteric and intra-allosteric interactions that govern the activity of the protein complexes and their specific roles in oncogenesis. This promotes elegant therapeutic strategies that exploit protein dynamics to target specific interactions.

Ultrashort optical pulses can trigger a variety of non-equilibrium processes in magnetic thin films affecting electrons and spins on femtosecond timescales. In order to probe the charge and magnetic degrees of freedom simultaneously, we developed an X-ray streaking technique that has the advantage of providing a jitter-free picture of absorption cross-section changes. In this paper, we present an experiment based on this approach, which we performed using five photon probing energies at the Ni M2,3-edges. This allowed us to retrieve the absorption and magnetic circular dichroism time traces, yielding detailed information on transient modifications of electron and spin populations close to the Fermi level. Our findings suggest that the observed absorption and magnetic circular dichroism dynamics both depend on the extreme ultraviolet (XUV) probing wavelength, and can be described, at least qualitatively, by assuming ultrafast energy shifts of the electronic and magnetic elemental absorption resonances, as reported in recent work. However, our analysis also hints at more complex changes, highlighting the need for further experimental and theoretical studies in order to gain a thorough understanding of the interplay of electronic and spin degrees of freedom in optically excited magnetic thin films.

The objectives of the experiment were to (i) examine the dynamics of WSC use and the recovery of leaf sheaths and blades of Bromus valdivianus Phil. and Lolium perenne L. subjected to two defoliation frequencies (DFs) determined by thermal time (TT); (ii) evaluate how DF influenced regrowth and accumulated herbage mass (AHM) during fall. Defoliation was carried out at frequencies of 135 and 270 accumulated growing degree days (AGDDs) for both species. Twelve plots were arranged in a three-block design. All plots had a conditioning period to establish the assigned DF prior to sampling. From the start of the experiment, “cores” were collected from each plot every three days until the DF was reached. Every core was separated into leaf and sheath material before measuring the WSC concentration. Lolium perenne had concentrated more WSCs than B. valdivianus. Both species adapted their WSC recovery according to the DF. The recovery of WSC was faster under a DF of 135 AGDDs than that of 270 AGDDs. Leaf sheaths contained more WSCs than leaf blades and were identified as WSC storage organs. This period can be used as the optimal defoliation interval in B. valdivianus and L. perenne grazing systems.

Nanostructured thin films of Co-doped zinc sulfide were synthesized through femtosecond pulsed laser deposition. The scheme involved ablation of physically mixed Co and ZnS with pairs of ultrashort pulses separated in time in the 0–300 ps range. In situ monitorization of the deposition process was carried out through a simultaneous reflectivity measurement. The crystallinity of generated nanoparticles and the inclusion of Co in the ZnS lattice is demonstrated by transmission electron microscopy and energy dispersive X-ray microanalysis (TEM-EDX) characterization. Surface morphology, Raman response, and photoluminescence of the films have also been assessed. The role of interpulse temporal separation is most visible in the thickness of the films obtained at the same total fluence, with much thicker films deposited with short delays than with individual uncoupled pulses. The proportion of Co in the synthesized doped ZnS nanoparticles is found to be substantially lower than the original proportion, and practically independent on interpulse delay.

Industrial nitrogen liquefaction cycles are based on the Collins topology but integrate variations. Several pressure levels with liquefaction to medium pressure and compressor–expander sets are common. The cycle must be designed aiming to minimise specific power consumption rather than to maximise liquid yield. For these reasons, conclusions of general studies cannot be extrapolated directly. This article calculates the optimal share of total compressed flow to be expanded in an industrial Collins-based cycle for nitrogen liquefaction. Simulations in Unisim Design R451 using Peng Robinson EOS for nitrogen resulted in 88% expanded flow, which is greater than the 75–80% for conventional Collins cycles with helium or other substances. Optimum specific compression work resulted 430.7 kWh/ton of liquid nitrogen. For some operating conditions, the relation between liquid yield and specific power consumption was counterintuitive: larger yield entailed larger consumption. Exergy analysis showed 40.3% exergy efficiency of the optimised process. The exergy destruction distribution and exergy flow across the cycle is provided. Approximately 40% of the 59.7% exergy destruction takes place in the cooling after compression. This exergy could be used for secondary applications such as industrial heating, energy storage or for lower temperature applications as heat conditioning.

The optimum pressure ratio for the stages of a multistage compression process is calculated with a well known formula that assigns an equal ratio for all stages, based on the hypotheses that all isentropic efficiencies are also equal. Although the derivation of this formula for two stages is relatively easy to find, it is more difficult to find for any number of stages, and the examples that are found in the literature employ complex mathematical methods. The case when the stages have different isentropic efficiencies is only treated numerically. Here, a step by step derivation of the general formula and of the formula for different stage efficiencies are carried out using Lagrange multipliers. A main objective has been to maintain the engineering considerations explicitly, so that the hypotheses and reasoning are clear throughout, and will enable the readers to generalise or adapt the methodology to specific problems. As the actual design of multistage compression processes frequently meet engineering restrictions, a practical example has been developed where the previous formulae have been applied to the design of a multistage compression plant with reciprocating compressors. Special attention has been put into engineering considerations.

Three alternatives for integrating a solar field with the bottoming cycle of a combined cycle plant are modeled: parabolic troughs with oil at intermediate and low cycle pressures and Fresnel linear collectors at low cycle pressure. It is assumed that the plant will always operate at nominal conditions, using post-combustion during the hours of no solar resource. A thermoeconomic study of the operation of the plant throughout a year has been carried out. The energy and exergy efficiencies of the plant working in fuel only and hybrid modes are compared. The energy efficiencies obtained are very similar; slightly better for the fuel only mode. The exergy efficiencies are slightly better for hybrid operation than for fuel-only mode, due to the high exergy destruction associated with post-combustion. The values for solar electric efficiency are in line with those of similar studies. The economic study shows that the Fresnel hybridization alternative offers similar performance to the others at a significantly lower cost.

Cigarette butts are one of the most common types of litter all around the world. This waste when disposed of in the environment pose a major threat to living organisms and ecosystem health. Cigarette butts are mainly made of cellulose acetate (2.45 substitution) that biodegrades slowly and can take up to 18 months to break down under normal litter conditions. Cellulose acetate is a valuable polymer that can be used for a great variety of applications. In this communication, we present the results from an ongoing study addressed to value cigarette butt waste based on the recovery of the cellulose acetate by a methodology that includes several solid-liquid extractions and a chemical precipitation. For that purpose three samples of cigarette butts were prepared and they were extracted with 5% (w/v) NaCl aqueous solution, 5% (w/v) NaAc aqueous solution or 0,02% (w/v) H2SO4 aqueous solution. After that, they were further extracted with absolute ethanol and diethyl ether. The cleaned butts were suspended in acetone and distilled water was added until a white precipitate of cellulose acetate was formed. Cellulose acetate was characterised by FTIR-ATR and its melting point. Extracts were analized by ICP-MS and GC-MS.

Although CO 2 as refrigerant is well known for having the lowest global warming potential (GWP), and commercial domestic heat pump water heater systems exist, its long expected wide spread use has not fully unfolded. Indeed, CO 2 poses some technological difficulties with respect to conventional refrigerants, but currently, these difficulties have been largely overcome. Numerous studies show that CO 2 heat pump water heaters can improve the coefficient of performance (COP) of conventional ones in the given conditions. In this study, the performances of transcritical CO 2 and R410A heat pump water heaters were compared for an integrated nearly zero-energy building (NZEB) application. The thermodynamic cycle of two commercial systems were modelled integrating experimental data, and these models were then used to analyse both heat pumps receiving and producing hot water at equal temperatures, operating at the same ambient temperature. Within the range of operation of the system, it is unclear which would achieve the better COP, as it depends critically on the conditions of operation, which in turn depend on the ambient conditions and especially on the actual use of the water. Technology changes on each side of the line of equal performance conditions of operation (EPOC), a useful design tool developed in the study. The transcritical CO 2 is more sensitive to operating conditions, and thus offers greater flexibility to the designer, as it allows improving performance by optimising the global system design.

This paper presents an abbreviated method for estimating exergy destruction in a heat exchanger, requiring only black-box data of the exchanger’s inputs and outputs, and eliminating part of the mathematical difficulties associated with the calculations. A well-known model for temperature distributions in an exchanger is adapted for this case, and is used to distinguish between the contributions of the three major causes of the total exergetic loss: heat transfer, fluid friction and energy dissipation to the surroundings. This provides insight into the relative importance of the three, allowing for identification of potential improvements to a given design.

This essay studies Afro-Asian sociocultural interactions in cultural production by or about Asian Latin Americans, with an emphasis on Cuba and Brazil. Among the recurrent characters are the black slave, the china mulata, or the black ally who expresses sympathy or even marries the Asian character. This reflects a common history of bondage shared by black slaves, Chinese coolies, and Japanese indentured workers, as well as a common history of marronage. These conflicts and alliances between Asians and blacks contest the official discourse of mestizaje (Spanish-indigenous dichotomies in Mexico and Andean countries, for example, or black and white binaries in Brazil and the Caribbean) that, under the guise of incorporating the other, favored whiteness while attempting to silence, ignore, or ultimately erase their worldviews and cultures.