It is generally accepted that phonons in a superfluid Bose gas are Goldstone bosons. This is justified by spontaneous symmetry breaking (SSB), which is usually defined as follows: the Hamiltonian of the system is invariant under the $U(1)$ transformation $\hatΨ(\mathbf{r},t)\rightarrow e^{iα}% \hatΨ(\mathbf{r},t)$, whereas the order parameter $Ψ(\mathbf{r},t)$ is not. However, the strict definition of SSB is different: the Hamiltonian and the boundary conditions are invariant under a symmetry transformation, while the ground state is not. Based on the latter criterion, we study a finite system of spinless, weakly interacting bosons using three approaches: the standard Bogoliubov method, the particle-number-conserving Bogoliubov method, and the approach based on the exact ground-state wave function. Our results show that the answer to the question in the title is ``no''. Thus, phonons in a real-world (finite) superfluid Bose gas are similar to sound in a classical gas: they are not Goldstone bosons, but quantised collective vibrational modes arising from the interaction between atoms. In the case of an infinite Bose gas, however, the picture becomes paradoxical: the ground state can be regarded as either infinitely degenerate or non-degenerate, making the phonon both similar to a Goldstone boson and different from it.
Wide application in the oil and gas industry made carbon steel suffer annual losses due to corrosion. The corrosion protection utilizes inhibitor have drawbacks expensive and harmful to the environment. Potato peel extract (solanum tuberosum L) and its main constituents, such as flavonoids, alkaloids, and tannins, have been investigated as a green corrosion inhibitor for low-carbon steel in a 3.5% NaCl solution. The inhibitor’s effectiveness and corrosion rate monitoring were measured using weight loss. Potentiodynamic polarization was used to investigate the type of corrosion inhibition and adsorption of plant extract on the surface. Fourier transform infrared spectroscopy (FTIR) was utilized to observe the presence of functional groups, natural compounds, and the type of bonding for adsorbed organic inhibitors on the surface. The results of the Tafel polarization analysis indicated that the potato peel extract acts as a mixed-type inhibitor. The inhibition efficiency increased with the concentration of the inhibitor extract. The optimal inhibition efficiency of 73.33% is was achieved with 6 ml of potato peel extract and 216 hours of immersion time. The inhibitive effect is due to the adsorption of inhibitor molecules on the steel surface, following the Langmuir adsorption isotherm.
Evaluating shale gas reservoir economic viability remains challenging due to different factors such as long transient flow period and liquid loading resulting in successful shut-ins. Such factors cause fluctuations in production data, with inherent noise impacting analysis methods like decline curve analysis (DCA). In this research, we investigated data smoothing techniques as an alternative to noise removal methods. By applying these techniques, the essential characteristics of the periodic events and signals are retained while reducing the influence of noise making identifying and analyzing patterns easier. Applying seven smoothing techniques to three shale gas datasets with different noise levels to investigate their performance, then, utilizing the cluster-based local outlier factor (CBLOF) algorithm to remove noise from the production data, then, applying seven different DCA models to the original, smoothed, and processed data with CBLOF, the study found that smoothing the data facilitated the extraction of the well's signals. Different smoothing techniques exhibited varying spike levels. The goodness of fit was superior using LOWESS and Fast Fourier Transform (FFT) methods compared to Binomial Smoothing. Moreover, each smoothing technique yielded variations in prediction using the same DCA model. Applying the DCA models that commonly underestimate the reserve to the smoothed data led to further underestimations; however, the DCA models that commonly reserve overestimating reserves also leaned towards underestimations. The Duong's DCA model achieved the highest correlation coefficient (R2), whereas the Wang's DCA model recorded the lowest. In conclusion, this research highlights the benefits of smoothing shale gas production data for better analysis.
Acid fracturing is a critical stimulation technology for enhancing production in ultra-deep marine carbonate reservoirs. A significant challenge in this process is maintaining the conductivity of acid-etched fractures under ultra-high temperature and high closure stress conditions. To address this, conductivity experiments were conducted using various acid solutions and their combinations. The morphology of the acid-etched fractures was captured using a three-dimensional laser scanner. The degree of fracture closure was analyzed using the Airy stress function and the complex variable method, integrated with the local cubic law and an acid fracturing model to create a numerical calculation method for evaluating the conductivity of acid-etched fractures. The results show that under high closure stress（90 MPa）, the conductivity of acids and their combinations decreases by an order of magnitude compared to low closure stress（5 MPa）. As closure stress increases, different acids and combinations exhibit distinct patterns of conductivity reduction, with potential for two rapid decline phases. Furthermore, specific acid combinations have been identified that enhance the conductivity of fractures under extreme conditions of temperature and pressure. The average error between the conductivity values calculated by the model and those obtained from experimental results is relatively low, about 10.6%, indicating that the model can effectively characterize the distribution and magnitude of conductivity across different points within the fracture. In Sichuan Basin, under identical engineering parameters, the conductivity of acid-etched fractures in the 4th member of Dengying Formation is higher than that in the 2nd member. This research provides valuable theoretical guidance for optimizing the design of acid fracturing stimulation schemes in ultra-deep marine carbonate rocks in Sichuan Basin.
Petroleum refining. Petroleum products, Gas industry
George-Cătălin Muntean, Dorina Simedru, Paul Uiuiu
et al.
The European Union’s (EU) agricultural self-sufficiency is challenged by its reliance on imported plant proteins, particularly soy from the Americas, contributing to deforestation and greenhouse gas emissions. Addressing the EU’s protein deficit, this study evaluates alternative protein sources for aquaculture, focusing on their nutritional value, elemental content, and polycyclic aromatic hydrocarbons (PAHs). Protein flours from gastropods (<i>Helix pomatia</i>, <i>Arion lusitanicus</i>, <i>Arion vulgaris</i>) and their hepatopancreas, along with plant-based proteins from food industry by-products (oilcakes, coffee grounds, spent brewer’s yeast), were analyzed. Results revealed that snail flour contained the highest protein content at 59.09%, significantly outperforming hepatopancreas flour at 42.26%. Plant-based proteins demonstrated substantial nutritional value, with coffee grounds flour exhibiting a remarkable protein content of 71.8% and spent brewer’s yeast flour at 57.9%. Elemental analysis indicated high levels of essential minerals such as magnesium in hepatopancreas flour (5719.10 mg/kg) and calcium in slug flour (48,640.11 mg/kg). However, cadmium levels in hepatopancreas flour (11.45 mg/kg) necessitate caution due to potential health risks. PAH concentrations were low across all samples, with the highest total PAH content observed in hepatopancreas flour at 0.0353 µg/kg, suggesting minimal risk of PAH-related toxicity. The analysis of plant-based protein sources, particularly oilcakes derived from sunflower, hemp, flax, and pumpkin seeds, revealed that these by-products not only exhibit high protein contents but present a promising avenue for enhancing the nutritional quality of feed. This study underscores the potential of utilizing gastropod and plant-based by-products as sustainable and nutritionally adequate alternatives to conventional feeds in aquaculture, contributing to the EU’s environmental sustainability goals.
In recent years, additive manufacturing (AM) has made considerable progress and has spread in many industries. Despite the advantages of this technology including freedom of design, lead time reduction, material waste reduction, special tools manufacturing elimination, and sustainability, there are still a lot of challenges regarding finding the beneficial application. In this study, the feasibility of replacing traditional manufacturing methods with additive manufacturing in the energy sector is investigated, with a specific focus on gas-insulated high-voltage switchgear (GIS). All aluminum parts in one specific GIS product are analyzed and a decision flowchart is proposed. Using this flowchart, printability and the best AM technique are suggested with respect to part size, required surface roughness, requirements of electrical and mechanical properties, and additional post processes. Simple to medium complexity level of geometry, large size, high requirements for electrical and mechanical properties, threading and sealing, and lack of a standard for printed parts in the high voltage industry make AM a challenging manufacturing technology for this specific product. In total, implementing AM as a short series production method for GIS aluminum parts may not be sufficient because of the higher cost and more complex supply chain management, but it can be beneficial in R&D cases or prototyping scenarios where a limited number of parts are needed in a brief time limit.
Kawtar Ibn Batouta, Sarah Aouhassi, Khalifa Mansouri
Industrial steam systems account for approximately 30 % of energy use in the manufacturing industry worldwide. In the context of energy transition, improving the energy efficiency of these systems is crucial, as it can significantly reduce energy losses, costs, and greenhouse gas (GHG) emissions. This study presents a comprehensive analysis of the steam system in a Moroccan agri-food plant, aiming to identify and quantify energy optimization opportunities. Initially, the Steam System Scoping Tool (SSST) benchmark revealed a score of 42.4 %, highlighting key areas for improvement. The study proceeded by diagnosing and modeling the baseline steam system, identifying major energy losses based on thermodynamic equations and Manufacturing Energy Assessment Software for Utility Reduction (MEASUR). Our study distinctively employs a systems-based approach, proposing eight energy-saving measures that holistically address all aspects of the steam system —generation, distribution, end-use, and recovery—rather than examining each component in isolation. These measures include optimizing boiler combustion, repairing insulation and leaks, reducing idle operations, and enhancing heat recovery through a feedwater economizer. Implementing these measures is projected to achieve annual energy savings of 5096 GJ, reduce CO2 emissions by 319 tons, and save $93,764, representing a 53 % reduction in the plant's thermal bill. This significant cost-saving potential should inspire optimism about the financial benefits of energy optimization, with payback periods ranging from immediate to a few months. This research marks a pioneering effort in Morocco's industrial sector, offering a replicable model that aligns with global sustainable development goals (SDGs) by reducing energy losses and enhancing production performance.
Flexitarian diets have gained attention for their potential positive impact on human health and greenhouse gas emissions reduction. However, a critical question remains: Can the segment of flexitarians significantly contribute to necessary changes in our current unsustainable food systems? Our study addresses this gap by examining meat consumption habits among young adults (<i>n</i> = 1023) in a country with traditionally high meat intake. Furthermore, we focus on a subset of flexitarians (<i>n</i> = 286). Our findings reveal two distinct groups of flexitarians: ethical (<i>n</i><sub>1</sub> = 140) and utilitarian (<i>n</i><sub>2</sub> = 148). Utilitarian flexitarians exhibit a stronger preference for meat (<i>t</i>(284)= −15.180, <i>p</i> < 0.001), greater food neophobia (<i>t</i>(284) = −4.785, <i>p</i> < 0.001), and lower environmental awareness (<i>t</i>(284) = 7.486, <i>p</i> < 0.001) compared to Ethical flexitarians. The Ethical group, predominantly female (<i>χ<sup>2</sup></i>(1) = 13.366, <i>p</i> < 0.001), demonstrates higher life satisfaction (<i>t</i>(284) = 5.485, <i>p</i> < 0.001), better health perceptions (<i>t</i>(284) = 5.127, <i>p</i> < 0.001), and stronger beliefs in reducing meat consumption (<i>t</i>(284) = −8.968, <i>p</i> < 0.001). Additionally, Ethical flexitarians hold more positive views on plant-based meat, perceiving it as healthier (<i>t</i>(284) = 4.326, <i>p</i> < 0.001) and more ethical (<i>t</i>(284) = 4.942, <i>p</i> < 0.001), and show a greater willingness to adopt it (<i>t</i>(284) = 7.623, <i>p</i> < 0.001). While both groups possess similar knowledge and willingness regarding cultured meat and insects, Ethical flexitarians view cultured meat more favourably (<i>t</i>(250.976) = 2.964, <i>p</i> = 0.003). Our study provides insights into the evolving trends of flexitarianism within Central and Eastern European countries, where research on meat consumption and flexitarianism is scarce. These insights hold value for promoting behaviour change toward reduced meat consumption for both health and environmental reasons. Additionally, they offer guidance to the food industry, including producers, sellers, and providers of meals in educational and employment facilities.
The polarized dipolar Fermi gas shows exotic properties at low temperatures, characterized by an axially-deformed Fermi surface and anisotropic single-particle energy, due to the long-range and anisotropic nature of dipole-dipole interaction. In cold-atom experiments such a system has been realized, e.g., in degenerate gas of Er and Dy atoms. In the case that non-dipolar impurity atoms are introduced in such system, they undergoes an induced interaction mediated by the density fluctuations of the background dipolar Fermi gas. We derive the induced interaction potential to the single-loop order of fluctuations and show that it becomes indeed an anisotropic Ruderman-Kittel-Kasuya-Yosida-type potential which preserves the axial symmetry around the polarization axis. We then solve the two-body problem of impurity atoms interacting via the anisotropic potential and figure out the dependence of bound state and scattering properties on the parameters of dipolar Fermi gas.
We study the Bose-Einstein condensation (BEC) of a free Bose gas under rigid rotation. The aim is to explore the impact of rotation on the thermodynamic quantities associated with BEC, including the Bose-Einstein (BE) transition temperature and condensate fraction. We begin by introducing the rotation in the Lagrangian density of free charged Klein-Gordon fields and determine the corresponding grand canonical partition function at finite temperature, chemical potential, and finite angular velocity. Assuming slow rotation, we derive analytical expressions for the pressure, energy, number, and angular momentum densities of a free Bose gas in nonrelativistic and ultrarelativistic limits in terms of the corresponding fugacities. We then focus on the phenomenon of BEC. We calculate the critical temperature of BEC transition and the condensate fraction in a slowly rotating Bose gas including only particles. Our findings indicate that the critical exponent associated with the BE transition in a rotating gas is lower compared to that in a nonrotating Bose gas. We also determine the fugacity in a rotating Bose gas in the aforementioned limits and examine how rotation affects its temperature dependence, both below and above the critical temperature. By analyzing the behavior of heat capacity at these temperatures, we demonstrate that in a nonrelativistic Bose gas, the rotation transforms the nature of the BE phase transition from a continuous to a discontinuous transition. In general, we find that a nonrelativistic Bose gas under rotation behaves similarly to a nonrotating Bose gas in ultrarelativistic limit.
Francesc Sabater, Abel Rojo-Francàs, Grigori E. Astrakharchik
et al.
We introduce an alternative expression for the ground state wave function of the fermionic Tonks-Girardeau gas. Our wave function is constructed based on the occupation numbers and natural orbitals of the one-body density matrix. We demonstrate that the newly found wave function describes the ground state of the fermionic Tonks-Girardeau gas under any external potential. By expressing the proposed wave function in the framework of second quantization, we show that the ground state of the fermionic Tonks-Girardeau gas is a number-conserving Bardeen-Cooper-Schrieffer (BCS) state. We provide explicit expressions for the corresponding coefficients that describe the fermionic Tonks-Girardeau gas as a number-conserving BCS state. Additionally, the suitable form of the proposed wave function in second quantization allows us to derive the necessary expectation values to experimentally detect pairing in the fermionic Tonks-Girardeau gas. With this, we prove and show how to detect that the fermionic Tonks-Girardeau gas not only exhibits non-trivial quantum correlations but is also a paired state.
Silk fibroin (SF) is a natural protein largely used in the textile industry with applications in bio-medicine, catalysis as well as in sensing materials. SF is a fiber material which is bio-compatible, biodegradable, and possesses high tensile strength. The incorporation of nanosized particles into SF allows the development of a variety of composites with tailored properties and functions. Silk and its composites are being explored for a wide range of sensing applications like strain, proximity, humidity, glucose, pH and hazardous/toxic gases. Most studies aim at improving the mechanical strength of SF by preparing hybrids with metal-based nanoparticles, polymers and 2D materials. Studies have been conducted by introducing semiconducting metal oxides into SF to tailor its properties like conductivity for use as a gas sensing material, where SF acts as a conductive path as well as a substrate for the incorporated nanoparticles. We have reviewed gas and humidity sensing properties of silk, silk with 0D (i.e., metal oxide), 2D (e.g., graphene, MXenes) composites. The nanostructured metal oxides are generally used in sensing applications, which use its semiconducting properties to show variation in the measured properties (e.g., resistivity, impedance) due to analyte gas adsorption on its surface. For example, vanadium oxides (i.e., V2O5) have been shown as candidates for sensing nitrogen containing gases and doped vanadium oxides for sensing CO gas. In this review article we provide latest and important results in the gas and humidity sensing of SF and its composites.
Abstract Pulp and paper industry is one of the eight critical industries for controlling carbon emissions in China. As the paper productions increase, the pulp and paper industry may fail in achieving the emission reduction target due to the rapid growth of greenhouse gas emissions. The study uses life cycle assessment to evaluate the greenhouse gas emissions of China's papermaking industry chain in order to propose emission reduction targets and find ways to achieve the emission reduction targets for China's papermaking industry. Considering the net carbon absorption of plant raw materials and the extensive paper industrial chain, this study obtained that the greenhouse gas emission of major paper types under corresponding pathways ranges from 1.96 t CO2 eq/t paper to 6.55 t CO2 eq/t paper. Plant carbon sink can reduce greenhouse gas emissions by 14.3%–42.9% under virgin fiber-based pathways. This study found that the greenhouse gas emissions caused by terminal products of 814 papermaking enterprises counted in China were 282.23 Mt CO2 eq in 2015, accounting for 10.23% of the total greenhouse gas emissions of manufacturing industries and construction. To achieve the emission reduction target by 2050, emissions of the pulp and paper industry in China have been investigated from the perspective of three ideal energy structures. The research findings show that the emission reduction target of Intended Nationally Determined Contribution will be achieved in 30 years if the energy structure of the pulp and paper industry is adjusted only based on the optimal 450 scenario. In terms of other energy structures, the pulp and paper industry should assume afforestation areas ranged from 5900 km2 to 223,000 km2 at least to make up for the greenhouse gas emissions beyond allowance, which accounts for 0.85%–32.16% of the existing areas of plantation forestry in China.