Terms Of Potential Research Articles

The three-dimensional conformation and activity of mitochondria in syncytial male germ line-cysts of medicinal leeches

We studied the spatial conformation and activity of mitochondria in the developing syncytial male germline cysts during spermatogenesis of the medicinal leeches using light, fluorescent, transmission electron microscopy, and serial block-face scanning electron microscopy. In cysts with spermatogonia and spermatocytes, mitochondria form networks and are in a dynamic hyperfusion state, while in cysts with spermatids, a single huge mitochondrion is observed. As spermiogenesis progresses, this huge mitochondrion is finally located in the future midpiece. The highest activity, in terms of membrane potential, of the mitochondria in H. medicinalis germline cysts was observed in cysts with spermatocytes; the lowest was in cysts with late elongated spermatids.

Unified dark energy from Chiral-Quintom model with a mixed potential in Friedmann–Lemaître–Robertson–Walker cosmology

For a spatially Friedmann–Lemaître–Robertson–Walker cosmology, we propose a multi-scalar field gravitational model. Specifically, we consider a two-scalar field cosmological model in which the kinetic components of the scalar fields establish a two-dimensional sphere of Lorentzian signature. For our Chiral-Quintom model we choose a mixed potential term Vleft( phi ,psi right) =V_{0}e^{lambda phi }+U_{0}e^{kappa phi }psi ^{frac{1}{sigma } } and we investigate the asymptotic limits of the cosmological parameters. This model for U_{0}=0, provides a generalization of the hyperbolic inflation where the equation of the state parameter can cross the phantom divide line. When U_{0}ne 0 we observe that this cosmological model exhibits asymptotic solutions that encompass accelerated universes, big rip singularities, and dust-like solutions. Hence, this multi-scalar field model it can be regarded as as a dark energy unify model which describes a variety of asymptotic cosmological scenarios.

Quantum Black Holes in Conformal Dilaton–Higgs Gravity on Warped Spacetimes

A promising method for understanding the geometric properties of a spacetime in the vicinity of the horizon of a Kerr-like black hole can be developed by applying the antipodal boundary condition on the two opposite regions in the extended Penrose diagram. By considering a conformally invariant Lagrangian on a Randall–Sundrum warped five-dimensional spacetime, an exact vacuum solution is found, which can be interpreted as an instanton solution on the Riemannian counterpart spacetime, R+2×R1×S1, where R+2 is conformally flat. The antipodal identification, which comes with a CPT inversion, is par excellence, suitable when quantum mechanical effects, such as the evaporation of a black hole by Hawking radiation, are studied. Moreover, the black hole paradoxes could be solved. By applying the non-orientable Klein surface, embedded in R4, there is no need for instantaneous transport of information. Further, the gravitons become “hard” in the bulk, which means that the gravitational backreaction on the brane can be treated without the need for a firewall. By splitting the metric in a product ω2g˜μν, where ω represents a dilaton field and g˜μν the conformally flat “un-physical” spacetime, one can better construct an effective Lagrangian in a quantum mechanical setting when one approaches the small-scale area. When a scalar field is included in the Lagrangian, a numerical solution is presented, where the interaction between ω and Φ is manifest. An estimate of the extra dimension could be obtained by measuring the elapsed traversal time of the Hawking particles on the Klein surface in the extra dimension. Close to the Planck scale, both ω and Φ can be treated as ordinary quantum fields. From the dilaton field equation, we obtain a mass term for the potential term in the Lagrangian, dependent on the size of the extra dimension.

Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights

Site index and stand age are important variables in forestry. Site index describes the growing potential at a given location, expressed as the height that trees can attain at a given age under favorable growing conditions. It is traditionally used to classify forests in terms of future timber yield potential. Stand age is used for the planning of management activities such as thinning and harvest. SI has previously been predicted using remote sensing, but usually relying on either very short time series or repeated ALS acquisitions. In this study, site index and forest stand age were predicted from time series of interferometric TanDEM-X data spanning seven growth seasons in a hemi-boreal forest in Remningstorp, a test site located in southern Sweden. The goal of the study was to see how satellite-based radar time series could be used to estimate site index and stand age. Compared to previous studies, we used a longer time series and applied a penetration depth correction to the phase heights, thereby avoiding the need for calibration using ancillary field or ALS data. The time series consisted of 30 TanDEM-X strip map scenes acquired between 2011 and 2018. Established height development curves were fitted to the time series of TanDEM-X-based top heights. This enabled simultaneous estimation of both age and site index on 91 field plots with a 10 m radius. The RMSE of predicted SI and age were 6.9 m and 38 years for untreated plots when both SI and age were predicted. When predicting SI and the age was known, the RMSE of the predicted SI was 4.0 m. No significant prediction bias was observed for untreated plots, while underestimation of SI and overestimation of age increased with the intensity of treatment.

Rosehip Extract-Loaded Liposomes for Potential Skin Application: Physicochemical Properties of Non- and UV-Irradiated Liposomes.

In the present study, rosehip (Rosa canina L.) extract was successfully encapsulated in phospholipid liposomes using a single-step procedure named the proliposome method. Part of the obtained liposomes was subjected to UV irradiation and non-treated (native) and UV-irradiated liposomes were further characterized in terms of encapsulation efficiency, chemical composition (HPLC analysis), antioxidant capacity, particle size, PDI, zeta potential, conductivity, mobility, and antioxidant capacity. Raman spectroscopy as well as DSC analysis were applied to evaluate the influence of UV irradiation on the physicochemical properties of liposomes. The encapsulation efficiency of extract-loaded liposomes was higher than 90%; the average size was 251.5 nm; the zeta potential was -22.4 mV; and the conductivity was found to be 0.007 mS/cm. UV irradiation did not cause a change in the mentioned parameters. In addition, irradiation did not affect the antioxidant potential of the liposome-extract system. Raman spectroscopy indicated that the extract was completely covered by the lipid membrane during liposome entrapment, and the peroxidation process was minimized by the presence of rosehip extract in liposomes. These results may guide the potential application of rosehip extract-loaded liposomes in the food, pharmaceutical, or cosmetic industries, particularly when liposomal sterilization is needed.

Size and Electronic Effects on the Performance of (Corrolato)cobalt-Modified Electrodes for Oxygen Reduction Reaction Catalysis.

Considering the worldwide efforts for designing catalysts that are not based on platinum group metals while still reserving the many advantages thereof, this study focused on the many variables that dictate the performance of cathodes used for fuel cells, regarding the efficient and selective reduction of oxygen to water. This was done by investigating two kinds of porous carbon electrodes, modified by molecular cobalt(III) complexes chelated by corroles that differ very much in size and electron-withdrawing capability. Examination of the electronic effect uncovered shifts in the CoII/CoIII redox potentials and also large differences in the affinity of the cobalt center to external ligands. Spontaneous absorption of the catalysts was found to depend on the size of the corrole's substituents (C6F5 ≫ CF3 ≫ H) and the metal's axial ligands (PPh3 versus pyridine), as well as on the porosity of the carbon electrodes (BP2000 > Vulcan). The better-performing cobalt-based catalysts were almost as active and selective as 20% platinum on Vulcan in terms of the onset potential and the only 2-10% undesirable formation of hydrogen peroxide. Durability was also addressed by using the best-performing modified cathode in a proper anion-exchange membrane fuel cell setup, revealing very little voltage change during 12 h of operation.

A comparative environmental Life Cycle Assessment study of hydrogen fuel, electricity and diesel fuel for public buses

Hydrogen fuel and electricity are energy carriers viewed as promising alternatives for the modernization and decarbonization of public bus transportation fleets. In order to choose development pathways that will lead transportation systems toward a sustainable future, the authors developed an environmental model based on the Life Cycle Assessment approach. The model tested the impact of energy carrier consumption during driving as well as the electricity origin employed to power electric buses and produce hydrogen. Energy sources such as wind, solar, waste and grid electricity were investigated. The scope of the study included the life cycles of the energy carrier and the necessary infrastructure. The results were presented from two perspectives: the total environmental impact and global warming potential. In order to create a roadmap, an original method for choosing sustainable development pathways was prepared. It was shown that the modernization of conventional bus fleets using hydrogen and electrical pathways can provide significant environmental benefits from both perspectives, but especially in terms of global warming potential. It was emphasized that attention should be paid to the use of low- and zero-emission energy sources, because their impact often strongly influenced the final environmental judgment. The energy carrier consumption also had a strong impact on the results obtained, and that is why efforts should be made to reduce it. In addition, it was confirmed that hydrogen and electricity production systems based on electricity generated by a waste-to-energy plant could be an environmentally reasonable dual solution for both sustainable waste management and meeting transport needs.

Speculating on social life

AbstractThis article addresses how a group of people in the San Francisco Bay Area turns social encounters into opportunities to make money. This group participated in sales schemes known as multi‐level marketing (MLM). MLM companies use a sales model in which participants earn money by selling products on behalf of companies while also recruiting people to join the companies as fellow salespeople. MLM participants earn financial commissions through selling products and recruiting others to join their network, leading them to hunt for new customers in public spaces or among existing social connections. The subjects of the study perceived social life as a commercial opportunity that could lead to financial gain, deliberately turning Saturday morning at the farmers' market or Sunday night dinner at a restaurant into an opportunity to recruit new customers. I interpret these activities as a form of social speculation: MLM participants invested their time in relationships that may 1 day be profitable, but they never knew whether their efforts would succeed. The potential to make money from social encounters was a constant motivator. Social speculation is an expression of a development in the United States in which people perceive social relationships in terms of economic potential because of precarious market conditions.

Holographic CFT phase transitions and criticality for rotating AdS black holes

Employing the novel exact dictionary between the laws of extended black hole thermodynamics and the laws of the dual CFT, we study the extended thermodynamics for CFT states that are dual to neutral singly-spinning asymptotically AdS black holes in d bulk spacetime dimensions. On the field theory side we include two independent pairs of thermodynamic conjugate variables: the central charge-chemical potential term and the pressure-volume term. In this setting we uncover various phase transitions and critical behaviour in the CFT, focusing on three different thermodynamic ensembles. Namely, for fixed angular momentum and central charge, we show there is a Van der Waals-like criticality for d = 4, 5 and reentrant phase transitions for d ≥ 6. At fixed angular velocity and central charge, there is a first-order (de)confinement phase transition in all dimensions d ≥ 3. Finally, at fixed angular momentum and chemical potential we find a plethora of zero-order phase transitions and unstable phases in both d = 4 and d = 6.

Investigation on energy-saving potential from heat rejection pressure management in a CO2 transcritical vapor compression system

Heat rejection pressure is an important factor influencing the performance of a CO2 (R-744) transcritical vapor compression system. Previous relevant studies have investigated the optimum heat rejection pressure ensuring the maximum coefficient of performance (COP) and operating parameters affecting the optimum pressure value. However, studies presenting quantitatively how much energy can save when an R-744 transcritical system operates in the optimum heat rejection pressure are still rather limited. This work aims to investigate an energy-saving potential gain achieved by managing heat rejection pressure in an R-744 transcritical system and provides quantitatively how much energy can save with that. In that way, this work tries to fill out the research gap. Simulations were carried out employing prevalidated model, the system COP was investigated in various operating conditions, and the optimum heat rejection pressure securing the maximum COP was found. The optimum heat rejection pressure found in this work was compared to the existing correlations, thereby the comparison results are provided in this paper. The system's dynamic performance was also investigated in two different cases: when the expansion valve opening was regulated for the optimum heat rejection pressure, and when the valve opening was adjusted with a thermostatic expansion valve conventionally. In this study, it is observed the given system reduces the compressor power consumption by 62% when the refrigerant temperature at the main gas cooler outlet varies within a range of 33 ℃ to 45 ℃ and the evaporator temperature of 1 ℃. Consequently, in terms of energy-saving potential, this paper highlights the importance of heat rejection pressure management in an R-744 transcritical system and the significance of proper selection for the control target of an expansion valve depending on the system's operating regime.

Quantum Big Bounce of the Isotropic Universe Using Relational Time

We analyze the canonical quantum dynamics of the isotropic Universe with a metric approach by adopting a self-interacting scalar field as relational time. When the potential term is absent, we are able to associate the expanding and collapsing dynamics of the Universe with the positive- and negative-frequency modes that emerge in the Wheeler–DeWitt equation. On the other side, when the potential term is present, a non-zero transition amplitude from positive- to negative-frequency states arises, as in standard relativistic scattering theory below the particle creation threshold. In particular, we are able to compute the transition probability for an expanding Universe that emerges from a collapsing regime both in the standard quantization procedure and in the polymer formulation. The probability distribution results similar in the two cases, and its maximum takes place when the mean values of the momentum essentially coincide in the in-going and out-going wave packets, as it would take place in a semiclassical Big Bounce dynamics.

Theoretical study of intramolecular effects and rotational spectra for H2–AgCl complex: A corrected intermolecular potential energy surface

An efficient model was developed by optimizing the terms of intermolecular potential and monomer rotations in the Hamiltonian, and then was applied to determine the global structures and rotational transitions of H2–AgCl complex. Based on this model, a detailed study of intramolecular effects were examined for intermolecuar vibrational modes, rotational transition frequencies, and spectroscopic parameters relative to those of rigid-rotor-approximation model. Firstly, the full-dimensional equilibrium geometry is determined to be (Re, r1e, r2e, θ1e, θ2e, φe) = (2.370 Å, 0.7785 Å, 2.2579 Å, 90.0°, 180.0°, 0.0°), and the averaged structure is determined to be (Rν, r1ν, r2ν, θ1ν, θ2ν, φν) = (2.436 Å, 0.7905 Å, 2.2604 Å, 76.4°, 172.8°, 0.0°), which are in excellent agree with the available data of experimental observations. In addition, the available transitions were accurately predicted with the maximal percentage error of 0.05%. Based on the determined spectroscopic parameters, two perpendicular bands were predicted and will be helpful to guide the further investigations in the far infrared spectral region experimentally.

The Z resonance, inelastic dark matter, and new physics anomalies in the Simple Extension of the Standard Model (SESM) with general scalar potential

We consider the generic scalar potential with CP-violation, and study the Z resonance and inelastic dark matter in the Simple Extension of the Standard Model (SESM), which can explain the dark matter as well as new physics anomalies such as the B physics anomalies and muon anomalous magnetic moment, etc. With the new scalar potential terms, we obtain the mass splittings for the real and imaginary parts of scalar fields. And thus we can have the DM co-annihilation process mediated by Z boson, which couples exclusively to the CP-even and CP-odd parts of scalar fields. This is a brand new feature compared to the previous study. For the CP conserving case, we present the viable parameter space for the Higgs and Z resonances, which can explain the B physics anomalies, muon anomalous magnetic moment, and dark matter relic density, as well as evade the constraint from the XENON1T direct detection simultaneously. For the CP-violating case, we consider the inelastic dark matter, and study four concrete scenarios for the inelastic DM-nucleon scatterings mediated by the Higgs and Z bosons in details. Also, we present the benchmark points which satisfy the aforementioned constraints. Furthermore, we investigate the constraints from the dark matter-electron inelastic scattering processes mediated by the Higgs and Z bosons in light of the XENONnT data. We show that the constraint on the Z mediated process is weak, while the Higgs mediated process excludes the dark matter with mass around several MeV.

Electrospun the oriented silk fibroin/ bioactive glass @ silk fibroin/ polycaprolactone composite bi-layered membranes for guided bone regeneration

Guided bone regeneration (GBR) technology has been extensively used in the treatment of alveolar bone defects. However, existing GBR membranes still have great shortcomings in terms of biological activity and regeneration potential. In order to improve the performance of existing GBR membranes, based on the principle of GBR, this study starts from two aspects of material and structure, adding BG particles with good biological properties and introducing directional structure to construct a new type of double-layer composite fiber membrane, which can not only achieve the barrier function, but also induce the directional migration and differentiation of osteoblasts, so as to play the role of bone tissue regeneration and repair more efficiently. In this study, a bi-layer composite GBR membrane with oriented structure of silk fibroin (SF) / bioactive glass (BG) @ silk fibroin (SF) / polycaprolactone (PCL) was prepared by high-speed electrospinning technology, which achieved the dual functions of bone regeneration and barrier. The morphology, mechanical properties, secondary structure, biocompatibility and bioactivity of the oriented bi-layer composite membranes were studied systematically. The results showed that the fiber diameter and the pore size of SF/PCL composite membranes were obviously smaller than that of SF/BG composite membranes. Compared with SF and SF/BG composite membranes, the Young's modulus and tensile stress of the oriented SF/BG composite membranes is significantly increased, but the elongation at break is relatively decreased. The water contact angle of the material significantly decreased after the addition of BG particles and the introduction of orientated structure, which greatly improved the hydrophilicity of the composite membranes. Furthermore, the oriented SF/BG@SF/PCL exhibited higher cell adhesion and proliferation compared with the disordered SF/BG fiber membranes, and the introduction of BG particles significantly enhanced osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Besides, the barrier effect of the SF/PCL membrane was verified by L929 cells. The relatively dense structure leads to a good barrier effect as well as the obvious proliferation on the cells. This bi-layer composite SF/BG@SF/PCL membrane is a competitive candidate in the field of GBR technology and bone regeneration.

Introduction to Hamiltonian formulation of general relativity and homogeneous cosmologies

We give a pedagogical introduction to the Hamiltonian formalism of general relativity at an advanced undergraduate and graduate levels. After covering the mathematical pre-requisites as well as the 3+1-decomposition of spacetime, we proceed to discuss the Arnowitt-Deser-Misner (ADM) formalism (a Hamiltonian approach) of general relativity. Then we proceed to give a brief but self-contained introduction to homogeneous (but not necessarily isotropic) universes and discuss the associated Bianchi classification. We first study their dynamics in the Lagrangian formulation, followed by the Hamiltonian formulation to show the equivalence of both approaches. We present a variety of examples to illustrate the ADM formalism: (i) free & massless scalar field coupled to homogeneous (in particular, Bianchi IX) universe, (ii) scalar field with a potential term coupled to Bianchi IX universe, (iii) electromagnetic field coupled to gravity in general, and (iv) electromagnetic field coupled to Bianchi IX universe.

Slow Kerr-NUT black hole solution in dynamical Chern-Simons modified gravity

The slow rotation of Kerr-NUT spacetime is explored by taking into account the linear form of rotation and NUT parameters in the dynamical Chern-Simon gravity theory, which can be formulated from a scalar field describing the background. We show that in the absence of the potential scalar field, the metric potential does not respect the effect of the NUT parameter, although the scalar field is affected by the rotation and NUT parameters. As a result, unlike the slowly rotating black hole solution presented in [1], the cross term of the metric potential, which has both rotation and NUT parameters, has no contribution up to the leading order of the first order perturbation.

Molecular dynamics modeling of thermodiffusion in solids with charged defects using uranium dioxide as the case study

Although thermodiffusion is generally much less efficient than diffusion for chemical species transport, this phenomenon can sometimes have a significant impact on natural or technological systems. More specifically, oxygen thermodiffusion is reported as a key mechanism for nuclear fuel evolution during high power transients in nuclear plant operation.To contribute to our understanding and characterization of this phenomenon, oxygen thermodiffusion in UO2 is simulated by molecular dynamics (MD) in order to evaluate the oxygen heat of transport. Specific formulae for the heat flux are derived to take into account the non-pairwise embedded atom model (EAM) term of the empirical potential used. No electronic defects are considered and a specific strategy is built to address this flaw, including the way to ensure electroneutrality with a background charge compensating for the deviation from stoichiometry. A specific thermodynamic model is designed, including the effect of the background charge and each point defect contribution.Five MD techniques are tested and compared, among which the Green-Kubo formalism and the imposed electric field give similar results. The results are interpreted in terms of the defect heats of transport whose combination yields the complete oxygen heat of transport, which is a function of the oxygen potential. The calculated ranges of the heats of transport for the oxygen vacancy and interstitial are [0.20,0.86] eV and [-3.75,-2.60] eV, respectively.

Temperature and Turgor "Limitation" and Environmental "Control" in Xylem Biology and Dendrochronology.

Trees and other woody plants are immensely ecologically important, making it essential to understand the causes of relationships between tree structure and function. To help these efforts, we highlight persistent traditions in plant biology of appealing to environmental factors "limiting" or "controlling" woody plant features. Examples include the idea that inevitable drops in cell turgor with plant height limit cell expansion and thus leaf size and tree height; that low temperatures prohibit lignification of cells and thus the growth of woody plants at high elevation; and notions from dendrochronology and related fields that climate factors such as rainfall and temperature "control" growth ring features. We show that notions of "control," "limitation," and the like imply that selection would favor a given trait value, but that these would-be favored values are developmentally impossible to produce. Such "limitation" scenarios predict trait frequency distributions that are very narrow and are abruptly curtailed at the upper limit of developmental possibility (the right-hand side of the distribution). Such distributions have, to our knowledge, never been observed, so we see little empirical support for "limitation" hypotheses. We suggest that, as a more productive starting point, plant biologists should examine adaptation hypotheses, in which developmental possibility is wide (congruent with the wide ranges of trait variation that really are observed), but only some of the possible variants are favored. We suggest that (1) the traditional the proximate/ultimate causation distinction, (2) purging scenarios of teleology/anthropomorphism, and (3) stating hypotheses in terms of developmental potential and natural selection are three simple ways of making "limitation" hypotheses clearer with regard to biological process and thus empirically testable.

Techno-economic assessment of glassmaking decarbonization through integration of calcium looping carbon capture and power-to-gas technologies

Glass industry involves high temperature melting processes mainly based on fossil fuel combustion so far. This paper proposes the integration of Power to Gas and carbon capture to reduce the CO2 emissions, as well as the dependency on fossil fuels. Four novel concepts, modelled in Aspen Plus, are analyzed separately and compared with a conventional glass plant in terms of CO2 reduction potential and energy and economic penalties. The economic scenarios of full electricity purchase and full self-production with a photovoltaic plant are compared. The reference case, also modelled in Aspen Plus, has been validated with bibliographic data, being deviations of the main parameters <6 %. The low-carbon alternatives take advantage of the synergies between the different technologies: Calcium Looping, methanation and glassmaking processes. The main results show great reductions in fossil natural gas consumption as well as in CO2 emissions, specifically up to 95 % and 87 %, respectively. Furthermore, the different assessed low-carbon strategies may be combined to reach higher savings of CO2 emisions, reducing economic penalties.

Singular elliptic problem involving a Hardy potential and lower order term

We consider the following non-linear singular elliptic problem (1) − div ( M ( x ) | ∇ u | p − 2 ∇ u ) + b | u | r − 2 u = a u p − 1 | x | p + f u γ in Ω u &gt; 0 in Ω u = 0 on ∂ Ω , where 1 &lt; p &lt; N; Ω ⊂ R N is a bounded regular domain containing the origin and 0 &lt; γ &lt; 1, a ⩾ 0 , b &gt; 0 , 0 ⩽ f ∈ L m ( Ω ) and 1 &lt; m &lt; N p . The main goal of this work is to study the existence and regularizing effect of some lower order terms in Dirichlet problems despite the presence of Hardy the potentials and the singular term in the right hand side.