Lowest Potential Energy Research Articles

Computational study of effective matrix metalloproteinase 9 (MMP9) targeting natural inhibitors.

Object: The present study screened ideal lead natural compounds that could target and inhibit matrix metalloproteinase 9 (MMP9) protein from the ZINC database to develop drugs for clear cell renal cell carcinoma (CCRCC)-targeted treatment.Methods: Discovery Studio 4.5 was used to compare and screen the ligands with the reference drug, solasodine, to identify ideal candidate compounds that could inhibit MMP9. The LibDock module was used to analyze compounds that could strongly bind to MMP9, and the top 20 compounds determined by the LibDock score were selected for further research. ADME and TOPKAT modules were used to choose the safe compounds from these 20 compounds. The selected compounds were analyzed using the CDOCKER module for molecular docking and feature mapping for pharmacophore prediction. The stability of these compound–MMP9 complexes was analyzed by molecular dynamic simulation. Cell counting kit-8, colony-forming, and scratch assays were used to analyze the anti-CCRCC effects of these ligands.Results: Strong binding to MMP9 was exhibited by 6,762 ligands. Among the top 20 compounds, sappanol and sventenin exhibited nearly undefined blood–brain barrier level and lower aqueous solubility, carcinogenicity, and hepatotoxicity than the positive control drug, solasodine. Additionally, these compounds exhibited lower potential energies with MMP9, and the ligand–MMP9 complexes were stable in the natural environment. Furthermore, sappanol inhibited CCRCC cell migration and proliferation.Conclusion: Sappanol and sventenin are safe and reliable compounds to target and inhibit MMP9. Sappanol can CCRCC cell migration and proliferation. These two compounds may give new thought to the targeted therapy for patients with CCRCC.

Phosphor copper-based flexible high voltage supercapacitors fabricated via laser irradiation and three-dimensional packaging

Supercapacitors (SCs) have garnered increasing attention as an alternative energy storage device but the relatively low potential window and energy density impede their application prospect. Herein, we propose a novel three-dimensional (3D) packaging method for the first time, utilizing high flexible phosphor-copper sheets (PCSs) sprayed with polytetrafluoroethylene (PTFE) and covered with polyimide (PI) films on their both sides as the serial medium followed by CO 2 laser irradiation to fabricate all-solid-state flexible high voltage supercapacitors (HVSCs). This method achieves double voltage output in the limited PI membrane compared with common 2D encapsulation. As a result, as-obtained HVSCs deliver not only an enhanced mechanical tensile strength up to 18.23 MPa but also the outstanding electrochemical performances, including ultrahigh working voltage window (10 V), high energy density (37.68 μWh/cm 2 ) and power density (3.38 mW/cm 2 ). Owing to the excellent flexibility, the HVSCs can be arbitrarily bent or twisted without obvious attenuation on capacitive property. After 10000 cycles, the capacitance retention of HVSCs still maintains to be 90.2%. This novel 3D packaging strategy may pave the way for developing high-performing SCs with wide operating voltage and high energy density for flexible displays, wearable equipment and integrated electrical devices. • PI films were pasted on the upper and lower surfaces of phosphor copper sheet. • Graphene formation from laser irradiation on PI film surface. • Phosphor copper-based supercapacitor was prepared by a novel 3D packaging method. • HVSCs deliver enhanced tensile strength, high working voltage and energy density.

Identification of effective natural PIK3CA H1047R inhibitors by computational study.

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer with a poor prognosis and a high recurrence rate. PIK3CA gene is frequently mutated in breast cancer, with PIK3CA H1047R as the hotspot mutation reported in TNBC. We used the ZINC database to screen natural compounds that could be structurally modified to develop drugs targeting the PIK3CA H1047R mutant protein in the PI3K pathway. The LibDock module showed that 2,749 compounds could strongly bind to the PIK3CA H1047R protein. Ultimately, the top 20 natural ligands with high LibDock scores were used for further analyses including assessment of ADME (absorption, distribution, metabolism, and excretion), toxicity, stability, and binding affinity. ZINC000004098448 and ZINC000014715656 were selected as the safest drug candidates with strong binding affinity to PIK3CA H1047R, no hepatotoxicity, less carcinogenicity, better plasma protein binding (PPB) properties, and enhanced intestinal permeability and absorption than the two reference drugs, PKI-402 and wortmannin. Moreover, their lower potential energies than those of PIK3CA H1047R confirmed the stability of the ligand-receptor complex under physiological conditions. ZINC000004098448 and ZINC000014715656 are thus safe and stable leads for designing drugs against PIK3CA H1047R as part of a targeted therapeutic approach for patients with TNBC.

Effect of Lewis Basic Amine Site on Proton Reduction Activity of NNN‐Co Pincer Complex

Electrochemical proton reduction is a promising energy storage method because H2 molecule has a simple structure with a relatively low potential energy. Current interest in hydrogen catalysts has increased research efforts on synthetic analogs of hydrogenase active sites. In this study, we demonstrated the electrochemical H2 evolution reactivity of [NNNR‐Co(CH3CN)3]2+ (R  CH2 (1b), NCH3 (2b)) complexes and examined a proton‐relay process in the H2 evolution reaction (HER). Upon one‐electron reduction, the Co(II) ion center in a high‐spin state dissociated a CH3CN ligand, while opening a reaction site. Cyclic voltammograms of the Co complexes indicated quasi‐reversible Co(II/I) redox behaviors, and both complexes 1b and 2b showed catalytic H2 evolution activity. Interestingly, 2b, assisted by a proton‐relaying NCH3 group, exhibited more efficient catalytic activity than 1b.

Strong Exciton-Vibrational Coupling in Molecular Assemblies. Dynamics Using the Polaron Transformation in HEOM Space.

In Frenkel exciton dynamics of aggregated molecules, the polaron transformation (PT) technique leads to decoupling of diagonal elements in the subspace of excited electronic states from vibrations. In this article we describe for the first time how PT becomes applicable in the framework of the "Hierarchical Equations of Motion" (HEOM) approach for treatment of open quantum systems. We extend the concept of formulating operators in HEOM space by deriving hierarchical equations of PT which lead to a shift in the excited state potential energy surface to compensate its displacement. While the assumption of thermal equilibration of the vibrational oscillators, introduced by PT, results in a stationary state in a monomer, in a dimer under the same assumption nonequilibrium dynamics appears because of the interplay of the transfer process and vibrational equilibration. Both vertical transitions generating a vibrationally hot state and initially equilibrated vibrational oscillators evolve toward the same stationary asymptotic state associated with polaron formation. The effect of PT on the dynamics of this process depends on initial excitation and basis representation of the electronic system. The developed approach facilitates a generic formulation of quantum master equations involving perturbative treatment of polaron dynamics.

Molecular Insight into Bubble Nucleation on the Surface with Wettability Transition at Controlled Temperatures.

A surface with a smart wettability transition has recently been proposed to enhance the boiling heat transfer in either macro- or microscale systems. This work explores the mechanisms of bubble nucleation on surfaces with wettability transitions at controlled temperatures by molecular simulations. The results of the interaction energy at the interface and potential energy distribution of water molecules show that the nanostructure promotes nucleation over the copper surface and causes lower absolute potential energy to provide fixed nucleation sites for the initial generation of the bubble nucleus and shortens the incipient nucleation time, as compared to the mixed-wettability or hydrophilic nanostructure surface. An investigation on more nanostructured surfaces shows that a surface (F) with a wettability transition temperature of 620.0 K has the shortest average incipient nucleation time at 1672 ps with a wall temperature of 634.3 K. The surface with tunable wettability has also a high interfacial thermal conductance at low superheats, but it may not promote the critical heat flux at high superheats. The heat-transfer performance of the smart surface is better than the plate, the hydrophobic nanostructure, and the mixed-wettability surfaces, while it is lower than the hydrophilic nanostructure surface. This proposes a new method and provides insight for promoting bubble nucleation on a surface with temperature-dependent wettability.

ANALYSIS OF THE CONVERSION OF PRIMARY ENERGY INTO HEAT FOCUSED ON A HEAT PUMP WITH A WORKING SUBSTANCE (REFRIGERANT) CO2

The need for research in the field of energy efficiency and the ecological aspects of primary energy use is currently receiving considerable attention in the framework of European Union policy as well as in the Slovak Republic. It is necessary to deal with this issue not only for the needs of normal operations, but especially in the current situation, when due to the threat of the COVID-19 virus, the requirements for thermal energy are increased. A suitable way to achieve this is the use of renewable resources, in Slovakia mainly biomass, solar, wind, water and geothermal energy. Ambient air, ground heat, heat contained in groundwater and various other waste heat from technological processes represent a huge potential for the use of low-potential energy. The article is focused on solving the problem of conversion of primary energy into heat using thermodynamic cycles and compressor circulation with working substance (refrigerant) CO2.

Influence of soil thermophysical properties on the flow of thermal energy taken by the energy pile

The depletion of traditional fossil energy sources leads to an increasing development of non-traditional energy sources. One of the promising directions of alternative energy is the use of low-potential energy of the soil for heating buildings and structures for various purposes. Heat extraction is possible through the use of energy foundation. However, their rational design is impossible without a careful assessment of a large number of factors that affect the potential value of thermal energy extracted from the soil. The purpose of this work was to build a whole methodology to assess the degree of influence of soil thermophysical properties, in particular, such as heat capacity and thermal conductivity, on the amount of heat energy selected energy pile. The formulation and analysis of the numerical experiment to identify the desired dependencies. The matrix of experiment planning is made. The numerical simulation of the energy pile of different geometric parameters in different soil conditions is performed. Statistical processing of the obtained experimental data was carried out. A quadratic regression equation was developed to determine the amount of heat through the side surface of the pile depending on the length of the pile, its diameter, heat capacity and thermal conductivity of the soil. The analysis of this equation for the purpose of estimation of degree of influence of initial thermophysical parameters of soil on value of thermal energy of the selected pile is carried out.

Dependence sandy soil thermal conductivity on grain-size composition

The development of renewable energy sources technologies is relevant. Sun radiant energy, wind energy, water energy, earth low-potential energy are main renewable energy sources. Energy foundations are used for earth low-potential energy extraction. The research results this paper presented can be used for energy foundations calculations. It is necessary to know soil thermal characteristics to the energy foundations calculations. At the moment, there are many calculation methods for determining soil thermal characteristics, but none of them take into account their grain-size composition. The research purpose is to assess the dependence sandy soil thermal conductivity on grain-size composition. According to the research results, firstly, the influence of the density and moisture content of the soil on its thermal conductivity was confirmed, and secondly, it was established that, at the same moisture content and density, the size of the soil grains matters. Particle size distribution affects the sandy soil thermal conductivity. With an increase in the particle size, sandy soil thermal conductivity increases.

Transient stability analysis of composite hydrogel structures based on a minimization-type variational formulation

We employ a canonical variational framework for the predictive characterization of structural instabilities that develop during the diffusion-driven transient swelling of hydrogels under geometrical constraints. The variational formulation of finite elasticity coupled with Fickian diffusion has a two-field minimization structure, wherein the deformation map and the fluid-volume flux are obtained as minimizers of a time-discrete potential involving internal and external energetic contributions. To analyze the structural stability of a certain equilibrium state of the gel satisfying the minimization principle, we apply the local stability criterion on the incremental potential, which is based on the idea that a stable equilibrium state has the lowest potential energy among all possible states within an infinitesimal neighborhood. Using this criterion in a finite-element context, it is understood that bifurcation-type structural instabilities are activated when the coupled global finite-element stiffness matrix loses its positive definiteness. This concept is then applied to determine the onset and nature of wrinkling instabilities occurring in a pair of representative film-substrate hydrogel systems. In particular, we analyze the dependencies of the critical buckling load and mode shape on the system geometry and material parameters.

TECHNIQUE FOR DESIGNING ENGINEERING SYSTEMS WHEN OPERATING ON A LOW-POTENTIAL ENERGY SOURCE

Statement of the problem. To develop a design methodology for air conditioning and heat supply systems operating for a long period on the basis of a vertical geothermal well. Results. A description and procedure of the proposed design methodology for calculating the main parameters of air conditioning and heat supply systems are given.Conclusions. As a result of the study, a methodology for designing air conditioning and heat supply systems based on a low-potential energy source (NIE) was proposed. It allows you to calculate the required number of geothermal wells as accurately as possible, taking into account the technological features of the operation of engineering systems, which allows you to minimize the amount of capital and operational investments for the installation of heat pump equipment and its components.

Revealing the structural heterogeneity of metallic glass: Mechanical spectroscopy and nanoindentation experiments

Microstructural heterogeneity is an important issue in understanding the mechanical and physical properties of metallic glasses (MGs). Theoretically, physical aging below the glass transition temperature relax the MGs systems to a lower potential energy state on the potential landscape (PEL) while the cold rolling rejuvenates MGs to a higher potential energy state. In the current work, we systemically turned the structural heterogeneity through dynamic mechanical relaxation and rejuvenation. Correlations among the structural heterogeneity, internal friction, and shear transformation zones (STZs) of the model alloy was connected. Based on the cooperative shear model and statistical analysis, the scale variation of the STZs was revealed. This study demonstrated that the spatial structural heterogeneity can be enhanced by severe plastic deformation which can reduce the energy barrier for STZs activation. And we proposed the barriers decrease and more nucleation sites of STZs from physical aging to rejuvenation, which may be potential mechanism for improving the plasticity in MGs.

Scheme analysis of Bath modification in West Campus of Beijing University of Chemical Technology

Air-resource heat pump, as a Green energy-saving equipment, which converts low potential energy into high potential energy, is commonly used as an auxiliary heat source of solar energy. Air-resource heat pump is driven by electric energy, makes heat (cold) quantity with ambient air as cold (hot) source. It can not only refrigerate in summer, but also heat in winter [1]. This article analyzes the current situation of the public bathroom in a university, updates and selects the equipment according to the new requirements, and reasonably adjusts and uses the original system device, and adds an automatic control system. After reconstruction, it meets the use requirement and achieves the purpose of energy conservation. Finally, the article also gives some advice of further modification.

CO2 dual roles in food scraps-derived biochar activation to enhance lead adsorption capacity

Driven by China's waste classification system, the recycling of food scraps is a work of great importance. The carbonate (CO32−) and phosphate (PO43−) in food scraps indicate that its derived biochar can be a good candidate for Pb immobilization. In the current study, Pb2+ adsorption sites (CO32− and PO43−) of biochar were adjusted by carrier gas atmosphere and activation temperature. Results indicate that CO2 has dual roles in activation of food scraps-derived biochar. CO2 can not only inhibit the decomposition of CO32− but also increase the content of PO43− via consuming aromatic carbon combined with phosphorus at high temperature (>600 °C). Thus, the biochar prepared at 700 °C and CO2 atmosphere has more adsorption sites, resulting in an outstanding Pb adsorption capacity (up to 555.6 mg/g) via coprecipitation mechanisms. As-prepared biochar sample also can be prepared to a hydrogel with a remarkable mechanic strength. But biochar hydrogel decreases Pb adsorption capacity to 104.2 mg/g due to the pore blocking effect. Life cycle assessment illustrates that the scene of food scraps activated by CO2 has lower Global Warming Potential (GWP) and Primary Energy Demand (PED). Therefore, current research provides a high-efficiency method for treatment of food scraps.

Mediating the Effects of Climate on the Temperature and Thermal Structure of a Monomictic Reservoir through Use of Hydraulic Facilities

Climate warming can alter the thermal conditions of reservoirs. However, some hydraulic interventions can be explored to mitigate this impact. This study investigates the long-term effects of climate on the temperature and thermal structure of a monomictic reservoir that has had varying operations from 1959 to 2016. Reservoir progressively operated through three distinct periods, namely, (A) deep penstock withdrawal (DPW; 1959–1991), (B) purely selective withdrawal (SW; 1992–2001), and (C) combination of SW and vertical curtain (VC; 2002–2016). Although annual air temperatures are increasing (+0.15 °C decade−1) in the long term, the reservoir’s surface water temperatures have been found to be decreasing (−0.06 °C decade−1). Periods B and C produced colder profiles and exhibited lower heat content and higher potential energy anomaly than Period A. Furthermore, stronger thermoclines, as indicated by Brunt–Vaisala frequency, were observed in the two latter periods. The results of this study show that varying operations bear a stronger influence on the reservoir’s temperature and thermal structure than climate change itself. Mitigating the thermal impacts of climate warming in reservoirs appears promising with the use of SW and VC.

A Case study of Exergy Losses of a Ground Heat Pump and Photovoltaic Cells System and Their Optimization

The aim of this scientific research is to experimentally determine the exergy losses of a ground heat pump and further optimization for more efficient use of operating modes and improvement of individual structural elements. In addition, it is proposed to use photovoltaic panels as a backup power source for the experimental installation under study. The exergetic losses are calculated, not only for the ground heat pump itself, with R407C refrigerant. The research methodology consists in a comprehensive assessment of exergetic flows, their optimization using new methods of approximation of piecewise linear functions, and the development of prerequisites for the use of anergy as one of the components of a new type of analysis of the efficiency of low-potential energy sources. As a result of processing the experimental data, the values of Coefficient of performance (COP) 4.136, exergetic temperature for the lower heat source 0.0253 and for the upper heat source 0.155, exergetic efficiency of the installation 0.62, and total loss of specific exergy of the heat pump 24.029 kJ/kg were obtained. Controllers with the Modbus protocol were used for data collection. Matlab Simulink was used to process the experimental data. When carrying out the procedure for optimizing the operating modes and selecting several modes with minimal exergetic losses, an important role is given to mathematical methods of processing statistical data. The method of increasing the efficiency of the heat pump is shown, first of all, based on the use of photovoltaic panels as a backup power source and optimization of exergetic losses due to exergo-anergetic evaluation of operating modes. The authors present the measurement errors of the heat pump plant parameters in the form of a 3D Gaussian curve, which becomes possible only when applying new approximation methods in the processing of measurements.

Molecular dynamics study of convective heat transfer in ordered rough nanochannels

Nanostructures can enhance the convective heat transfer process in nanochannels. The ordered rough nanochannels with different periodic sinusoidal structures are established using the molecular dynamics method to explore the internal mechanism of the effects of nanostructures on convective heat transfer. The potential energy distribution, the mass density distribution, the temperature distribution, and the velocity distribution are obtained to analyze the effects on heat transfer and fluid flow caused by different types of ordered rough surfaces. Moreover, the velocity slip length, the thermal length, and the Nusselt number are also calculated. The results show that with the increase in surface roughness, the thermal slip length decreases, and the Nusselt number increases, indicating that the heat transfer process is improved. However, the decrease of velocity slip length indicates that the fluid flow process becomes worse. The expansion of the low potential energy region and the high mass density region enhances the heat transfer process at the solid–liquid interface. The accumulation of more atoms at the solid–liquid interface hinders the development of the flow field and makes the flow process worse. This research provides an understanding of the convective heat transfer in ordered rough nanochannels, which can guide the design of electronic devices' cooling and fluid transport.

Icosahedral clusters in Cu100-xZrx (x=32,34,36,38.2,40 at.%) metallic glasses near the peak of glass-forming ability (x=36): A balance between population and encaging strength

Understanding the origin of glass-forming ability (GFA) is important for the discovery or development of new metallic glasses (MGs). It is well known that the GFA in Cu–Zr binary MGs is sensitive to the composition and possesses a peak around Cu64Zr36 (at.%). The reason for this, however, is still not fully understood due to the complexity of the physics behind glass formation. Here, we use molecular dynamics simulations and statistics to study the structure and particularly the atomic energy state of the supercooled liquid and glass phases in the Cu100-xZrx (x = 32, 34, 36, 38.2, 40 at.%) alloy series. We show that the shell atoms of icosahedral clusters (the most dominant cluster type) in all these alloys have significantly lower (by > 1 eV/atom) potential energy than the core atoms. With rising Zr-content, the core–shell energy difference of the icosahedral clusters increases, making these clusters more strongly encaged and harder to break before or during crystallization. This effect counteracts the decrease in the population of the icosahedral clusters that has been noticed in previous studies. The net result of the interplay between these two factors can be represented by the product of the fraction of icosahedral shell-atoms and the core-shell energy difference, which exhibits a maximum at 36% Zr where the highest GFA has been observed. These findings provide new insights into the origin and peaking behavior of the GFA in this important binary bulk MG system, which could facilitate the search for the best glass-forming compositions in other alloy systems.

A Communicating-Vessels Proof of Hölder’s Inequality

Hölder’s inequality receives a variety of proofs in the literature. This note gives a new derivation, interpreting the inequality as the tendency of still water to settle in the lowest potential energy.

On the vibrational free energy of hydrated proteins

When the hydration shell of a protein is filled with at least 0.6 gram of water per gram of protein, a significant anti-correlation between the vibrational free energy and the potential energy of energy-minimized conformers is observed. This means that low potential energy, well-hydrated, protein conformers tend to be more rigid than high-energy ones. On the other hand, in the case of CASP target 624, when its hydration shell is filled, a significant energy gap is observed between the crystal structure and the best conformers proposed during the prediction experiment, strongly suggesting that including explicit water molecules may help identifying unlikely conformers among good-looking ones.