Effects Of Structural Characteristics Research Articles

Emulsification capacity of pectin extracts from persimmon waste: Effect of structural characteristics and pectin-polyphenol interactions

Polyphenol-rich pectin extracts obtained from persimmon waste might have great potential due to their emulsification capacity. Their emulsion stabilizing properties may be influenced by pectin molecular structure and pectin-polyphenol interactions which in turn can be determined by the extraction conditions. Hence, this work aimed to study the influence of the molecular structure characteristics and their respective pectin-polyphenol interactions of three polyphenol-rich persimmon pectin extracts obtained by three different extraction conditions. Low, medium and high severity extraction conditions resulted in covalent phenolics-extract (CP-E), non-covalent phenolics-extract (NCP-E) and free phenolics-extract (FP-E), respectively. The electrical charge of pectin was strongly dependent on the pH, becoming more negative at increasing pH due to carboxyl group dissociation. CP-E and NCP-E in solution had more expanded conformations than FP-E, with greater intermolecular distances and hydrodynamic diameters ranging from 1089 to 1791 nm for CP-E and NCP-E, whereas from 529 to 782 nm for FP-E. Their interfacial layer thickness was thicker at pH 3 than at pH 7, probably due to multilayer organization as a result of less repulsion between pectin chains. All pectin extracts were able to decrease the interfacial tension of an oil droplet from 35 to at least 25 mN/m, with FP-E at pH 3 being the most efficient (13.89 ± 1.07 mN/m). Even so, submicron O/W emulsions with negative ζ-potential values could be formed with all pectin extracts. However, CP-E rendered O/W emulsions with higher colloidal stability than FP-E or NCP-E, which showed aggregation and creaming. These findings provide novel insights to re-valorize pectin from persimmon waste.

Influence of beeswax-based fish oil oleogels on the mechanism of water and oil retention in Pacific white shrimp (Litopenaeus vannamei) meat emulsion gels: Filling, emulsification and phase transition

Oleogels have been used in the gelled surimi products to replace animal fats due to its structure characteristics. The effect of structure characteristics in fish oil oleogels on the mechanism of oil/water retention was investigated in meat emulsions. Beeswax assembly improved the oil and water retention. The unsaturation degree of fatty acids lowered the mobility of bound water, immobilized water as well as bound fat in the fish oil oleogel, but enhanced the mobility of free water and protons of unsaturated fatty acids. Beeswax addition and oil phase characteristics could enhance β-sheets, disulfide bonds and hydrophobic force to improve the viscoelasticity, gel strength and oil/water retention. Beeswax assembly facilitated the tight micro-sol network and filling effect, and high unsaturation degree promoted the emulsification effect, thus reducing phase transition temperature and juice loss. The study could lay the foundation for development of gelled shrimp meat products with EPA and DHA.

Effect of structural characteristics on charring shrinkage and cracking of densified wood under radiative heatings

Densified wood (DW) is a novel engineering material with excellent mechanical properties. It forms a thermally insulating and hardly-cracked char layer during pyrolysis and combustion. However, the scientific fundamentals regarding how wood structural characteristics (e.g. density) affect its charring behavior remain unknown, which is important for the fire safety of wood. In this work, the charring shrinkage and cracking of NW and DW with various densities (ρ) under heating exposures (Qr) are investigated and analyzed. Partial crack closure was observed due to the oxidation. As wood ρ increases or Qr decreases, the number of cracks (Nc) decreases and cracking time (tc) is delayed because both the surface temperature (Tsurf) and altered thermal stress concentrations on the wood surface are reduced. DW presents an earlier mass loss peak and lower peak value due to the delignification. DW presents high fluctuations in Tsurf due to the combing effect of thermal inertia and radial rebound. As wood ρ increases, char shrinkage depth at tc decreases and shrinkage gradient at tc increases first and then decreases. An empirical correlation is proposed and well-predicts the Nc based on ρ and Qr. It can be potentially implemented in the combustion model to improve prediction accuracy.

Evaluation of the thermal hazard and pyrolysis mechanism of 1-allyl-3-methylimidazole nitrate and 1-propyl-3-methylimidazole nitrate via thermal analysis and DFT calculation: Effect of structural characteristics

Imidazole ionic liquid, as a green solvent, is one of the most widely used ionic liquids. Understanding its thermal safety characteristics and mechanism is the essential basis for its safe application. In this paper, the thermal hazard characteristics of two ionic liquids with typical structural characteristics are systematically studied, which were 1-allyl-3-methylimidazole nitrate and 1-propyl-3-methylimidazole nitrate ionic liquids. The thermal decomposition peculiarities of two ionic liquids were systematically analyzed by thermogravimetric analyzer, differential scanning calorimetry and accelerating rate calorimeter techniques, and the risk of thermal runaway is also evaluated. In addition, the pyrolysis products and microscopic pyrolysis mechanism of ionic liquids were studied via thermogravimetry-Fourier transform infrared spectroscopy, thermogravimetric mass spectrometry and density functional theory calculation, and the essential mechanism of thermal hazard were determined. The influence of substituent structure on the thermal hazard characteristics of imidazole nitrate ionic liquid was preliminarily analyzed from macroscopic experiment and microscopic mechanism two aspects. This study provides a theoretical basis for the safe application, design and development of imidazole nitrate ionic liquids.

Numerical investigation on the effect of repeated surface surcharge loading on soil deformation and tunnel displacement in structured soft clay

Shanghai soft clay is a typical marine clay with specific structural characteristics. The tunnel and overlying soft clay may undergo repeated surface surcharge loading, such as the temporary soil stacking. Assessing the extent of structured soft clay deformation and tunnel displacement caused by repeated surface surcharge loading is of great significance for evaluating of the safety of ground structures and underground tunnels. In this study, the effects of repeated surface surcharge loading on the soil and tunnel displacement were numerically investigated. The finite element code DBLEAVES with an elasto-plastic constitutive model (Shanghai model) that describes the mechanical properties and structural characteristics of natural clay was used to simulate the soil response. The parameters of the constitutive model were obtained through geotechnical testing. The effects of the soil structural characteristics, seepage conditions, and loading conditions on the soil response and tunnel displacement were analyzed. The numerical results show that the maximum excess pore pressure of clay decreased as the number of loading cycles increased. The effects of the structural characteristics cause greater displacement, whereas the effects of the degradation parameters of the structure are more significant than the initial degree of the structure. The differences in the vertical displacement of the tunnel and overlying soils owing to the structural characteristics become apparent with an increase in surface surcharge loading. However, the effects of structural characteristics become less significant as the depth increases. The seepage conditions and loading method primarily affect the build-up of excess pore pressure and the development of effective stress paths. For soils inside the surcharge area, a flexible surcharge produces a greater vertical displacement than a rigid surcharge. As the burial depth increased, the effects of the seepage conditions and loading method showed a declining tendency.

Screening of the Antagonistic Activity of Potential Bisphenol A Alternatives toward the Androgen Receptor Using Machine Learning and Molecular Dynamics Simulation.

Over the past few decades, extensive research has indicated that exposure to bisphenol A (BPA) increases the health risks in humans. Toxicological studies have demonstrated that BPA can bind to the androgen receptor (AR), resulting in endocrine-disrupting effects. In recent investigations, many alternatives to BPA have been detected in various environmental media as major pollutants. However, related experimental evaluations of BPA alternatives have not been systematically implemented for the assessment of chemical safety and the effects of structural characteristics on the antagonistic activity of the AR. To promote the green development of BPA alternatives, high-throughput toxicological screening is fundamental for prioritizing chemical tests. Therefore, we proposed a hybrid deep learning architecture that combines molecular descriptors and molecular graphs to predict AR antagonistic activity. Compared to previous models, this hybrid architecture can extract substantial chemical information from various molecular representations to improve the model's generalization ability for BPA alternatives. Our predictions suggest that lignin-derivable bisguaiacols, as alternatives to BPA, are likely to be nonantagonist for AR compared to bisphenol analogues. Additionally, molecular dynamics (MD) simulations identified the dihydrotestosterone-bound pocket, rather than the surface, as the major binding site of bisphenol analogues. The conformational changes of key helix H12 from an agonistic to an antagonistic conformation can be evaluated qualitatively by accelerated MD simulations to explain the underlying mechanism. Overall, our computational study is helpful for toxicological screening of BPA alternatives and the design of environmentally friendly BPA alternatives.

Horizontal flame spread behavior of densified wood: Effect of structural characteristics

Densified wood (DW) is a recently developed material with excellent mechanical properties, considered as an ideal construction material for high-rise timber buildings. However, its flame spread behavior has not been well understood limiting its applications. This work for the first time experimentally and analytically investigates the horizontal flame spread behavior of DW. The influences of material structural characteristics (e.g. density) on heat transfer characteristics are focused. Thermally thin DW with density ranges of 441–1025 kg/m3 and a constant thickness of 2 mm were tested. The flame spread rate, mass loss rate (MLR) and flame height decreased with the increased wood density. A power-law correlation between the dimensionless MLR and dimensionless density is proposed, which well predicts the experiments with an R2 of 0.922. The increased wood density decreases flame height and reduces flame radiation. The gas-phase heat transfer shifts from radiation-dominant to convection-dominant. The longitudinal and radial thermal conductivities of DW increased with wood density. Empirical equations are optimized to predict the thermal conductivities of DW with R2 of 0.870 (longitudinal) and 0.837 (radial). The preheating zone length and the temperature gradient per unit length don’t vary significantly with wood density. Their values are averaged to 25.62 mm and 9.312 K/mm respectively. The longitudinal heat conduction is increased with the wood density due to the increased conductivity. However, this conduction increase is lower than the radiation decrease as the wood density increases. Thus, the total heat flux is slightly decreased with the wood density. The gas phase heat transfer dominates the flame spread. However, the longitudinal heat conduction can account for more than half of the gaseous heat transfer, and thus cannot be negligible. Results of this work improve the understanding of DW flame spread, which helps to evaluate the fire behaviors of timber construction.

Effect of methyl substituent on adamantane pyrolysis at atmospheric and high pressure: A combined experimental and theoretical study

Adamantane derivatives, as promising high-density fuels, have been widely concerned in fields of volume-limited aerospace vehicles due to high density, heat of combustion and thermal oxidation stability. To reveal insights into their high-temperature decomposition behaviors, an experimental and theoretical investigation of adamantane (A) and 1-methyl adamantane (1-MA) pyrolysis was performed in a flow tube reactor at atmospheric to high pressure. Over twenty species were detected and identified, including C1-C5 light hydrocarbons, C5-C7 cyclic olefins as well as C6-C12 aromatics. The favorable decomposition channels of A and 1-MA are proposed and the effects of fuel structure characteristics and pressures on product formation behaviors are revealed. For the primary decomposition of A and 1-MA, the contributions of reaction types exhibit the obvious dependence on the pressures and temperatures, involving the unimolecular C-C dissociations by ring-opening, CH3-elimination as well as H-abstractions by H and CH3 attacking. Considering methyl-substitution weakens dissociation energies of C-C and C-H bonds and leads more H-abstraction sites, 1-MA shows a higher pyrolysis reactivity than A. The effects of structure characteristics are also embodied in the formation of newly chain-branched unsaturated species and the concentrations of common small hydrocarbons and aromatics. Compared to A decomposition, the methyl substituent in 1-MA promotes the emergence of 1-butene, 2-methyl-1-butene, mesitylene, methylindane and methylnaphthalene, and increases the concentrations of methane, 2-methylpropene and xylene isomers, formed via β-scission, hydrogen transfer, isomerization and dehydrogenation routes of fuel radicals. Meanwhile, more methyl-substitutions accelerate the decomposition of alkyl-adamantanes and pyrolysis activity follows by a sequence of dimethyl-adamantane > methyl-adamantane > adamantane, boosting the production of methyl-specific species.

Effect of structural characteristics on functional properties of textured vegetable proteins

Meat analogues are predominantly composed of a pre-structured form of protein called textured vegetable protein (TVP) that is designed to mimic the fibrous structure of animal muscle meat. Limited information is available regarding the link between structural characteristics of TVPs and their functional properties. This study investigated the relationships between the structural characteristics of commercial TVPs and (a) their rehydration behaviour, as well as (b) the mechanical properties and serum release (cooking loss and expressible liquid) of patties prepared from these TVPs. The micro- and macrostructural features of thirteen commercial TVPs were quantified using X-ray microtomography. Apparent density (205–1042 kg m−3), porosity (27.1–80.9%), pore size (251–4790 μm), wall thickness (108–657 μm), and wall density (597–1515 kg m−3) varied largely across samples. In the early stages of water absorption, thicker walls promoted the absorption of larger volumes of water. In contrast, the maximum water absorption capacity as well as water holding capacity were higher for TVPs with thinner walls and higher porosity, highlighting the impact of structural features of TVPs on water absorption during rehydration. Significant positive correlations between cooking loss and expressible liquid indicated that patties with higher serum release during cooking also tended to release more during compression. TVPs with thicker walls resulted in stiffer patty batters, and TVPs with smaller pores resulted in stiffer grilled patties. We conclude that the structural characteristics of TVPs influence their rehydration behaviour and various functional properties of patties made with them.

Effect of introducing chemically activated biochar as support material on thermal properties of different organic phase change materials

Chemically activated biochar with richer pore structure and higher specific surface area is well suited for loading phase change materials (PCMs). However, the effect of structural characteristics and abundant surface functional groups of chemically activated biochar on the thermal properties of PCMs has not been systematically investigated. Here, shape-stable samples were prepared by introducing biochar obtained by activation with different chemical reagents (ZnCl2, H3PO4, KOH, and K2CO3) into three organic PCMs (paraffin, stearic acid, and polyethylene glycol). The results indicated that the biochar activated by KOH possessed the highest specific surface area of 1344.45 m2/g, followed by biochar activated by ZnCl2, H3PO4, and K2CO3 of 1297.35, 1062.74, and 891.38 m2/g, respectively. The loading capacity of KOH-activated biochar was as high as 82.12 %, 83.13 %, and 80.81 % for the three organic PCMs, and the melting enthalpies of corresponding composite PCMs were 163.82, 168.54, and 139.96 kJ/kg. Additionally, the influence degree on the enthalpies of the three PCMs was only 10.84 %, 12.26 %, and 7.74 %, while that of ZnCl2 and H3PO4-activated biochar was as high as 53.61 % and 44.22 %, 52.10 %, and 57.74 %, 55.35 % and 45.79 % indicating the two biochar were not suitable as support materials for PCMs. Moreover, ZnCl2-activated biochar has the most apparent upgradation on PCMs' thermal conductivity, which could increase the thermal conductivity of the three organic PCMs by 1.318, 1.34, and 1.229 times, respectively, followed by H3PO4, K2CO3, and KOH-activated biochar.

Effect of structural characteristics on the transport characteristics of solid particles in the thermal storage and release system of circulating fluidized bed

Coal-fired power generation stands as the most economically viable modulating power source in present-day China. It holds the potential to offer prospective solutions to the challenges posed by the rapid expansion of intermittent, unpredictable, and unstable renewable energy sources. Solid particle thermal storage technology emerges as an effective means to enhance the flexibility of coal-fired circulating fluidized bed power units. To attain an optimized structure for the solid particle thermal storage and release system in circulating fluidized bed units, experimental research was conducted on a 0.1 MWth circulating fluidized bed test platform. This study delved into the impact of ash storage bin geometries and the shapes of their feed-discharge valves on the control properties of solid particle transportation. The experimental outcomes reveal that employing inverted m-shaped valve and dual U-shaped valves for feed control, alongside U-shaped valves and N-shaped valves for discharge control, both enable efficient and rapid storage and release of solid particles within the circulating fluidized bed. Under similar air distribution conditions, the inverted m-shaped valve exhibits lower conveying energy consumption than the dual U-shaped valves, while the N-shaped valve excels in control characteristics over the U-shaped valve. Furthermore, the inverted m-shaped valve and the N-shaped valve demonstrate optimal overflow port heights, and the ash storage bin exhibits an optimum height-to-diameter ratio.

A multiphase flow study for lubrication characteristics on the internal flow pattern of ball bearing

This work proposes a general method for establishing the lubrication analysis model of ball bearing and the oil-air multiphase flow characteristics inside ball bearing is revealed by CFD. Based on the geometric feature, the micro-clearance in the chamber is introduced into the simulation model, and the complicated boundary shape of ball bearing is developed. Meanwhile, the simulation model is divided by the hexahedron elements and the mesh density near the contact region is increased, which promotes the convergence and accuracy of solution. Then, the lubrication performance experiment of ball bearing is conducted, which demonstrate that this model could capture the lubrication characteristics of ball bearing. Moreover, the evolution of hydrodynamic behavior, including the oil-air distribution, temperature and flow characteristics during different lubrication states, is displayed. The effects of structure characteristics and working condition are quantified. The results represent that the suitable clearance size could improve the internal flow patterns and hydrodynamic performance of ball bearing.

Performance analysis of the salinity based on hexagonal two-dimensional photonic crystal: computational study

We have designed a unique structure for a liquid sensor based on two-dimensional PCs with a triangular lattice constant in the periodicity by drilling a hexagonal cylinder in a dielectric host material. Using the COMSOL multiphysics approach, we investigated the given structure and sensing performance based on the finite element method. We will optimize two-dimensional hexagonal photonic crystals to localize the photonic band gap region in the mid and far infra-red frequency range, as water is a good absorber for this range of frequencies. Then, we inject the central hexagonal cylinder with saline water and calculate the sensor parameters for different values of the refractive index of saline water at different frequencies related to photonic band gaps. We could reach the optimum conditions of the salinity sensor as the half diagonal of the hexagonal shape (R) = 500 nm, the perpendicular distance between the two diagonal hexagonal (D) = 250 nm, and the number of periods (N) = 5, which gives a high efficiency with sensitivity (S) = 525 nm/RIU, figure of merit (FOM) = 80.7 RIU−1, and quality factor (Q) = 375. The effects of structural characteristics on sensing performance are investigated, with new approaches for improving salinity sensors proposed. Furthermore, traditional salinity sensors may be replaced by the proposed method in the photo-sensing application, which is simple and practical for use in the thermal desalination techniques.

Effect of structural characteristics and surface functional groups of biochar on thermal properties of different organic phase change materials: Dominant encapsulation mechanisms

In this article, waste phoenix leaf biochar was introduced into three most used organic phase change materials (PCMs) to prepare shape-stable composite PCMs by the vacuum impregnation method. The encapsulation capacity and encapsulation efficiency of steam activated biochar for paraffin, stearic acid, and polyethylene glycol were 59.28% and 49.14%, 63.03% and 57.62%, 71.38% and 46.84%, respectively, which was related to the mechanisms of biochar encapsulated organic PCMs. The dominant mechanisms of biochar encapsulated organic PCMs are summarized as pore-filling, hydrogen-bonding, hydrophobic interaction between biochar and PCMs, and other potential mechanisms. Influence degree η was introduced to illustrate the effect of biochar on organic PCMs, 16.56%, 8.72%, and 35.75% for steam activated biochar on paraffin, stearic acid, and polyethylene glycol. In addition, compared with original PCMs, the thermal conductivity of biochar-based composite PCMs first decreased and then increased with the increase of biochar pyrolysis temperature. Moreover, biochar-based composite PCMs had better thermal stability, concerned with the dominant mechanisms of biochar encapsulated organic PCMs. Therefore, biochar-based composite PCMs proposed in this study expand the application of biochar and organic PCMs in thermal energy storage, building energy conservation, solar energy utilization, and battery thermal management system.

Functional porous carbon derived from waste eucalyptus bark for toluene adsorption and aqueous symmetric supercapacitors

It is of great significance to synthesize functional porous carbon from renewable waste biomass resources to solve the problems of energy storage and environmental pollution. Herein, the eucalyptus bark was converted into porous carbon materials for toluene adsorption and aqueous symmetric supercapacitors by hydrothermal treatment combined with KOH activation. Toluene adsorption experiments indicated that the toluene adsorption capacities of BPCs increased with increase of activated temperature and activator concentration, and the toluene adsorption capacities of BPCs were inversely related to adsorption temperature and relative humidity. The effects of structural characteristics and functional groups on toluene adsorption were analyzed in detail. Besides, the supercapacitance performance of samples under different preparation conditions was tested, the BPC-3-600 electrode exhibited the best specific capacitance of 263.2 F g−1 at 0.5 A g−1 and 207.5 F g−1 at 10 A g−1 in a three-electrode system using 6 M KOH as the electrolyte. Moreover, the aqueous symmetric supercapacitor assembled in 6 M KOH showed a high specific capacitance of 191.2 F g−1 at 0.2 A g−1 and an outstanding capacitance retention of 105.1 % at 5 A g−1 after 10,000 cycles. Most importantly, the supercapacitor assembled in 1 M Na2SO4 can provide an energy density as high as 10.5 Wh kg−1 at a power density of 159.5 W kg−1, and a remarkable energy density of 5.2 Wh kg−1 can be retained even at a power density as high as 12,480.0 W kg−1.

Effect of structural characteristics on the natural convective heat transfer performance of copper foam

• Copper foam with highly controllable structure was manufactured. • The relationship between structure and heat transfer performance was studied. • When the porosity is > 78%, the heat transfer performance drops sharply. • The optimal porosity and pore size for convective heat transfer have been found. • Side-heated foams exhibit better heat transfer than the bottom-heated foams. The effects of porosity, pore diameter and heating direction on the heat transfer performance of copper foam under natural convection were experimentally investigated. The open cell copper foam with highly controllable porosity ranging from 65% to 85% and mean pore diameters of 330 μm, 560 μm, 850 μm and 1200 μm were manufactured using a space holder method. The natural convective heat transfer coefficient of the copper foam was measured using a purpose-designed device. The influence mechanism of porosity, pore diameter and heating direction on heat transfer was analysed and discussed. The results showed that when the porosity is less than 75%, the effect of porosity on heat transfer is not significant, but as the porosity increases further, the heat transfer performance decreases significantly. The optimal pore size was found to be 850 μm, while the heat transfer performance of other pore sizes depends on the porosity. It was also found that the samples heated from the side generally showed better heat transfer performance than the samples heated from the bottom. The influence of porosity and pore size on natural convective heat transfer performance is mainly caused by changes in thermal conductivity and permeability. This research provides important guidance for the design of future heat sinks.

The effect of structural characteristics and external conditions on the dynamic behavior of shear deformable FGM porous plates in thermal environment

The effect of structural characteristics and external conditions on the dynamic behavior of shear deformable FGM porous plates in thermal environment

Effect of structural characteristics on damping modification factors for floor response spectra in RC buildings

Floor response spectra (FRS) are used to compute the design floor accelerations for seismic design of acceleration-sensitive non-structural components (NSCs) in a building. In the present study, the elastic FRS at different floor levels are investigated for a set of linear and nonlinear models of both low- and mid-rise reinforced concrete (RC) frame structures. The damping modification factors (DMFs) for the elastic FRS are derived for seven different damping ratios of the NSC's (i.e. 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, and 10%), and six different levels of inelastic response in the building structure. It is observed that DMFs for the elastic FRS are influenced by both NSC and building structure characteristics. The factors affecting the DMFs for the elastic FRS include the damping ratio of the NSC, the tuning ratio (i.e. the ratio between the period of vibration of the NSC, Ts, to the fundamental period of vibration of the building structure, T1), the modal periods (T1 and T2), and the level of the building structure's inelasticity. Conversely, the vertical location of the NSC in the building structure does not affect DMFs significantly. Further, in the case of a tuned response of the NSC, the DMFs for elastic FRS are significantly higher for NSC damping ratios less than 5% and lower for NSC damping ratios greater than 5%, than those conventionally used for the elastic ground response spectra (GRS). This is true for the elastic response as well as for low levels of inelasticity in the building structure. On the other hand, at high levels of the building structure's inelasticity, the DMFs for elastic FRS approach to the conventional DMFs derived for the elastic GRS. Considering these observations, a design-oriented multilinear model is proposed to compute DMFs for the elastic FRS, accounting for the specific characteristics of the NSC (i.e. the period and the damping ratio of the NSC) and the building structure (i.e. the modal periods and the level of the inelasticity). The proposed model for computing the DMFs for elastic FRS is validated by comparing the model predictions with those obtained by time-history analyses, using a different RC frame building and an entirely different suite of ground-motion records than those that were used to develop the proposed model. The proposed model to compute DMFs for the elastic FRS can be used with both the current code-based and the performance-based seismic design of NSCs located in the inelastic building structures.

Effects of structure characteristics and fluid on the effective thermal conductivity of sintered copper foam

Heat exchangers with excellent heat transfer performance are highly demanded as the development of the powerful chips and integrated circuit. Due to the large surface area and good thermal conductivity, porous metal has become a potential candidate material for the future heat exchangers. A powder metallurgy-based method was used to manufacture copper foam samples with highly controllable particle size, porosity and pore size in this study. The effects of particle size, porosity and natural convection on the so-called effective thermal conductivity (ETC) of the copper foam and the heat transfer mechanism of copper foam-fluid system were experimentally investigated. The effect of natural convection was studied by comparing the ETC of the copper foam, copper foam-air and copper foam-water system. Results show that the thermal conductivity of sintered copper sample was strongly affected by the particle size of the starting copper powder. The medium particle size (45–70 μm) was ideal for obtaining the best thermal conductivity. The dependence of ETC on porosity can be properly described by the Power Law model. A linear correlation was also proposed to describe the effects of porosity and pore size on the contribution of the fluid to the metal foam–fluid system.

In silico de novo Design of NNRTIs of HIV-1: Functional Group Based Computational Molecular Modeling Approach

Seven novel lead compounds, acting as NNRTIs of HIV-1, are extracted from a database of, in silico de novo designed, 500 compounds. Functional group based computational molecular modelling techniques are used for such design of Acylthiocarbamate derivatives. Effect of structural characteristics on the antiviral activity of these derivatives has also been studied. Statistical regression techniques namely, Non-linear (Back Propagation Neural Network, Support Vector Machine) and linear (Multiple Linear) chemometric regression methods are used in developing the relationships of Kier-Hall Electrotopological State Indices (E RingA, E O8, E N9, E O14, E S16, E N17, E O19, E R, and E R1 ) with the HIV-1 antiviral activity. The results of assessment of relative potentials of these methods suggest that BPNN (r 2 = 0.845, MSE = 0.142, q 2 = 0.818) describes the relationship between the descriptors and antiviral activity in a better manner than SVM - ε-radial (r 2 = 0.844, MSE = 0.144, q 2 = 0.807) and MLR (r 2 = 0.836, MSE = 0.150, q 2 = 0.805).