Transfer Factor Research Articles

Conduction Shape Factors for Thermally Active Retaining Walls

The walls of a structure below the ground level can also be utilised for exchanging heat energy from shallow depths, thereby accessing shallow geothermal energy for indoor heating and cooling, in addition to their primary role of resisting structural loads. This thermal activation of walls is achieved by installing the heat exchanger pipes at the time of construction of the wall, and these are commonly termed energy walls. These energy walls are used for underground parking spaces, basements and underground stations. For the efficient thermal design of these structures, simple analytical solutions are required to characterise their heat transfer. In this extended abstract, we compare the temperature change computed across energy walls for different calculation methods, including steady-state shape factors and numerical approaches.
 Energy walls follow a repetitive pipe arrangement which can be installed horizontally and vertically; however, vertical arrangements are more common due to ease of installation [1]. This leads to a simplified repetitive geometry shown in Figure 1(a), where the pipe is placed closest to the ground, whether we assume a constant temperature, and the other side of the wall is assumed insulated as per [2]. These pipe arrangements within walls can be compared with pipes buried in the ground, e.g. for district heating or other applications (Figure 1(b), (c)). These buried pipes, mostly large-diameter pipes, carry fluids at higher temperatures for large distances, making understanding heat transfer and heat losses extremely important. Therefore, heat conduction in this field has been explored in more detail with the result that shape factors for steady-state heat transfer are readily available [3].
 Conduction shape factors (S) are easy to apply and can be used to assess the temperature difference between the heat transfer fluid and the back of the energy wall (TC) due to the thermal resistance (R) of the wall concrete via equation (2). There are two shape factors which are tested in the work; SB1=single buried pipe (Figure 1(c), equation (3) [4] and SB2=equally spaced buried pipes (Figure 1(b), equation (4)) [4], and compared to steady state shape factor (SN) calculated numerically. The reason for testing them both is because the pipes in the wall are of minimal diameter, 20mm to 28mm, compared with wall dimensions of 0.4m to 1.2m or pipe spacing of 0.3m to 0.8m. TC calculated from the two shape factors is compared with results from two numerical models for a range of geometries. At first, the geometry shown in Figure 1(a) is solved for the steady state, after which a ground length is added to it, the transient state is analysed, and TC is calculated via equation (1).
 …(1) …(2)
 …(3) …(4)
 where Q (W/m) is the heat flux, S is the shape factor, s is spacing between the consecutive pipes (m), D is the pipe diameter(m), and K is the thermal conductivity of concrete (W/mK). TP and TW are the temperature changes at the temperature changes The results are presented in Figure 1 for varying pipe spacing and wall thicknesses: wall thickness W=0.6m, 0.8m, 1m, and 1.2m; 3 pipe spacing s=0.3m, 0.5m, and 0.8m. In all cases, the pipes are 25mm in diameter and offset 75mm from the back of the wall. Constant heat flux per unit area, q=12*s W/m2, is applied for 1 year in the case of the transient analysis.
 he buried pipes in the ground form a good analogy with the embedded pipes of energy walls for the calculation of temperature changes due to thermal resistivity. Compared to the results from the steady state numerical analysis, TSN, TC from the equally spaced pipes model has an accuracy between 99.1-99.7%, while that from the single buried pipe model has an accuracy between 81.5-97.3%. This shows that for shape factors in energy walls, pipe spacing is essential, but wall thickness does not play such a significant role in the general range. Therefore, in Figure 1(e), the steady-state responses from different thicknesses overlaps. However, when the effect of the ground behind the wall is included for the transient simulation, the results at a pseudo-steady state are not identical and depend on the pipe spacing and wall thickness. Models with smaller wall thicknesses reach a steady-state-like condition quicker, whereas models with higher wall thicknesses may need almost a year to reach a steady state. Through this analysis, it can be concluded that the shape factors used for the buried pipe can also be used for the energy walls. Of the two studied shape factors, the formulation SB2 shows values very similar to the numerically calculated values.

Trophic transfer of nanomaterials and their effects on high-trophic-level predators

Nanotechnology offers great opportunities for numerous sectors in society. One important challenge in sustainable nanotechnology is the potential of trophic transfer of nanomaterials (NMs), which may lead to unintentional impacts on environmental and human health. Here, we highlight the key advances that have been made in recent 15 years with respect to trophic transfer of heterogeneous NMs, including metal-based NMs, carbon-based NMs and nanoplastics, across various aquatic and terrestrial food chains. Particle number-based trophic transfer factors (TTFs), rather than the variable mass-based TTFs, capture the particle-specific transfer, for which NMs exhibit dynamic and complex biotransformation (e.g., dissolution, sulfidation, reduction, and corona formation). Trophic transfer of NMs has toxicological significance to predators at molecular (e.g., increased oxidative stress and modified metabolites), physiological (e.g., feeding inhibition) and population (e.g., reproduction inhibition) levels. However, linking NM exposure and toxicity remains a challenge, partly due to the dynamic biotransformation along the food chain. Although NMs have been used to increase crop yield in agriculture, they can exert detrimental impacts on crop yield and modify crop quality, depending on NMs type, exposure dose, and crop species, with unknown consequences to human health via crop consumption. Given this information, we describe the challenges and opportunities in understanding the significance of NMs trophic transfer to develop more sustainable, effective and safer nanotechnology.

Dataset of rare earth elements distribution in soils and vegetables

This paper presents a comprehensive data set on rare earth elements (REE) and their distribution in soils and vegetables in an area where the soil background is enriched with these elements. The study examined REE distribution in six vegetables commonly grown in local residents' gardens, including fennel, garlic, lettuce, parsley, onion, and raddichio, and each plant was analyzed for REE composition in its root, stem, and leaf or bulb. In addition to total REE concentrations in soils and plants, the data set includes transfer factors and fractionation indices for REE in soils, as well as normalized curves. This dataset may be useful in the field of soil geochemistry and research on the uptake of lanthanides into plants and the food chain, as well as their potential effects on human health.

Assessment of Soil to Cassava Transfer Factor of Radionuclides in Ughelli North Local Government Area, Delta State, Nigeria

Background:
 This research was conducted to estimate the activity concentration level of 40K, 238U and 232Th in soil and cassava and determine the transfer factor from soil to cassava in Ughelli North, Delta State, Nigeria.
 Materials and Methods:
 These were examined using gamma spectrometry and considering a lead-shielded 3 x 3inch coaxial type Sodium Iodide Thallium doped detector.
 Results:
 The mean activity concentrations of 40K, 238U and 232Th are 45.49 ± 4.28 BqKg−1, 3.15 ± 0.77 BqKg−1 and 0.56 ± 0.06 BqKg−1 respectively in soil samples and 134.08 ± 11.59 BqKg−1, 3.89 ± 0.93 BqKg−1 and 0.81 ± 0.09 BqKg−1 correspondingly in cassava samples. The mean transfer factor of 40K, 238U and 232Th from soil to cassava are 3.44 ± 0.75, 1.94 ± 0.32 and 1.34 ± 0.54 respectively. Peak values of the TF were noted as 8.52 for 40K at U18, D18, 25.58 for 238U at U12, D12 and 5.71 for 232Th at U11, D11.
 Conclusion:
 The activity concentration of 40K, 238U and 232Th in the area are lower than the world average values. Consequently, it will not pose any radiological hazard if consumed. The high value of Transfer factor is attributed to the richness of the organic matter in the soil and may indicate high ability to transfer radionuclides in the soil to food crops but from the concentration information, these radionuclides present in the soil are low as well as annual effective doses. There is no radiological risk of ingestion.

The Effect of EDTA on the Ability to Absorb Different Concentrations of Nickel, Cadmium, and Lead in Soil by Corn Plants

Background & Aims: The use of resistant and widely used species such as corn in agriculture and industry can be an effective solution for the bioremediation of soil pollutants, including heavy elements. The current research aimed to investigate the effect of EDTA on the ability to absorb different concentrations of heavy metals in the soil of corn plants in 2019. Materials and Methods: This research was conducted as a three-factor pilot design at concentrations of 0, 50, and 100 mg/kg in the greenhouse. The samples were analyzed using an atomic absorption device. The laboratory pilot design was based on Taguchi’s algorithm. Finally, transfer factor (TF), bioconcentration factor (BCF), and bioaccumulation coefficient (BAC) were calculated. Results: The results showed that different organs (root, stem, and leaf) show different levels of bioaccumulation under the influence of variable factors in different concentrations of heavy elements (nickel, cadmium, and lead). Also, there is a significant difference between the measured amounts of heavy elements in different organs of the corn plant (P≤0.05). The average TF levels for elements at concentrations of 50 and 100 mg/kg were 0.79 and 1.66 for nickel, 0.82 and 0.78 for cadmium and 1.361, 1.378, and 1.387 for lead. Based on the results, with the increase in nickel concentration, the absorption level increased, and with the increase in cadmium concentration, the absorption level decreased. Conclusion: The results of this research showed that it is possible to use EDTA to increase the efficiency of corn plants in absorbing heavy elements of nickel, cadmium, and lead.

Perturbation and mechanism of non-antibiotic drug in regulating resistome and metabolome of anammox consortia: An overlooked and underrated cause of multiresistance

Given that antibiotic resistance genes (ARGs) become emerging pollutants, their accumulation and transfer caused by extensive use of antibiotic and non-antibiotic drugs raise concerns. In contrast, the impacts of non-antibiotic drugs have been largely overlooked, and their regulation mechanism in anammox system remains unclear. In this study, the single and combined effects of typical antibiotic (doxycycline) and non-antibiotic drug (propranolol) on anammox consortia were evaluated and compared from process performance, community succession, metabolic and gene regulation perspectives. Significant reduction in the nitrogen removal efficiency (49.0 ± 0.5%) was only observed in the anammox process stressed by propranolol and doxycycline, but it was reversible. Metabolome results showed that anammox consortia upregulated amino acid metabolism under propranolol stress, while the abundance of pyrimidine and purine metabolic pathways significantly increased under doxycycline and multidrug stress. Microorganisms adapted to these stresses by changing the utilization preference for metabolites. Metagenomic analyses indicated that doxycycline and propranolol induced the high frequency of gene transfer through increasing oxidative stress level, membrane permeability, pili and efflux pumps. Significant correlations between ARGs and mobile genetic elements (MGEs), especially intI1, demonstrated the conjugative transfer of ARGs. Furthermore, structural equation models showed that microbial community, bacterial metabolism, MGEs, reactive oxygen species (ROS) and corresponding SOS response were key driving factors for ARGs transfer in the anammox systems. These findings fill the gap in the effect of non-antibiotic drugs on anammox system and their regulation mechanism, which further provides a theoretical guidance for anammox-based process to treat multidrug-containing wastewater.

Effectiveness of a tubular heat exchanger and a novel perforated rectangular flow-deflector type baffle plate with opposing orientation

Purpose The purpose of this experimental research was to examine a novel axial heat exchanger featuring swirling air movement over heated tubes. This apparatus is designed with perforated circular baffle plates complemented by rectangular air deflectors operating at different inclination angles. The tubes were arranged in a consistent layout parallel to the longitudinal airflow. The deflector’s heightened air-side turbulence initiates the frenzied motion, escalating the surface heat transfer rate. Design/methodology/approach The tubes maintained a constant heat flux condition over the surface. In each baffle plate, eight deflectors with identical inclination angles were devised in a reverse position, forming a rotation of air inside a circular duct that held tubes (carrying hot water) which elevated air-side turbulence, thereby enhancing the rate of heat transference on the surface. The baffle plates were equally situated from each other at changing pitch ratios. The Reynolds quantity was preserved in the scope of 16,000–30,000. The performance of the heat exchanger considering pitch ratios and inclination angles was examined. Findings The research indicates that when examined under similar conditions, an exchanger with a deflector baffle plate shows a strong dependence on the pitch ratio and inclination angle with a mean rise of 0.19 times in thermal enhancement factor at an inclination angle of 30° and a pitch ratio of 1.2 contrasted with an exchanger with segmental baffle plates. Originality/value The result shows the dependence of pitch ratio, Reynolds number and inclination on the heat transfer and friction factor rate.

Evaluation of the operating conditions of the Stirling engine heat exchangers

The development of modern energy is inextricably linked with the further improvement of heat engines, which are still the only primary sources of mechanical energy on an industrial scale. Given the existing environmental problems, Stirling engines can be a good alternative to internal combustion engines and turbines. Of the many problems of creating such a sufficiently powerful and economical engine, it is customary to consider three main ones: 1) efficient transfer of large heat fluxes in the heater, regenerator and refrigerator; 2) creation of reliable and durable seals to hold the working fluid in the cylinder; 3) ensuring minimal friction in bearings and seals. And yet, of the three listed problems, the first should be given more attention, first of all, due to the unique conditions associated with the continuously changing thermo and mechanical loads. The instability of the loads is further complicated by the sharply different heat transfer coefficient on the external and internal heat transfer surfaces. That is, there are factors that contradict the requirements for the size of the heat transfer surface, the friction resistance of the working medium and the dead volume of the engine as a whole. In this regard, it is of interest to search for possible ways to reduce the effect of negative factors of non-stationary heat transfer in the calculation of heat exchangers. The current lack of suitable theoretical methods of calculation forces the use of semi-empirical methods. The aim of the paper is to assess the significance of the unique, characteristic of Stirling engines, the negative phenomenon of the delay in the flow of the working fluid in heat exchangers. For this purpose, a real kinematic diagram of the movement of the engine pistons with a rhombic drive by R. Meyer, created using the design program, is used. The analogue is the 4–235 type real engine of the Philips Company. In the calculations, a step-by-step procedure for calculating the time-varying parameters of the working fluid is used. The need for such a solution is due to the fact that in the rhombic drive of R. Meyer, the pistons movement and the change in the displaced volumes complexly depend on the angle of rotation of the engine shaft. In addition, the exact value of the real change in volume is possible only when the terms of the analytic equation of volume change under consideration are decomposed into a Fourier series.

Computational investigation of dyes-sensitized solar cells containing various π-bridges achieving high photovoltaic performance with triazatruxene-based dyes

In this work, three organic triazatruxene-based dyes, containing cyanoacrylic acid as acceptor and different five-membered rings in the π-bridge, such as 5,5-Dimethylcyclopentadiene for TAT-C, furan for TAT-O and 1,1-dimethyl-1H-silole for TAT-Si, were theoretically investigated by density functional theory (DFT) and time-dependent (TD-DFT) for application in dye-sensitized solar cells (DSSCs). Geometry, electrical structure, intramolecular charge transfer (ICT), reorganization energy, light-harvesting efficiency (LHE), and other microscopic factors were examined to determine how the π-bridges affected short-circuit current (JSC) and open circuit voltage (VOC). Our theoretical findings show that dye TAT-C exhibits remarkably better light-harvesting ability in the near-infrared region, with a broader LHE curve and a greater JSC. In parallel, all three dyes have a fast interfacial electron transfer (IET) rate. Furthermore, based on the overall evaluation model, we estimate the power conversion efficiency (PCE) for the TAT-C dye is 27.23 % (JSC = 37.30 mA.cm-2, VOC=0.838 V), followed by the dye TAT-O (PCE = 25.80 %, JSC=34.19 mA.cm-2, VOC= 0.868 V), and finally, the TAT-Si (PCE = 24.12 %, JSC=30.80 mA.cm-2, VOC= 0.898 V).Consequently, the principal objective of this investigation is to contribute a theoretical framework for creating and making novel organic dyes for promising DSSC applications.

Thermodynamic flow of radiative induced magneto modified Maxwell Sutterby fluid model at stretching sheet/cylinder

A steady flow of Maxwell Sutterby fluid is considered over a stretchable cylinder. The magnetic Reynolds number is considered very high and induced magnetic and electric fields are applied on the fluid flow. Joule heating and radiation impacts are studied under the temperature-dependent properties of the liquid. Having the above assumptions, the mathematical model has been evolving via differential equations. The differential equations are renovated in the dimensionless form of ordinary differential equations using the appropriate transformations. The numerical results have been developed employing numerical techniques on the ordinary differential equations. The impact of involving physical factors on velocity, induced magneto hydrodynamic, and temperature function is debated in graphical and tabular form. The velocity profile is boosted by thicker momentum boundary layers, which are caused by higher values of the magnetic field factor. So, the fluid flow becomes higher velocity due to enlarging values of the magnetic field factor. Heat transfer factor and friction at surface factor boosted up for increment of {gamma }_{0} (Magnetic field factor). The {gamma }_{0}(Magnetic field factor) is larger which better-quality of heat transfer at surface and also offered the results of friction factor boosting up in both cases of stretching sheet/cylinder. The {lambda }_{0}(Magnetic Prandtl number) increased which provided better-quality of heat transfer at surface.

Rational design process for gas turbine exhaust to supercritical CO2 waste heat recovery heat exchanger using topology optimization

Advances in additive manufacturing (AM) technologies and topology optimization methodologies are enabling sophisticated novel designs for heat exchanger performance. These tools have been demonstrated for development of high-performance heat sinks considering local or component-level performance factors (e.g., heat transfer per volume). To leverage such capabilities in larger-scale energy systems, structured design methodologies are needed that consider system-level factors, such as production cost, cycle-level efficiency, and operational constraints. This study seeks to develop and assess a rational approach for designing thermo-economically optimal heat exchangers for such applications. The methodology is illustrated through development of the Primary Heat Exchanger (PHX) for a supercritical carbon dioxide (sCO2) power cycle recovering exhaust heat from a 6 MW-scale natural gas turbine. The proposed approach begins with a detailed thermodynamic cycle model, which is then extended to account for techno-economics. Next, an optimal PHX heat transfer capacity target is identified, and a high-level geometry is selected based on operating characteristics. This geometry is then divided into repeating 2D prismatic unit cells, for which topology optimization is applied to identify high-performance heat transfer geometries. A key aspect of this process is that the unit cell geometries are optimized using the total PHX mass as the objective function, which represents a surrogate for production cost. This leads to distinct designs compared with approaches that optimize local heat transfer and flow resistance factors. A second topology-optimized design is developed using a representative local thermal-fluid performance objective function and is found to require 1.6× the mass of the design generated with the system-level techno-economic objective for the same unit cell size. Conventional-type PHX designs with simple longitudinally finned tubes are developed for comparison, and are found to require total masses 1.5× or greater than the design obtained with the proposed process. Integrating this approach with detailed additive manufacturing costing models and experimentally validated fabrication constraints can yield a streamlined workflow for HX design for future energy systems.

Microstructural study of apple slices during hot air‐explosion puffing drying

AbstractIn order to reveal the change laws of microstructure in apple slices during hot air‐explosion puffing drying, the microstructure images and parameters of apple slices under different drying conditions were obtained by using paraffin sectioning, microscopic observation, and image processing techniques with apples as raw material and CO2 as drying medium. Subsequently, the changes in internal cell and pore structure of dried apple slices were analyzed, as well as the relationship between micro‐parameters of apple slices and macro‐measurement indicators was further obtained. Results indicated that the overall cross‐sectional area, cross‐sectional perimeter, equivalent diameter, and porosity of cells increased by explosion puffing drying, while the cell roundness and wall roughness factors changed relatively little. Meanwhile, macro–micro parameters of expanded apples were fitted and analyzed. Then, the obtained mathematical model showed a nonlinear correlation as experimental and predicted results exhibited good agreement, with determination coefficients R2 more significant than 0.8, which could better expect the macro–microparameters to change in the drying process. The results of this research could provide an essential reference for exploring the change laws of tissue microstructure parameters in apples dried by hot air‐explosion puffing drying, with expansion and rehydration ratios under different experimental conditions, as well as optimizing the puffing drying process and designing corresponding drying equipment.Practical ApplicationsFresh apples have high moisture content and are not easy to store, so drying is usually used to reduce the moisture content to extend shelf time and increase economic benefits. For the drying process of fruit and vegetable products, scholars mainly focused on the influence of microstructure parameters on moisture migration, drying rate, heat and mass transfer and other factors, but did not give a quantitative description of how microstructure parameters affect macroscopic parameters. In this article, the relationship between microstructural changes and macroscopic indicators was investigated by taking puffed apple slices as an example. Research could provide an essential reference for exploring the change laws of tissue microstructure parameters in apples dried by hot air‐explosion puffing drying, with expansion and rehydration ratios under different experimental conditions, as well as optimizing the puffing drying process and designing corresponding drying equipment.

Contour integration for the view factor calculation between two rectangular surfaces

AbstractThe calculation of the view factor is an important consideration in radiative heat transfer analysis. Thermal engineering requires the view factor calculations between complex geometries containing parallel and inclined surfaces. There is currently no analytic formula available for this, so the summation rule (SR) must be used. However, when complex geometries are analyzed, processing SR becomes a very intensive task. Therefore, the present study aims to exploit vector calculus to develop a formula for calculating the view factors for radiative heat transfer from any two rectangular oblique or parallel surfaces. The exact solution obtained by means of the contour integration was compared with the numerical integration of the quadruple integral using the multiple Simpson's rule 1/3 with five intervals (MSR) and the summation rule via the Hamilton–Morgan solution (HMS). The lack of similar precedents in the literature reinforces the scientific and practical nature of the proposed method.

Numerical Study on Enhanced Heat Transfer of Downhole Slotted-Type Heaters for In Situ Oil Shale Exploitation.

In order to improve the flow state of the heater shell side and enhance the performance evaluation of the heater, this paper proposes a perforated plate-type heater model. Based on Fluent, numerical studies are conducted on the heat transfer performance and shell-side fluid flow characteristics of a perforated plate-type heater. The variations of the heat transfer factor Nu, friction factor f, and evaluation parameter Nu/f1/3 are analyzed for different helix angles β and ratios of the long and short semiaxes of the circular holes on the heating plate under different Reynolds numbers Re. The results reveal that under the same shell-side Reynolds number Re, the heat transfer factor Nu shows an increasing trend with the increase in the proportion of the helix angle β. The heat transfer factor Nu for the heating plate with the hole shape ratio a/b = 1 does not exhibit significant improvement compared to hole shape ratios a/b = 0.8 and a/b = 0.6, but it increases by 4.87 to 7.07% compared to the hole shape ratio a/b = 0.4 in the perforated plate-type heater. On the other hand, the friction factor f decreases as the helix angle β and the ratio of hole shapes on the heating plate increase. The lowest friction factor f is observed for the helix angle β of 25° and the hole shape ratio a/b = 1 in the perforated plate-type heater. When the helix angle β is 25° and the hole shape ratio is a/b = 1, the evaluation parameter Nu/f1/3 reaches its highest value, indicating the optimal overall performance of the perforated plate-type heater.

Essential role of multi-element data in interpreting elevated element concentrations in areas impacted by both natural and anthropogenic influences.

This article presents a detailed analysis of a dataset consisting of 27 elements found in soils, soil eluates, and vegetables from private gardens in a region with a long history of coal mining and burning. With coal being one of the world's most significant energy sources, and previous studies highlighting elevated element levels in vegetables from this region, the objective of this study was to identify the factors that impact soil geochemistry and metal(loid) uptake in plants. Total major and trace element concentrations were analyzed in soils, soil eluates and vegetables by high resolution inductively coupled plasma mass spectrometry. The vegetable samples included six species: fennel, garlic, lettuce, parsley, onion, and radicchio. Each plant was divided into roots, stems, leaves, and/or bulbs and analyzed separately. In addition, the soil pollution status, bioavailable fractions and transfer factors from soil and soil eluates to different plant parts were determined. The comprehensive dataset revealed that, apart from the substrate enriched with various elements (Al, As, Co, Cr, Mo, Ni, Pb, Sb, Sn, Ti, U, V, and Zn), other anthropogenic factors such as the legacy of coal mining and combustion activities, associated industries in the area, transport, and agricultural practices, also influence the elevated element concentrations (Cd, Cu, Fe, Mn, and Se) in locally grown vegetables. The transfer factors based on element concentrations in aqueous soil eluates and element bioavailable fractions confirmed to be an effective tool for evaluating metal uptake in plants, emphazising to some extent the effects of plant species and revealing unique patterns for each pollution source within its environmental context (e.g., Cd, Mo, S, and Se in this case). The study highlights the crucial importance of utilizing comprehensive datasets that encompass a multitude of factors when interpreting the impacts of element uptake in edible plants.

Heat transfer and thermal efficiency enhancement using twisted tapes in sinusoidal wavy tubes with nanofluids: a numerical study

PurposeThe purpose of the study is to propose a novel implementation of twisted tape in sinusoidal wavy-walled tubes to enhance the rate of heat transfer without compromising thermal efficiency. The study numerically investigates the fluid flow characteristics and analyzes the effect of different geometrical configurations, including wall wave amplitude, tape twist angles and nanoparticle volume fractions, on heat transfer improvement and performance factor.Design/methodology/approachThis problem is numerically investigated using computational fluid dynamics, and the method is the finite volume method. A two-phase mixture model is used for nanofluid modeling.FindingsThe study investigated the effect of wall waviness, twisted tape, and nanoparticles on forced convective heat transfer and friction factor behavior in laminar pipe flow in three different Reynolds number regimes. The results showed that implementing twisted tape in wavy tubes significantly increased the rate of heat transfer and the performance factor, with the best twist ratio between 90 and 180°. Adding nanoparticles also enhanced heat transfer and performance factor, but to a lesser extent than wavy wall-twisted tape combinations. The study suggests selecting a proper combination of wavy wall and twisted tape at each Reynolds number to achieve an optimum solution.Originality/valueTo the best of the authors’ knowledge, the implementation of the selected passive methods in sinusoidal wavy tubes has not been studied before, and no previous studies have taken into account such a mix of heat transfer improvement techniques.

Grassland restoration with plant material transfer – bridging the knowledge gap between science and practice

In Central Europe, species-rich grasslands have strongly diminished over the last century. The transfer of seed-containing plant material from donor sites with a desired species composition to restoration sites is a well-established method to restore species-rich grasslands. Despite a plethora of available literature, restoration projects with plant material transfer often fail or do not reach the planned goals. Practitioners’ knowledge is a highly important but underexplored source of information on factors deciding about success of restoration projects. At the same time, it is unclear to which degree scientific findings on success factors are known and considered by practitioners, and if science actually investigates the most relevant aspects for practice. To bridge the gap between practitioners’ knowledge and restoration science, we conducted semi-structured interviews with 33 practitioners involved in plant material transfer projects. Using qualitative content analysis, we analysed the interviews for success factors, and compared them to success factors of plant material transfer as investigated in peer-reviewed European studies on the method. We found that science investigated a broad range of practical, technical, and ecological success factors, and that practitioners were generally well aware of this evidence, trying to make use of the knowledge. Failure of practitioners’ projects often resulted from organizational obstacles, which were founded in lacking trust and low experience levels among the involved people. We advise unexperienced practitioners to involve more experienced practitioners in their projects if possible. Furthermore, we emphasize the importance of identifying relevant local stakeholders and building trustful regional networks. Interdisciplinary scientific studies considering success factors beyond practical and ecological aspects are required to support widespread effective grassland restoration with plant material transfer.

Influence of the expansive sites distribution on alkali-silica reaction expansion under applied stress: Crack orientation as a key factor for expansion transfer

The influence of the expansive site distribution of the alkali-silica reaction (ASR) on the expansion behavior under applied stresses was numerically investigated to verify the mechanical factor of expansion transfer. In the analysis, the aggregate and mortar phases were individually modelled by mesoscale discrete analysis. To reproduce expansive site distribution and time-dependent behavior, expansive phase model, pressure development model, and creep model were developed. As a result, expansion transfer was observed for the model based on the reaction rim assumption and the crack effect model under applied stress of less than 10 MPa. A detailed numerical investigation identified that the cracks under applied stress in the reaction rim model are modified more easily than those in the gel pocket model, despite crack generation being inhibited. Consequently, expansion transfer was found to be significantly influenced by the crack orientation because of the mechanical interactions at the expansive sites under applied stress.

Aggregated transfer factors of fresh Cs and Sr pollution to various vegetables from six common European soils – mesocosm experiment

Aggregated transfer factors (Tag) were identified for three common vegetables grown in six common European soils freshly contaminated by 134Cs and 85Sr. The experiment was carried out as a mesocosm experiment in pots with an average soil weight of 15.8 kg per pot. The vegetables were grown one after the other during one vegetation season, in the order lettuce, onion, and radish (the order usually applied in private gardens and small farms). Despite the fact that lettuce was grown in the most contaminated soil, it had the lowest Tag (in m2/kg) of both radionuclides (3.6E-4 for Cs, 2.0E-2 for Sr), while onion had 6.4E-3 for Cs and 3.2E-2 for Sr and radish had 1.9E-3 for Cs and 8.1E-2 for Sr. Potassium supply did not show any statistically significant effect on Cs Tag; there was a significant impact of K on the decrease in Sr Tag.The experiments indicated that Tag is more affected by plant species than by soil type; therefore, selection of plants with a lower capacity to uptake radionuclides may be an important measure to reduce food contamination and thus minimize the committed effective dose.

In silico and in vitro potentials of crocin and amphotericin B on Leishmania major: Multiple synergistic mechanisms of actions.

A significant barrier to optimal antileishmanial treatment is low efficacy and the emergence of drug resistance. Multiple approaches were used to monitor and assess crocin (a central component of saffron) mixed with amphotericin B (AmpB) potential in silico and in vitro consequences. The binding behavior of crocin and iNOS was the purpose of molecular docking. The results showed that crocin coupled with AmpB demonstrated a safe combination, extremely antileishmanial, suppressed Leishmania arginase absorption, and increased parasite death. This natural flower component is a robust antioxidant, significantly promoting the expression of the Th1-connected cytokines (IL12p40, IFN-γ, and TNF- α), iNOS, and transcription factors (Elk-1, c-Fos, and STAT-1). In comparison, the expression of the Th2-associated phenotypes (IL-10, IL-4, and TGF-β) was significantly reduced. The leishmanicidal effect of this combination was also mediated through programmed cell death (PCD), as confirmed by the manifestation of phosphatidylserine and cell cycle detention at the sub-GO/G1 phase. In conclusion, crocin with AmpB synergistically exerted in vitro antileishmanial action, generated nitric oxide and reactive oxygen species, modulated Th1, and Th2 phenotypes and transfer factors, enhanced PCD profile and arrested the cell cycle of Leishmania major promastigotes. The main action of crocin and AmpB involved wide-ranging mechanistic insights for conducting other clinical settings as promising drug candidates for cutaneous leishmaniasis. Therefore, this combination could be esteemed as a basis for a potential bioactive component and a logical source for leishmanicidal drug development against CL in future advanced clinical settings.