bluuebunny/crossref_metadata_2025 huggingface dataset:
The prevalence and associated factors of metabolic syndrome in Chinese aging population
Authors: Ge Huisheng , Yang Zihui , Li Xiaoyu , Liu Dandan , Li Yan , Pan Yue , Luo Dan , Wu Xixi
Published: November 2020

Metabolic syndrome (MetS) is hitting high notes in the aging society in China. However, the prevalence and associated factors in Chinese aging population lack clarity to some extent. In the present study, we projected to inquire into the prevalence of MetS and its associated factors by analyzing datasets downloaded from the China Health and Retirement Longitudinal Study (CHARLS). Data comprising age, gender, socioeconomic status, lifestyle and health behaviors as well as blood biomarkers were subjected to descriptive statistics followed by univariate logistic regression and multivariate logistic regression. The overall prevalence of MetS was 33.38% (95% CI 32.42–34.34%). With age augments, prevalence increased during 40–70 years, while declined in participants aged 70 years above. Females had 2.94 times of risks (95% CI 2.55–3.39, P < 0.001). Marital status and alcohol consumption contributed nothing to the suffering of MetS. Participants with GDP per capita > 10,000 RMB and a non-agricultural hukou sustained higher risks than other participants (P < 0.05). Participants under education of middle school suffered 1.16 times of risks than other level of education (95% CI 1.01–1.34, P < 0.05). Smokers, participants with high low-density lipoprotein (LDL) or hyperuricemia or high glycosylated hemoglobin HbA1c sustained increased risks (P < 0.05). In Chinese aging population, with the augment of age, the prevalence ascended in men, while descended in women and was interfered by socioeconomic status, lifestyle and health behaviors as well as blood biomarkers, but not marital status and alcohol consumption.
Arctic riparian shrub expansion indicates a shift from streams gaining water to those that lose flow
Authors: Liljedahl Anna K. , Timling Ina , Frost Gerald V. , Daanen Ronald P.
Published: November 2020

Shrub expansion has been observed across the Arctic in recent decades along with warming air temperatures, but tundra shrub expansion has been most pronounced in protected landscape positions such as floodplains, streambanks, water tracks, and gullies. Here we show through field measurements and laboratory analyses how stream hydrology, permafrost, and soil microbial communities differed between streams in late summer with and without tall shrubs. Our goal was to assess the causes and consequences of tall shrub expansion in Arctic riparian ecosystems. Our results from Toolik Alaska, show greater canopy height and density, and distinctive plant and soil microbial communities along stream sections that lose water into unfrozen ground (talik) compared to gaining sections underlain by shallow permafrost. Leaf Area Index is linearly related to the change in streamflow per unit stream length, with the densest canopies coinciding with increasingly losing stream sections. Considering climate change and the circumpolar scale of riparian shrub expansion, we suggest that permafrost thaw and the resulting talik formation and shift in streamflow regime are occurring across the Low Arctic.
Design and Synthesis of Peptides for Developing Biomaterials
Authors: Guler Mustafa O. , Garifullin Ruslan
Published: November 2020

In this chapter, an intelligent design of synthetic peptides and their implementation in biomaterials is discussed. Potential biocompatibility, bioactivity and availability through well-established synthetic methods indisputably make peptides one of the indispensable tools in developing new materials for biomaterials engineering. Synthetic peptides are used to display bioactivity by various approaches, such as supramolecular self-assembly forming biomimetic systems, preparation of peptide-based polymeric scaffolds, as well as post-synthetic immobilization on polymeric scaffolds. The design of the peptides is the most crucial part, as it defines functionality and the mode of bioactivity of the final product. A variety of design principles and fabrication of functional materials in peptide biomaterials are presented in detail in this chapter.
Designing Enzyme-responsive Biomaterials
Authors: Pashuck E. Thomas
Published: November 2020

Enzymes are a class of protein that catalyze a wide range of chemical reactions, including the cleavage of specific peptide bonds. They are expressed in all cell types, play vital roles in tissue development and homeostasis, and in many diseases, such as cancer. Enzymatic activity is tightly controlled through the use of inactive pro-enzymes, endogenous inhibitors and spatial localization. Since the presence of specific enzymes is often correlated with biological processes, and these proteins can directly modify biomolecules, they are an ideal biological input for cell-responsive biomaterials. These materials include both natural and synthetic polymers, cross-linked hydrogels and self-assembled peptide nanostructures. Within these systems enzymatic activity has been used to induce biodegradation, release therapeutic agents and for disease diagnosis. As technological advancements increase our ability to quantify the expression and nanoscale organization of proteins in cells and tissues, as well as the synthesis of increasingly complex and well-defined biomaterials, enzyme-responsive biomaterials are poised to play vital roles in the future of biomedicine.
Self-assembled Peptide Nanostructures for Antibacterial Applications
Authors: Shi Y. , Wareham D. W. , Phee L. M. , Azevedo H. S.
Published: November 2020

Antimicrobial-resistant (AMR) bacteria are unequivocally identified as the most important global threat to human, animal and plant health in the 21st century. In humans, AMR is predicted to outstrip cancer, cardiovascular, neurological and metabolic disorders as the most important cause of death by 2050. Tackling AMR requires multidisciplinary approaches, including the repurposing and revitalization of older drugs, development of new compounds and novel strategies to deliver them for treating and preventing the spread of multidrug-resistant bacterial infections. In this chapter, research exploiting supramolecular peptide nanotechnology for the development of antimicrobial nanomaterials is summarized, with particular emphasis on the role of molecular design and self-assembly in harnessing antimicrobial activities.
New Functions Emerging from Peptide–DNA Materials
Authors: Daly Margaret L. , Klawa Stephen J. , Freeman Ronit
Published: November 2020

A new class of hybrid biomaterials has recently evolved from the combination of peptides and DNA. In this chapter, we survey the unique systems and properties made possible by merging the bioactivity and mechanical properties of peptides with the programmability and reversibility of DNA. We explore peptide–DNA probes and switches, peptide-decorated DNA scaffolds and DNA-decorated peptide structures. We illustrate the rich variety of architectures made from the interplay of orthogonal peptide and DNA assembly motifs in cooperative assemblies, with examples of peptide-directed or DNA-directed hybrid structures. We present systems with hierarchical organization and dynamic assembly, presenting fascinating emergent properties made possible by peptide–DNA combinations. Finally, we discuss the future possibilities and open challenges presented by this intriguing class of hybrid biomaterials.
Three-dimensional nitrogen-doped graphene-based metal-free electrochemical sensors for simultaneous determination of ascorbic acid, dopamine, uric acid, and acetaminophen
Authors: Jiang Jingjing , Ding Dong , Wang Jing , Lin Xinyi , Diao Guowang
Published: November 2020

Three-dimensional nitrogen-doped graphene-dependent metal-free electrochemical sensors were developed for simultaneous determination of ascorbic acid, dopamine, uric acid, and acetaminophen.
Point-of-care testing (POCT) of patients with a high concentration of uric acid by using alginate hydrogel microspheres embedded with CdZnTeS QDs and urate oxidase (Alg@QDs-UOx MSs)
Authors: Lu Fan , Yang Yeling , Liu Yucheng , Wang Fubing , Ji Xinghu , He Zhike
Published: November 2020

A more convenient method for POCT of patients with a high concentration of uric acid by using Alg@QDs-UOx MSs is developed.
A rolling circle amplification based platform for ultrasensitive detection of heparin
Authors: Lin Lei , Li Bingzhi , Han Xiaorui , Zhang Fuming , Zhang Xing , Linhardt Robert J.
Published: November 2020

A dumbbell probe-aided RCA sensing platform for ultrasensitive heparin analysis.
Design of experiments a powerful tool to improve the selectivity of copper antimony sulfide nanoparticles synthesis
Authors: Pretto Tatiane , Baum Fábio , Fernandes Souza Andrade Gustavo , Leite Santos Marcos José
Published: November 2020

Design of experiments to find the main factors governing phase compositions and nanoparticle size.
Myoglobin molecule charging in electrolyte solutions
Authors: Batys Piotr , Nattich-Rak Małgorzata , Adamczyk Zbigniew
Published: November 2020

The compensated charge of myoglobin molecule in electrolyte solution is considerably smaller than the nominal charge.
Conformational dynamics of aqueous hydrogen peroxide from first principles molecular dynamics simulations
Authors: Biswas Aritri , Mallik Bhabani S.
Published: November 2020

We performed first principles molecular dynamics simulations of a relatively dilute aqueous hydrogen peroxide (H2O2) solution to examine its structural alterations and relevant dynamics upon solvation.
Correction: Electric field induced band tuning, optical and thermoelectric responses in tetragonal germanene: a theoretical approach
Authors: Ghosal Supriya , Bandyopadhyay Arka , Jana Debnarayan
Published: November 2020

Correction for ‘Electric field induced band tuning, optical and thermoelectric responses in tetragonal germanene: a theoretical approach’ by Supriya Ghosal et al., Phys. Chem. Chem. Phys., 2020, 22, 19957–19968, DOI: 10.1039/D0CP03892J.
Quantification of water transport in a CO2 electrolyzer
Authors: Wheeler Danika G. , Mowbray Benjamin A. W. , Reyes Angelica , Habibzadeh Faezeh , He Jingfu , Berlinguette Curtis P.
Published: November 2020

The distribution and flow of water in a CO2 electrolyzer can be defined at variable operating conditions using a 3D model coupled with an analytical electrolyzer.
Multi-channel photodissociation and XUV-induced charge transfer dynamics in strong-field-ionized methyl iodide studied with time-resolved recoil-frame covariance imaging
Authors: Allum Felix , Anders Nils , Brouard Mark , Bucksbaum Philip , Burt Michael , Downes-Ward Briony , Grundmann Sven , Harries James , Ishimura Yudai , Iwayama Hiroshi , Kaiser Leon , Kukk Edwin , Lee Jason , Liu Xiaojing , Minns Russell S. , Nagaya Kiyonobu , Niozu Akinobu , Niskanen Johannes , O’Neal Jordan , Owada Shigeki , Pickering James , Rolles Daniel , Rudenko Artem , Saito Shu , Ueda Kiyoshi , Vallance Claire , Werby Nicholas , Woodhouse Joanne , You Daehyun , Ziaee Farzaneh , Driver Taran , Forbes Ruaridh
Published: November 2020

The photodissociation dynamics of strong-field ionized methyl iodide were probed using intense extreme ultraviolet (XUV) radiation produced by the SPring-8 Angstrom Compact free electron LAser.
On the improvement of properties of bioplastic composites derived from wasted cottonseed protein by rational cross-linking and natural fiber reinforcement
Authors: Yue Hangbo , Zheng Yuru , Zheng Pingxuan , Guo Jianwei , Fernández-Blázquez Juan P. , Clark James H. , Cui Yingde
Published: November 2020

Biocomposites made entirely by renewable biomass demonstrate excellent mechanical, hydrophobic and thermal properties thanks to rational cross-linking and fiber reinforcement.
Carbon dioxide derived carbonized polymer dots for multicolor light-emitting diodes
Authors: Liu Bin , Chu Bo , Wang Ya-Ling , Hu Lan-Fang , Hu Shengliang , Zhang Xing-Hong
Published: November 2020

Immobilization of carbon dioxide into fluorescent CPDs is achieved, and multiple-color LEDs are fabricated using the CPDs as single phosphors.
Bamboo-flour-filled cost-effective poly(ε-caprolactone) biocomposites: a potential contender for flexible cryo-packaging applications
Authors: Bhagabati Purabi , Das Deepshikha , Katiyar Vimal
Published: November 2020

Improvement of the physico-mechanical properties in melt mixed bamboo-root flour reinforced biodegradable poly(ε-caprolactone) biocomposites is demonstrated, aimed at flexible cryo-packaging applications.
Flame spheroidisation of dense and porous Ca2Fe2O5 microspheres
Authors: Molinar Díaz Jesús , Samad Sabrin Abdus , Steer Elisabeth , Neate Nigel , Constantin Hannah , Islam Md Towhidul , Brown Paul D , Ahmed Ifty
Published: November 2020

Compositionally uniform magnetic Ca2Fe2O5 (srebrodolskite) microspheres created via a rapid, single-stage flame spheroidisation (FS) process using magnetite and carbonate based porogen (1 : 1 Fe3O4 : CaCO3) feedstock powders, are described.
Polymorphism in metal halide perovskites
Authors: Alaei Aida , Circelli Abigail , Yuan Yihang , Yang Yi , Lee Stephanie S.
Published: November 2020

Polymorphism in metal halide perovskites follow similar temperature- and pressure-dependent trends across compositions and can significantly influence the optoelectronic performance of these materials.
Oxygen evolution reaction activity and underlying mechanism of perovskite electrocatalysts at different pH
Authors: Kim Bae-Jung , Fabbri Emiliana , Borlaf Mario , Abbott Daniel F. , Castelli Ivano E. , Nachtegaal Maarten , Graule Thomas , Schmidt Thomas J.
Published: November 2020

The members of the perovskite oxide family have been vastly explored for their potential as active electrocatalysts for an efficient anodic reaction (i.e. the oxygen evolution reaction, OER) of the water splitting process.
Lanthanum chloride causes blood–brain barrier disruption through intracellular calcium-mediated RhoA/Rho kinase signaling and myosin light chain kinase
Authors: Wu Jie , Yang Jinghua , Yu Miao , Sun Wenchang , Han Yarao , Lu Xiaobo , Jin Cuihong , Wu Shengwen , Cai Yuan
Published: November 2020

Rare earth elements (REEs) have caused bioaccumulation and adverse health effects attributed to extensive application. The penetrability of REEs across the blood–brain barrier (BBB) contributes to their neurotoxicity process, but potential mechanisms affecting BBB integrity are still obscure. The present study was designed to investigate the effects of lanthanum on BBB adheren junctions and the actin cytoskeleton in vitro using bEnd.3 cells. After lanthanum chloride (LaCl3, 0.125, 0.25 and 0.5 mM) treatment, cytotoxicity against bEnd.3 cells was observed accompanied by increased intracellular Ca2+. Higher paracellular permeability presented as decreased TEER (transendothelial electrical resistance) and increased HRP (horse radish peroxidase) permeation, and simultaneously reduced VE-cadherin expression and F-actin stress fiber formation caused by LaCl3 were reversed by inhibition of ROCK (Rho-kinase) and MLCK (myosin light chain kinase) using inhibitor Y27632 (10 μM) and ML-7 (10 μM). Moreover, chelating overloaded intracellular Ca2+ by BAPTA-AM (25 μM) remarkably abrogated RhoA/ROCK and MLCK activation and downstream phosphorylation of MYPT1 (myosin phosphatase target subunit 1) and MLC2 (myosin light chain 2), therefore alleviating LaCl3-induced BBB disruption and dysfunction. In conclusion, this study indicated that lanthanum caused endothelial barrier hyperpermeability accompanied by loss of VE-cadherin and rearrangement of the actin cytoskeleton though intracellular Ca2+-mediated RhoA/ROCK and MLCK pathways.
The green one-step electrodeposition of oxygen-functionalized porous g-C3N4 decorated with Fe3O4 nanoparticles onto Ni-foam as a binder-free outstanding material for supercapacitors
Authors: Song Qichao , Yang Chunguang , Yu Chun-Ming
Published: November 2020

In this study, the binder-free high-performance nanocomposite of Fe3O4/oxygen-functionalized g-C3N4 was fabricated through a one-pot electrophoretic-electrochemical (EP-EC) process.
Nanoparticle cages as microreactors for producing acrolein from glycerol in the liquid phase
Authors: Zhang Jiaojiao , Zhao Jie , Cui Xiaojing , Hou Xianglin , Su Lijuan , Wang Hongliang , Deng Tiansheng
Published: November 2020

A highly viscous oil phase forms a smaller Pickering emulsion, increasing the acrolein yield from glycerol by intensified mass transfer.
Building trans-bicyclo[4.4.0]decanes/decenes in complex multifunctional frameworks: the case for antibiotic development
Authors: Zhang Wanli , Kaplan Anna R. , Davison Emma K. , Freeman Jared L. , Brimble Margaret A. , Wuest William M.
Published: November 2020

This highlight reviews the efficient synthesis of trans-bicyclo[4.4.0]decane/decene-containing natural products, providing handles for selectively constructing next generation therapeutics for a post-antibiotic era.
Reversible electrodeposition and stripping of magnesium from solvate ionic liquid–tetrabutylammonium chloride mixtures
Authors: Geysens Pieter , Fransaer Jan , Binnemans Koen
Published: November 2020

Mixtures of magnesium-containing solvate ionic liquids and tetra-n-butylammonium chloride have low volatility and can be used as innovative electrolytes for reversible deposition of magnesium metal at high current density.
Bentonite clay barriers in nuclear waste repositories
Authors: Laloui Lyesse , Ferrari Alessio , Bosch Jose A.
Published: November 2020

Deep disposal of high-level radioactive waste is the preferred solution worldwide for the long-term disposal of nuclear waste. This concept involves a series of geological and engineered barriers that provide isolation of the waste from the biosphere. Most designs involve bentonite clays as seals in different forms. During the operation of the repository, the bentonite will be subjected to a series of complex thermo-hydro-mechanical phenomena that will interact with each other. Predicting the long-term safety of geological repositories thus involve a rigorous analysis of these multi-physical processes. This paper presents a review of recent numerical approaches and analyses that have aimed to improve the understanding of processes that will take place in clay barriers over the lifetime of nuclear waste repositories. The understanding of bentonite behavior from laboratory experiments under relevant conditions is analyzed. Constitutive models that attempt to predict such behavior are presented, focusing on the stress-strain model ACMEG-TS. These models are implemented in the finite element code Lagamine which allows for the study of real scale tests. Two application cases are presented: the performance of a clay barrier according to the Swiss design, and a model of the FEEBX in situ experiment, which was modelled after a real repository under natural conditions. Overall, the relevant processes are well captured quantitatively by the models, allowing for the establishment of sound basis for future prediction and long-term design of the final underground repositories.
Effects of different parameters on transient heat transfer surrounding energy piles in unsaturated soils
Authors: Yazdani Cherati Davood , Ghasemi-Fare Omid , Hashemi Senejani Hussein
Published: November 2020

Energy piles are one of the best candidates to harvest shallow geothermal energy. Continuing harvesting and rejecting thermal energy from/to the ground may permanently change the soil temperature and consequently, may lead to different soil resistance parameters. Therefore, careful prediction of soil temperature variation close to energy geostructures is needed. This paper investigates the various parameters of heat source and soil media on transient heat transport in unsaturated soils. Green’s function and the method of separation of variables are employed to analytically analyze the transient heat transfer in the vicinity of energy piles. Results indicate that although higher heat flux increases the soil temperature surrounding a heat source, it has negligible effect on thermal influence zone where the soil temperature varies. In contrast, higher thermal diffusivity results in lower soil temperature close to a heat source while it increases the thermal influence zone.
Investigation of the feasibility of energy piles in Bangkok and their impacts on pile behavior
Authors: Jotisankasa Apiniti , Chantawarangul Korchoke , Sittidumrong Jittavee , Thangkhumwong Kachen , Aowphitak Phongphat , Laohasrisakul Pattadol , Chanchayanon Thiti , Aonkam Sineenart , Satayanan Sakaorat
Published: November 2020

The energy pile concept, which involves using piles as heat exchanging units for ground source heat pump (GSHP) system, have recently been proposed as a promising way of using shallow geothermal energy resource for cooling buildings to improve energy efficiency and reduce the heat island phenomena in Bangkok Thailand. The power rating of heat exchange capacity of the piles is one of the most important design parameters to consider when evaluating the feasibility of the system. In this study, a full-scale thermal response test was conducted on a spun pile equipped with a single U-loop with the power rating of 60 W/m, yielding the effective thermal conductivity of 3.3 W/m°C, while that on steel micro pile yielded the value between 1.49 and 2.01 W/m°C with power rating of 10W/m. Effects of possible thermal cycles on the compression of Bangkok sand was also investigated in order to evaluate any adverse effects of using piles on pile settlement.
Numerical investigation of the performance of group of geothermal energy piles in unsaturated sand
Authors: Sani Abubakar Kawuwa , Singh Rao Martand
Published: November 2020

The use of foundation structures (piles) coupled to a heat pump system, commonly referred to as geothermal energy pile (GEP) system, provides a renewable energy solution of achieving space heating and cooling in buildings; whilst also being utilised for the structural stability of the overlying structures. The system operates by exchanging the low-grade heat energy within the shallow earth surface with the building, via the circulation of heat carrier fluid enclosed in a high-density polyethylene plastic pipes. In summer, heat energy is extracted from the building and transferred into the ground to achieve space cooling. While in winter, the ground heat energy is harnessed and transferred to the building to achieve sustainable space heating. This paper investigates the thermal performance of group of GEP system under the effects of different initial soil pore water content. Through the five-year simulation’s period, it was found that the increase in soil pore water content decreases the possibility of thermal interaction between the GEPs in the group. Also, it was observed that the trend in maximum temperature witnessed within the soil domain decreases nonlinearly during the five years period.
Exploring the curing condition and age effect on thermal conductivity of concrete
Authors: Bahnick Raychel , Joshaghani Mohammad , Ghasemi-Fare Omid , Sun Zhihui
Published: November 2020

Energy piles are used around the world to partially heat/cool buildings or de-ice pavements. Thermal conductivity of concrete is one of the key parameters which highly affects the thermal performance of energy geostructures. Application of higher thermally conductive concrete in energy piles helps to harvest more shallow geothermal energy. Besides, higher thermally conductive concrete results in more uniform temperature distribution and will significantly increase the efficiency of the geothermal bridge deck de-icing. It is expected that the thermal conductivity of the concrete depends on its age and the applied curing conditions. The thermal conductivity of concrete can progress with the progression of hydration. While the hydration process is highly dependent on the curing condition that is applied. In this study, several concrete samples are prepared and cured under different conditions (inside the humidity room, indoor, and outdoor). Then the thermal conductivity of concrete samples at different ages are measured according to ASTM D5470-17. Results show an increase in thermal conductivity of concrete cured in humidity room for the first 30 to 40 days that thermal conductivity were measured In addition comparison of thermal conductivity of the outdoor and indoor samples show the importance of the ambient temperature and relative humidity on the thermal conductivity value.
Simplified two-step, cross-sectional approach for coupled heat and moisture transfer modeling of shallow, horizontal, ground-based heat Exchangers
Authors: Oh Hyunjun , Tinjum James M.
Published: November 2020

This study evaluates a two-step, cross-sectional approach for designing shallow, unsaturated, horizontal, ground-based heat exchangers (GHXs). Numerical modeling was conducted for coupled heat and moisture transfer around GHXs under transient climatological conditions through a cooling season. Soil samples were collected in Texas and Wisconsin to measure thermal conductivity dry-out curves and soil-water characteristic curves for use in the modeling. Average daily meteorological data from central Texas was applied for the top boundary condition. Heat generation from the GHX was calculated by total condenser heat rejection from an environmental control unit based on ambient temperatures and unit specifications. In the first step of the modeling, results showed that the fluid temperature through the GHX loop was approximately 43 ºC, and rapid heat and moisture fluxes were observed around the GHX loops. High moisture flux along the upper surface was also observed due to high ambient temperatures that occur during the summer season. Using these results, exiting temperature of the GHX was estimated for the second cross-sectional modeling step. This two-step, cross-sectional modeling approach provides a systematic analysis of coupled heat and moisture transfer around shallow, horizontal, unsaturated GHX loops, thus simplifying high computational effort needed for full three-dimensional modeling of shallow GHX systems.
A simplified method to evaluate geothermal storage in an aquifer with consideration of heat transfer between aquifer and caprock/baserock
Authors: Cinar Alp , Sun Xiang , Soga Kenichi , Lu Xiaoyu , Nico Peter , Dobson Patrick
Published: November 2020

Storing and extracting heat during different seasons of the year is possible through the utilization of a ground aquifer with an open loop Ground Source Heat Pump (GSHP) system. Being able to predict the hydrothermal performance of geothermal storage is required for an efficient operation of the system for cooling and heating of buildings. Complex 2D and 3D hydrothermal numerical models can simulate the thermal performance of geothermal storage accurately but often lack the desired computational speed for conducting large number of simulations for performance optimization. Instead, a 1D radial model can be used to conduct fast evaluation. However, it is important that the model computes the amount of heat loss from an aquifer into the overburden and underlying layers accurately to evaluate the amount of geothermal storage in the aquifer at different times. In this study, a source term is introduced into a 1D model to simulate the heat transfer between the aquifer and caprock/baserock in the vertical direction. The following two heat loss models are introduced in the heat advection-conduction equation: (i) Newton’s heating/cooling law, which leads to a closed form solution, and (ii) a conduction-based semi-analytical model, which requires a 1D finite element solution. When compared to a full 2D axisymmetric simulation result, it was found that the Newton’s heating/cooling law model with a constant heat transfer coefficient works well in cases of fast heat flow rate in thick aquifers of around 100 meters. But large errors in estimating heat dissipation are observed in cases with low heat flow rate in thin aquifers, especially for simulations exceeding two to five years. On the other hand, the model with the conduction-based semi-analytical solution gives a better match for these conditions.
Thermal energy storage in embankments: Investigation of the thermal properties of an unsaturated compacted soil
Authors: Lahoori Mojdeh , Rosin-Paumier Sandrine , Jannot Yves , Boukelia Ahmed , Masrouri Farimah
Published: November 2020

Thermal energy storage in compacted soils can be considered as a new economically efficient and environmentally friendly technology in geotechnical engineering. Compacted soils are usually unsaturated; therefore, reliable estimates and measurements of their thermal properties are important in the efficiency analysis of these structures. In this study, a method is used to estimate the thermal properties of an unsaturated compacted soil. Several temperature sensors were placed in a thermo-regulated metric scale container to monitor the imposed temperature variation in the range of the 20 to 50 °C. This imposed temperature variation reproduced the temperature variation in the thermal energy storages. An inverse analytical model based on a one-dimensional radial heat conduction equation is used to estimate the thermal diffusivity using the temperature variation between two temperature sensors. The volumetric heat capacity was measured using a calorimeter in the laboratory, enabling the estimation of the thermal conductivity of the compacted soil. Then, this estimated thermal conductivity was compared with the thermal conductivity values measured with two other methods (steady-state and transient-state method). The difference between them are discussed in terms of the sample heterogeneity, sample size, and measurement method.
Quantification of grain breakage during creep based on X-ray microtomography
Authors: Buscarnera Giuseppe , Sohn Changbum , Seo Dawa
Published: November 2020

Delayed compression is among the leading causes of long-term deterioration in granular systems, especially when it is mediated by the action of pore fluids. This time-dependent process is often classified as ‘creep’, a term conveying time-dependence without specifying the causes of deformation. This paper presents a methodology based on X-ray synchrotron microtomography to track delayed microstructural changes in compacted sand. Experiments on materials characterized by different grain size and shape have been designed to measure macroscopic variables such as strain rate, as well as to visualize the topological and morphological alterations of the constituting particles. The results reveal that non-negligible inelastic processes such as grain breakage manifest during the first stages of loading, as well as during the ensuing constant-stress delayed compaction. A substantial role of the grain morphology was detected in both stages. Specifically, while samples made of angular grains displayed early breakage due to the exacerbated fragility of the particles, specimens made of rounded grains did not develop a markedly polydisperse structure prior to creep, which led to comparably more intense delayed fracturing. Furthermore, samples consisting of round grains were also found to exhibit more intense shape alterations, with morphological indicators that tended to converge over time towards those of initially angular grains. These results suggest that characterization and simulation of creep in granular media need to encompass a variety of microscopic processes controlled by grain-scale properties, thus requiring multi-scale testing and modelling techniques.
Compression behaviour of hydrate bearing carbonate sand - fines mixtures
Authors: MA Lu , CHIU Abraham C.F. , CHENG Y.P.
Published: November 2020

High gas hydrate content has been found in fine-grained sediments containing substantial amount of foraminifera in the South China sea. One of the possible hydrate accumulation habits is filling the intra- particle voids in the foraminifera. To understand the effects of this hydrate accumulation habit on the compression behaviour of the fine-grained sediment, two series of isotropic compression tests were conducted. Due to high intra-particle porosity, carbonate sand (CS) was mixed with the fines to mimic the hydrate formation in the intra-particle voids in the laboratory prepared soil specimens. The compression test results revealed that the mixtures of fines with as high as 40% CS content can exhibit the transitional behaviour such that non-convergent compression lines are observed at the high stress level. It is evident that breakage of CS grains is negligible in these mixtures. Hence, the initial fabrics are not erased under the high stress level resulting in non-convergent compression lines. The compression curves of the hydrate bearing CS-fines mixtures can be classified into three different stress regimes. There is no significant difference in the compressibility of the soil mixtures with and without hydrate in the low stress regime. As the stress increases further reaching the medium stress regime, the hydrate reduces the compressibility of the soil mixtures with increasing hydrate saturation. Upon reaching the high stress regime, the bond breakage at the inter-particle contacts becomes significant leading to the convergence of compression curves between the hydrate bearing and host soil mixtures. It is also found that a new effective hydrate saturation, representing the amount of hydrate in the inter-particle voids, is better correlated to the compressibility of the hydrate bearing soil mixtures.
Insight of in-situ porosity and compressibility of the GC 955 Gulf of Mexico hydrate reservoir
Authors: Fang Yi , Flemings Peter B. , Daigle Hugh , Phillips Steve C. , Germaine John T.
Published: November 2020

We characterize the in-situ porosity and compressibility of a coarse-grained hydrate reservoir in Green Canyon Block 955 in the deepwater Gulf of Mexico by performing experiments both on a hydrate-bearing sandy silt pressure core and on the same reservoir material after reconstituting. Uniaxial consolidation experiments demonstrate a small difference in porosity between a reconstituted sandy silt sample (Sh= 0,n= ~ 0.38) and a hydrate-bearing sandy silt (Sh= 83%,n= 0.39-0.40) at in-situ effective stress (3.8 MPa). Both measured porosities generally agree with the in-situ porosity (~0.38 to 0.39) of the reservoir formation that was best-estimated from both LWD and calibrated PCATS densities. The compression index of pressure core at 3.8 MPa is ~ 0.05 to 0.1, slightly stiffer than reconstituted sandy silts (Cc= 0.11). This difference in porosity and compression behaviors between hydrate pressure cores and reconstituted material implies that (1) analysis of reconstituted sediments from hydrate-bearing pressure cores provides a simple and intuitive approach to understand some petrophysical components of the hydrate reservoir; and (2) the high-saturation hydrate in the pores of sediments makes the hydrate reservoir slightly less compressible, suggesting a non-contact-cementing hydrate morphology in the pressure core.
Suction as an untapped natural soil reinforcement to reduce embodied carbon in geotechnical structures: the case study of flood embankments in Hamburg area
Authors: Beber Raniero , Becker Patrick , Tarantino Alessandro
Published: November 2020

The commitment to cut CO2 emissions is now becoming a matter of legal obligations in several countries worldwide and the construction industry, one of the main sectors contributing to carbon emissions, is required to develop new approaches for carbon-efficient design. A study was undertaken to examine whether the inclusion of negative pore-water pressures (or ‘suction’) in the design of a flood embankment could reduce the embodied carbon associate with the construction of a new embankment or the retrofitting of an existing one. The case considered here are the embankments of the tidal Elbe area in Germany that require to be raised because of the new projection of extreme river levels due to climate change. Simple uncoupled water flow and stability analyses were considered to examine the performance of given embankment geometry. The purpose of the study is to examine whether incorporating suction into the design could allow for steeper landside slopes of the flood embankment. This would allow raising the embankment by saving considerable material and, hence, reducing the embodied carbon. At the same time, this would reduce the footprint of the raised embankment, which is a design requirement when flood embankments are embedded in the built environment as it happens in Hamburg.
A numerical parametric study on the efficiency of prestressed geogrid reinforced soil
Authors: Das Soukat Kumar , Samadhiya N. K.
Published: November 2020

Prestressing geosynthetics offers a rapid and safe method of improving the poor ground conditions. This paper aims to find out the effect of prestressing the geogrid layer on load bearing and settlement performance. This study also takes into account the impact of the size, depth of placement and the adjacency of footing, for unreinforced (UR), geogrid reinforced (GR) and prestressed geogrid reinforced (PGR) soil on the load-bearing and the settlement characteristics by using the finite element program Plaxis 3D. Based on numerical simulation, it appears that PGR soil can enhance the bearing pressure of the UR soil by almost 500% and reduced the settlement by nearly 88 % by reducing the energy consumption. The footing placed at higher depths for PGR soil gives better performance as compared to GR soil. Moreover, placing two adjacent square footing increases the interference zone of PGR soil by 67% as compared to UR soil. This method can be instrumental in reducing the total input energy requirement to achieve a certain settlement during placement of shallow foundation for various important structures while being economic simultaneously.
The advanced p-y method for analyzing the behaviour of large-diameter monopiles supporting offshore wind turbines
Authors: Van Impe William F , Wang Shin-Tower
Published: November 2020

The analyses of monopile foundations have been heavily based on the p-y response curves (to represent lateral soil resistances) published by API RP 2GEO (2011) and DNV (2013), which are proven reliable and applicable for piles with smaller diameters that were normally used for jacket structures in the offshore industry. However, concerns have been raised about the validity of semi-empirical p-y criteria for large-diameter piles. Wind turbine monopiles have a significantly larger diameter and smaller length to diameter ratio than typical piles used for offshore structures. The ratio of the length to the diameter for a monopile typically is also significantly smaller than those used in the API load tests. Therefore, the response of a monopile may be more like a rigid rotation, with components of resistance mobilized at the tip and axially along the sides as it rotates. This behaviour is in contrast to long slender piles that respond to lateral loading in bending rather than rotation. The objective of this paper is to analyze the factors that may contribute to the apparent conservatism in the current design practice for large-diameter monopile foundations and to provide improved solutions on how to analyze and design the large-diameter monopiles for offshore wind turbine using the p-y method.
Analysis of energy efficiency of air handling unit with integrated air to air heat exchanger in heating mode
Authors: Valchev Slav , Mihaylov Ivan
Published: November 2020

Object of the present study is an experimental determination of energy efficiency parameters of air handling unit with integrated air to air heat exchanger: effectiveness of air to air heat exchanger, coefficient of performance and specific fan power of air handling unit. A daily performance of air handling unit is conducted. Effectiveness of supply side of air to air heat exchanger in range of 42.4 % to 52.5 % is received. Coefficient of performance in range of 1.50 to 2.08 and specific fan power of air handling unit in range of 1.39 kW/(m3/s) to 2.08 kW/(m3/s) are received. It was found experimentally that effectiveness of air to air heat exchanger depends on values of mass flow of supply and the exhaust air. High values of mass flow of the exhaust air responds to high effectiveness of supply side of air to air heat exchanger.
Electronic equipment measuring device for heat quantity through a flat wall
Authors: Yordanov Krastin , Hadzhidimov Iliya , Zlateva Penka
Published: November 2020

In the paper, an experimental study for calculation the heat quantity through a flat wall by electronic system has been presented. The aim is temperature measurement on outer and inner walls of a room for 20 days at 1-minute interval of measurement. A transient regime has been considered. The data measured has been collected on a non-insulated south wall of a Technical University of Varna campus building. The wall layers parameters have to be known for the choice of surrounding area. In order to reduce errors of the outer side of wall temperature measurement caused by the solar radiation, the temperature sensor has been painted grey. The experimental equipment for the heat quantity measurement consists of two plates, each with 4 temperature fixed in a rectangle. The sensors are situated in а flat area in order to obtaining more precise results of experimental study. The problem has been solved by finding decision of the classic heat conduction equation. The experimental temperatures are treated by microprocessor’s platform based on Arduino board. As a result, the average temperature of each plate with sensors has been estimated.
Physicochemical, thermodynamic and thermal properties of linalyl acetate-ethanol-water system
Authors: Gandova Vanya , Tasheva Stanislava , Dobreva Krasimira , Prodanova-Stefanova Vanya , Marinova Krasimira , Stoyanova Albena
Published: November 2020

Some physicochemical, thermodynamic and thermal properties of linalyl acetate - ethanol - water solutions with different ethanol concentrations (70%, 75%, 80%, 85%, 90%, and 95%) in three ratios (1:5, 1:6, and 1:7) were determined. The properties were calculated to describe the stability of the system. Multiply linear regression model was obtained for surface tension prediction. Good correlation was observed between calculated and experimental surface tension values.
Assessment of the annual performance of solar collectors by means of the utilizability method
Authors: Zlateva Merima
Published: November 2020

This report presents some results from a comparative analysis of the long-term efficiency of flat-plate and evacuated tube solar collectors under different operating conditions. The analysis involves calculation of the daily utilizibility factor, which is defined as the fraction of total monthly solar radiation over an inclined surface that exceeds the critical value. The monthly values of the critical radiation and the daily utilizability factor for the solar collectors are determined under different climatic conditions and different temperatures of the heat transfer fluid. The obtained results are used to compare the annual performance of the solar collectors.
Deformation behavior of textile electrodes during compression
Authors: Germanova-Krasteva Diana , Nikolova Elena
Published: November 2020

Textile electrodes are increasingly used to measure biomedical signals (ECG, EMG, EEG) needed for diagnostic activities in medical practice. Tight contact between the electrode and the human body is required to obtain a quality biopotential signal. Pressure is applied to the electrode to secure it. The aim of the work is to study the deformations caused by the applied efforts. The deformation curves of two models of textile electrodes were determined, which have been examined before and after a certain number of washing cycles (10 and 50), in a wide range of pressure changes on the electrodes - from 0.1 to 17 kPa. Analyses of the deformation behaviour of the electrodes and its changes after washing are made. Characteristic zones in the deformation curves are defined; reasons for their formation and change after washing are commented.
Comparison of Model Predictive Control (MPC) and Linear-Quadratic Gaussian (LQG) Algorithm for Electrohydraulic Steering Control System
Authors: Mitov Alexander , Kralev Jordan , Slavov Tsonyo , Angelov Ilcho
Published: November 2020

The paper compares the performance of two embedded controllers applied in electrohydraulic steering systems – model predictive controller (MPC) and linear-quadratic Gaussian (LQG) controller with Kalman filtering for state estimation. Both controllers are designed on the basis of single input multiple output “black box” model obtained via identification approach. The controllers are implemented into industrial logic controller for mobile applications and their workability is experimentally checked with a laboratory model of a steering system for non-road mobile machinery. The results corresponding to investigation of performance of the closed-loop system are presented.
Study on the formability by TPIF technology for aluminium sheet at room temperature
Authors: Van Viet Ma , Truong Thinh Nguyen , Van Sy Le , Antonov Svetlin
Published: November 2020

Two Point Incremental Forming technology (TPIF) is one forming method of incremental sheet forming technology (ISF) which is an innovation sheet forming process with potential advantages such as simplicity, less-time consumption, and high flexibility. This technology using a hemispherical-end tool under CNC movement deforms a metal sheet which is fixed on simple frame. The sheet metal clamped between movable plate and clamp plate, under the metal sheet has a support die which is fixed on bottom plate. The lower plate is firmly positioned on the CNC machine table in while upper plate (included sheet material, movable plate and clamp plate) is able to move easily up and down along guide bars. The sheet material is plastically deformed layer by layer until final-shape product by CNC tool path. This technology is very suit for the rapid prototyping process and the low batch production. In this research, formability of the TPIF process due to operating parameters was investigated with aluminum sheet at room temperature. Four operating parameters such as depth step, feed rate, tool diameter, and spindle speed, was considered their effects on the formability of TPIF process through DOE strategy. The forming results showed that TPIF process for metal sheet material at room temperature has potential applicability in the metal sheet-product manufacturing.
Possibilities of Energy Utilization of Waste from the Automotive Industry at Present
Authors: Pilát Peter , Patsch Marek
Published: November 2020

The car is now a consumer product and its use has significantly decreased over the last decades. According to the sources of the Ministry of the Internal Affairs of the Slovak Republic, is to 31 January 2020 registered 3.286.258 motor vehicles and of which 2.395.362 are passenger cars, which means that per slovak citizen there is something below 0.5 of passenger vehicle. Used passenger cars make up the largest part of the car waste. This paper deals with how the waste from cars after their lifecycle in currently operating energy facilities.
Numerical Modelling of Gaseous Fuel Combustion Process with the Stepwise Redistribution of Enriched Combustion Air
Authors: Rimár Miroslav , Kizek Ján , Kulikov Andrii
Published: November 2020

The authors of this paper present the results of simulations for burner system design changes in the smelting aggregate. Based on the analysis of the existing burner system in the experimental aluminium smelting equipment, changes in the burner design were proposed. The obtained results are presented in tables and figures. The properties of the proposed changes were investigated using the simulation software ANSYS. The simulations confirmed the suitability of the proposed system for shortening the flame length and intensification of the mixing of gaseous media.