bluuebunny/crossref_metadata_2025 huggingface dataset:
Umami synergy as the scientific principle behind taste-pairing champagne and oysters
Authors: Schmidt Charlotte Vinther , Olsen Karsten , Mouritsen Ole G.
Published: November 2020

Food and flavour pairing are commonly used as an empirically based phenomenology by chefs and food innovators for creating delicious dishes. However, there is little if any science behind the pairing systems used, and it appears that pairing is determined by food culture and tradition rather than by chemical food composition. In contrast, the pairing implied by the synergy in the umami taste, elicited by free glutamate and free nucleotides, is scientifically founded on an allosteric action at the umami receptor, rendering eggs-bacon and cheese-ham delicious companions. Based on measurement of umami compounds in champagnes and oysters we suggest that a reason why champagne and oysters are considered good companions may be the presence of free glutamate in champagne, and free glutamate and 5′-nucleotides in oysters. By calculations of the effective umami potential we reveal which combinations of oysters and champagnes lead to the strongest umami taste. We also show that glutamate levels and total amount of free amino acids are higher in aged champagnes with long yeast contact, and that the European oyster (Ostrea edulis) has higher free glutamate and nucleotide content than the Pacific oyster (Crassostrea gigas) and is thus a better candidate to elicit synergistic umami taste.
Transcranial direct current stimulation (tDCS) over the auditory cortex modulates GABA and glutamate: a 7 T MR-spectroscopy study
Authors: Heimrath K. , Brechmann A. , Blobel-Lüer R. , Stadler J. , Budinger E. , Zaehle Tino
Published: November 2020

Transcranial direct current stimulation (tDCS) is one of the most prominent non-invasive electrical brain stimulation method to alter neuronal activity as well as behavioral processes in cognitive and perceptual domains. However, the exact mode of action of tDCS-related cortical alterations is still unclear as the results of tDCS studies often do not comply with the somatic doctrine assuming that anodal tDCS enhances while cathodal tDCS decreases neuronal excitability. Changes in the regional cortical neurotransmitter balance within the stimulated cortex, measured by excitatory and inhibitory neurotransmitter levels, have the potential to provide direct neurochemical underpinnings of tDCS effects. Here we assessed tDCS-induced modulations of the neurotransmitter concentrations in the human auditory cortex (AC) by using magnetic resonance spectroscopy (MRS) at ultra-high-field (7 T). We quantified inhibitory gamma-amino butyric (GABA) concentration and excitatory glutamate (Glu) and compared changes in the relative concentration of GABA to Glu before and after tDCS application. We found that both, anodal and cathodal tDCS significantly increased the relative concentration of GABA to Glu with individual temporal specificity. Our results offer novel insights for a potential neurochemical mechanism that underlies tDCS-induced alterations of AC processing.
Highly colloidally stable trimodal 125I-radiolabeled PEG-neridronate-coated upconversion/magnetic bioimaging nanoprobes
Authors: Kostiv Uliana , Kučka Jan , Lobaz Volodymyr , Kotov Nikolay , Janoušková Olga , Šlouf Miroslav , Krajnik Bartosz , Podhorodecki Artur , Francová Pavla , Šefc Luděk , Jirák Daniel , Horák Daniel
Published: November 2020

“All-in-one” multifunctional nanomaterials, which can be visualized simultaneously by several imaging techniques, are required for the efficient diagnosis and treatment of many serious diseases. This report addresses the design and synthesis of upconversion magnetic NaGdF4:Yb3+/Er3+(Tm3+) nanoparticles by an oleic acid-stabilized high-temperature coprecipitation of lanthanide precursors in octadec-1-ene. The nanoparticles, which emit visible or UV light under near-infrared (NIR) irradiation, were modified by in-house synthesized PEG-neridronate to facilitate their dispersibility and colloidal stability in water and bioanalytically relevant phosphate buffered saline (PBS). The cytotoxicity of the nanoparticles was determined using HeLa cells and human fibroblasts (HF). Subsequently, the particles were modified by Bolton-Hunter-neridronate and radiolabeled by125I to monitor their biodistribution in mice using single-photon emission computed tomography (SPECT). The upconversion and the paramagnetic properties of the NaGdF4:Yb3+/Er3+(Tm3+)@PEG nanoparticles were evaluated by photoluminescence, magnetic resonance (MR) relaxometry, and magnetic resonance imaging (MRI) with 1 T and 4.7 T preclinical scanners. MRI data were obtained on phantoms with different particle concentrations and during pilot long-time in vivo observations of a mouse model. The biological and physicochemical properties of the NaGdF4:Yb3+/Er3+(Tm3+)@PEG nanoparticles make them promising as a trimodal optical/MRI/SPECT bioimaging and theranostic nanoprobe for experimental medicine.
Radiographic characterisation of spinal curvature development in farmed New Zealand Chinook salmon Oncorhynchus tshawytscha throughout seawater production
Authors: Lovett B. A. , Firth E. C. , Tuck I. D. , Symonds J. E. , Walker S. P. , Perrott M. R. , Davie P. S. , Munday J. S. , Preece M. A. , Herbert N. A.
Published: November 2020

Spinal anomalies are a recognised source of downgrading in finfish aquaculture, but identifying their cause(s) is difficult and often requires extensive knowledge of the underlying pathology. Late-onset spinal curvatures (lordosis, kyphosis, scoliosis) can affect up to 40% of farmed New Zealand Chinook (king) salmon (Oncorhynchus tshawytscha) at harvest, but little is known about their pathogenesis. Curvature development was radiographically documented in two related cohorts of commercially-farmed Chinook salmon throughout seawater production to determine (1) the timing of radiographic onset and relationships between (2) the curvature types, (3) the spinal regions in which they develop and (4) their associations with co-existing vertebral body anomalies (vertebral compression, fusion and vertical shift). Onset of curvature varied between individuals, but initially occurred eight months post-seawater transfer. There were strong associations between the three curvature types and the four recognised spinal regions: lordosis was predominantly observed in regions (R)1 and R3, kyphosis in R2 and R4, manifesting as a distinct pattern of alternating lordosis and kyphosis from head to tail. This was subsequently accompanied by scoliosis, which primarily manifested in spinal regions R2 and R3, where most of the anaerobic musculature is concentrated. Co-existing vertebral body anomalies, of which vertebral compression and vertical shift were most common, appeared to arise either independent of curvature development or as secondary effects. Our results suggest that spinal curvature in farmed New Zealand Chinook salmon constitutes a late-onset, rapidly-developing lordosis–kyphosis–scoliosis (LKS) curvature complex with a possible neuromuscular origin.
Time-of-day-dependent responses of cyanobacterial cellular viability against oxidative stress
Authors: Tanaka Kenya , Shimakawa Ginga , Nakanishi Shuji
Published: November 2020

As an adaptation to periodic fluctuations of environmental light, photosynthetic organisms have evolved a circadian clock. Control by the circadian clock of many cellular physiological functions, including antioxidant enzymes, metabolism and the cell cycle, has attracted attention in the context of oxidative stress tolerance. However, since each physiological function works in an integrated manner to deal with oxidative stress, whether or not cell responses to oxidative stress are under circadian control remains an open question. In fact, circadian rhythms of oxidative stress tolerance have not yet been experimentally demonstrated. In the present work, we applied an assay using methyl viologen (MV), which generates reactive oxygen species (ROS) under light irradiation, and experimentally verified the circadian rhythms of oxidative stress tolerance in photosynthetic cells of the cyanobacterium Synechococcus elongatus PCC 7942, a standard model species for investigation of the circadian clock. Here, we report that ROS generated by MV treatment causes damage to stroma components and not to the photosynthetic electron transportation chain, leading to reduced cell viability. The degree of decrease in cell viability was dependent on the subjective time at which oxidative stress was applied. Thus, oxidative stress tolerance was shown to exhibit circadian rhythms. In addition, the rhythmic pattern of oxidative stress tolerance disappeared in mutant cells lacking the essential clock genes. Notably, ROS levels changed periodically, independent of the MV treatment. Thus, we demonstrate for the first time that in cyanobacterial cells, oxidative stress tolerance shows circadian oscillation.
Prediagnostic serum 25-hydroxyvitamin D and melanoma risk
Authors: Stenehjem Jo S. , Støer Nathalie C. , Ghiasvand Reza , Grimsrud Tom K. , Babigumira Ronnie , Rees Judy R. , Nilsen Lill Tove , Johnsen Bjørn , Thorsby Per M. , Veierød Marit B. , Robsahm Trude E.
Published: November 2020

Previous studies of serum 25-hydroxyvitamin D (25(OH)D) in relation to melanoma have shown conflicting results. We conducted a nested case–control study of 708 cases and 708 controls, using prediagnostically collected serum, to study 25(OH)D and melanoma risk in the population-based Janus Serum Bank Cohort. Stratified Cox regression was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) adjusted for ultraviolet radiation (UVR) indicators and stratified by ambient UVB of residence and body mass index (BMI). Non-linear associations were studied by restricted cubic splines. Missing data were handled with multiple imputation by chained equations. We found an HR of melanoma risk of 1.01 (95% CI: 0.99, 1.04) and an HRimputed of 1.02 (95% CI: 1.00, 1.04) per 5-nmol/L increase. The spline model showed exposure-risk curves with significantly reduced melanoma risk between 60 and 85 nmol/L 25(OH)D (reference 50 nmol/L). Non-significant J-shaped curves were found in sub-analyses of subjects with high ambient UVB of residence and of subjects with BMI < 25 kg/m2. Our data did not yield persuasive evidence for an association between 25(OH)D and melanoma risk overall. Serum levels within the medium range might be associated with reduced risk, an association possibly mediated by BMI.
Large enhancement of simultaneous color contrast by white flanking contours
Authors: Kanematsu Tama , Koida Kowa
Published: November 2020

Simultaneous color contrast and assimilation are mutually opposing effects on color appearance, and their magnitude depends on spatial context. The Monnier–Shevell illusion induces a large color shift by a synergy of simultaneous assimilation and contrast using the alternating color of proximal and distant surrounds. The illusion induces a prominent effect along the blue-yellow color axis, but a subtle effect along the orthogonal color axis. In this study, we report an illusion generated by an extremely thin gray line on a cyan background that appears reddish when the line is flanked by thin white contours. We quantified the color appearance of the gray line in a color matching experiment and found that the color shift of the gray line with white contours induced large color shifts. It is also known that luminance contrast between a center and its surrounds affects the magnitude of simultaneous color contrast. However, our color contrast effects were larger for a dark line rather than for a pale line. In contrast, the perceived color shift of the line without the contours increased as the luminance of the gray line increased, supporting the known effect of Kirschmann’s third law. These results indicate that Kirschmann’s third law fails to explain the perceived color shift of our illusion, even after accounting for optical factors like aberrations. Observed color shifts could be explained by an augmented synergy theory based on intensity space, rather than chromaticity.
Machine learning to predict mortality after rehabilitation among patients with severe stroke
Authors: Scrutinio Domenico , Ricciardi Carlo , Donisi Leandro , Losavio Ernesto , Battista Petronilla , Guida Pietro , Cesarelli Mario , Pagano Gaetano , D’Addio Giovanni
Published: November 2020

Stroke is among the leading causes of death and disability worldwide. Approximately 20–25% of stroke survivors present severe disability, which is associated with increased mortality risk. Prognostication is inherent in the process of clinical decision-making. Machine learning (ML) methods have gained increasing popularity in the setting of biomedical research. The aim of this study was twofold: assessing the performance of ML tree-based algorithms for predicting three-year mortality model in 1207 stroke patients with severe disability who completed rehabilitation and comparing the performance of ML algorithms to that of a standard logistic regression. The logistic regression model achieved an area under the Receiver Operating Characteristics curve (AUC) of 0.745 and was well calibrated. At the optimal risk threshold, the model had an accuracy of 75.7%, a positive predictive value (PPV) of 33.9%, and a negative predictive value (NPV) of 91.0%. The ML algorithm outperformed the logistic regression model through the implementation of synthetic minority oversampling technique and the Random Forests, achieving an AUC of 0.928 and an accuracy of 86.3%. The PPV was 84.6% and the NPV 87.5%. This study introduced a step forward in the creation of standardisable tools for predicting health outcomes in individuals affected by stroke.
Author Correction: Aquaponics using a fish farm effluent shifts bacterial communities profile in halophytes rhizosphere and endosphere
Authors: Oliveira Vanessa , Martins Patrícia , Marques Bruna , Cleary Daniel F. R. , Lillebø Ana I. , Calado Ricardo
Published: November 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Genome-wide association studies and heritability analysis reveal the involvement of host genetics in the Japanese gut microbiota
Authors: Ishida Sachiko , Kato Kumiko , Tanaka Masami , Odamaki Toshitaka , Kubo Ryuichi , Mitsuyama Eri , Xiao Jin-zhong , Yamaguchi Rui , Uematsu Satoshi , Imoto Seiya , Miyano Satoru
Published: November 2020

Numerous host extrinsic and intrinsic factors affect the gut microbiota composition, but their cumulative effects do not sufficiently explain the variation in the microbiota, suggesting contributions of missing factors. The Japanese population possesses homogeneous genetic features suitable for genome-wide association study (GWAS). Here, we performed GWASs for human gut microbiota using 1068 healthy Japanese adults. To precisely evaluate genetic effects, we corrected for the impacts of numerous host extrinsic and demographic factors by introducing them as covariates, enabling us to discover five loci significantly associated with microbiome diversity measures: HS3ST4, C2CD2, 2p16.1, 10p15.1, and 18q12.2. Nevertheless, these five variants explain only a small fraction of the variation in the gut microbiota. We subsequently investigated the heritability of each of the 21 core genera and found that the abundances of six genera are heritable. We propose that the gut microbiota composition is affected by a highly polygenic architecture rather than several strongly associated variants in the Japanese population.
Highly branched and defect-rich PdP nanosheets for ethanol oxidation electrocatalysis
Authors: Lv Hao , Teng Yuxiang , Wang Yaru , Xu Dongdong , Liu Ben
Published: November 2020

Highly branched, defect-rich, and ultrathin PdP alloy nanosheets with enhanced electrocatalytic ethanol oxidation reaction (EOR) performance.
The effects of contact atom distribution at the interface on the phonon transport
Authors: Liu Chenhan , Lu Ping , Gu Zhongzhu , Yang Juekuan , Chen Yunfei
Published: November 2020

The effects of contact atom distribution at the interface on phonon transport are investigated. The results indicate that phonon transport has a strong dependence on the distribution based on the match degree of vibration modes across the interface.
Design of PtZn nanoalloy catalysts for propane dehydrogenation through interface tailoring via atomic layer deposition
Authors: Ingale Piyush , Knemeyer Kristian , Preikschas Phil , Ye Mengyang , Geske Michael , Naumann d'Alnoncourt Raoul , Thomas Arne , Rosowski Frank
Published: November 2020

Synthetic approach for precise formation of PtZn bimetallic nano-alloys is reported, which are highly active and selective towards propane dehydrogenation.
Determination of excited state molecular structures from time-resolved gas-phase X-ray scattering
Authors: Yong Haiwang , Moreno Carrascosa Andrés , Ma Lingyu , Stankus Brian , Minitti Michael P. , Kirrander Adam , Weber Peter M.
Published: November 2020

We present a comprehensive investigation of a recently introduced method to determine transient structures of molecules in excited electronic states with sub-ångstrom resolution from time-resolved gas-phase scattering signals.
Discovery of hCES2A inhibitors from Glycyrrhiza inflata via combination of docking-based virtual screening and fluorescence-based inhibition assays
Authors: Song Yun-Qing , Guan Xiao-Qing , Weng Zi-Miao , Liu Jun-Ling , Chen Jing , Wang Lu , Cui Long-Tao , Fang Sheng-Quan , Hou Jie , Ge Guang-Bo
Published: November 2020

An integrated strategy via combination of chemical profiling, docking-based virtual screening and fluorescence-based high-throughput inhibitor screening assays was used to efficiently identify natural hCES2A inhibitors from herbal medicines.
Conversion of conducting polypyrrole nanostructures to nitrogen-containing carbons and its impact on the adsorption of organic dye
Authors: Stejskal Jaroslav , Kohl Miroslav , Trchová Miroslava , Kolská Zdeňka , Pekárek Michal , Křivka Ivo , Prokeš Jan
Published: November 2020

New types of materials were produced by gradual heating of a conducting polymer, polypyrrole, to elevated temperatures.
Nanostructured copper selenide as an ultrasensitive and selective non-enzymatic glucose sensor
Authors: Umapathi Siddesh , Singh Harish , Masud Jahangir , Nath Manashi
Published: November 2020

CuSe nanostructures exhibit high-efficiency for glucose detection with high sensitivity (19.419 mA mM−1 cm−2) and selectivity at low applied potential (0.15 V vs. Ag|AgCl), low detection limit (0.196 μM) and linear detection range (100 nM to 40 μM).
Study on the preparation parameters and combustion performance of Al/PTFE composites prepared by a mechanical activation-sintering method
Authors: Li Yaning , Hang Siyu , Li Jian , Guo Wanxiao , Xiao Wei , Han Zhiwei , Wang Boliang
Published: November 2020

In this paper, a composite material with enhanced combustion performance and close fuel-oxidant contact was prepared by mechanical activation-sintering.
Fabrication of a novel ternary heterojunction composite Ag2MoO4/Ag2S/MoS2 with significantly enhanced photocatalytic performance
Authors: Li Luqiu , Yin Dongguang , Deng Linlin , Xiao Songtao , Ouyan Yinggen , Khaing Kyu Kyu , Guo Xiandi , Wang Jun , Luo Zhaoyue
Published: November 2020

A novel ternary heterojunction Ag2MoO4/Ag2S/MoS2 was successfully fabricated via a facile two-step method. The prepared ternary heterojunction showed much enhanced catalytic activity compared with monomers and binary heterojunctions.
Cobalt ion redox and conductive polymers boosted the photocatalytic activity of the graphite carbon nitride–Co3O4 Z-scheme heterostructure
Authors: Li Tao , Cui Jiandong , Lin Yezhan , Liu Kecheng , Li Rui , Wang Bo , Xie Haiquan , Li Kui
Published: November 2020

The enhanced photocatalytic hydrogen evolution performance of g-C3N4–Co3O4 2D–1D Z-scheme heterojunctions was achieved through the synergistic effect of the cobalt ion redox, conductive polyaniline, and a Co3O4 nanobelt.
Transition metal complexes as potential tools against SARS-CoV-2: anin silicoapproach
Authors: Pal Maynak , Musib Dulal , Roy Mithun
Published: November 2020

Screening of selected transition metal-based antiviral agents,in silico, predicted the potential inhibition of RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 which emerged as the potential drug candidate for COVID-19.
Dimensionality-controlled self-assembly of CdSe nanorods into discrete suprastructures within emulsion droplets
Authors: Xie Yangen , Wang Chunsheng , Yang Zhijie , Wei Huiying , Wei Jingjing
Published: November 2020

Self-assembly of inorganic nanocrystals into ordered superlattices is of particular importance for their application in biomedicine and solid-state optoelectronic devices.
Temperature-mediated molecular ladder self-assembly employing Diels–Alder cycloaddition
Authors: Leguizamon Samuel C. , Alqubati Abdulla F. , Scott Timothy F.
Published: November 2020

Thermal annealing of sequence-defined, maleimide- and furan-bearing oligomers enables sequence-selective hybridization to afford molecular ladders incorporating Diels–Alder adduct-based rungs.
Correction: Tacticity, molecular weight, and temporal control by lanthanide triflate-catalyzed stereoselective radical polymerization of acrylamides with an organotellurium chain transfer agent
Authors: Imamura Yuji , Fujita Takehiro , Kobayashi Yu , Yamago Shigeru
Published: November 2020

Correction for ‘Tacticity, molecular weight, and temporal control by lanthanide triflate-catalyzed stereoselective radical polymerization of acrylamides with an organotellurium chain transfer agent’ by Yuji Imamura et al., Polym. Chem., 2020, DOI: 10.1039/d0py01280g.
Facile star-shaped tetraphenylethylene-based molecules with fused ring-terminated diarylamine as interfacial hole transporting materials for inverted perovskite solar cells
Authors: Chen Yung-Chung , Lin Ding-Zhi , Wang Jhong-Ci , Ni Jen-Shyang , Yu Yang-Yen , Chen Chih-Ping
Published: November 2020

Three p-type small molecules (CL-1–3) based on tetraphenylethylene as the core and different π-conjugation diarylamines as linkers are synthesized. The bilayer HTL of the NiOx/CL-3-based cell exhibits the best power conversion efficiency of 20.15%.
Minor alkyl modifications for manipulating the fluorescence and photomechanical properties in molecular crystals
Authors: Li Pengyu , Wang Junxiao , Li Pengfei , Lai Liming , Yin Meizhen
Published: November 2020

Responsive fluorescent solid-state materials, especially light-driven mechanical motions, have received interest owing to the potential applications in advanced smart reponsive devices.
Effects of the surface polarity of nanomaterials on their interaction with complement protein gC1q
Authors: Wang Shuai , Ou Xinwen , Wutthinitikornkit Yanee , Yi Ming , Li Jingyuan
Published: November 2020

The dependence of the recognition mode of gC1q on the surface polarity of nanomaterials is mainly attributed to its distinct surface residue composition.
Hot electron prompted highly efficient photocatalysis based on 3D graphene/non-precious metal nanoparticles
Authors: Zhang Suling , Lu Yanhong , Wan Xingchen , Duan Yaxin , Gao Junlin , Ge Zhen , Wei Lei , Chen Yu , Ma Yanfeng , Chen Yongsheng
Published: November 2020

Based on the highly energetic hot/free electrons, 3DGraphene loaded nitrogen-doped carbon-coated Co catalysts show remarkably enhanced photocatalytic activities.
Coalbed methane diffusion and water blocking effects investigated by mesoscale all-atom molecular dynamic simulations
Authors: Zhu Qingzhong , Lin Ling , Liu Zhong , Luo Yunxiang , Fan Hongming , Guo Wei , Zhang Chen , Wang Sanshuai , Luo Wenjia
Published: November 2020

Molecular dynamics simulations of coalbed methane diffusion and water-blocking effects were performed based on mesoscale molecular models.
Active site-dominated electromagnetic enhancement of surface-enhanced Raman spectroscopy (SERS) on a Cu triangle plate
Authors: Li Chang , Chen Mingqiang
Published: November 2020

Chemical etching CTP to create a rough surface that has high enhancement factors of SERS.
Selective leaching of lead from lead smelter residues using EDTA
Authors: Palden Thupten , Machiels Lieven , Onghena Bieke , Regadío Mercedes , Binnemans Koen
Published: November 2020

Lead was selectively extracted from lead smelter residues as a lead sulfide by EDTA leaching and ammonium sulfide precipitation, with subsequent EDTA recovery and reuse.
Nucleophilic reactivity of the gold atom in a diarylborylgold(i) complex toward polar multiple bonds
Authors: Suzuki Akane , Guo Xueying , Lin Zhenyang , Yamashita Makoto
Published: November 2020

A di(o-tolyl)borylgold complex added to CO/N double bond to form Au–C and B–O/N bonds. DFT calculations revealed a two-step mechanism consisting of the coordination of O/N atom to B atom followed by nucleophilic migration of Au atom.
A singlet oxygen self-reporting photosensitizer for cancer phototherapy
Authors: Xiong Tao , Li Mingle , Chen Yingchao , Du Jianjun , Fan Jiangli , Peng Xiaojun
Published: November 2020

Photodynamic cancer therapy has attracted great attention with the increasing threat of tumors, and improving its therapeutic efficacy is highly desirable.
Correction: A straightforward approach to antibodies recognising cancer specific glycopeptidic neoepitopes
Authors: Wakui Hajime , Tanaka Yoshikazu , Ose Toyoyuki , Matsumoto Isamu , Kato Koji , Min Yao , Tachibana Taro , Sato Masaharu , Naruchi Kentaro , Martin Fayna Garcia , Hinou Hiroshi , Nishimura Shin-Ichiro
Published: November 2020

Correction for ‘A straightforward approach to antibodies recognising cancer specific glycopeptidic neoepitopes’ by Hajime Wakui et al., Chem. Sci., 2020, 11, 4999–5006, DOI: 10.1039/D0SC00317D.
Correction: Strongly coloured thiocyanate frameworks with perovskite-analogue structures
Authors: Cliffe Matthew J. , Keyzer Evan N. , Dunstan Matthew T. , Ahmad Shahab , De Volder Michael F. L. , Deschler Felix , Morris Andrew J. , Grey Clare P.
Published: November 2020

Correction for ‘Strongly coloured thiocyanate frameworks with perovskite-analogue structures’ by Matthew J. Cliffe et al., Chem. Sci., 2019, 10, 793–801, DOI: 10.1039/C8SC04082F.
A facile approach to construct organic D–π–A dyes via sequential condensation reactions for dye-sensitized solar cells
Authors: Chen Hongjin , Islam Ashraful , Chowdhury Towhid H. , Bedja Idriss , Ghaithan Hamid M. , Zhang Rui , Liu Jian
Published: November 2020

We developed a facile strategy to construct organic D–π–A dyes via sequential condensation reactions for dye-sensitized solar cells.
Observation of early ZIF-8 crystallization stages with X-ray absorption spectroscopy
Authors: Buzanich Ana Guilherme , Kulow Anicó , Kabelitz Anke , Grunewald Christian , Seidel Robert , Chapartegui-Arias Ander , Radtke Martin , Reinholz Uwe , Emmerling Franziska , Beyer Sebastian
Published: November 2020

The present study investigates structural evolution of early ZIF-8 crystallization up to 5 minutes post mixing of precursor solutions using Dispersive X-ray Absorption Spectroscopy (DXAS).
Ionic strength and polyelectrolyte molecular weight effects on floc formation and growth in Taylor–Couette flows
Authors: Metaxas Athena E. , Panwar Vishal , Olson Ruth L. , Dutcher Cari S.
Published: November 2020

A Taylor–Couette cell capable of radial injection was used to study the effects of varying solution ionic strength and polyelectrolyte molecular weight on the polyelectrolyte-driven flocculation of bentonite suspensions.
Suppression of spurious harmonic responses in superconducting microstrip spiral filters using gold overlay and stagger tuning
Authors: Huang Frederick , Bolli Pietro , Mariotti Sergio
Published: November 2020

The higher order resonances of microwave superconducting filters with spiral resonators were suppressed, giving a very wide stop‐band. In one filter spirals were modified to have equal fundamental resonances, but different higher order resonances, by adding stubs and using non‐uniform line width. The higher resonances were reduced to −39 dB, in a stop band up to 4.3 times the pass band centre. In another filter, parasitic resistive resonators were added, suppressing the responses to −57 dB. The resistance is provided by patterning the 200 nm gold overlay already required for the external contacts. The increase in pass band loss is not measurable. Measurements of a single spiral resonator with a gold‐YBCO bi‐layer (200 and 600 nm respectively) suggest that the resistivity of the gold layer at 15 K is the order of 22 times that of bulk gold, a slight advantage for the present application. At 100 K, it is about double.
Towards higher temperatures in nuclear waste repositories
Authors: Gens Antonio , de Vasconcelos Ramon B. , Olivella Sebastià
Published: November 2020

Recently, there is a tendency to explore the possibility of increasing the maximum design temperature in deep geological repositories for high-level nuclear waste and spent fuel. In the paper, a number of issues related to the use of higher temperatures are reviewed. Both bentonite barriers and argillaceous host rocks are addressed. An application involving the modelling of a large-scale field test conducted at a maximum temperature of 140ºC is presented. It is shown that currently available theoretical formulations and computer codes are capable to deal with temperatures above 100ºC and to reproduce satisfactorily the thermally-induced overpressures in the rock.
The EGS Collab Project: An intermediate-scale field test to address enhanced geothermal system challenges
Authors: Timothy Kneafsey ,   the EGS Collab Team
Published: November 2020

Three components are typically needed to extract geothermal energy from the subsurface: 1. hot rock, 2. a heat transfer fluid, and 3. flow pathways contacting the fluid and the rock. These naturally occur in many locations resulting in hydrothermal systems, however there are enormous regions containing hot rock that do not naturally have adequate fluid, and/or appropriate fluid permeability to allow hot fluid extraction. Some type of engineering or enhancement of these systems would be required to extract the energy. These enormous regions provide the possibility of long-term extraction of significant quantities of energy. Enhanced (or engineered) Geothermal Systems (EGS) are engineered reservoirs created to extract economical amounts of heat from low permeability and/or porosity geothermal resources. There are technological challenges that must be addressed in order to extract the heat. These include proper stimulation, effective monitoring, reservoir control, and reservoir sustainability. The US DOE Geothermal Technologies Office and geothermal agencies from other countries have supported field tests over a range of scales and conditions. A current US field project, the EGS Collab Project, is working nearly a mile deep in crystalline rock at the Sanford Underground Research Facility (SURF) to study rock stimulation under EGS stress conditions. We are creating intermediate-scale (tens of meters) test beds via hydraulic stimulation and are circulating chilled water to model the injection of cooler water into a hot rock which would occur in an EGS, gathering high resolution data to constrain and validate thermal-hydrological-mechanical-chemical (THMC) modeling approaches. These validated approaches would then be used in the DOE’s flagship EGS field laboratory, Frontier Observatory for Research in Geothermal Energy (FORGE) underway in Milford, Utah and in commercial EGS. In the EGS Collab project, numerous stimulations have been performed, characterized, and simulated and long-term flow tests have been completed.
Energy geostructures: Theory and application
Authors: Rotta Loria Alessandro F.
Published: November 2020

The subsurface represents space and resource of ever-growing importance to meet human activity needs associated with the availability of built environments and energy. So-calledenergy geostructuresrepresent a breakthrough technology in this context. By integrating the structural support role of earth-contact structures with the heating-cooling role of shallow geothermal heat exchangers, energy geostructures can sustain or enclose built environments while providing them with renewable thermal energy. Despite such promising features, the integrated roles of energy geostructures pose various challenges to understand their behavior and performance, and to address the related analysis and design. Appropriate formulation and application of scientific theory are crucial for the successful analysis and design of energy geostructures. This Bright Spark Lecture Paper presents selected theory for addressing the behavior and performance of energy geostructures, and discusses the application of this theory to analysis and design. In this context, the work focuses on energy piles and barrettes, energy tunnels, as well as energy walls and slabs. The ultimate goal of this paper is to provide competence for facilitating future research and development of energy geostructures across science and engineering.
Seismic velocity change in sandstone during CO2 injection
Authors: Gutierrez Marte , Katsuki Daisuke , Almrabat Abdulhadi
Published: November 2020

This paper presents analytical and experimental studies of the effects of supercritical CO2 injection on the seismic velocity of sandstone initially saturated with saline water. The analytical model is based on poroelasticity theory, particularly the application of the Biot-Gassmann substitution theory in the modeling of the acoustic velocity of porous rocks containing two-phase immiscible fluids. The experimental study used a high pressure and high temperature triaxial cell to clarify the seismic response of samples of Berea sandstone to supercritical CO2 injection under deep saline aquifer conditions. Measured ultrasonic wave velocity changes during CO2 injection in the sandstone sample showed the effects of pore fluid distribution in the seismic velocity of porous rocks. CO2 injection was shown to decrease the P-wave velocity with increasing CO2 saturation whereas the S-wave velocity was almost constant. The results confirm that the Biot-Gassmann theory can be used to model the changes in the acoustic P-wave velocity of sandstone containing different mixtures of supercritical CO2 and saline water provided the distribution of the two fluids in the sandstone pore space is accounted for in the calculation of the pore fluid bulk modulus.
Verification benchmark for a single-phase flow hydro - mechanical model comparison between COMSOL Multiphysics and DuMuX
Authors: Zhou Dejian , Tatomir Alexandru , Tomac Ingrid , Sauter Martin
Published: November 2020

Numerical modelling of hydromechanical processes in geological environments has become an invaluable tool in understanding and predicting system behaviour. However, due to the different algorithms and numerical schemes implemented in the different models, model reliability may vary considerably. Modelling of single- and multi-phase flow in porous media has been widely employed in various engineering applications such as geological disposal of nuclear waste, geological storage of carbon dioxide, high-temperature geothermal systems, or hydraulic fracturing for shale gas exploitation. Coupled hydro-mechanical (H-M) processes play a key role in the prediction of the behaviour of geological reservoirs during their development and testing operations. In this paper, we present a benchmark test on a single-phase flow problem in a hydrogeological reservoir with 5 horizontal layers of different properties. The aim is to compare two hydromechanical (H-M) models that use a vertex-centred finite-volume discretization and a finite element discretization. The first model is constructed with the free-open source simulator DuMuX, and the second with the commercial software COMSOL Multiphysics. The verification study suggests general confidence in the model reliability, but also highlights and discusses several areas of discrepancies between two models.
CO2-enriched brine injection’s impact on mechanical properties of a sandstone specimen
Authors: Foroutan Maziar , Ghazanfari Ehsan
Published: November 2020

CO2 capture and geological sequestration is one of the most practical and efficient methods of mitigating anthropogenic CO2 emissions. Due to the uncertainties associated with CO2 injection into deep saline reservoirs, the interaction between the host rock and the injected CO2 needs to be better understood as it can lead to considerable pore-structure changes. The geochemical reactions, especially mineral dissolution, can compromise the mechanical properties of the reservoir rock, which consequently threatens the reservoir stability and integrity. Therefore, it is crucial to capture the variation of mechanical properties of the reservoir rock upon CO2 injection. In this study the variation of elastic properties (e.g. Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio) of a brine-saturated sandstone specimen upon injecting CO2-enriched brine is investigated. The elastic properties of the specimen were initially characterized through multi-stage elastic (MSE) test before injecting the CO2-enriched brine. Then, the synthetic brine solution was enriched with CO2 and injected into the brine saturated sandstone specimen. The mechanical test results revealed that a significant mechanical weakening occurred upon injecting CO2-enriched brine into the sandstone specimen. This mechanical degradation can be attributed to the dissolution of calcite and clay minerals. The results from this study indicated that the mechanical deterioration of reservoir rock during CO2 injection should be considered through the entire CO2 sequestration process (i.e. site selection, injection operation, and post-injection monitoring).
CO2 geological storage: Microstructure and mechanical behavior of cement modified with a biopolymer after carbonation
Authors: Barría Juan Cruz , Manzanal Diego , Pereira Jean-Michel , Ghabezloo Siavash
Published: November 2020

Large amounts of CO2 could be stored underground in deep rock reservoirs and could help reducing emissions into the environment. Carbon geo-storage technologies have several years in development and new techniques and materials are being studied to make this procedure more effective and less expensive. The risk of leakage from geological reservoirs to other rock formations or even towards the surface means that long-term behavior must be carefully studied. The carbonation of the cement used for sealing the wellbore may compromise the borehole integrity. In light of this problem, this work aims to analyze the poromechanical behavior of cement with and without a new additive in a CO2 environment. Bacterial nanocellulose is a biopolymer that modifies important cement properties such as compressive strength, thermal behavior and hydration degree. Two cement types were studied: class G cement and modified class G cement with bacterial nanocellulose. These samples were submitted to a supercritical CO2 environment (temperatures higher than 32 °C and pressures higher than 8 MPa) during 30 days. Mercury intrusion porosimetry and uniaxial compressive strength tests were performed on these samples to study the effect of carbonation. Both types of cement are affected after carbonation by reducing compressive strength and Young’s modulus (E), however, the strength of modified cement was reduced by 8%, while non-modified cement was reduced by 20%.
Hot water injection in relation to 1982-84 microseismic events at Campi Flegrei Caldera by thermo-hydro-mechanical simulation
Authors: Akande Waheed Gbenga , Gan Quan , De Siena Luca , Cornwell David G.
Published: November 2020

The repeated deformations and seismic unrests at Campi Flegrei caldera (southern Italy) have been identified due to a fluid injection source in volcano active area. We investigated the role of hot water injection in the seismic unrests of 1982-1984 with a view to gaining insights into the caldera’s dynamics, by applying coupled TOUGHREACT-FLAC3Dsimulator to our computational domain of 10 × 1 × 3 km with a single-phase steam isothermal (HM) and non-isothermal (THM) simulations comparison. The results indicated that the overlying caprock blocks the uprising hot water injection, leading to the building up of pore pressure and shear stress underneath over time. This process substantially modified the ambient stress regime, strained the caprock, led to microfractures formation which enhanced hydraulic properties of the system, and ultimately provided conductive migration pathways for hot fluids to pressurize the shallow overlying fault. The prolonged shear stress accumulation period culminated in shear fracturing, dilation and fault slips, whose displacements are in order of millimetres to few centimetres. The moment magnitudes of seismicity generated were generally in order of 3.0. The seismic slips occurred at ~7 and ~6 days under HM and THM cases, respectively – giving a time delay in the order of ~1 day in the isothermal case. A comparison of our results for isothermal and non-isothermal cases suggests that seismic slips occurred generally earlier at higher fluid injection rates and under non-isothermal conditions. Further examinations of thermal effects showed that fault slips generally occur earlier at higher injection temperatures and/or at high host rock/fluid injection temperature contrasts. At very low permeabilities (e.g., 10-19m2), fault slips were delayed and the required time for shear stress accumulation to trigger slips is about 8 days. It is concluded that an interplay among variables such as injection rates, fluid injection temperatures and caprock permeabilities determines the timing of a seismic fault slip and associated seismicity at the caldera.
Effect of fracture orientation on ultrasonic wave signatures
Authors: KC Bijay , Ghazanfari Ehsan
Published: November 2020

Fluid flow through low-permeable rock masses is dominated by transport through discontinuities such as fractures, faults, and joints present in the rock. These discontinuities are beneficial for some geo-resources such as geothermal, oil and gas reservoir, but detrimental for other applications such as CO2 storage and hazardous waste isolation. Fracture orientation plays a critical role during the design of the geo-resources. Often times, ultrasonic waves are used in the field to locate and characterize the fractures. In this study, the effect of fracture orientation (0° to 90°) on ultrasonic wave signatures was investigated by conducting a series of experiments on a granite rock with a longitudinal fracture under confining pressures of 15, 30, and 45 MPa. Ultrasonic wave signatures during the experiment were collected using the ultrasonic transducers embedded in the core holders that were attached to the two ends of the specimen. Results indicated sensitivity of the ultrasonic wave velocities, waveforms, and amplitudes (cross-polarized S-waves) to the fracture orientation.
Geomechanical properties of the Vaca Muerta Formation
Authors: Espinoza D. Nicolas
Published: November 2020

Unconventional oil and gas resources have transformed the energy industry in the United States. Likewise, other countries have followed up with hydrocarbon exploitation from tight unconventional formations. One of the most developed unconventional fields outside North America is the Vaca Muerta Formation in the Neuquén Basin, Argentina. This study summarizes experimental results of quasi-static loading and elastic wave propagation in rocks from the Vaca Muerta Formation along the entire producing interval. The work summarizes experimental results from our laboratory and from the literature. The results highlight the variability of mechanical properties with mineralogy and composition, and the mechanical anisotropy induced by layering. The discussion section explores the implications of spatial variability and anisotropy on in-situ stresses and fluid-driven fractures. Accurate characterization of rock mechanical properties is critical for predicting the geometry of fluid-driven fractures in unconventional rock formations, particularly those subjected to a tectonically active environment such as the Vaca Muerta Formation.
Aspects of drying and cracking of geomaterials in energy applications
Authors: Mielniczuk Bolesław , El-Youssoufi Said Moulay , Hueckel Tomasz
Published: November 2020

Because of common exposure to high temperatures and forced ventilation of geomaterials in energy production and storage, their failure mode often involves intense drying and constrained shrinkage associated cracking. Previous experiments show that drying cracking occurs when the materials are completely saturated, practically simultaneously with the onset of air entry and start of desaturation. The paper reports on the adhesion forces evolving in drying granular clusters and their critical value associated with the first air entry and formation of the drying cracks, as well as a critical saturation for meso-scale evaporating several grain cluster models of different porosities.
Shear strength behaviour of sand-bentonite mixtures with pumice additivite under high temperature
Authors: Güneri Esra , Yükselen Aksoy Yeliz
Published: November 2020

Depending on increase in the number and type of energy geostructures, studies on the change in soil behavior against heat increase becomes more important. The engineering properties such as permeability, volume deformation of surrounding soils around energy structures mustn’t alter in the presence of heat and thermal cycles. Pumice is a material used in many fields especially for thermal insulation. For that reason, pumice can be used for increasing the resistance of soils in the presence of heat. In this study, the shear strength behavior of sand-bentonite mixtures was investigated with pumice additive under high temperature. In the experiments, 10% and 20% pumice were added to 10% and 20% sand-bentonite mixtures and compaction, direct shear tests were conducted. The direct shear tests were performed both room temperature and under 80°C. The results have shown that the pumice additive increased the shear strength of sand-bentonite mixtures under high temperature when compared the test results under room temperature.
Numerical modelling of a geothermal pile in tropical environment based on a TRT Test
Authors: de Almeida Caique R. , Boscov Maria Eugênia G. , Albuquerque Neto Cyro , de H.C.Tsuha Cristina
Published: November 2020

The continuous search for sustainable renewable energy sources has motivated the use of geothermal piles to heat or cool buildings, resulting in lower electric energy consumption. Geothermal piles are foundation elements used to provide structural support and thermal comfort. In countries with tropical climate, geothermal piles dissipate heat from the internal environment of the building to the foundation soil. This paper presents a numerical model of a geothermal pile inserted in a saturated sandy soil in São Paulo City, Brazil. The model was developed with ANSYS CFX version 19.2 program, a high performance CFD (Computational Fluid Dynamics) tool. Data from a Thermal Response Test (TRT) carried out for 10 days in the campus of São Paulo University was used to calibrate the model. The development of the model comprised experimental data, geometry, mesh, boundary conditions and simplifying assumptions. The calibration was carried out as back-analysis of experimental data. The obtained numerical results are considerably close to the experimental results, showing that the model is consistent. The validated model will be used to study the influence of geotechnical, hydraulic, thermal, and geometrical parameters on heat transfer, involving water, pipes, concrete and soil.