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1.
Chemosphere ; 361: 142554, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38851502

RESUMO

Increasing multidrug-resistant pathogenic microbial around the world become a global problem, making it imperative to develop effective methods for bacterial inactivation in wastewater. In this study, we propose a multifunctional photoelectrochemical (PEC) system to successfully disinfect microbial cells and degrade orange (II) dyes. CoOx NP were synthesized by spin-coating onto hydrothermally synthesized TiO2 nanorod arrays followed by electrodeposited NiFe-LDH to develop the NiFe-LDH/CoOx NP-TiO2 NRs. Interestingly, spin-coated CoOx NP-TiO2 NRs exhibited a 1.5-fold enhancement in photocurrent (1.384 mA/cm2) than pristine TiO2 NRs (0.92 mA/cm2). A NiFe-layered double hydroxide (LDH) cocatalysts layer further exhibits the maximum photocurrent density of 1.64 mA/cm2 with IPCE of 84.5% at 1.0 VAg/AgCl at 380 nm. Furthermore, NiFe-LDH/CoOx-TiO2 NR photoanodes were effectually employed for photoelectrochemical bacteria disinfection and organic pollutant removals. With NiFe-LDH/CoOx-TiO2 NR, 99% (120 min) bacterial inactivation and 99% (60 min) orange II dye decomposition efficiency was achieved. Superoxide radicals (-O2•), hydroxyl radicals (HO•), and holes (h+) played a critical role in the PEC degradation systems. Due to the synergy between NiFe-LDH cocatalyst and CoOx interlayer, surface water oxidation reactions were accelerated over NiFe-LDH/CoOx NP-TiO2 NRs. The charge transport process in NiFe-LDH/CoOx NP-TiO2 NRs photoanode-based PEC system was proposed in detail.


Assuntos
Eletrodos , Titânio , Águas Residuárias , Titânio/química , Águas Residuárias/química , Catálise , Técnicas Eletroquímicas/métodos , Poluentes Químicos da Água/química , Hidróxidos/química , Eliminação de Resíduos Líquidos/métodos , Processos Fotoquímicos , Nanotubos/química , Corantes/química , Compostos Azo/química , Purificação da Água/métodos , Desinfecção/métodos
2.
Mol Cells ; 47(6): 100075, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38823606

RESUMO

Excessive blood vessel wall thickening, known as intimal hyperplasia, can result from injury or inflammation and increase the risk of vascular diseases. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) plays key roles in tumor surveillance, autoimmune diseases, and apoptosis; however, its role in vascular stenosis remains controversial. Treatment with recombinant isoleucine zipper hexamerization domain soluble TRAIL (ILz(6):TRAIL) significantly inhibited the progression of neointimal hyperplasia (NH) induced by anastomosis of the carotid artery and jugular vein dose dependently, and adenovirus expressing secretable ILz(6):TRAIL also inhibited NH induced by balloon injury in the femoral artery of rats. This study demonstrated the preventive and partial regressive effects of ILz(6):TRAIL on anastomosis of the carotid artery and jugular vein- or balloon-induced NH.


Assuntos
Hiperplasia , Neointima , Ratos Sprague-Dawley , Ligante Indutor de Apoptose Relacionado a TNF , Animais , Neointima/patologia , Neointima/prevenção & controle , Ratos , Masculino , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Artérias Carótidas/patologia , Artérias Carótidas/cirurgia , Veias Jugulares/patologia , Artéria Femoral/lesões , Artéria Femoral/patologia , Artéria Femoral/cirurgia
3.
Sci Rep ; 14(1): 11453, 2024 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-38769161

RESUMO

Stratified water columns are often found in lakes and oceans. Stratifications result from differences in density due to salt concentration, temperature, solid content and oxygenation. The stability of stratifications affects bioactivity, sedimentation, contaminant transport and environmental remediation. This study investigates the evolution of 6 stratified water columns created by differences in salinity, suspended minerals and the presence of a bottom heat source. We use acoustic wave reflection, photography, and both electrical conductivity and temperature profiles to track changes in stratification. Results show that multiple concurrent processes emerge across layers in otherwise quiescent water bodies. Dissimilar chemo-thermo conditions give rise to chemical and thermal diffusion, convection, and double-diffusion convection. When stratification involves suspended particles, interlayer processes include diffusiophoresis, flocculation/aggregation, sedimentation, osmosis, and chemo-consolidation; in this case, the specific surface and surface charge of suspended particles, and the salt concentration in contiguous layers determine aggregation-sedimentation-consolidation patterns. The interlayer transition zone acts as a high-pass filter that preferentially reflects low-frequency long-wavelength P-waves; invasive thermal and electrical conductivity probes provide complementary information and may identify stratification even when it is undetected by acoustic signals.

4.
J Environ Manage ; 360: 121161, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38761626

RESUMO

Recent attention on the detrimental effects of pharmaceutically active compounds (PhACs) in natural water has spurred researchers to develop advanced wastewater treatment methods. Carbamazepine (CBZ), a widely recognized anticonvulsant, has often been a primary focus in numerous studies due to its prevalence and resistance to breaking down. This study aims to explore the effectiveness of a bio-electrochemical system in breaking down CBZ in polluted water and to assess the potential harmful effects of the treated wastewater. The results revealed bio-electro degradation process demonstrated a collaborative effect, achieving the highest CBZ degradation compared to electrodegradation and biodegradation techniques. Notably, a maximum CBZ degradation efficiency of 92.01% was attained using the bio-electrochemical system under specific conditions: Initial CBZ concentration of 60 mg/L, pH level at 7, 0.5% (v/v) inoculum dose, and an applied potential of 10 mV. The degradation pathway established by identifying intermediate products via High-Performance Liquid Chromatography-Mass Spectrometry, revealed the complete breakdown of CBZ without any toxic intermediates or end products. This finding was further validated through in vitro and in vivo toxicity assays, confirming the absence of harmful remnants after the degradation process.


Assuntos
Biodegradação Ambiental , Carbamazepina , Poluentes Químicos da Água , Carbamazepina/toxicidade , Poluentes Químicos da Água/toxicidade , Águas Residuárias/química , Animais
5.
Chemosphere ; 360: 142450, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38801902

RESUMO

Herein, we successfully synthesized Hf/Zr co-doping on Fe2O3 nanorod photocatalyst by a hydrothermal process and quenching methods. The synergistic roles of Hf and Zr double-doping on the bacteria inactivation test and decomposition of organic pollutants were investigated in detail for the 1 wt% CoOx loaded Hf/Zr-Fe2O3 NRs and CuOx/CoOx loaded Hf/Zr-Fe2O3 NRs photocatalyst. Initially, the rod-like porous morphology of the Hf/Zr-doped Fe2O3 NRs was produced via a hydrothermal method at various Hf co-doping (0, 2, 4, 7 and 10)%. Further, CoOx and CuOx loaded by a wet impregnation approach on the Hf/Zr-Fe2O3 NRs and a highly photoactive Hf(4)/Zr-Fe2O3 [CoOx/CuOx] NRs photocatalyst were developed. After the Hf(4)/Zr-Fe2O3 [CoOx/CuOx] NRs photocatalyst treatment, the Bio-TEM imagery of bacterial cells showed extensive morphological deviations in cell membranes. Hf(4)/Zr-Fe2O3 NR achieved 84.1% orange II degradation upon 3 h illumination, which is higher than that of Hf-Fe2O3 and Zr-Fe2O3 (68.7 and 73.5%, respectively). Additionally, the optimum sample, Hf(4)/Zr-Fe2O3 [CoOx/CuOx] photocatalyst, exhibited 95.5% orange II dye degradation after light radiation for 3 h. Optimized Hf(4)/Zr-Fe2O3 [CoOx/CuOx] catalysts exhibited 99.9% and 99.7% inactivation of E. coli and S. aureus with 120 min, respectively. Further, scavenger experiments revealed that the electrons are the primary responsible species for photocatalytic kinetics. This work will provide a rapid method for the development of high photocatalytic performance materials for bacterial disinfection and organic degradation.


Assuntos
Antibacterianos , Cobre , Compostos Férricos , Nanotubos , Zircônio , Zircônio/química , Antibacterianos/química , Antibacterianos/farmacologia , Catálise , Nanotubos/química , Compostos Férricos/química , Cobre/química , Cobre/farmacologia , Háfnio/química , Óxidos/química , Cobalto/química , Processos Fotoquímicos
6.
Sensors (Basel) ; 23(21)2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37960409

RESUMO

Interfacial tension varies with temperature. This paper investigates the effects of temperature-dependent interfacial tension on shear wave velocity. We designed a nylon cell equipped with bender elements in a cross-hole configuration to measure the shear wave velocity of nine sand-silt mixtures with different degrees of saturation (S = 0%, 2.5%, 5%, 10%, and 100%). All specimens were subjected to a temperature change from 10 °C to 1 °C. The results demonstrate that shear wave velocity tends to be very sensitive to changes in temperature at a low degree of saturation. Particle-scale analyses overlapped with the experimental results and captured the critical role of temperature-dependent interfacial tension in small-strain skeletal stiffness. In fact, the temperature should be considered during laboratory and field shear modulus measurements of the long-term performance of energy geosystems subjected to thermally induced repetitive loads.

7.
J Appl Microbiol ; 134(12)2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37989872

RESUMO

AIM: To assess the effectiveness of Lentilactobacillus parafarraginis A6-2 cell lysate for the removal of aluminum (Al), which induces neurotoxicity, and its protective effect at cellular level. METHODS AND RESULTS: The cell lysate of the selected L. parafarraginis A6-2 strain demonstrated superior Al removal compared to live or dead cells. The Al removal efficiency of L. parafarraginis A6-2 cell lysate increased with decreasing pH and increasing temperature, primarily through adsorption onto peptidoglycan. Neurotoxicity mitigation potential of L. parafarraginis A6-2 was evaluated using C6 glioma cells. C6 cells exposed with increasing concentration of Al led to elevated toxicity and inflammation, which were gradually alleviated upon treatment with L. parafarraginis A6-2. Moreover, Al-induced oxidative stress in C6 cells showed a concentration-dependent reduction upon treatment with L. parafarraginis A6-2. CONCLUSIONS: This study demonstrated that L. parafarraginis A6-2 strain, particularly in its lysate form, exhibited enhanced capability for Al removal. Furthermore, it effectively mitigated Al-induced toxicity, inflammation, and oxidative stress.


Assuntos
Alumínio , Estresse Oxidativo , Humanos , Alumínio/toxicidade , Inflamação , Anti-Inflamatórios/farmacologia
8.
Int Microbiol ; 2023 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-37659056

RESUMO

Bisphenol A (BpA) is an endocrine-disrupting substance commonly found in plastics and resins. It is reported that BpA exposure induces lipid accumulation in humans, similar to obesogenic compounds. The main objective of this study is to investigate the removal of BpA using Lactiplantibacillus sp. D10-2, and to examine its potential for reducing BpA-induced lipid accumulation in 3T3-L1 cell line model. The heat-dried cells of Lactiplantibacillus sp. D10-2 showed 69.7% removal efficiency for initial BpA concentration of 10 µg/mL, which was 30.5% higher than the live cells. The absence of metabolites or intermediates in BpA removal studies indicates that the Lactiplantibacillus sp. D10-2 strain removed BpA by adsorption process. The hydrophobic interactions of heat-dried Lactiplantibacillus sp. D10-2 cells were observed to be higher with 33.7% compared to live cells (15.0%), suggesting a stronger ability to bind with BpA. Although the BpA binding onto Lactiplantibacillus sp. D10-2 was not affected by pH, it was confirmed that as the temperature increases, the binding ability got decreased due to mass transfer and diffusion of BpA molecules. Treatment with Lactiplantibacillus sp. D10-2 (0.1, 0.25, 0.5, 1%) reduced lipid accumulation by 61.7, 58.0, 52.7 and 60.4% in 3T3-L1 cells exposed with BpA. In addition, it was confirmed that Lactiplantibacillus sp. D10-2 treatment suppressed the protein expression levels of lipogenesis-related PPARγ and C/EBPα in 3T3-L1 cells. The results of the study suggest that the Lactiplantibacillus sp. D10-2 strain can remove BpA and reduce BpA-accelerated lipid accumulation in 3T3-L1 cells.

9.
Chemosphere ; 343: 140230, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37734496

RESUMO

Antibiotics have revolutionized modern day living with their ability to effectively treat infectious diseases in humans and animals. However, the release of antibiotic compounds into the environment has led to toxic consequences. To reduce this environmental impact, it is important to employ an inexpensive and rational technology to reduce the amount of antibiotics released into the ecosystem. This study aims to explore the potential of using a bio-electrochemical system (BES) to remove Amoxicillin (AMX) from artificially contaminated soil using a microbial consortium and pure culture isolates. Under desired conditions, including an initial AMX concentration of 150 mg/L, 5 mg/L tryptone as the nitrogen source, pH of 7, temperature of 29 °C, an applied potential of 0.8 V, and an inoculum dose of 1% w/v, the BES showed a maximum degradation of 97.9% of AMX with the microbial consortium (HP03, HP09, and HP10). High performance liquid chromatography-mass spectrometry was used to analyse the intermediates formed during the degradation process, and the pathway elucidated revealed complete degradation of AMX. Phytotoxicity studies and degradation efficiency against multiple antibiotics confirmed the environmental significance of the BES with microbial consortium. Overall, this study highlights the potential of BES as a cost-effective and efficient method for reducing the release of antibiotics into the environment and provides valuable insights into the mechanisms and pathways of antibiotic degradation.


Assuntos
Amoxicilina , Ecossistema , Humanos , Animais , Amoxicilina/análise , Antibacterianos/química , Bactérias/metabolismo , Instalações de Eliminação de Resíduos
10.
Food Sci Biotechnol ; 32(9): 1257-1268, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37362805

RESUMO

The limited yield of Ulmus davidiana var. japonica root bark (URB) extract is considered an economic loss to the food industry. Improving extraction yield and bioactivity through fermentation increase the industrial usage of URB. The study aims to optimize the fermentation with cellulolytic and pectinolytic bacteria and evaluate the bioactivity and anti-Helicobacter pylori activity of the fermented URB extract. URB fermentation with the Bacillus licheniformis FLa3, isolated from salted seafood (Sardinella zunasi), under optimal conditions (37 °C, pH 6, 10% inoculum dose, and 36 h) improved the extraction yield by 36% compared to the control. The antioxidant and antimicrobial activity of the fermented extract were significantly higher than non-fermented extract. High-performance liquid chromatography results confirmed that the fermentation increased the proportion of bioactive components such as catechin (171.7%), epicatechin (144.3%), quercetin (27.3%), and kaempferol (16.7%). The results confirmed that the fermentation increased both the extraction yield and bioactivity.

11.
Mycobiology ; 51(2): 67-71, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37122682

RESUMO

A powdery mildew (Erysiphaceae) has been continuously collected on the leaves of Lonicera harae in the southern part of the Korean Peninsula, where this shrub is indigenous. Microscopic examination of the asexual morphs revealed that the current collections are differentiated from the all known Erysiphe species on Lonicera spp. by its longer conidiophores and longer conidia. Although the morphology of the chasmothecia is reminiscent of Erysiphe ehrenbergii and E. lonicerae, the specimens on L. harae differ from them in having smaller ascospores. A phylogenetic tree generated from a combined dataset of the internal transcribed spacer region and 28S rDNA gene sequences demonstrates that sequences obtained from three powdery mildew collections on L. harae clustered together as an independent species clade with high bootstrap values distant from other Erysiphe species on Lonicera, representing a species of its own. Based on morphological differences and molecular-phylogenetic results, the powdery mildew on L. harae is proposed as a new species, Erysiphe lonicerigena, and the holomorph of the fungus is described and illustrated in this study.

12.
J Extracell Vesicles ; 11(10): e12274, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36239712

RESUMO

Extracellular vesicles (EVs) are nano-sized membranous structures involved in intercellular communication and various physiological and pathological processes. Here, we present a novel method for rapid (within 15 min), large-scale production of high-purity EVs using eMTDΔ4, a peptide derived from Noxa. The treatment of mesenchymal stem cells derived from human Wharton's jelly after trypsinization and subsequent eMTDΔ4 stimulation in a chemically defined sucrose buffer with orbital shaking led to a substantial increase (approximately 30-fold) in EV production with markedly high purity (approximately 45-fold). These EVs (TS-eEVs) showed higher regenerative and immunomodulatory potential than natural EVs obtained from the culture media after 48 h. The calcium chelator BAPTA-AM and calpain inhibitor ALLM, but not the natural EV biogenesis inhibitor GW4869, blocked the TS-eEV production induced by eMTDΔ4, indicating that the eMTDΔ4-mediated regulation of intracellular calcium levels and calpain activity are closely associated with the rapid, mass production of TS-eEVs. The present study may lead to considerable advances in EV-based drug development and production of stem cell-derived EVs for cell therapy.


Assuntos
Calpaína , Vesículas Extracelulares , Quelantes de Cálcio , Meios de Cultura , Humanos , Peptídeos , Sacarose
13.
Sci Rep ; 12(1): 16690, 2022 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-36202983

RESUMO

Foam cement is an engineered lightweight material relevant to a broad range of engineering applications. This study explores the effects of aluminum chips on cement-bentonite slurry expansion, pressure development, and the evolution of pore topology. The terminal volume expansion under free-boundary conditions or the pressure build up under volume-controlled conditions are a function of the aluminum mass ratio, bentonite mass ratio, and aluminum chip size. X-ray CT images show that finer aluminum chips create smaller pores but result in a larger volume expansion than when larger sized chips are used; on the other hand, large chip sizes result in unreacted residual aluminum. Time-lapse CT images clearly show the sequence of processes which lead to the development of foam cement: gas bubble nucleation, bubble growth, capillary-driven grain displacement enhanced by the presence of bentonite, coalescence, percolation, gas leakage and pore collapse. These results illustrate the potential to customize the mixture composition of chemically-induced gassy cement to control expansion and pressure build up, and to minimize percolating discontinuities and gas release.

14.
Healthcare (Basel) ; 10(7)2022 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-35885789

RESUMO

The quality of life (QoL) of an individual is affected in a complex way by the person's physical health, psychological state, social relationships, and their relationship to their environment. We assessed the QoL of international university students using the World Health Organization Quality of Life (WHOQOL-BREF) tool and explored the QoL-associated factors. We conducted a cross-sectional study between January and March 2021. The WHOQOL-BREF was summarized as a four-domain construct following the WHO guidelines and QoL scores for each domain were compared through a t-test and chi-squared test. To determine the factors associated with international students' QoL we used multiple linear regression models, with each of the domains serving as the outcome variable. In total, 261 students participated, with 52.5% being males. We reported predicted means (PM) along with 95% confidence intervals (CI). Cronbach's alpha for the overall WHOQOL-BREF tool was 0.88. Students' self-reported QoL mean score was 3.67 ± 0.71 and the mean score of their overall satisfaction with health was 3.61 ± 0.83. The social relationships domain had the highest mean score at 56.88 ± 19.55 and was significantly associated with age (>25 years: PM: 59.7; 95% CI: 56.2−63.2, p = 0.033) and region of origin (Asia: PM: 54.4; 95% CI: 42.5−64.8, p = 0.027). Students above 25 years had significantly higher scores in all domains (p < 0.05). Our results showed that the social relationships and psychological health domains have more positive impact on international students' QoL compared to the physical and environmental health domains. To cope with factors influencing international students' QoL, universities should develop and provide efficient support systems for foreign students in South Korea.

15.
Healthcare (Basel) ; 10(2)2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-35206809

RESUMO

Emotional intelligence plays an important role at the time of determination of job stress or in controlling emotions arising from job stress. This study uses a cross-sectional descriptive design to assess the extent of job stress, emotional intelligence, and burnout of general hospital administrative staff, and to identify an influencing effect of emotional intelligence on the relationship between job stress and burnout. Data were collected by using a structuralized questionnaire survey conducted on 191 administrative staff at 4 general hospitals in a metropolitan city in Korea in September 2021. The effects of emotional intelligence on the relationship between job stress and burnout were analyzed by using hierarchical multiple regression analysis. The results of analysis showed: (a) job stress and burnout displayed positive correlation (r = 0.57, p < 0.001) while (b) emotional intelligence and burnout displayed negative correlation (r = -0.26, p < 0.001), and (c) factors with significant effects on burnout included age (≥40 years), job stress, and emotional intelligence. Emotional intelligence had direct (independent) effects on burnout. Thus, the improvement of emotional intelligence is necessary to decrease burnout levels in general hospital administrative staff.

16.
Foods ; 10(9)2021 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-34574320

RESUMO

ε-Polylysine (ε-PL) is a safe food additive that is used in the food industry globally. This study evaluated the antimicrobial and antibiofilm activity of antibacterial peptides (ε-PL) against food poisoning pathogens detected in chicken (Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli). The results showed that minimum inhibitory concentrations (MICs) ranged between 0.031-1.0 mg/mL, although most bacterial groups (75%) showed MICs of 1.0 mg/mL. The reduction in the cell viability of pathogens due to ε-PL depended on the time and concentration, and 1/2 × MIC of ε-PL killed 99.99% of pathogens after 10 h of incubation. To confirm biofilm inhibition and degradation effects, crystal violet assay and confocal laser scanning microscopy (CLSM) were used. The biofilm formation rates of four bacterial groups (Salmonella, Listeria, E. coli, and multi-species bacteria) were 10.36%, 9.10%, 17.44%, and 21.37% at 1/2 × MIC of ε-PL, respectively. Additionally, when observed under a CLSM, ε-PL was found to induce biofilm destruction and bacterial cytotoxicity. These results demonstrated that ε-PL has the potential to be used as an antibiotic and antibiofilm material for chicken meat processing.

17.
J Microbiol Biotechnol ; 31(6): 875-881, 2021 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-34024890

RESUMO

The mitochondrial targeting domain (MTD) of Noxa contributes to its mitochondrial localization and to apoptosis induction. As a peptide, MTD fused with octa-arginine (R8), a CPP, induces necrosis related to intracellular calcium influx and destruction of mitochondria and endoplasmic reticulum. We searched for homologs of MTD, and compared their cell killing capability when fused with R8. Three of the seven peptides triggered cell death with similar mechanisms. The comparative analysis of peptide sequences showed that four amino acid sites of MTD are critical in regulating necrosis, suggesting the potential to generate artificial, adjustable cytotoxic peptides, which could be effective medicines for many diseases. Thus, homologs functionality could hint to the functions of their belonging proteins.


Assuntos
Proteínas Reguladoras de Apoptose/química , Morte Celular/efeitos dos fármacos , Retículo Endoplasmático/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Sequência de Aminoácidos , Proteínas Reguladoras de Apoptose/metabolismo , Cálcio/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Células HeLa , Humanos , Mitocôndrias/metabolismo , Necrose , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Oligopeptídeos/farmacologia , Domínios Proteicos , Espécies Reativas de Oxigênio/metabolismo , Alinhamento de Sequência
18.
Sensors (Basel) ; 21(9)2021 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-33923238

RESUMO

Freeze-thaw cycles caused by seasonal temperature fluctuations significantly affect the geotechnical engineering properties. This study investigated the crucial role of water distribution patterns in the characterization of elastic wave properties for the fine F-110 sand during a freeze-thaw cycle. Sand specimens with four different water distribution patterns were prepared, namely homogeneously-mixed, evaporation-driven, vertically-, and horizontally-layered specimens. The P- and S-wave signatures of the specimens were monitored using piezo crystal sensors. Results indicated the criticality of water distribution patterns in the determination of small-strain soil properties even though the specimens had identical global water saturation. The nuclear magnetic resonance-based water volume depth profiles indicated that the evaporation-driven specimens had more heterogeneous pore-invasive ice-bonding layers at a high water saturation region; by contrast, the drying process facilitated uniform meniscuses around the particle contacts near the air percolation threshold. Elastic wave measurements for laboratory-prepared specimens might over/underestimate the small-strain soil stiffness of sediments in nature, wherein the drying processes prevailed to control the water saturation. This study highlighted a clear transition from capillary-controlled to cementation-controlled elastic wave properties during temperature oscillations.

19.
Sensors (Basel) ; 21(7)2021 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-33917596

RESUMO

The major and minor components in granular soil materials determine their properties and behavior. This study explores the transitional behavior within threshold fines fraction of soil mixtures based on the data from the literature and experiments. From the literature survey, the void ratio, shear wave velocity, compression index, and friction angle capture the transitional turning point between the low and data-adjusted high threshold fines fractions. In particular, there is a dramatic change in hydraulic conductivity below the low threshold fines fraction that highlights the critical role of small amounts of fines in the fluid flow (e.g., clogging). From an experimental study, the engineering properties of natural soil samples identified using deformation and elastic wave sensors show transitional trends within the Revised Soil Classification System framework. The evolution of compressibility and shear wave velocity indicate that either coarse, fine, or both particles are likely to contribute to large and small strain stiffnesses when the effective stress is below 400 kPa. Thereafter, both engineering properties indicate that the soil sample retains a memory of in-situ overburden pressure when the effective stress is around 400 kPa. There is a critical role of fines that are slightly higher than low threshold fines fraction on engineering properties that promote the application of Revised Soil Classification System RSCS to natural soils.

20.
Sci Rep ; 10(1): 21692, 2020 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-33303780

RESUMO

Cell counts decrease with sediment depth. Typical explanations consider limiting factors such as water availability and chemistry, carbon source, nutrients, energy and temperature, and overlook the role of pore size. Our analyses consider sediment self-compaction, the evolution of pore size with depth, and the probability of pores larger than the microbial size to compute the volume fraction of life-compatible pores. We evaluate cell counts vs. depth profiles gathered at 116 sites worldwide. Results confirm the critical role of pore size on cell counts in the subsurface and explain much of the data spread (from ~ 9 orders of magnitude range in cell counts to ~ 2 orders). Cells colonize pores often forming dense biofilms, thus, cell counts in pores are orders of magnitude higher than in the water column. Similar arguments apply to rocks.


Assuntos
Carga Bacteriana , Sedimentos Geológicos/microbiologia , Porosidade , Microbiologia do Solo
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