A Comprehensive Investigation on Microscale Properties and Macroscopic Behavior of Natural Expansive Soils

Understanding the complicated behavior of expansive soil requires in-depth exploration of microscopic phenomena under varying situations, especially when the soil stays unsaturated and experiences swell-shrink cycles. This study is dedicated to a comprehensive investigation of eleven micro-scale properties that function as revealing factors of these electro-physico-chemical mechanisms and the associated surface forces. These microscale properties include: specific surface area (Sa), cation exchange capacity (CEC), surface conductance (λddl), soil acidity (pH), mineralogy (from X-ray diffraction), structure (from scanning electron microscopy), elemental composition (from energy-dispersive X-ray spectrometry), diffuse double layer thickness (t), real relative permittivity (κ'), effective conductivity (σ) and suction (s). Four naturally collected and two laboratory stabilized expansive soils were selected as the study objects. The roles of some microscale properties in determining the macroscopic behavior of volume change and shear strength have been thoroughly examined through experimental work including three dimensional water content-volume-suction studies and a triaxial test program on unsaturated specimens along three capillary paths. The effects of chemical stabilization by fly ash have also been extensively evaluated from a microscopic point of view.Some innovative testing and analysis approaches were proposed; highlights include (1) constructing a two-terminal electrode system integrated in conventional oedometer equipment and performing dielectric measurements on natural expansive soils at various hydromechanical stages; (2) quantifying diffused double layer (DDL) in terms of thickness and surface conductance; (3) establishing an unsaturated triaxial testprogram based on the predetermined hysteretic soil water characteristic curves (HSWCCs) and the chilled mirror hygrometer tests after shear. Additional newly developed approaches were applied in the studies of soil mineralogy, structure and pore fluid (e.g., assessment of the degree of interfacial polarization and the electrical anisotropy).This research establishes a comprehensive framework of expansive soil behavior based on experimental efforts and analysis founded in geology, geochemistry, electronics and geomechanics. The outcome will not only help field engineers explain and find solutions for natural threats on civil infrastructure caused by expansive soils, but also provide evidence and a database for verification or improvement of the present geophysical and mechanical constitutive models. Some potential research efforts, especially the imaging of intact soil structure and the adoption of dielectric testing as a common geotechnical practice, are suggested based on the findings of this study

Members of miR-169 family are induced by high salinity and transiently inhibit the NF-YA transcription factor

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are endogenously expressed small RNAs with a length of about 21 nt. MiRNAs silence their target genes at the post-transcriptional level. In plants, miRNAs play various developmental and physiological roles by cleavaging mRNAs predominantly. Drought and high salinity are the most severe environmental abiotic stresses and cause crop losses all over the world.</p> <p>Results</p> <p>In this study, we identified miR-169g and miR-169n (o) as high salinity-responsive miRNAs in rice. MiR-169n and miR169o were in a miRNA cluster with a distance of 3707 base pairs (bp). The high degree of conservation and close phylogenic distance of pre-miR-169n and pre-miR-169o indicated that they were derived from a very recent tandem duplication evolutionary event. The existence of a cis-acting abscisic acid responsive element (ABRE) in the upstream region of miR-169n (o) suggested that miR-169n (o) may be regulated by ABA. In our previous study, we found that miR-169g was induced by the osmotic stress caused by drought via a dehydration-responsive element (DRE). Thus, our data showed that there were both overlapping and distinct responses of the miR-169 family to drought and salt stresses. We also showed that these miR-169 members selectively cleaved one of the NF-YA genes, Os03g29760, which is a CCAAT-box binding transcription factor and participates in transcriptional regulation of large number genes. Finally, we found one or more ath-miR-169 member that was also induced by high salinity.</p> <p>Conclusion</p> <p>We identified members of the miR-169 family as salt-induced miRNAs and analyzed their evolution, gene organization, expression, transcriptional regulation motif and target gene. Our data also indicated that the salt-induction of some miR-169 members was a general property in plants.</p

Generation of Kerr soliton microcomb in a normally dispersed lithium niobate microdisk resonator by mode trimming

Anomalous microresonator dispersion is mandatory for Kerr soliton microcomb formation, which depends critically on the geometry of the microresonator and can hardly be tuned after the structure is made. To date, cavity-based microcombs have only been generated with fundamental whispering gallery modes (WGMs) of anomalous dispersion in microresonators. Moreover, microcomb generation in highly Raman-active platforms such as lithium niobate (LN) microresonators frequently suffers from stimulated Raman scattering and mode crossing due to the existence of multiple families of high-order WGMs. Here, we reveal a unique Kerr soliton microcomb generation mechanism through mode trimming in a weakly perturbed LN microdisk resonator. Remarkably, the soliton comb is generated with fundamental WGMs of normal dispersion and free from the mode crossing and Raman scattering effects. A robust soliton with a spectrum spanning from 1450 nm to 1620 nm at an on-chip pump power of 35 mW. Our discovery offers a powerful solution to circumvent the stringent requirements on high-precision dispersion engineering and termination of Raman excitation for soliton generation in the high-Q microdisk.Comment: 16 pages,and 5 figure

Electro-optically tunable low phase-noise microwave synthesizer in an active lithium niobate microdisk

Photonic-based low-phase-noise microwave generation with real-time frequency tuning is crucial for a broad spectrum of subjects, including next-generation wireless communications, radar, metrology, and modern instrumentation. Here, for the first time to the best of our knowledge, narrow-bandwidth dual-wavelength microlasers are generated from nearly degenerate polygon modes in a high-Q active lithium niobate microdisk. The high-Q polygon modes formation with independently controllable resonant wavelengths and free spectral ranges is enabled by the weak perturbation of the whispering gallery microdisk resonators using a tapered fiber. The stable beating signal confirms the low phase-noise achieved in the tunable laser. Owing to the high spatial overlap factors between the two nearly degenerate lasing modes as well as that between the two lasing modes and the pump mode, gain competition between the two modes is suppressed, leading to stable dual-wavelength laser generation and in turn the low noise microwave source. The measured microwave signal shows a linewidth of ~6.87 kHz, a phase noise of ~-123 dBc/Hz, and an electro-optic tuning efficiency of -1.66 MHz/V.Comment: 13 pages, 5 figure

Transcriptional activation of follistatin by Nrf2 protects pulmonary epithelial cells against silica nanoparticle-induced oxidative stress

Silica nanoparticles (SiO2 NPs) cause oxidative stress in respiratory system. Meanwhile, human cells launch adaptive responses to overcome SiO2 NP toxicity. However, besides a few examples, the regulation of SiO2 NP-responsive proteins and their functions in SiO2 NP response remain largely unknown. In this study, we demonstrated that SiO2 NP induced the expression of follistatin (FST), a stress responsive gene, in mouse lung tissue as well as in human lung epithelial cells (A549). The levels of Ac-H3(K9/18) and H3K4me2, two active gene markers, at FST promoter region were significantly increased during SiO2 NP treatment. The induction of FST transcription was mediated by the nuclear factor erythroid 2-related factor 2 (Nrf2), as evidenced by the decreased FST expression in Nrf2-deficient cells and the direct binding of Nrf2 to FST promoter region. Down-regulation of FST promoted SiO2 NP-induced apoptosis both in cultured cells and in mouse lung tissue. Furthermore, knockdown of FST increased while overexpression of FST decreased the expression level of NADPH oxidase 1 (NOX1) and NOX5 as well as the production of cellular reactive oxygen species (ROS). Taken together, these findings demonstrated a protective role of FST in SiO2 NP-induced oxidative stress and shed light on the interaction between SiO2 NPs and biological systems

Study on energy dynamic change law in the process of water-contained coal caused by liquid nitrogen freezing

To study the energy dynamic change law of moisture-contained coal in the process of liquid nitrogen freezing, a self-developed acoustic emission (AE) experimental system for the whole process of liquid nitrogen frozen coal was utilized to analyze the characteristics and the change laws of AE energy dissipation in the whole process of liquid nitrogen freezing in coal with different moisture contents. The results shown that AE energy during liquid nitrogen freezing of coal was divided into steep, fluctuating and calm periods in the time domain. The primary and secondary peaks of energy were both positively linearly related to moisture content, and the primary and secondary energy peak of 5.96% moisture content were 1.66 and 2.26 times higher than those of dry coal. The cumulative energy of liquid nitrogen frozen coal, divided into three stages of steep increase, slow growth and stabilization versus time, was positively linearly related to moisture content, which of 5.96% moisture contained coal was 2.88 times higher than that of dry coal. The energy amplitude of different moisture content coals was mostly concentrated in the range of 40-50 dB, accounting for 94.39%-99.11% of the total, and decreased linearly with the increasing moisture content of coal. The time series of acoustic emission ringing counts in liquid nitrogen frozen coals had chaotic fractal characteristics, and the correlation dimensions of the steep increase, slow growth and stable stages were positively exponentially, linearly and linearly correlated with the moisture content, respectively. Furthermore, the correlation dimension in the steep increase stage of 5.96% moisture contained coal was 2.00 and 5.78 times higher than that of the slow growth and stable stage, respectively. The type of coal cracks produced by the liquid nitrogen freezing was mainly tensile, its proportion with the increasing moisture content was a negative exponential decrease, and the proportion of shear cracks positively linearly increased with the increasing moisture content. The increase of moisture in coal strengthened the freezing and expansion force generated by the water-ice phase transition during the liquid nitrogen freezing process, and the increase of energy dissipation contributed to the rapid development of pore-crack and the structural damage and plastic deformation of coal. However, the structural damage was difficult to detect in real time and can be inverted by AE energy

Deciphering the contributions of cuproptosis in the development of hypertrophic scar using single-cell analysis and machine learning techniques

Hypertrophic scar (HS) is a chronic inflammatory skin disease characterized by excessive deposition of extracellular matrix, but the exact mechanisms related to its formation remain unclear, making it difficult to treat. This study aimed to investigate the potential role of cuproptosis in the information of HS. To this end, we used single-cell sequencing and bulk transcriptome data, and screened for cuproptosis-related genes (CRGs) using differential gene analysis and machine learning algorithms (random forest and support vector machine). Through this process, we identified a group of genes, including ATP7A, ULK1, and MTF1, as novel therapeutic targets for HS. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to confirm the mRNA expression of ATP7A, ULK1, and MTF1 in both HS and normal skin (NS) tissues. We also constructed a diagnostic model for HS and analyzed the immune infiltration characteristics. Additionally, we used the expression profiles of CRGs to perform subgroup analysis of HS. We focused mainly on fibroblasts in the transcriptional profile at single-cell resolution. By calculating the cuproptosis activity of each fibroblast, we found that cuproptosis activity of normal skin fibroblasts increased, providing further insights into the pathogenesis of HS. We also analyzed the cell communication network and transcription factor regulatory network activity, and found the existence of a fibroblast-centered communication regulation network in HS, where cuproptosis activity in fibroblasts affects intercellular communication. Using transcription factor regulatory activity network analysis, we obtained highly active transcription factors, and correlation analysis with CRGs suggested that CRGs may serve as potential target genes for transcription factors. Overall, our study provides new insights into the pathophysiological mechanisms of HS, which may inspire new ideas for the diagnosis and treatment