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As endogenous biomolecules, guanine, guanine-based nucleosides, and nucleotides are essential for cellular DNA/RNA synthesis, energy metabolism, and signal transduction. However, these biomolecules have been found to have a cell-specific antiproliferation effect at higher concentrations, and the mechanism is unclear. In this study, we demonstrate that guanine deaminase (GDA) is a major factor in determining the cell-type selectivity to the antiproliferation effect of guanine-based biomolecules. GDA catalyzes the deamination of guanine to xanthine, which is an essential part of the guanine degradation pathway. GDA deficient cells could not efficiently remove the excess guanine-based biomolecules. These excess molecules disturb the metabolism of adenine-, cytosine-, and thymine-based nucleotides; subsequently inhibit the DNA synthesis and cell growth; and eventually result in the apoptosis/death of GDA deficient cells. The inhibition of DNA synthesis could be relieved by simultaneous addition of adenine- and cytosine-based nucleosides, and the inhibited DNA synthesis could be restarted by post addition of them, which subsequently reduces the antiproliferation effect of guanine-based biomolecules or even totally restores the cell proliferation. These results provide important information for the development of guanine-based drugs or guanine-rich oligonucleotide drugs, as well as for the safety evaluation of food with a high level of guanine-based compounds.

In order to reduce noise in gamma-ray spectrum measured by carbon/oxygen logging instrument, an improved wavelet thresholding algorithm was proposed in this paper. This algorithm established a thresholding function with an adjustable parameter, which could obtain various filtering performances by means of different parameters, and then a modified genetic algorithm combined with opposition-based learning theory was put forward to optimize the parameter and wavelet thresholds. By using Monte Carlo simulation, the objective function of the modified genetic algorithm was determined. Finally, the actual measured spectra processing results of the optimized wavelet thresholding algorithm was compared with traditional thresholding algorithms and other filtering algorithms, and the effectiveness of the proposed algorithm was verified based on signal-to-noise ratio index.

Ovarian cancer is regarded as the most lethal gynecologic malignancy with poor prognosis and high mortality rate. Drug-resistance was thought to be the main obstacle to improving overall survival rate of ovarian cancer. New ligands for drug-resistant ovarian cancer cells have potential for the development of diagnosis and therapy of ovarian cancer. In present work, we reported two aptamers, HF3-58 and HA5-68 generated by cell-SELEX, against a paclitaxel-resistant ovarian cancer cell line (A2780T). Both two aptamers exhibited high selectivity and strong affinity to target cells with low nanomolar dissociation constants. The binding of aptamers to target cells was independent of divalent ions, and was tolerant of incubation temperature and nucleases in serum. Molecular targets of the two aptamers were preliminarily demonstrated to be two different glycoproteins on cell surface of A2780T cells. Owing to the structure stability and high resistance to nuclease, these two aptamers had good performance in the detection of drug-resistant ovarian cancer cells in human serum.

Aerosol particulate matter with dynamic diameter smaller than 2.5 μm (PM2.5) is the main cause for haze pollution in China. As a dominant precursor of PM2.5, SO2 emitted from industrial process is now strictly controlled by using limestone/gypsum Wet Flue Gas Desulfurization (WFGD) system in China. However, a phenomenon that fine particle derived from WFGD is recently addressed, and is suggested to be a potential source of primary PM2.5. Herein, a first investigation into the particle generation mechanism in WFGD system is conducted with a novel droplet (containing particles) drying and breakage model. The proposed model considers a random and porous crust instead of the previous regular crust assumption, and is verified by comparing the modeling results with measurements. An orthogonal test with four factors and three levels is carried out through modeling calculation, and flue gas temperature (Tg) in the inlet is found to be a governing parameter for PM2.5 yields in WFGD. With Tg in range of 120–160 °C, PM2.5 yields in desulfurizing tower can reach a maximum value at ∼2 × 108 cm−3 under typical WFGD condition. To avoid this situation and reduce the PM2.5 generation, Tg is suggested to be lower than 120 °C. Additionally, a new insight of the elimination effect of gas-gas heater (GGH) on “gypsum rain” in WFGD system is provided.

General cancer-targeted ligands that can deliver drugs to cells have been given considerable attention. In this paper, a high-affinity DNA aptamer (HG1) generally binding to human tumor cells was evolved by cell-SELEX, and was further optimized to have 35 deoxynucleotides (HG1-9). Aptamer HG1-9 could be taken up by live cells, and its target protein on a cell was identified to be human transferrin receptor (TfR). As a man-made ligand of TfR, aptamer HG1-9 was demonstrated to bind at the same site of human TfR as transferrin with comparable binding affinity, and was proved to cross the epithelium barrier through transferrin receptor-mediated transcytosis. These results suggest that aptamer HG1-9 holds potential as a promising ligand to develop general cancer-targeted diagnostics and therapeutics.

Viscosity of cell microenvironment plays a significant role in maintaining the normal life activities of cells. Particularly, the abnormal viscosity in mitochondria is closely associated with lots of diseases and cellular dysfunctions. Herein, we developed a group of p-aminostyryl thiazole orange derivatives with different amino side chains. These probes showed good fluorescence response to viscosity with twisted intramolecular charge transfer mechanism, among them, the probes with diethylamino (TOB), dibutylamino (TOC) and pyrrolidin (TOE) side chains showed better response to the viscosity with 78-fold, 55-fold, and 88-fold fluorescence enhancement in 95% glycerol solution respectively. TOB, TOC, and TOE could enter live cells and mainly located in mitochondria. Treatment HeLa cells with nystatin, lipopolysaccharide or oleic acid caused significant fluorescence enhancement of these probes, suggesting the good potential for monitoring the variation of mitochondrial viscosity, as well as for investigating the related physiological process of inflammation and lipid metabolism.

A blue light activated anti-cancer prodrug, NST, was designed based on a photoactive 4-aminonaphthalimide derivative and an anticancer drug, 10-hydroxycamptothecin. NST was hard to be taken up by living cells and showed negligible dark cytotoxicity. The irradiation caused photocleavage of NST and resulted in high cytotoxicity.

The slip velocity between phases is an important parameter for evaluating the volumetric flow rate of each phase in vertical pipes. This paper presents an improved empirical correction for calculating the slip velocity of two-phase, oil-water bubble flows in large-diameter vertical pipes, based on a series of experimental tests. Water holdup data were obtained through experiments on an oil-water mixture flowing through a transparent test section in a 16-m-long vertical pipe with an inner diameter of 124 mm. The water holdup ranged from 0.58 to 1, and the observed flow pattern was bubble flow. Based on these experimental data, a modified correction was developed to improve the accuracy of the prediction of slip velocity for oil-water bubble flow systems. In addition, the proposed correction was validated against published experimental data for pipes with diameters of 2–6 in. The performance of the proposed correction against an experimental dataset (from our tests and published data) was also compared with that of six other, widely accepted corrections. The proposed correction predicted the slip velocity of two-phase, oil-water bubble flow in large-diameter vertical pipes more accurately than previous corrections did.

Mycosis fungoides (MF), the most common form of cutaneous T-cell lymphoma, undergo large-cell transformation (LCT) in the late stage, manifesting aggressive behavior, resistance to treatments, and poor prognosis, but the mechanisms involved remain unclear. To identify the molecular driver of LCT, we collected tumor samples from 133 MF patients and performed whole-transcriptome sequencing on 49 advanced-stage MF patients, followed by integrated copy number inference and genomic hybridization. Tumors with LCT showed unique transcriptional programs and enriched expressions of genes at chr7q. Paternally expressed gene 10 (PEG10), an imprinted gene at 7q21.3, was ectopically expressed in malignant T cells from LCT, driven by 7q21.3 amplification. Mechanistically, aberrant PEG10 expression increased cell size, promoted cell proliferation, and conferred treatment resistance by a PEG10/KLF2/NF-κB axis in in vitro and in vivo models. Pharmacologically targeting PEG10 reversed the phenotypes of proliferation and treatment resistance in LCT. Our findings reveal new molecular mechanisms underlying LCT and suggest that PEG10 inhibition may serve as a promising therapeutic approach in late-stage aggressive T-cell lymphoma.

Elastic parameters are important parameters in the study of shale anisotropy, exploration, and development, and their accuracy is of great significance. In this study, shale in the lower Silurian Longmaxi Formation of southeastern Chongqing was investigated by obtaining the acoustic velocity of the partial bedding angle through an acoustic transmission experiment based on the elastic wave theory of the VTI medium and the least squares method, thus establishing a shale elastic parameter inversion method for improved accuracy. Results found that (1) the stratification angle was negatively correlated with the wave velocity; (2) velocity results calculated using the inversion-obtained elastic parameter were consistent with the measured results, with a maximum relative error of less than 1.52%, demonstrating that elastic parameters obtained by the proposed inversion method are valid; and (3) Longmaxi Formation shale has strong anisotropy, with the most significant direction of shear wave splitting being the direction in which the bedding angle is 0°. The results of this study provide a working foundation for using acoustic logging data to more accurately obtain the elastic parameters of shale and to study shale anisotropy characteristics, which have important theoretical value and practical significance.

The Permian Lucaogou Formation in the Jimusar sag, Junggar Basin, northwestern China, is increasingly receiving attention for its shale oil potential, which is still in the exploration stage. In this work, core samples were obtained from two wells in the Jimusar sag, and their mineralogy, pore structure, and fractal characteristics were investigated by XRD (X-ray diffraction) analysis, LPNA (low-pressure N2 adsorption) analysis, FE-SEM (field emission scanning electron microscopy), CTS (casting thin sections), and fractal analysis. The results showed that the major mineral compositions were plagioclase (average 34.82%), quartz (average 17.07%), and dolomite (average 17.66%). Compared with well-known marine shales in China, the shales have higher feldspar (average 44.64%) and carbonate (average 26.03%), and lower quartz (average 17.07%). Based on the FE-SEM and CTS, organic matter, intergranular, interlayer, dissolved, intercrystalline pores, and microfractures were observed. The specific surface area ranged from 10.181 to 26.648 m2/g, and the total pore volume was between 0.03595 and 0.07102 cm3/g. The results of the DFT-PSD curves indicated that shales showed multi-modal distribution characteristics, whereas the results of the BJH-PSDs curves revealed that shales displayed unimodal distribution characteristics with a peak between 20 and 40 nm. Pore sizes of less than 5 nm had an important influence on the specific surface areas, whereas pore sizes ranging from 20 to 40 nm had an important influence on the total pore volume. The fractal dimension values ranged from 2.7564 to 2.8382. The fractal dimension decreased as the average pore size increased and increased as the total pore volume and specific surface area increased.

Recently, the machine learning (ML) atomic force field has emerged as a powerful atomic simulation approach because of its high accuracy, low computational cost, and transferability. In this mini review, we first summarize the disadvantages of traditional force field and the unique advantages of ML-based force field for molecular dynamics simulations. Then the basic workflow to develop the ML atomic force field is discussed in each step. Furthermore, taking carbon material as a typical example, the various applications of ML-based force fields for studying the carbon allotropic materials are reviewed. Finally, the perspectives are discussed and future directions for studying atomic force field by ML are given.

To improve the evaluating ability of the electrical contact properties of the materials, a test device with a good comprehensive performance is designed based on eddy current repulsion mechanism. The working principle, mechanical structure and driving circuit of the device are introduced. A prototype of the device is made and tested. The result shows that the device has a wide range of speed regulation, wide application scope and small volume.

In order to solve the problems such as violent contact bounce, low utilization rate of core and coil materials of traditional AC contactor ， the dynamic characteristics and contact bounce of AC contactors with different inclined angles surface are simulated and analyzed based on electromagnetics and multi-body dynamics. On this basis, the improved pigeon colony optimization algorithm is used to optimize the electromagnetic mechanism of AC contactor, and the movement process of the armature and contact are captured by high-speed camera to verify the simulation results. Experimental results show that the contact bounce of AC contactor with inclined pole surface is effectively restrained, the core and coil materials are greatly reduced, and the economic benefits are improved.

Gas medium (N 2 , H 2 or N 2 -H 2 mixtures) and magnetic field are usually applied to extinguish the arc in high-voltage direct current (HVDC) relays. The presence of hydrogen will increase the probability of arc restriking, and when the arc extinguishing chamber is poorly sealed, it may also cause an explosion. The nitrogen reduces the probability of arc restriking, but the arc extinguishing time is similar to air. Therefore, in order to enhance the ability of arc extinguishing, avoid the arc restriking and increase the lifetime of the HVDC relay, the characteristics of the arc in the metal splitter plate and that of the arc root motion in the magnetic field are simulated by means of magnetohydrodynamics (MHD). The voltage and images of the arc are obtained by DC Arc Test System. The results show that increasing the external magnetic field is beneficial to the motion of the arc and shortens the time of arc movement on the contact surface. At the same time, the addition of the metal splitter plate on both sides of the contact is beneficial to increase the arc voltage and accelerate the arc extinguishing.

Large evaporite provinces (LEPs) represent prodigious volumes of evaporites widely developed from the Sinian to Neogene. The reasons why they often quickly develop on a large scale with large areas and thicknesses remain enigmatic. Possible causes range from warming from above to heating from below. The fact that the salt deposits in most salt-bearing basins occur mainly in the Sinian-Cambrian, Permian-Triassic, Jurassic-Cretaceous, and Miocene intervals favours a dominantly tectonic origin rather than a solar driving mechanism. Here, we analysed the spatio-temporal distribution of evaporites based on 138 evaporitic basins and found that throughout the Phanerozoiceon, LEPs occurred across the Earth’s surface in most salt-bearing basins, especially in areas with an evolutionary history of strong tectonic activity. The masses of evaporites, rates of evaporite formation, tectonic movements, and large igneous provinces (LIPs) synergistically developed in the Sinian-Cambrian, Permian, Jurassic-Cretaceous, and Miocene intervals, which are considered to be four of the warmest times since the Sinian. We realize that salt accumulation can proceed without solar energy and can generally be linked to geothermal changes in tectonically active zones. When climatic factors are involved, they may be manifestations of the thermal influence of the crust on the surface.

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) hold great potential for many important device applications, such as field effect transistors and sensors, which require a robust control of defect type, density, and distribution. However, how to control the defect type, density, and distribution in these materials is still a challenge. In this study, we explore the kinetics and dynamics of four types of grain boundaries (GBs) in monolayer MoS

Herein, we report a FnCas12a/crRNA assisted Dumbbell-PCR method for the detection of isomiRs with double specificity and magnification. The single nucleotide variant of isomiRs in terminals and/or inner sequence could be discriminated by this strategy. Using this method, let-7a isomiRs in MCF-7 and MCF-7R cell lines were analyzed.

Based on the cracked chevron notched Brazilian disc method, the I-type fracture toughness of Longmaxi Formation shale is measured and the influence of different factors on the fracture toughness of the shales are also discussed. The results show that the fracture toughness of the cores drilled parallel to the bedding ranges from 0.4744 to 0.8752 MPa m0.5 and that of the cores drilled perpendicular to the bedding ranges from 0.4259 to 0.6159 MPa m0.5, which means that the fracture toughness of shale is significantly anisotropy. The clay minerals in the shales have a positive effect on shale fracture toughness while the brittle minerals in shale play a negative role on shale fracture toughness. Being through high temperature processes, the microstructures of the shales are damaged, resulting in lower fracture toughness. Due to the hydration of shales, the interaction between the shale and the water leads to the decrease in the fracture toughness. The increase in the immersion pressure also cause the fracture toughness to decrease.

Circulating tumor-related materials (CTRMs) shed from original or metastatic tumors, carry a lot of tumor information and are considered as important markers for cancer diagnosis and metastasis prognosis. Herein, we report a colorimetric detection strategy for CTRMs based on aptamer-based magnetic isolation and endogenous alkaline phosphatase (AP)-signal amplification. This strategy exhibited high sensitivity and selectivity toward the CTRMs that express AP heterodimers (the target of aptamer, a potential tumor marker). For clinical samples, this CTRM assay significantly discriminated colorectal cancer patients (n = 50) from healthy individuals (n = 39, p < 0.0001). The receiver operating characteristic (ROC) analysis indicated the sensitivity and specificity reached 92% and 82%, respectively, at the optimal cutoff point, the area under the curve of ROC reached 0.93, suggesting great potential for colorectal cancer diagnosis and therapeutic monitoring. Compared with CTC assays, this strategy is simple and has the potential for point-of-care testing.

To remedy the lack of human leukocyte antigen (HLA)-matched donors and address the problems bedeviling traditional allogeneic hematopoietic stem cell transplantation which induces the resultant graft-versus-host disease, we designed a scheme called HLA-mismatched hematopoietic stem cell microtransplantation (MST) for patients with acute myeloid leukemia (AML), where encouraging results were achieved. In providing answers to such questions as how to select the donors of MST and which factors were involved in the outcome of MST. One hundred thirty-one AML patients from four centers with lower or standard risk of prognosis after complete remission were given three courses of MST: high dose of cytarabine plus infusion of granulocyte colony-stimulating factor mobilized peripheral blood stem cells from HLA-mismatched donors. Leukemia-free survival (LFS) and overall survival were compared, with respect to gender difference, number of HLA-matched loci, killer cell immunoglobulin-like receptor (KIR), and ligand mismatch between donors and recipients. Median LFS of recipients with different KIR ligands from those of donors was found to be significantly higher than that of recipients having identical ligands with donors (

Lycium barbarum L. is a widely used functional food and medicinal herb in Asian countries. L. barbarium polysaccharides (LBP) are considered as one of the major medicinal components of L. barbarium fruit and exhibits a wide range of biological activities. Here, we investigated the immunomodulatory effects of LBP and its uptake behaviors at the cellular level. LBP was prepared by water extraction and ethanol precipitation, and divided into two fractions based on the molecular weight distribution by ultrafiltration (LBP &gt, 10 kDa and LBP &lt, 10 kDa). The physicochemical properties of LBP and LBP fractions were well characterized. The LBP &gt, 10 kDa fraction greatly enhanced the viability of macrophages RAW264.7 cells and induced cell polarization, but had weak effects to other tested tumor cell lines and normal cell line. This fraction could regulate the production of NO, TNF-&alpha, IL-6 and ROS in RAW264.7 cells, suggesting both pro-inflammatory and anti-inflammatory effects. The dye-labeled LBP could be internalized into all tested cell lines and accumulated in lysosomes. The internalization of LBP in RAW264.7 cells is mainly through the clathrin-mediated endocytosis pathway. The Caco-2 intestinal transport experiment demonstrated that the dye labeled LBP could be transported through the Caco-2 cell monolayer (mimic intestinal epithelium) through clathrin-mediated endocytosis. These results demonstrate the immunomodulatory effects of LBP and its effective uptake by macrophages and intestine.

Grain boundaries (GBs) widely exist in black phosphorene (BP), which plays a vital role in determining the properties of 2D materials. Significant GB effect on the thermal boundary resistance in BP structures is found by using molecular dynamics calculations and lattice dynamic analysis. A remarkably high interface thermal resistance is observed. By analyzing the strain distribution and phonon vibrational spectra, we reveal this high thermal resistance originates from phonon localization and strong phonon boundary scattering induced by the local stress at the GB area. Particularly, it is interesting to find that the partial phonon modes display weak localization when GBs present. The fraction of atoms participating in a particular phonon vibrational mode has been quantified through the calculation of phonon participation ratio. In addition, the thermal boundary resistance is found size-dependent, which further induces interesting thermal rectification effect in the BP structures. A high rectification ratio is obtained by adjusting the structural length and temperature bias. These findings provide a through insight into the GB effects on individual phonon mode transmission across the GBs, and highlight that the GB effect is an important factor and should be taken into account for the applications of BP-based phononic devices.

Neurite outgrowth is the critical step of nervous development. Molecular probes against neurites are essential for evaluation of the nervous system development, compound neurotoxicity, and drug efficacy on nerve regeneration. To obtain a neurite probe, we developed a neurite-SELEX strategy and generated a DNA aptamer, yly12, that strongly binds neurites. The molecular target of yly12 was identified to be neural cell adhesion molecule L1 (L1CAM), a surface antigen expressed in normal nervous system and various cancers. Here, yly12 was successfully applied to image the three-dimensional network of neurites between live cells, as well as the neurite fibers on normal brain tissue section. This aptamer was also found to have an inhibitory effect on neurite outgrowth between cells. Given the advantages of aptamers, yly12 hold great potential as a molecular tool in the field of neuroscientific research. The high efficiency of neurite-SELEX suggests that SELEX against a subcellular structure instead of the whole cells is more effective in obtaining the desired aptamers.

Investigation of the geomorphologic evolution of drainage basins can provide insight into the response of mountain-basin systems to paleoclimate fluctuations. This study investigates the evolution of geomorphic units and their connectivity, from upstream piedmont to downstream salt lake, since the late Quaternary in the Golmud River catchment of the eastern Kunlun Mountains (KLM). The study aims to elucidate the debate over linkages between: (1) landform evolution and paleoclimatic change and (2) dynamic geomorphic processes and lake evolution in the lower basin. Based on geomorphic and sedimentological observations and an optically stimulated luminescence (OSL) chronology, we show three main phases of geomorphic processes: (1) upstream piedmont alluvial fans and an alluvial delta fan at the salt lake margin have surface sediment OSL ages of 12.8–11.4 ka, suggesting a valley aggradation stage in which mass periglacial detritus were eroded and redeposited in the drainage basin; (2) incision terraces in alluvial valley fills provide ages between 11.4 and 8.8, 8.1–6.2, and 4.9–3.9 ka. Incision is ascribed to the reduction in supply of detritus owing to glacial recession and enhanced precipitation in the early to middle Holocene; and (3) widely distributed swamp sediments in the distal delta fan date to 3.2–1.8 ka, suggesting a wetter stage within the late Holocene climatic deterioration. Loess, indicative of aridity, was deposited intermittently during the middle to late Holocene. We reconstructed a wetness index, based on wetness scores of drainage geomorphic units, which is consistent with published moisture proxies. This association implies that (1) landform processes in KLM responded well to precipitation fluctuations in Indian summer monsoon (ISM) dominant regions, indicating their climatic forcing and (2) precipitation variations in the eastern KLM have been mainly controlled by ISM intensity since 12.8 ka. Linking the geomorphologic evolution of mountain-basin systems to downstream arid basin evolution shows that the periods of fluvial terrace incision (early to middle Holocene) were probably important sources of lake salt mineral enrichment. The landscape evolution patterns of mountain-basin systems in the eastern KLM offer a model for assessing the linkages between geomorphic processes, paleoclimatic changes, and lake evolution in other arid regions.

Using a post-IR IRSL (pIRIR290) K-feldspar luminescence dating method, Long et al. (2018) suggest the highest exposed shoreline features of Qinghai Lake date to early MIS 3. This age estimate is in conflict with a host of quartz and post-IR IRSL (pIRIR290) K-feldspar luminescence age estimates suggesting lake highstands in other basins, which, like Qinghai Lake, are also fed by Qilian Mountains precipitation, date to MIS 5. We think the apparent conflict may be due to the use of different average water content estimates. Depending on whether estimates of 10–20% are used, many samples can date to anywhere from late MIS 5 to early MIS 3. It thus becomes critical that better ways to estimate water content must be developed before OSL chronologies can be used for understanding lake histories, and by extension, climatic change.

As the water injected during hydraulic fracturing is imbibed and then displaced in the matrix of tight reservoirs, it is meaningful to characterize the fluid distributions and percolation dynamics during these two processes as they significantly affect production. In this study, 6 tight sandstone cores from the Chinese Ordos Basin were selected to experimentally study the fluid seepage and distributions during spontaneous imbibition and drainage using a low-field nuclear magnetic resonance (NMR) core analysis unit. Dry cores were first tested via cocurrent imbibition and then centrifuged from fully saturated to irreducible water saturation to simulate the imbibition and drainage processes, respectively. The weights and T2 spectra were measured concurrently for each step. The results showed that the volume of imbibed water increased rapidly during the first 3000 min and reached a constant value at the end of the experiment; the final imbibition water saturation Swim ranged from 48.52% to 89.20%. The irredu...

The northeastern Tibetan Plateau (NETP) is located in the climatically sensitive semiarid zone between the regions controlled by the East Asian monsoon and the Westerlies and loess deposits there may preserve a record of regional paleoenvironmental change. Establishing a robust loess chronology is critical for interpreting and correlating environmental records. In this study, quartz optical stimulated luminescence (OSL) and K-feldspar post-IR infrared (IR) stimulated luminescence (pIR-IRSL) dating methods have been used to date the Ledu loess section in the Huangshui river valley, on the NETP. In terms of quartz OSL dating, the results from both the 63–90 μm and 38–63 μm quartz fractions are consistent within errors. The reliability of the 63–90 μm K-feldspar pIRIR dating was confirmed by internal check using preheat plateau, dose recovery, anomalous fading, and residual dose tests. The results suggest that the K-feldspar pIRIR signals at stimulation temperatures of 170 and 225 °C were well bleached before deposition of Ledu loess. Comparison between quartz OSL and K-feldspar pIRIR dating indicates that quartz ages older than 50 ka (∼150 Gy) may be underestimated. In establishing the chronological framework for the study section, we selected quartz OSL results for ages 50 ka. The results demonstrate that aeolian dust accumulated continuously between 67 and 25 ka, and there were two gaps in deposition, between 25 and 2 ka and from 80 to 67 ka.

Qinghai Lake is the largest lake on the Tibetan Plateau (TP) and in China and has been a focus of paleoenvironmental and climatic research for decades. However, limited understanding of lake 14C reservoir effects (LRE) has led to inconsistent interpretations among proxies of different sediment cores. As such, the onset of LRE variability during the Holocene is still unclear. 14C dating of archeological samples from four locations (Gangcha, Shaliuheqiaoxi, and Shinaihai sites, and Niaodao section) including naked carp ( Gymnocypris przewalskii, Kessler) fish bones, animal bones and teeth, and charcoal was employed to estimate variations in LRE over the last few thousand years. LRE offsets calculated as the difference between LRE of animal bones and fish bones are more reliable than that of charcoal and fish bones due to the ‘old wood’ effect in charcoal. LRE offsets recorded in fish bones were ~0.5, ~0.6, and ~0.7 ka during the periods of 3.0–3.4 cal ka BP, 0.58–0.60 cal ka BP, and modern lake times, respectively, which may indicate a temporal minimum LRE offset. Unlike the wide spatial variations of LRE ages obtained from surface total organic carbon (TOC) samples of the modern Qinghai Lake, LRE offsets from the three contemporaneous locations in Qinghai Lake were all ~0.5 ka, suggesting efficient carbon mixing occurred in naked carp. However, the late-Holocene (~3.1 ka BP) LRE increased slightly with increasing salinity and decreasing lake level.

The accurately determining the lake 14C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence (OSL) dating method is employed to date samples from highstand lacustrine sediments, palaeoshoreline, fluvial terrace, and the alluvial fan of the Heihai Lake catchment. Accelerator mass spectrometry (AMS) 14C dating was also used to date fossil plants from highstand lacustrine sediments. Based on the calculations of linear regression with OSL against radiocarbon ages for same layers of two sections, the quantitative 14C reservoir ages were estimated to lie between 3 353 and 3 464 yr during the 1.8 to 2.4 ka, which showed temporal variation. The sources of old carbon are the dissolution of carbonate bedrocks distributed along the Kunlun Mountain. The OSL ages of the different members of the hydatogen sedimentary system at Heihai Lake catchment indicate that a stronger hydrologic condition occurred from 3.0±0.2 to 1.8±0.2 ka, with a maximum lake level of 9 m higher than present. This humid stage was widely recorded in different sediments on the QTP and Chinese Loess Plateau (CLP), indicating its broad synchronicity across the Asian Summer Monsoon region. The enhanced East Asian Summer Monsoon (EASM) and the Indian Summer Monsoon (ISM) resulted in the increase of moisture availability for the Heihai Lake area during this stage.

Osteosarcoma is a common bone tumor and a frequently occuring cancer-associated threat to children. Notably, the prognosis of osteosarcoma is very poor when it is diagnosed with metastasis. A growing number of studies have indicated that various microRNAs (miRs) serve important regulatory roles in the pathogeny of different types of cancer. However, the functions of miR-210 in osteosarcoma need to be elucidated comprehensively. The aim of the present study was to investigate the potential roles of miR-210 in osteosarcoma by targeting fibroblast growth factor receptor-like 1 (FGFRL1). Reverse transcription-quantitative polymerase chain reaction results revealed that the expression of miR-210 was highly elevated while FGFRL1 expression was reduced inversely in osteosarcoma tissues compared with matched normal tissues. The results of Transwell assays showed that miR-210 promoted osteosarcoma cell migration and invasion. Furthermore, the luciferase reporter assay results suggested that miR-210 could directly bind to FGFRL1 in osteosarcoma cells. In addition, the present findings demonstrated that miR-210 could negatively regulate FGFRL1 expression by targeting the 3'untranslated region. In conclusion, the findings of the present study suggested that miR-210 exerted tumor carcinogenic functions in osteosarcoma by targeting FGFRL1. The findings of this study demonstrated that FGFRL1 was a direct target of miR-210 in osteosarcoma involved in the promoting functions mediated by miR-210 in the invasion and migration of osteosarcoma, suggesting that miR-210/FGFRL1 may be promising for discovering diagnostic and prognostic biomarkers for the therapies of osteosarcoma.

Wellbore collapse is a common problem during drilling operations in the Longmaxi shale formation, which vastly restricts drilling efficiency and shale gas development. For a horizontal well in particular, the long period of drilling increases the possibility of collapse. The central reason for the frequent wellbore collapses in shale formations is that shale has abundant planes of weakness, that is, bedding planes and fracture planes. These weak planes reduce shale strength and increase the anisotropy of the shale, complicating the wellbore instability issue. Therefore, this paper extends results of previous work and presents an attempt to establish a new model to investigate the influence of multiple groups of weak planes on wellbore stability in shale formation. By using this model, the influences of weak planes on stress distribution and shale strength are analysed respectively. It is shown that the anisotropy of shale formation makes stress distribution variable. Besides, the presence of weak planes decreases shale strength and this reduction of strength becomes larger with the increasing number of groups of weak planes. In particular, with more than four groups of weak planes, shale strength is entirely controlled by the weak plane. Based on the analysis of shale strength and effective stress at the wall of borehole, the investigation on influence factors of wellbore stability in shale formation has been conducted. The results indicate that collapse pressure has increment with increasing anisotropy of shale formation. Additionally, different occurrence and number of weak planes cause variation in collapse pressure. For a horizontal well, the selection of appropriate drilling azimuths can reduce the effect of weak planes on the borehole. The interaction between drilling fluid and shale leads to incremental collapse pressure, and this increment is higher in the multiple groups of weak planes and strong anisotropy condition. Finally, this model was applied to a field case in the southern Sichuan Basin, China. The model was consistent with field experience, proving its practicability in drilling operations.

In this work, the swelling, transformation, and dissolution of clay minerals after steam injection in heavy oil reservoir were investigated, and the damage mechanism of steam injection was discussed to research the microscopic mechanism of clay minerals on reservoir damage during steam injection in unconsolidated sandstone. The results show that the swelling of clay minerals increases with the increase of the pH of the brine and decreases with the increase of the salinity of the brine. As we all know, the swollen clay minerals are liable to fall from the inner wall of the pass, which may cause the blockage of reservoirs. What is more, the environment of high temperature and high pH would promote the transformation of the clay minerals. Montmorillonite can be transformed into illite and analcime, and kaolinite can be transformed—due to the water sensitivity of the clay mineral—to montmorillonite and analcime, whereas illite is relatively stable. For the movement of particles in the reservoir during the inj...

Hydraulic fracturing has been the common method of stimulation treatment. Effective fracture network needs to be formed for having efficient hydraulic fracturing. The forming process of fracture network can be divided into 2 parts, i.e., initiation and propagation. In particular, the initiation part is the foundation of forming fracture network, and also basic parameter for analyzing fracture propagation. However, in fractured formation, it is very tricky to obtain initial fracture pressure due to the influence of rich natural fractures. Therefore, based on the rock mechanics and spatial geometry theory, this paper presents a mechanical model for predicting fracture initiation in fractured formation. Unlike conventional model, this new model considers multiple fractures conditions and the intersection method between natural fractures and perforated borehole. The model has been used to investigate influence factors of initial fracture pressure. These computed results reveal that the initial fracture pressure has complex distribution, and changes with variable occurrence of natural fracture. There are different kinds of intersections between natural fracture and perforated borehole. When fracture plane intersects through perforated borehole, influence of fracture plane on fracture initiation is relatively larger. Furthermore, with increasing number of natural fractures, initial fracture pressure decreases and the initiation mode tends to be tensile failure along natural fracture plane. Additionally, engineering parameters, like well trajectory and perforation azimuth, are related to fracture initiation pressure. Their optimizations can contribute to perform optimization of reservoir stimulation. Results from this model used in this paper aim at offering reference for field fracturing practice in fractured formation.

The Rb/Sr ratio is an important indicator of weathering intensity in both lacustrine and loess sediments because of the inertness of the Rb element and the activity of the Sr element during the weathering process. Generally, the environmental interpretation of Rb/Sr ratio proxy in lacustrine sediments is contrary to that in the loess-paleosol sequence: it shows a negative correlation between the Rb/Sr ratio and chemical weathering intensity in lacustrine sediments, but shows a positive pattern in the loess-paleosol sequence. However, in this study, we investigated the Rb/Sr ratio of a lacustrine core (ISL1A) from Qarhan Salt Lake (QSL) in eastern Qaidam Basin (QB), and found the Rb/Sr ratio indicated a positive correlation with regional precipitation. This pattern is similar to that of the loess-paleosol sequence rather than the lacustrine sediments. According to grain size statistics and the comparison of Rb/Sr ratio with other proxies (halite and calcite contents, grain size, and F values of grain size discriminant function), we preliminarily proposed that the abundant input of aeolian materials, transported by the strong northwest wind, cause these unexpected Rb/Sr ratio fluctuations in the ISL1A core. The comparison between background Rb and Sr elemental data of relevant regions and these of the core indicated the aeolian origin of Rb/Sr ratio in the lacustrine sediments, and the Rb and Sr elemental composition probably represents the geochemical characteristics of the dust source area. The Sr-Nd isotopic composition indicates that the erosive paleo-lake strata in western QB could be the origin of aeolian materials in lacustrine sediments in the QSL, as well as the loess deposits in Dulan County, Qinghai Lake Basin, and Xining Basin. The regional correlation between proxies of the ISL1A core and other aeolian records also supports the aeolian origin of detrital input in the core. Finally, we propose that the origin of the detrital input must be distinguished before the Rb/Sr ratio is applied as a weathering intensity proxy in lacustrine sediments, especially in arid basins.

The removal and control of inclusions has always been a hot issue in the field of metallurgy, and rare earth modifying is a proven method. However, some rare earth inclusions cannot be accurately judged due to the necessary assumptions for thermodynamic calculations and the lack of certain thermodynamic data. On the other hand, most of the currently reported researches focus on the changes in the morphology of the inclusions, and rarely involve the inherent properties of the inclusions. To address these two deficiencies, this work investigated elaborately the stability, elastic modulus, elastic anisotropy and thermal expansion coefficient of yttrium (Y) inclusions in micro alloyed steels by first-principles calculation. Then, the role of yttrium inclusion in the initial stage of crack initiation was discussed. The results showed that it was practical to judge the possibility of unknown inclusions formation in steel by formation enthalpy. The inclusions were changed from Al2O3 to Y2O3, Y2O2S, YAlO3-Y2Si2O7 composite inclusions with yttrium treatment, which was consistent with the metallographic observations. The bulk modulus (B), shear modulus (G), Young’s modulus (E), and Poisson’s ratio (σ) were calculated in a framework of the Voigte-Reusse-Hill approximation. In light of B/G and σ values, Al2O3 showed apparent brittleness, and the toughness of yttrium inclusions were improved to varying degrees compared to Al2O3 inclusions. Moreover, the order of the degree of elastic anisotropy for these inclusions was Y2Si2O7 > Al2O3 > Y2O3 > Y2O2S > YAlO3. Furthermore, the thermal expansion coefficient of Y2O3, Y2O2S, YAlO3 inclusions at any temperature were greater than that of Al2O3 and were relatively close to that of Fe, whereas, Y2Si2O7 inclusion was much larger than that of Fe. Finally, the difference between yttrium inclusions and iron matrix in the aspect of incompressibility, brittleness, toughness, mechanical anisotropy, and thermal expansion was reduced significantly, thereby improving the consistency of the matrix, this could be used to explain the phenomenon of alleviating stresses concentration and delaying the formation of micro voids.