This study proposes a label-free aptamer biosensor for the sensitive detection of malachite green(MG) using gold nanoparticles/multi-walled carbon nanotubes @ titanium dioxide(AuNPs/MWCNTs@TiO2). The ...nanocomposite provides a large surface area and good electrical conductivity, improving current transfer and acting as a platform for aptamer immobilization. The aptamer and the complementary chain(cDNA) are paired by base complementary to form the recognition element and fixed on the AuNPs by sulfhydryl group, which was modified on the cDNA. Since DNA is negatively charged, the redox probe in the electrolyte is less exposed to the electrode surface under the repulsion of the negative charge, resulting in a low-electrical signal level. When MG is present, the aptamer is detached from the cDNA and binds to MG, the DNA on the electrode surface is reduced, and the rejection of the redox probe is weakened, which leads to an enhanced electrical signal and enables the detection of MG concentration by measuring the change in the electrical signal. Under the best experimental conditions, the sensor demonstrates a good linear relationship for the detection of MG from 0.01 to 1000 ng/mL, the limit of detection (LOD)is 8.68 pg/mL. This sensor is stable, specific, and reproducible, allowing for the detection of various small-molecule pollutants by changing the aptamer, providing an effective method for detecting small-molecule pollutants.
The δ13C, δ18O and Sr/Ca series of a stalagmite from Kyrgyzstan, provide so far, the highest-resolved (~3 yr) and most precisely-dated (~6‰) precipitation record in Arid Central Asia covering the ...middle to late Holocene. The record reveals a 640-yr megadrought between 5820 and 5180 a BP, which likely delayed prehistoric trans-Eurasian cultural exchange along the proto-Silk Road.
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Arid Central Asia (ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean. Ecological pockets and ecoclines in ACA are largely determined by local precipitation. However, little research has gone into the effects of hydroclimatic changes on trans-Eurasian cultural exchange. Here, we reconstruct precipitation changes in ACA, covering the mid-late Holocene with a U-Th dated, ~3 a resolution, multi-proxy time series of replicated stalagmites from the southeastern Fergana Valley, Kyrgyzstan. Our data reveal a 640-a megadrought between 5820 and 5180 a BP, which likely impacted cultural development in ACA and impeded the expansion of cultural traits along oasis routes. Instead, it may have diverted the earliest transcontinental exchange along the Eurasian steppe during the 5th millennium BP. With gradually increasing precipitation after the megadrought, settlement of peoples in the oases and river valleys may have facilitated the opening of the oasis routes, “prehistoric Silk Roads”, of trans-Eurasian exchange. By the 4th millennium BP, this process may have reshaped cultures across the two continents, laying the foundation for the organized Silk Roads.
Herein, we developed a novel plasmon-enhanced fluorescence (PEF)-based telomerase-responsive nanoprobe for in situ fluorescence “turn on” visualization of telomerase activity in live cells. The ...as-prepared nanoprobe was composed of a nicked molecular beacon (which contains Cy5.5-labeled hairpin-DNA sequences hybridized with telomerase primers)-functionalized gold nanobipyramids (Au NBPs). Au NBPs were selected as both fluorescence resonance energy-transfer and PEF dual-functional substrates, while DNA was selected to be the precise spacer to manage the interval between the Au NBPs and Cy5.5. On the basis of this target-triggered PEF probe, optimal fluorescence enhancement can be obtained with 49 DNA bases, which was higher than gold nanorods. The proposed method accomplishes sensitive telomerase activity detection down to 23 HeLa cells with a dynamic range of 40–1200 HeLa cells. On the basis of this, in situ fluorescence imaging of telomerase activity in live cells and real-time analysis of the variation in intracellular telomerase activity can be achieved. Moreover, cancer cells and normal cells can also be successfully discriminated even in their co-cultured mixtures, indicating promising potential in clinical diagnoses.
From AD 1048 to 1128, Yellow River flooding killed over a million people, left many more homeless and destitute, and turned parts of the once fertile North China Plain into a silted-up agricultural ...wasteland. Brought on in part by climate change and the Northern Song dynasty’s (AD 960–1127) mismanagement of the environment, the Yellow River floods likely hastened the collapse of the Northern Song dynasty. Despite the magnitude of this flood event, no sedimentary deposits have yet been linked to these historically recorded floods. In this research paper, we provide archaeological, sedimentary, and radiocarbon evidence of the AD 1048–1128 Yellow River floods at the Dazhanglongcun, Xidacheng, and Daguxiancun sites in Neihuang County, Henan Province. Based on our data, we argue that the AD 1048–1128 Yellow River floods deposited over 5 m of alluvium on villages in the North China Plain, radically changing both the physical and political landscape of Northern Song dynasty China.
Human settlement and agricultural development are closely linked to local geomorphological and climatic environments. However, the variation in agricultural systems in different environmental and ...prehistoric contexts remains unknown. We report new archaeobotanical and radiocarbon dates from 34 Neolithic and Bronze Age sites in the Hutuo River Valley (HTRV) in north-central China and compare them with updated archaeobotanical studies in the Sushui River Valley (SSRV) and Henan Province (HNP), to explore the similarities and differences of agricultural patterns under different geomorphologic and climatic environments in north-central China. Our results reveal that humans consistently cultivated foxtail and broomcorn millet in the HTRV from the Miaodigou (6000–5700 cal. a BP) to the Shang-Zhou (3600–2256 cal. a BP) period, despite the introduction of wheat and barley into the area around 4000 a BP. Climate conditions and hilly landforms in the HTRV, SSRV and some parts of the HNP led people to develop foxtail and broomcorn millet dry land farming practices between 7000 and 3000 a BP. Alternatively, in other areas of the HNP, the climate conditions and alluvial plains enabled people to develop a mixed agriculture of millets, soybeans, and rice from 7000 to 4000 a BP, with the addition of wheat between 4000 and 3000 a BP. Farmers’ different agricultural technologies and interactions with foreign cultures may have also influenced the formation of different agricultural patterns in the three regions between 7000 and 3000 a BP. Population growth during 7000–3000 a BP can explain the overall propensity of the higher-yield foxtail millet rather than broomcorn millet as the main cultivated crop. In the HTRV, however, higher proportions of broomcorn millet (as compared to the SSRV and HNP), may reflect the greater drought and heat tolerance of broomcorn millet, representing an adaptive agricultural strategy in the river valley.
Endothelial dysfunction and inflammation are the main manifestations of diabetes-associated atherosclerosis. This paper studied the roles of NF-κB-inducing kinase (NIK) and sine oculis homeobox ...homolog 1 (SIX1) in regulating high glucose-induced endothelial dysfunction and inflammation. The expression of NIK and SIX1 in human umbilical vein endothelial cells (HUVECs) was silenced by transfection with the specific shRNAs. HUVECs exposed to high glucose were considered as a cell model of endothelial dysfunction. Expression of NIK and SIX1 following transfection was measured by qRT-PCR and western blotting analysis. The proliferation, migration, and inflammation of HUVECs were evaluated by EdU staining, scratch test, ELISA, and western blotting. High glucose (30 mM) significantly decreased the proliferation and migration of HUVECs. High glucose-induced the expression of adhesion molecules VCAM-1 and ICAM-1. Moreover, high glucose increased the release of IL-1β, IL-6, TNF-α, and MCP-1. Transfection of cells with NIK shRNA significantly reversed the toxic effects of high glucose on HUVECs. Of contrast, SIX1 shRNA accelerated the effects of high glucose on HUVECs. NIK shRNA inhibited the accumulation of RelA, RelB, and p52. Meanwhile, NIK shRNA led to SIX1 downregulation which further induced the activation of the NF-κB pathway. NIK-SIX1 signalling axis was suggested to be critical in the regulation of high glucose-induced endothelial dysfunction and inflammation. SIX1 may function as an immunological gatekeeper to control the excessive inflammation mediated by NIK in diabetes-associated atherosclerosis.
The emergence and diffusion of metallurgical technology had tremendous environmental consequence, however, the spatial-temporal consequences of the metallurgy during Bronze Age are not clear in ...China. In this paper, X-ray fluorescence (XRF) measurement and principal component analysis (PCA) were conducted on heavy metal element (Cu, Ni, Pb, Zn, Cr and As) concentrations (HMEC) of natural and anthropogenic sediment samples systematically collected from 22 late Neolithic-Bronze Age sites in Hexi corridor to explore the potential for subcontinental-wide changes in soil geochemistry. We place this data within the context of the Cu concentrations in lacustrine sediments located near smelting and mining centers in Bronze Age China. Our results show that variation of HMEC in anthropogenic sediment in Hexi corridor is contemporaneous with the increases of the Cu concentrations in lacustrine sediment around 4000 BP. Comparative data suggests the metallurgical production diffused from the Hexi corridor to central and southwestern China around 3600 BP. We argue that sediment pollution is not an isolated phenomenon during the Bronze Age China, but rather occurred on regional scales and is closely related to the intensity of smelting activities.
•Analyzing heavy metal elements in 22 late Neolithic-Bronze Age archaeological sites in Hexi corridor•Comparing the Cu concentrations in sediment from various lakes near metallurgical center in China•Revealing the spatial-temporal difference of human smelting activities impact on environment in Bronze Age China•Providing valuable case study for understanding ‘Anthropocene’
The direct reduction characteristics of iron oxide by cellulose, hemicellulose (it is difficult to prepare; xylan is used in its place in this work), and lignin were determined using X-ray ...diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric Fourier transform infrared (TG-FTIR) combined with several other chemical analyses. The reduction of iron oxide by biomass is determined by gas and fixed carbon in biomass. The characteristic temperature of gas-based reduction ranges from 788 to 823 K, while the characteristic temperature of carbon-based reduction ranges between 1085 and 1154 K. Lignin plays a major role in the reduction of iron oxide mainly by its fixed carbon, while cellulose is mainly achieved by reducing the gases that come from its volatile components. The order of carbon reduction ability of the three kinds of biomass components from the strong to weak was lignin > hemicellulose > cellulose. The capacity for lignin was determined to depend on the morphology and quality of the lignin residue. The thin film structures or with higher carbon content in lignin accelerated the reduction reaction. There are two sources of hydrogen involved in the reduction of iron oxides by the three biomass components. Hydrogen from cellulose- and hemicellulose-based reduction of iron oxide is derived from cellulose and hemicellulose through its own pyrolysis, while hydrogen from lignin-based reduction is derived from carbon or carbon monoxide reacting with water.
A study was carried out to assess the chemical composition of pre-hydrolysate liquor (PHL) produced in a dissolving pulp production facility in Eastern Canada. The true PHL contains high amount of ...both mono- and oligo-sugars (1.50–1.65%). Xylose/xylan was the predominate sugar in the PHL. Glucose, galactose, and mannose were also found in the PHL. Furfural, which was generated from further degradation of five carbon sugars, was also found in the PHL. Acetic acid released during pre-hydrolysis from the labile acetyl groups present in the hemicelluloses was about 25% of the total solids in the PHL. The sum of sugars, acetic acid, lignin and ash contents account for 91.4–95.6% of the total solid content of the PHL. The presence of sugars in the neutralized PHL was negligible while a large amount of furfural was found.
An effective method was developed to improve the interfacial interaction between Mutiwalled carbon nanotubes (MWCNTs) and epoxy matrix. The performance of thermal conductivity and strength of the ...epoxy vitrimer were enhanced by polydopamine (PDA) coating. Polydopamine is a commonly used photothermal agent, which of course, was effective in modifying MWCNTs used in photoresponsive epoxy resin. The surface temperature of the epoxy composite with 3% MWCNTs@PDA fillers added increased from room temperature to 215 °C in 48 s. The metal–catechol coordination interactions formed between the catechol groups of PDA and Zn2+ accelerated the stress relaxation of epoxy vitrimer. Moreover, the shape memory, repairing, and recycling of epoxy vitrimer were investigated. Therefore, dopamine coating is a multifunctional approach to enhance the performance of epoxy vitrimer.
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