Phosphate (Pi) starvation response (PHR) transcription factors play key roles in plant Pi homeostasis maintenance. They are negatively regulated by stand-alone SPX proteins, cellular receptors for ...inositol pyrophosphate (PP-InsP) nutrient messengers. How PP-InsP-bound SPX interacts with PHRs is poorly understood. Here, we report crystal structures of the rice SPX2/InsP
/PHR2 complex and of the PHR2 DNA binding (MYB) domain in complex with target DNA at resolutions of 3.1 Å and 2.7 Å, respectively. In the SPX2/InsP
/PHR2 complex, the signalling-active SPX2 assembles into a domain-swapped dimer conformation and binds two copies of PHR2, targeting both its coiled-coil (CC) oligomerisation domain and MYB domain. Our results reveal that the SPX2 senses PP-InsPs to inactivate PHR2 by establishing severe steric clashes with the PHR2 MYB domain, preventing DNA binding, and by disrupting oligomerisation of the PHR2 CC domain, attenuating promoter binding. Our findings rationalize how PP-InsPs activate SPX receptor proteins to target PHR family transcription factors.
Inertial pendulum components are key parts of a miniature wire suspended pendulum accelerometer. They are with varied shapes and multiple scales individually, which results in a complex assembly ...structure and assembly process. At present, the assembly mainly relies on manual operation, and assembly consistency and productivity cannot be guaranteed. In our previous work, an assembly system based on a Cartesian-coordinate robot was presented, where the mechanical structure and control system composition was mainly described. Here, a detailed assembly principle and process are given besides structure, explaining how to achieve assembly accuracy by combination of well-designed fixtures and automatic position/attitude alignment. Moreover, error analysis and error compensation methods are supplemented, and the locking method of combination fixture/suspended wire is modified to be more reliable. The experimental results demonstrate that assembly accuracy is less than 15 µm, which meets the requirement.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The MSWI fly ash which contains a large number of heavy metal substances is a subsidiary product of waste incineration power generation technology. If the MSWI fly ash is disposed improperly, heavy ...metal pollutants will pose a great threat to environmental safety and human health. Based on the technology of electrokinetic remediation, the feasibility of removing heavy metal pollutants from the MSWI fly ash using a modified electrokinetic remediation device - cylinder device was evaluated in this study. Differing from the traditional cuboid device with the volume ratio of the cathode chamber to the anode chamber being 1:1, the volume ratio of the cathode chamber to the anode chamber of the cylinder device was 16:1. Changes in parameters, such as pH values and conductivity in the cathode and the anode chambers as well as current and voltage in the sample area were analysed under the voltage gradient of 2 V/cm. After the experiment, the average removal efficiencies for Zn, Pb, Cd and Cu in the sample area were 53.2%, 31.4%, 42.3% and 30.7%, respectively. It indicates that the cylinder device is effective in removing heavy metals from the MSWI fly ash. Adopting the cylinder device for the experimental study on the electrokinetic remediation technology could provide a better way of thinking for the future engineering practices and applications.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
Currently, the magic-angle graphene has given a tremendous boost to the study of unconventional superconductors. On the other hand, there were still limited experimental studies on ...superconductivity in one-dimensional (1D) carbon nanotube systems. The study of experimental systems in demonstrating superconductivity was therefore scientifically important. In this review, we have shown strategies toward demonstrating the superconductivity for the single double-wall carbon nanotube (DWCNT). In general, there have been two directions to analyse superconducting properties of one-dimensional materials: (i) strong correlated states (ii) anomalous electron transport operations. We introduced the transmission electron microscope (TEM) and Rayleigh scattering spectroscopy to describe the strong correlation. The theoretical foundations of moiré physics have also been described. Given all the methods, we concluded that the most intuitive way to demonstrate the superconductivity of single double-walled carbon nanotubes is the critical temperature. The sharp drop of the resistance could be directly observed, and the T
c
could be obtained from the electrical transport data. In the last section, we also summarized the challenges that need to be addressed in future superconductivity studies of 1D carbon nanotubes.
Perfluorooctanoic acid (PFOA), a typical perfluorinated carboxylic acid, is an emerging type of permanent organic pollutants that are regulated by the Stockholm Convention. The degradation of PFOA, ...however, is quite challenging largely due to the ultra-high stability of C-F bonds. Compared with other techniques, photocatalytic degradation offers the potential advantages of simple operation under mild conditions as well as exceptional decomposition and defluorination efficiency. Titanium dioxide (TiO
2
) is one of the most frequently used photocatalysts, but so far, the pristine nanosized TiO
2
(e.g., the commercial P25) has been considered inefficient for PFOA degradation, since the photo-generated hydroxyl radicals from TiO
2
are not able to directly attack C-F bonds. Mesoporous Sb
2
O
3
/TiO
2
heterojunctions were therefore rationally designed in this work, of which the confined Sb
2
O
3
nanoparticles in mesoporous TiO
2
framework could not only tune the band structure and also increase the number of active sites for PFOA degradation. It was found that, after loading Sb
2
O
3
, the absorption of UV light was enhanced, indicating a higher efficiency of light utilization; while the band gap was reduced, which accelerated the separation of photo-generated charge carriers; and most importantly, the valence band edge of the Sb
2
O
3
/TiO
2
heterojunction was significantly lifted so as to prevent the occurrence of hydroxyl radical pathway. Under the optimal ratio of Sb
2
O
3
–TiO
2
, the resulting catalysts managed to remove 81.7% PFOA in 2 h, with a degradation kinetics 4.2 times faster than the commercial P25. Scavenger tests and electron spin resonance spectra further revealed that such improvement was mainly attributed to the formation of superoxide radicals and photo-generated holes, in which the former drove the decarboxylation from C
7
F
15
COOH–C
7
F
15
•
, and the latter promoted the direct electron transfer for the conversion of C
7
F
15
COO
−
–C
7
F
15
COO
•
. The Sb
2
O
3
/TiO
2
photocatalysts were highly recyclable, with nearly 90% of the initial activity being retained after five consecutive cycles, guaranteeing the feasibility of long-term operation.
Tumor suppressor p53 prevents tumorigenesis by promoting cell cycle arrest and apoptosis through transcriptional regulation. Dysfunction of p53 occurs frequently in human cancers. Thus, p53 becomes ...one of the most promising targets for anticancer treatment. A bacterial effector protein azurin triggers tumor suppression by stabilizing p53 and elevating its basal level. However, the structural and mechanistic basis of azurin-mediated tumor suppression remains elusive. Here we report the atomic details of azurin-mediated p53 stabilization by combining X-ray crystallography with nuclear magnetic resonance. Structural and mutagenic analysis reveals that the p28 region of azurin, which corresponds to a therapeutic peptide, significantly contributes to p53 binding. This binding stabilizes p53 by disrupting COP1-mediated p53 ubiquitination and degradation. Using the structure-based design, we obtain several affinity-enhancing mutants that enable amplifying the effect of azurin-induced apoptosis. Our findings highlight how the structure of the azurin-p53 complex can be leveraged to design azurin derivatives for cancer therapy.
The China–Pakistan Economic Corridor (CPEC) is the flagship project of the Belt and Road Initiative. At the end of the CPEC, the Gwadar port on the Arabian Sea is being built quickly, providing an ...important economical route for the flow of Central Asia’s natural resources to the world. Gwadar city is in a rapid urbanization process and will be developed as a modern, world-class port city in the near future. Therefore, monitoring the urbanization process of Gwadar at both high spatial and temporal resolution is vital for its urban planning, city ecosystem management, and the sustainable development of CPEC. The impervious surface percentage (ISP) is an essential quantitative indicator for the assessment of urban development. Through the integration of remote sensing images and ISP estimation models, ISP can be routinely and periodically estimated. However, due to clouds’ influence and spatial–temporal resolution trade-offs in sensor design, it is difficult to estimate the ISP with both high spatial resolution and dense temporal frequency from only one satellite sensor. In recent years, China has launched a series of Earth resource satellites, such as the HJ (Huangjing, which means environment in Chinese)-1A/B constellation, showing great application potential for rapid Earth surface mapping. This study employs the Random Forest (RF) method for a long-term and fine-scale ISP estimation and analysis of the city of Gwadar, based on the density in temporal and multi-source Chinese satellite images. In the method, high spatial resolution ISP reference data partially covering Gwadar city was first extracted from the 1–2 meter (m) GF (GaoFen, which means high spatial resolution in Chinese)-1/2 fused images. An RF retrieval model was then built based on the training samples extracted from ISP reference data and multi-temporal 30-m HJ-1A/B satellite images. Lastly, the model was used to generate the 30-m time series ISP from 2009 to 2017 for the whole city area based on the HJ-1A/B images. Results showed that the mean absolute error of the estimated ISP was 6.1–8.1% and that the root mean square error (RMSE) of the estimation results was 12.82–15.03%, indicating the consistently high performance of the model. This study highlights the feasibility and potential of using multi-source Chinese satellite images and an RF model to generate long-term ISP estimations for monitoring the urbanization process of the key node city in the CPEC.
Perfluorocarboxylic acids (PFCAs) are an emerging class of persistent organic pollutants. During the fabrication process, it is unavoidable to form PFCA homologs or isomers which exhibit distinct ...occurrence, bioaccumulation, and toxicity. The precision measurement of PFCAs is therefore of significant importance. However, the existing characterization techniques, such as LC-MS/MS, cannot fully meet the requirement of isomer-specific analysis, largely due to the lack of authentic standards. Single-molecule sensors (SMSs) based on nanopore electrochemistry may be a feasible solution for PFCAs determination, thanks to their ultra-high spatiotemporal resolutions. Hence, as a first step, this work was to elucidate the influence of electrolyte concentration on the four most critical indicators of nanopore measurements, and furthermore, performance of nanopore SMSs. More specifically, three of the most representative short-chain PFCAs, perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA), were adopted as the target analytes, aerolysin nanopore was employed as the sensing interface, and 2, 3 and 4 M KCl solutions were used as electrolytes. It was found that, when the concentration of KCl solution increased from 2 to 4 M, the conductance of aerolysin nanopore increased almost linearly at a rate of 0.5 nS per molar KCl within the whole voltage range, the current blockade of PFPeA at -50 mV increased from 61.74 to 66.57% owing to the enhanced steric exclusion effect, the maximum dwell time was more than doubled from 14.5 to 31.5 ms, and the barrier limited capture rate increased by 8.3 times from 0.46 to 3.85 Hz. As a result, when using 4 M KCl as the electrolyte, over 90% of the PFPeA, PFHxA and PFHpA were accurately identified from a mixed sample, and the calculated limit of detection of PFPeA reached 320 nM, more than 24 times lower than in 2 M KCl. It was thus clear that tuning the electrolyte concentration was a simple but very effective approach to improve the performance of nanopore SMSs for PFCAs determination.
Polyacrylamide hydrogel used in conformance control is subjected to poor stability at an elevated temperature. In this paper, nanosilica has been found to be a very effective stabilizing agent for ...the polyacrylamide/polyethylenimine hydrogel, and the reinforcing performance of nanosilica on the hydrogel was investigated in detail. The result showed that the strength of hydrogel is enhanced obviously by the nanosilica, and the hydrogel syneresis is also significantly inhibited by the nanosilica, which can increase the hydrogel stability time from 18 to 180 days at 130 °C. Besides, nanosilica can increase the shear viscosity and hydrodynamic radius of polyacrylamide, and the bound water in the hydrogel is also grown in the presence of nanosilica. In comparison to the micromorphology of common hydrogel, the dense and strong mesh structure is formed as a result of the reinforcing behavior of nanosilica. According to the above results, it is inferred that the silanol group of nanosilica cross-links with the amidogen of polyacrylamide via the hydrogen bond, which is considered as the primary cause of the reinforcing performance of nanosilica for the hydrogel. In addition, as a result of the improving strength and stability and increasing absorption of the polymer to rock surface, the hydrogel enhanced by nanosilica has a higher water shutoff ratio and residual resistance factor and a longer period of validity.
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IJS, KILJ, NUK, PNG, UL, UM
•A new method for meteorological interpolation was propose by a decomposing way.•RF and IDW was coupled in predicting meteorological surfaces with covariates.•RF-IDW well depicts the relationship ...between meteorological value and covariates.•RF-IDW have good performance in the complex region.
Spatially interpolated temperature and precipitation are hydrological variables that are widely applied in models of ecology, hydrology, agronomy, and other environmental sciences. The accuracy of meteorological data directly determine model performance. However, the interpolation of temperature and precipitation over complex areas is affected by the value observed with surrounding meteorological stations and also by aspects of the physical environment, such as terrain and land cover effects. These effects significantly limit the precise interpolation of temperature and precipitation. To normalize these effects, a new method coupling random forest (RF) and inverse distance weighting (IDW) was proposed, RF-IDW. The proposed method was applied to generate the climate surfaces of both precipitation and temperature in China in 2015. During the interpolation with RF-IDW, the temperature and precipitation were decomposed into a basic part (indicating the atmospheric properties) and local parts (representing the effects of the physical environment). The complex correlations were determined between precipitation/temperature and multiple-covariates of landcover, normalized difference vegetation index (NDVI), elevation, slope, longitude, soil moisture, latitude and Land Surface Temperature (LST) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) data. Next, 10-fold and leave-one-region-out cross-validation were applied to verify the accuracy of RF-IDW for the interpolation of meteorological values. We also compared the RF-IDW performance to that of RF, IDW, Anusplin, and MLR to further investigate its feasibility. Based on 10-fold cross-validation, the coefficient of determinations (R2) between interpolated value and observed values were 0.962 for precipitation and 0.990 for temperature, indicating that the RF-IDW can accurately interpolate climate surfaces. The performance comparison showed that the RF-IDW reduced the mean absolute error by 55 mm to 120 mm for precipitation interpolation and 0.06 ℃ to 0.8 ℃ for temperature interpolation, especially in the complex region. The result of monthly interpolations implied the good robustness of the RF-IDW. Overall, the proposed RF-IDW approach allows improved spatial interpolation of complex region and suggest alternate methods for the spatial interpolation of hydrological variables.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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