To reduce the waste from yak hair and introduce resource recycling into the yak-related industry, an eco-friendly yak keratin-based bioplastic film was developed. We employed yak keratin (USYK) from ...yak hair, soy protein isolate (SPI) from soybean meal as a film-forming agent, transglutaminase (EC 2.3.2.13, TGase) as a catalytic crosslinker, and glycerol as a plasticizer for USYK-SPI bioplastic film production. The structures of the USYK-SPI bioplastic film were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-Ray diffraction (XRD). The mechanical properties, the thermal behavior, light transmittance performance, and water vapor permeability (WVP) were measured. The results revealed that the added SPI possibly acted as a reinforcement. The formation of Gln-Lys isopeptide bonds and hydrophobic interactions led to a stable crosslinking structure of USYK-SPI bioplastic film. The thermal and the mechanical behaviors of the USYK-SPI bioplastic film were improved. The enhanced dispersion and formation of co-continuous protein matrices possibly produced denser networks that limited the diffusion of water vapor and volatile compounds in the USYK-SPI bioplastic films. Moreover, the introduction of SPI prompted the relocation of hydrophobic groups on USYK molecules, which gave the USYK-SPI bioplastic film stronger surface hydrophobicity. The SPI and USYK molecules possess aromatic amino residuals (tyrosine, phenylalanine, tryptophan), which can absorb ultraviolet radiation. Thus, the USYK-SPI bioplastic films were shown to have an excellent UV barrier. The synergy effect between USYK and SPI is not only able to improve rigidity and the application performance of keratin-based composite film but can also reduce the cost of the keratin-based composite film through the low-cost of the SPI alternative which partially replaces the high-cost of keratin. The data obtained from this research can provide basic information for further research and practical applications of USYK-SPI bioplastic films. There is an increasing demand for the novel USYK-SPI bioplastic film in exploit packaging material, biomedical materials, eco-friendly wearable electronics, and humidity sensors.
Photosynthetic conversion of CO2 into fuel and chemicals is a promising but challenging technology. The bottleneck of this reaction lies in the activation of CO2, owing to the chemical inertness of ...linear CO2. Herein, we present a defect‐engineering methodology to construct CO2 activation sites by implanting carbon vacancies (CVs) in the melon polymer (MP) matrix. Positron annihilation spectroscopy confirmed the location and density of the CVs in the MP skeleton. In situ diffuse reflectance infrared Fourier transform spectroscopy and a DFT study revealed that the CVs can function as active sites for CO2 activation while stabilizing COOH* intermediates, thereby boosting the reaction kinetics. As a result, the modified MP‐TAP‐CVs displayed a 45‐fold improvement in CO2‐to‐CO activity over the pristine MP. The apparent quantum efficiency of the MP‐TAP‐CVs was 4.8 % at 420 nm. This study sheds new light on the design of high‐efficiency polymer semiconductors for CO2 conversion.
Defects that overcome deficiency: A steam engineering strategy was developed to construct carbon vacancies (CVs) in a melon‐based carbon nitride polymer matrix. The CVs in the material effectively promoted the activation of CO2 while prolonging the charge lifetime of the carbon nitride polymer, thus promoting CO2 reduction (see picture).
Deep learning methods have recently been successfully explored for hyperspectral image (HSI) classification. However, training a deep-learning classifier notoriously requires hundreds or thousands of ...labeled samples. In this paper, a deep few-shot learning method is proposed to address the small sample size problem of HSI classification. There are three novel strategies in the proposed algorithm. First, spectral-spatial features are extracted to reduce the labeling uncertainty via a deep residual 3-D convolutional neural network. Second, the network is trained by episodes to learn a metric space where samples from the same class are close and those from different classes are far. Finally, the testing samples are classified by a nearest neighbor classifier in the learned metric space. The key idea is that the designed network learns a metric space from the training data set. Furthermore, such metric space could generalize to the classes of the testing data set. Note that the classes of the testing data set are not seen in the training data set. Four widely used HSI data sets were used to assess the performance of the proposed algorithm. The experimental results indicate that the proposed method can achieve better classification accuracy than the conventional semisupervised methods with only a few labeled samples.
The water oxidation half-reaction is considered to be a bottleneck for achieving highly efficient solar-driven water splitting due to its multiproton-coupled four-electron process and sluggish ...kinetics. Herein, a triadic photoanode consisting of dual-sized CdTe quantum dots (QDs), Co-based layered double hydroxide (LDH) nanosheets, and BiVO4 particles, that is, QD@LDH@BiVO4, was designed. Two sets of consecutive Type-II band alignments were constructed to improve photogenerated electron–hole separation in the triadic structure. The efficient charge separation resulted in a 2-fold enhancement of the photocurrent of the QD@LDH@BiVO4 photoanode. A significantly enhanced oxidation efficiency reaching above 90% in the low bias region (i.e., E < 0.8 V vs RHE) could be critical in determining the overall performance of a complete photoelectrochemical cell. The faradaic efficiency for water oxidation was almost 90%. The conduction band energy of QDs is ∼1.0 V more negative than that of LDH, favorable for the electron injection to LDH and enabling a more efficient hole separation. The enhanced photon-to-current conversion efficiency and improved water oxidation efficiency of the triadic structure may result from the non-negligible contribution of hot electrons or holes generated in QDs. Such a band-matching and multidimensional triadic architecture could be a promising strategy for achieving high-efficiency photoanodes by sufficiently utilizing and maximizing the functionalities of QDs.
•CH appears to be the most abundant species on Pt(111) surface in CH4 dissociation.•CO2*+H*→COOH*+*→CO*+OH* is the dominant reaction pathway in CO2 activation.•Major reaction pathway in CH oxidation: ...CH*+OH*→CHOH*+*→CHO*+H*→CO*+2H*.•C*+OH*→COH*+*→CO*+H* is the dominant reaction pathway in C oxidation.
Dry reforming of methane (DRM) is a well-studied reaction that is of both scientific and industrial importance. In order to design catalysts that minimize the deactivation and improve the selectivity and activity for a high H2/CO yield, it is necessary to understand the elementary reaction steps involved in activation and conversion of CO2 and CH4. In our present work, a microkinetic model based on density functional theory (DFT) calculations is applied to explore the reaction mechanism for methane dry reforming on Pt catalysts. The adsorption energies of the reactants, intermediates and products, and the activation barriers for the elementary reactions involved in the DRM process are calculated over the Pt(111) surface. In the process of CH4 direct dissociation, the kinetic results show that CH dissociative adsorption on Pt(111) surface is the rate-determining step. CH appears to be the most abundant species on the Pt(111) surface, suggesting that carbon deposition is not easy to form in CH4 dehydrogenation on Pt(111) surface. In the process of CO2 activation, three possible reaction pathways are considered to contribute to the CO2 decomposition: (I) CO2*+* → CO*+O*; (II) CO2*+H* → COOH*+* → CO*+OH*; (III) CO2*+H* → mono-HCOO*+* → bi-HCOO*+* CO2*+H* → bi-HCOO*+* → CHO*+O*. Path I requires process to overcome the activation barrier of 1.809eV and the forward reaction is calculated to be strongly endothermic by 1.430eV. In addition, the kinetic results also indicate this process is not easy to proceed on Pt(111) surface. While the CO2 activation by H adsorbed over the catalyst surface to form COOH intermediate (Path II) is much easier to be carried out with the lower activation barrier of 0.746eV. The CO bond scission is the rate-determining step along this pathway and the process needs to overcome the activation barrier of 1.522eV. Path III reveals the CO2 activation through H adsorbed over the catalyst surface to form HCOO intermediate firstly. This reaction requires a quite high activation barrier and is a strongly endothermic process leading to a very low forward rate constant. In conclusion, Path II is the dominant reaction pathway in CO2 activation. Additionally, there are two pathways of CH oxidation by O: (A) CH*+O*→CHO*+*→CO*+H*; (B) CH*+O*→COH*+*→CO*+H*. Both the activation barriers and kinetic results demonstrate that Path A is the prior reaction pathway. Furthermore, in the two pathways of CH oxidation by OH: (C) CH*+OH*→CHOH*+*→CHO*+H*; (D) CH*+OH*→CHOH*+*→COH*+H*. Path C is easier to proceed. In conclusion, the main reaction pathway in CH oxidation according to the mechanism: CH*+OH*→CHOH*+*→CHO*+H*→CO*+2H*. These results could provide some useful information for the operation of DRM over Pt catalysts, and are helpful to understand the mechanisms of DRM from the atomic scale.
Rapid and accurate judgment of the rock mass condition is the key to guaranteeing the safety and efficiency of tunnel boring machine (TBM) tunneling. This paper proposes a method for evaluating rock ...mass parameters based on K-means clustering, grouping tunneling areas according to the values of TBM tunneling parameters. A dataset including rock mass and TBM tunneling data is treated by logistic normalization and principal component analysis (PCA), and large volumes of tunneling data with different features are transformed into appropriate volumes of dimensionless data. K-means clustering is used, samples are grouped according to the values of tunneling data, and the specific ranges as defined by clustering are regarded as the unified evaluated results of each group. Based on the C1 part of the Pearl Delta water resources allocation project, 100 training samples and 30 testing samples were field-collected, and the proposed method was realized by the training samples and verified by the testing samples. The evaluation accuracies of uniaxial compressive strength (UCS), and joint frequency (Jf) were 90%, and 86.7% respectively, demonstrating that the evaluation had acceptable values, and the proposed method was greatly helpful for judging rock conditions.
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•Northward migration of arc magmatism and formation of ca. 802–704 Ma and ca. 759–685 Ma magmatic suites.•The two magmatic suites show contrasting geochemical and Sr-Nd-Hf isotopic ...features.•Magmatism associated with slab rollback during Neoproterozoic oceanic subduction.
The South Qinling Belt was located in the northern part of the Yangtze Block during the Neoproterozoic. Here we investigate two major magmatic intrusions in the northern and southern part of the belt, the Douling plutons (DLP) and the Fenghuangshan plutons (FHSP), to gain insights into the Neoproterozoic tectonic processes along the northern segment of the Yangtze Block. Zircon grains in the DLP yield weighted mean 206Pb/238U ages of 750–709 Ma, whereas those from the FHSP show ages of 749–728 Ma. The new results, together with the published data, reveal that these plutons were emplaced at ca. 759–685 Ma and ca. 802–704 Ma, respectively. Geochemically, the intermediate-felsic rocks from the DLP and FHSP show enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE) (Rb, Ba and K), depletion of high field strength elements (HFSE) (Nb, Ta, P and Ti), and low Sr/Y and (La/Yb)N values, which are typical features of arc magmatic rocks. The gabbros from the FHSP have high Mg#, and display LREE and LILE (Rb, Ba, K, and Sr) enrichment and depletion of HFSE (Th, U, Nb, Ta, and Ti), suggesting that they were probably formed in a mantle wedge setting. Both DLP and FHSP show arc-related geochemistry modified by slab-derived fluids, and were formed at relatively high-temperature and low-pressure conditions. However, they display distinct Sr-Nd-Hf isotopic compositions. Zircon grains of two samples from the DLP respectively show mean εHf(t) values of −2.6 ± 0.3 and 0.9 ± 0.3, whereas zircon grains of four samples from the FHSP show mean εHf(t) values ranging from 7.5 ± 0.5 to 8.7 ± 0.4. The DLP shows dominantly negative εNd(t) values and inconsistent initial 87Sr/86Sr ratios, whereas FHSP shows relatively constant and positive εNd(t) values (3.69–3.74) but variable initial 87Sr/86Sr ratios. The Sr-Nd-Hf isotopic and geochemical features suggest that the enriched mantle and crustal materials were involved in the magma evolution of the DLP, whereas the FHSP is characterized by significant juvenile components with a rising asthenospheric mantle source playing a key role. We propose a subduction-related setting for these intrusions, and envisage slab rollback during the Neoproterozoic.
Abstract
Silicon (Si), the second most abundant element in Earth’s crust, exerts beneficial effects on the growth and productivity of a variety of plant species under various environmental ...conditions. However, the benefits of Si and its importance to plants are controversial due to differences among the species, genotypes, and the environmental conditions. Although Si has been widely reported to alleviate plant drought stress in both the Si-accumulating and nonaccumulating plants, the underlying mechanisms through which Si improves plant water status and maintains water balance remain unclear. The aim of this review is to summarize the morphoanatomical, physiological, biochemical, and molecular processes that are involved in plant water status that are regulated by Si in response to drought stress, especially the integrated modulation of Si-triggered drought stress responses in Si accumulators and intermediate- and excluder-type plants. The key mechanisms influencing the ability of Si to mitigate the effects of drought stress include enhancing water uptake and transport, regulating stomatal behavior and transpirational water loss, accumulating solutes and osmoregulatory substances, and inducing plant defense- associated with signaling events, consequently maintaining whole-plant water balance. This study evaluates the ability of Si to maintain water balance under drought stress conditions and suggests future research that is needed to implement the use of Si in agriculture. Considering the complex relationships between Si and different plant species, genotypes, and the environment, detailed studies are needed to understand the interactions between Si and plant responses under stress conditions.
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•Contrasting Neoproterozoic magmatism between the northern and southern South Qinling Belt.•Ca. 850–780 Ma magmatic rocks correspond to syn- and post-collisional ...magmatism.•Mid-Neoproterozoic tectonic transition from subduction to post-collision.
The South Qinling Belt was located in the northernmost domain of the Yangtze Block during Neoproterozoic, and witnessed extensive magmatism in its southern part (<800 Ma) and northern part (>800 Ma). The mechanism and implications of the contrasting magmatism on the southern and northern sectors of this major orogenic belt remain unclear. Here we investigate a suite of magmatic intrusions along the Ningshan-Xianghe Fault that separates these two domains to gain insights into the Mid-Neoproterozoic tectonic processes in the northern segment of the Yangtze Block. LA-ICP-MS zircon U-Pb dating yields ages of ca. 851–783 Ma for the Precambrian stocks along the Ningshan-Xianghe Fault. Our result suggests that the ca. 851 ± 5 Ma Xiaolingguan diorite has an adakitic affinity, and was derived from the partial melting of thickened basaltic lower crust. The ca. 834 ± 4 Ma Yaolinghe diorite was formed through the recycling of Paleoproterozoic crustal materials in a syn-collisional setting. The ca. 783 ± 5 Ma Liangjiawan granite is inferred to have formed by partial melting of crustal high-K metabasaltic rocks in a post-collisional setting. This event may be attributed to a Mid-Neoproterozoic tectonic transition from subduction to collision and post-collision, which gave rise to syn- and post-collisional magmatism in the northern margin of the Yangtze Block.
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