Search

Carbon dots (CDs) as a new type of room temperature phosphorescence (RTP) materials possess great advantages, such as low cost, simple preparation, high biocompatibility, especially exhibiting more diverse structural designs and better luminescence tunability. However, most of current RTP CDs are derived from organic chemicals, which will inevitably increase the consumption of resources and endanger the ecological environment in the long run. Biomass, as natural, abundant, and renewable carbon resource has been used in preparing RTP CDs. The aromatization structure, abundant -OH, -COOH, -NH 2 groups, etc., heteroatom self-doping performance of biomass are conducive to the construction of conjugated carbon cores and RTP active sites (C O/C N) of CDs. Moreover, the biomass-derive RTP CDs also solve the biowaste problem, reduce production costs, achieve sustainable carbon development and effectively promote the reuse of resources, simultaneously. Nevertheless, although the RTP characteristics of biomass-derived CDs have been discovered and made significant progress, there was not any review article being published to provide a systematic summary of these progress. Here, a summary of the recent progress on biomass-derived RTP CDs, such as the structure composition, luminescence mechanism, property regulation, synthetic approaches, and potential applications is given. Firstly, a brief introduction is given to the apparent composition and carbon core structure of biomass-derived RTP CDs. Then, the RTP luminescence mechanism are summarized based on two aspects, including matrix-free and matrix-protected biomass-derived RTP CDs. Moreover, the regulation of RTP properties from kinds of biomass raw materials, preparation methods, heteroatom doping and composite matrix is presented aiming to highlight the unique advantages of biomass to prepare RTP CDs. Afterwards, the potential applications of biomass-derived RTP CDs, such as anti-counterfeiting, information encryption, sensing, light emitting diodes and biological applications, etc., are reviewed. Finally, the current challenges and further prospects on the development of biomass-derived RTP CDs are proposed. [Display omitted] • This review provides valuable insights into the latest developments of biomass-derived RTP CDs. • The unique advantages of biomass-derived RTP CDs different from chemical-derived CDs are emphasized. • The regulation of RTP is discussed from raw materials, preparation methods, heteroatom doping and composite matrix. • The RTP mechanism are summarized based on matrix-free - and matrix-protected biomass-derived RTP CDs. • The potential applications and further prospects of biomass-derived RTP CDs are reviewed. [ABSTRACT FROM AUTHOR]

Given that there is lack of effective therapies for castration-resistant prostate cancer (CRPC), the combination of photothermal (PTT), photodynamic (PDT), and chemical therapy (CT) has emerged as a prominent strategy. Tumor-targeted delivery and controlled release of antitumor drug are key-elements of any combined therapy. Considering these important elements, we designed and constructed tumor microenvironment (TME)-activated nanoprobes (PGP/CaCO 3 @IR820/DTX-HA). The CaCO 3 shell could efficiently entrap the photosensitizer IR820 and the chemotherapeutic docetaxel (DTX) on the surface of pentagonal gold prisms (PGPs) to prevent elimination from the circulation, and it could act as a TME-trigger to achieve TME-responsive drug release. After modification with hyaluronic acid, PGP/CaCO 3 @IR820/DTX-HA was capable of synergistic TME-triggered PTT/PDT/CT and tumor-targeted delivery. Our in vitro and in vivo studies demonstrate that PGP/CaCO 3 @IR820/DTX-HA could achieve synergistic antitumor effects following near-infrared (NIR)-light irradiation. In addition, using the NIR fluorescence signal from IR820 and the photoacoustic (PA) signal from PGPs, i.e., through multimodal fluorescence/photoacoustic imaging, we could monitor the in vivo distribution and excretion of PGP/CaCO 3 @IR820/DTX-HA. Therefore, it can be concluded that PGP/CaCO 3 @IR820/DTX-HA shows promising clinical translational potential as a treatment for CRPC. Utilizing pentagonal gold prisms (PGPs), we constructed a multifunctional nanoplatform (PGP/CaCO 3 @IR820/DTX-HA) for effectively delivering agents into the tumor microenvironment (TME) for the diagnosis and therapy of castration-resistant prostate cancer (CRPC). The synthetic nanoplatform can satisfy TME-activated synergistic photothermal therapy (PTT)/photodynamic therapy (PDT)/chemical therapy (CT) and NIR fluorescence imaging/photoacoustic (PA) imaging. Hyaluronic acid (HA) on the surface of nanoplatform allowed the specific tumor-targeting capacity and biocompatibility. In conclusion, PGP/CaCO 3 @IR820/DTX-HA could be a promising integrated nanoplatform for CRPC diagnosis and treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new multivariate sensitivity analysis (MSA) technique is proposed. • It can perform MSA for dynamic models with both random and random process inputs. • Individual and general sensitivity indices are defined based on SVD. • The properties of the new sensitivity indices are derived. • An efficient algorithm based on UT is established for estimating the new indices. Dynamic models with both random and random process inputs are frequently used in engineering. However, sensitivity analysis (SA) for such models is still a challenging problem. This paper, therefore, proposes a new multivariate SA technique to aid the safety design of these models. The new method can decompose the SA of dynamic models into a series of SA of their principle components based on singular value decomposition, which will make the SA of dynamic models much more efficient. It is shown that the effect of both random and random process inputs on the uncertainty of dynamic output can be measured from their effects on both the distributions and directions of the principle components, based on which the individual sensitivities are defined. The generalized sensitivities are then proposed to synthesize the information that is spread between the principal components to assess the influence of each input on the entire uncertainty of dynamic output. The properties of the new sensitivities are derived and an efficient estimation algorithm is proposed based on unscented transformation. Numerical results are discussed with application to a hydrokinetic turbine blade model, where the new method is compared with the existing variance-based method. [ABSTRACT FROM AUTHOR]

A fluorescent probe for the determination of nitrite (NO 2 −) was fabricated by using green fluorescent nitrogen doped carbon dots (NCDs). The NCDs were synthesized via a one-pot hydrothermal carbonization of citric acid in the presence of p -phenylenediamine as the nitrogen source. The N content of the NCDs was high to 17.09% and consisted of a variety of functional groups on the NCDs surface, including sp2-hybridized C N, porphyrin C–N–C and amino N in N-(C) 3 or H–N-(C) 2 et al. N atoms were also doped within the framework of the NCDs. The almost monodisperse NCDs (average particle diameter = 3.67 nm) exhibited green photoluminescence (PL) with excitation/emission maxima of 360/505 nm. The PL of the NCDs was dependent on both excitation wavelength and solution pH. The NCDs showed a strong PL quenching response to NO 2 − under acidic conditions (pH = 2.5). The PL intensity of the NCDs was inversely proportional to the concentration of NO 2 − between 0.02 and 40 μM (R2 = 0.992), with a detection limit of 21.2 nM. The practical use of the nanoprobe for NO 2 − determination in food samples was also demonstrated, successfully. NCD-nitroso compounds formed because of reaction between the abundant amide groups on the surface of NCDs with the NO 2 −, which caused an inner filter effect and static PL quenching. Importantly, the NCDs had low cellular toxicity and were successfully used as a multicolor cellular imaging agent for Hepg2 cells. One-pot hydrothermal synthesis of nitrogen doped carbon dots that emit green fluorescence and their applications for nitrite detection based on inner filter effect and static quenching and multicolor cellular imaging. Image 1 • Nitrogen doped carbon dots (NCDs) were prepared by hydrothermal treatment of citric acid and p -phenylenediamine. • The NCDs showed selective and sensitive nitrite determination property. • The NCDs were successfully used to detect the content of nitrite in food samples. • The NCDs possessed high efficiency for multicolor cellular imaging. [ABSTRACT FROM AUTHOR]

• A new dependence measure for importance analysis is presented. • The mathematical properties of the proposed measure are derived and discussed. • The nonparametric method for estimating the new measure is presented. • The new method is applied to a risk assessment model and the Level E model. • The advantages of the new measure with respect to the existing ones are highlighted. This paper presents a new dependence measure for importance analysis based on multivariate probability integral transformation (MPIT), which can assess the effect of an individual input, or a group of inputs on the whole uncertainty of model output. The mathematical properties of the new measure are derived and discussed. The nonparametric method for estimating the new measure is presented. The effectiveness of the new measure is compared with the well-known delta and extended delta indices, respectively, through a linear example, a risk assessment model and the Level E model. Results show that the proposed index can produce the same importance rankings as the delta and extended delta indices in these three examples. Yet the computation of the proposed measure is quite tractable due to the univariate nature of MPIT. The results also show that the established estimation method can provide robust estimate for the new measure in a quite efficient manner. [ABSTRACT FROM AUTHOR]

• A Bayesian updating framework for dynamic systems is developed based on PCA. • Likelihood function associated with output principal components is constructed. • The key property of the new likelihood function is derived and given in this paper. • New likelihood function can provide equivalent likelihood measures for input samples. • An efficient method combing aBUS and Kriging is proposed to execute the framework. Bayesian updating has been a successful tool for model calibration in uncertainty analysis, especially in reliability analysis. However, Bayesian updating of dynamic systems with high-dimensional output remains challenging work due to the heavy computational burden associated with evaluating a high-dimensional likelihood function. In this case, even the efficient surrogate model methods can fall short of their expected potential. To solve this problem, this paper develops a novel Bayesian updating framework for dynamic systems based on principal component analysis (PCA), which can significantly reduce the output dimension and overcome the "curse of dimension". In the proposed framework, a new likelihood function is constructed based on the low-dimensional output principal components (PCs), and it is analytically proved that the new likelihood function can provide the equivalent likelihood measures to the original one. In this way, any common Bayesian updating method can be applied in the low dimensional PC space by using the new likelihood function. To further improve the efficiency, an efficient Bayesian updating algorithm is proposed in the PCA-based framework, which adopts adaptive Bayesian updating with structural reliability methods (aBUS) and the Kriging model. Finally, four examples are investigated to test the validity of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract Blueberries (Vaccinium ssp.) show relatively high resistance to pollution and have been reported to successfully colonize acid and heavy metal-contaminated soils. Blueberries were subjected to cadmium stress using a simulated pot-culture method. The intact CDS regions of VcCXIP4 and VcYSL6 were obtained, VcCXIP4 was located in the nucleus, while VcYSL6 was located in the chloroplast. Both genes were constructed into a modified plant expression vector pCambia1301 for tobacco transformation with agrobacterium infection methods. Results showed that VcCXIP4 did not function alone in regulating cadmium (Cd) transport. Cd content of Cd in the leaves of VcYSL6 transgenic tobacco by 15.57% under high Cd concentration. Both , VcCXIP4 and VcYSL6 genes were up-regulated under Cd stress. Blueberry primarily accumulated excess Cd in the root, but Cd content in the fruit was almost independent of Cd content in the soil. Further, the effect of soil Cd content on fruit Cd content was not significant. VcCXIP4 is likely to interact with other proteins to regulate excess Cd in blueberry, while VcYSL6 is a Cd transporter required for excess Cd detoxification in blueberry. Highlights • Blueberry trees can grow in heavy-metal contaminated soils. • VcCXIP4 and VcYSL6 expression levels varied with Cd concentration treatment. • Expression of VcCXIP4 was up-regulated with increasing Cd concentration. • Expression of VcYSL6 was up-regulated with increasing Cd concentration. • Cd content in fruit did not increase significantly with increasing soil Cd content. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Nitrogen and boron co-doped carbon quantum dots (NB-CQDs) were prepared by hydrothermal treatment of citric acid, borax and p -phenylenediamine. • The NB-CQDs showed regular photoluminescence (PL) under different excitation wavelengths, and had pH- and solvent polarity-dependent PL. • The NB-CQDs displayed great PL detection ability for acetone and dopamine, and the detection limits were 0.54 μM and 11 nM, respectively. • The NB-CQDs and poly(vinyl alcohol) composite film demonstrated good PL response to acetone vapor. • The NB-CQDs were used for multicolor cellular imaging. Abstract Nitrogen and boron co-doped carbon quantum dots (NB-CQDs) were prepared via one-pot hydrothermal treatment of citric acid, borax, and p -phenylenediamine. The synthesized NB-CQDs were characterized by transmission electron microscopy, Fourier-transform infrared spectra, X-ray photoelectron spectra, dynamic light scattering, ultraviolet-visible absorption and fluorescence spectra to characterize their surface morphology, crystal structure, functional groups and elemental composition, and optical properties. It was found that N and B species were efficiently doped into the carbon framework of the dots, the N- and B-Containing groups formed on the surface of NB-CQDs during the hydrothermal reaction. The element doping and surface functionalization of NB-CQDs efficiently modulated their physicochemical properties. The NB-CQDs were nearly mono-disperse with an average particle diameter of 3.53 nm, and the excitation/emission wavelengths were 360/490 nm, respectively. The NB-CQDs showed regular photoluminescence (PL) emission under different excitation wavelengths, and possessed pH-dependent and solvent polarity-dependent PL properties. In addition, the NB-CQDs and a NB-CQD/poly(vinyl alcohol) composite film showed good PL responses to acetone solution and vapor. A PL sensor for the determination of acetone solution with a limit of detection (LOD) of 0.54 μM (R2 = 0.9956) was then designed. The NB-CQDs were also used for the determination of dopamine. The PL intensity of the NB-CQDs was inversely proportional to the concentration of dopamine in the range of 0.1–70 μM (R2 = 0.9958). The LOD of dopamine was 11 nM, and PL quenching occurred via a static quenching mechanism. Additionally, these NB-CQDs can be used for multicolor cellular imaging and showed good uptake by Hepg2 cells. [ABSTRACT FROM AUTHOR]

Prognostics and health management (PHM) is crucial in the lifecycle monitoring of a product, especially for complex equipment working in a harsh environment. In order to improve the accuracy and efficiency of PHM, digital twin (DT), an emerging technology to achieve physical–virtual convergence, is proposed for complex equipment. A general DT for complex equipment is first constructed, then a new method using DT driven PHM is proposed, making effective use of the interaction mechanism and fused data of DT. A case study of a wind turbine is used to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In recent years, reliability analysis based on adaptive Kriging (AK) has been extensively studied. However, constructing the Kriging model of high-dimensional systems during adaptive learning faces huge computational challenges. This paper combines partial least squares (PLS) with AK to develop an efficient method for reliability analysis of high-dimensional systems, which is named as PLS-AK. The proposed method takes PLS algorithm as the dimensionality reduction (DR) technique of high-dimensional input variables. Then, in the reduced space of input principal components (PCs), a low-dimensional Kriging model is constructed with U learning function for reliability analysis. Since PLS usually requires adequate samples to determine the latent relationship between input and output variables, using too many initial samples before adaptive learning will weaken the advantages of AK. To avoid this problem, this paper also proposes a synchronous updating method for both the projection direction and AK model. In this way, only a few initial samples are required to determine the initial input projection, and the input projection will be updated and converge gradually as the number of training samples increases. At last, three examples can prove the effectiveness of the proposed PLS-AK method. • A reliability analysis (RA) method is proposed for high-dimensional input systems. • The proposed method adopts PLS to reduce the dimension of input variables. • Adaptive Kriging (AK) is performed in low-dimensional input space for RA. • The updating strategy can update input projection and Kriging model simultaneously. • The proposed method can greatly improve the efficiency of AK modeling for RA. [ABSTRACT FROM AUTHOR]

The blood brain barrier (BBB) could be damaged within the thrombolytic time window and is considered to be a precursor to hemorrhagic transformation during reperfusion. Although we have recently reported the association between BBB damage and tissue injury within the thrombolytic time window, our knowledge about this early BBB damage is limited. In this study, rats were subjected to 2-h middle cerebral artery occlusion (MCAO) followed by 10 min reperfusion with Evan's blue as a tracer to detect BBB damage. Rat brain was sliced into 10 consecutive sections and with TTC staining, a macro and full view of the spatial distribution of BBB damage and tissue injury could be clearly seen in the same group of animals. After 2-h MCAO, tissue injury started from 2nd slice and the BBB leakage started from the 5th slice, of note, there is no colocalization between BBB damage and tissue injury. Fluoro Jade B was employed to explore the localization of neuronal degeneration, and our results showed that 2-h MCAO produced greater number of positive cells in ischemic cortex and dorsal striatum than other areas. More important, 2-h MCAO induced occludin but not claudin-5 degradation in the ischemic hemisphere and pretreatment with MMP inhibitor GM6001 significantly reduced occludin degradation as well as BBB damage detected by IgG leakage. Taken together, our findings demonstrated a “mismatch” between ischemic tissue injury and BBB leakage and a differential degradation of occludin and claudin-5 by MMP-2 after 2-h MCAO. [ABSTRACT FROM AUTHOR]

• An efficient Bayesian updating method based on Kriging is proposed, i.e. BUS-AK2. • BUS-AK2 adopts two-step adaptive Kriging to perform the BUS analysis. • BUS-AK2 provides a solution to determining the constant c in BUS by Kriging. • The steps of BUS-AK2 for the BUS problem with a small acceptance rate are given. • The proposed method can well deal with the BUS problem with multiple observations. Bayesian model updating is a powerful tool for system identification and model calibration as new measurements or observations become available. At present, Bayesian updating with structural reliability methods (BUS) is an efficient and easy-to-implement method, which can transform the multi-dimensional integration in Bayesian updating into a reliability problem by introducing an auxiliary variable. However, the efficiency and accuracy of BUS are dependent on the constant c in the performance function constructed in BUS for some reliability methods, while c is not available in advance generally. Therefore, this paper proposes an efficient Bayesian updating method with two-step adaptive Kriging (AK), which is named as BUS-AK2, where both c and the transformed reliability problem can be efficiently solved by AK. In the proposed method, BUS-AK2 first constructs the Kriging model of likelihood function by expected improvement (EI) learning function, and the maximum of likelihood function and c can be obtained. Then the Kriging model of the performance function in BUS is constructed, where U learning function is employed to obtain samples from the posterior distribution. In addition, for the BUS problem with a small acceptance rate, combined global and local sampling technique is incorporated into the proposed method to further improve modeling efficiency. Examples show that the proposed method has obvious computational advantages for the BUS problem with a small acceptance rate and multiple observations. [ABSTRACT FROM AUTHOR]

Abstract: The attapulgite/Fe3O4 magnetic nanoparticles (ATP–Fe3O4) were prepared by co-precipitation technique in the aqueous suspension of attapulgite pre-modified with FeCl3. The co-precipitation occurred by ammonia in presence of ferrous chloride at 90°C under magnetic stirring. Morphology observation showed that the Fe3O4 nanoparticles were absorbed to attapulgite nano-needles’ surfaces and their dispersibilities in water was also studied. The ATP–Fe3O4 particles had been characterized with Fourier transform infrared (FT-IR) spectroscopy analysis, X-ray diffraction (XRD), pore surface area (BET), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). [Copyright &y& Elsevier]