Carbon quantum dots (C-Dots) have drawn extensive attention in recent years due to their stable physicochemical and photochemical properties. However, the development of nitrogen-doped carbon quantum ...dots (N-doped C-Dots) is still on its early stage. In this paper, a facile and high-output solid-phase synthesis approach was proposed for the fabrication of N-doped, highly fluorescent carbon quantum dots. The obtained N-doped C-Dots exhibited a strong blue emission with an absolute quantum yield (QY) of up to 31%, owing to fluorescence enhancement effect of introduced N atoms into carbon dots. The strong coordination of oxygen-rich groups on N-doped C-Dots to Fe3+ caused fluorescence quenching via nonradiative electron-transfer, leading to the quantitative detection of Fe3+. The probe exhibited a wide linear response concentration range (0.01–500 μM) to Fe3+ with a detection limit of 2.5 nM. Significantly, the N-doped C-Dots possess negligible cytotoxicity, excellent biocompatibility, and high photostability. All these features are favorable for label-free monitoring of Fe3+ in complex biological samples. It was then successfully applied for the fluorescence imaging of intracellular Fe3+. As an efficient chemosensor, the N-doped C-Dots hold great promise to broaden applications in biological systems.
In order to solve the problems of low correction accuracy and long correction time in the traditional English grammar error correction system, an English grammar error correction system based on deep ...learning is designed in this paper. This method analyzes the business requirements and functions of the English grammar error correction system and then designs the overall architecture of the system according to the analysis results, including English grammar error correction module, service access module, and feedback filtering module. The multilayer feedforward neural network is used to construct the language model to judge whether the language sequence is a normal sentence, so as to complete the correction of English grammatical errors. The experimental results show that the designed system has high accuracy and fast speed in correcting English grammatical errors.
Hypochlorite (ClO–) and ascorbic acid (AA) are reported to have a high correlation with oxidative stress and related diseases, so it is necessary and critical to develop sensitive and fast response ...sensors to investigate the dynamical variation of these redox substances, especially those sensors which can detect ClO– and AA in real time in two manners. However, it is still an unmet challenge for now. Herein, novel carbon dots (RD-CDs) which can respond to ClO– and AA rapidly, reversibly, and dynamically by fluorescence and colorimetry were synthesized. In the fluorescence manner, the constructed nanosensor possessed high selectivity toward ClO– in the range of 0.1–100 μM with a detection limit of 83 nM, and can be selectively recovered by AA. It endows this sensor with good capacity as a fluorescent probe for dynamic detection of ClO– and AA in living cells, which can be monitored by a fluorescence microscope. In the colorimetric manner, ClO– and AA can be detected by UV–vis in the range of 5–200 μM and 1–30 μM, respectively. The concentrations of ClO– and AA in humor can be measured by RD-CDs in both fluorescence and colorimetric mode. The results above-mentioned demonstrate its great potential in biosensing.
•Monthly baseflow can be a useful index for environmental flow needs (EFN).•A presumptive standard based on a fixed percentage of monthly baseflow of EFN does not fully meet the requirement in the ...Okanagan Basin, Canada.•Watershed management should recognize local aquatic life conditions in setting EFN using baseflow.
Environmental flow need (EFN) is defined as the quantity, quality, and timing of flow that are required to maintain the health of riverine ecosystems and human and societal sustainable development. Numerous research frameworks have been developed and used with a range of sophistication, data requirements, and management strategies. Recently, 90% of the monthly baseflow derived from groundwater has been proposed as the presumptive standard for the groundwater contribution of EFN. However, this proposed groundwater presumptive standard has not been compared to the field-based EFN, which limited its practical application in water management. Therefore, we ask whether baseflow can be used as an index of EFN, and if so, is 90% of monthly baseflow robust for aquatic ecosystems? We selected nine watersheds in the Okanagan Basin (Canada) with well-established EFN based on extensive fieldwork and local experts' knowledge to address this research question. Four baseflow separation methods were adopted to derive the long-term monthly baseflow. We then compared the baseflow against field-based EFN and found that different ranges of baseflow can represent field-based EFN. Specifically, 86%-159%, 93%-151%, and 128%-139% of monthly baseflow can be used as EFN standards for snow-melting, summer, and fall-winter, respectively. Further, we found that 102%-150% of the monthly baseflow should be maintained, implying that the presumptive standard underestimated EFN in our study region. Finally, we recommended that baseflow can be an effective index for EFN; however, watershed management should recognize local aquatic conditions in applying the baseflow EFN index for conjunctive watershed management.
Fluorescence sensing of specific biological molecules by artificial chemosensors is a versatile technique. In the present work, a switch-on fluorescence sensor for rapid, sensitive, and selective ...sensing of glutathione (GSH) in food samples was developed. This method was based on the g-CNQDs–Hg2+ system, in which the initial fluorescence from g-CNQDs was quenched by Hg2+ with an electron transfer process. In the presence of GSH, the fluorescence sensor was switched to the “on” state, which was attributed to a competitive affinity of Hg2+ to GSH and the functional groups on the surface of g-CNQDs. Under the optimal conditions, the limit of detection (LOD) of 37 nM for GSH was achieved with a wide range of 0.16–16 μM. The repeatability was better than 5.3% for GSH in both standard and food samples (n = 3). Finally, this fluorescence sensor was successfully employed for the determination of GSH in various kinds of food samples with excellent recoveries. Furthermore, this application may pave a new way for fluorescence sensing of other substances in food samples.
Plant roots are constantly exposed to a variety of abiotic stresses, and high salinity is one of the major limiting conditions that impose constraints on plant growth. In this study, we describe that ...OsMADS25 is required for the root growth as well as salinity tolerance, via maintaining ROS homeostasis in rice (Oryza sativa). Overexpression of OsMADS25 remarkably enhanced the primary root (PR) length and lateral root (LR) density, whereas RNAi silence of this gene reduced PR elongation significantly, with altered ROS accumulation in the root tip. Transcriptional activation assays indicated that OsMADS25 activates OsGST4 (glutathione S-transferase) expression directly by binding to its promoter. Meanwhile, osgst4 mutant exhibited repressed growth and high sensitivity to salinity and oxidative stress, and recombinant OsGST4 protein was found to have ROS-scavenging activity in vitro. Expectedly, overexpression of OsMADS25 significantly enhanced the tolerance to salinity and oxidative stress in rice plants, with the elevated activity of antioxidant enzymes, increased accumulation of osmoprotective solute proline and reduced frequency of open stoma. Furthermore, OsMADS25 specifically activated the transcription of OsP5CR, a key component of proline biosynthesis, by binding to its promoter. Interestingly, overexpression of OsMADS25 raised the root sensitivity to exogenous ABA, and the expression of ABA-dependent stress-responsive genes was elevated greatly in overexpression plants under salinity stress. In addition, OsMADS25 seemed to promote auxin signaling by activating OsYUC4 transcription. Taken together, our findings reveal that OsMADS25 might be an important transcriptional regulator that regulates the root growth and confers salinity tolerance in rice via the ABA-mediated regulatory pathway and ROS scavenging.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
China is one of the leading producers of citrus in the world. Gannan in Jiangxi Province is the top navel orange producing area in China. In the present study, an essential oil was prepared by cold ...pressing of Gannan navel orange peel followed by molecular distillation. Its chemical composition was analyzed by GC-MS. Twenty four constituents were identified, representing 97.9% of the total oil. The predominant constituent was limonene (74.6%). The anticancer activities of this orange essential oil, as well as some of its major constituents, were investigated by MTT assay. This essential oil showed a positive effect on the inhibition of the proliferation of a human lung cancer cell line A549 and prostate cancer cell line 22RV-1. Some of the oil constituents displayed high anticancer potential and deserve further study.
In this work, we report a durable and sensitive H2O2 biosensor based on boronic acid functionalized metal-organic frameworks (denoted as MIL-100(Cr)-B) as an efficient immobilization matrix of ...horseradish peroxidase (HRP). MIL-100(Cr)-B features a hierarchical porous structure, extremely high surface area, and sufficient recognition sites, which can significantly increase HRP loading and prevent them from leakage and deactivation. The H2O2 biosensor can be easily achieved without any complex processing. Meanwhile, the immobilized HRP exhibited enhanced stability and remarkable catalytic activity towards H2O2 reduction. Under optimal conditions, the biosensor showed a fast response time (less than 4s) to H2O2 in a wide linear range of 0.5–3000μM with a low detection limit of 0.1μM, as well as good anti-interference ability and long-term storage stability. These excellent performances substantially enable the proposed biosensor to be used for the real-time detection of H2O2 released from living cells with satisfactory results, thus showing the potential application in the study of H2O2-involved dynamic pathological and physiological process.
•Hierarchically porous MIL-100(Cr)-B was used for the immobilization of HRP.•The biosensor is durable for high sensitive and selective detection of H2O2.•The biosensor has been successfully used to the real-time detection of H2O2 released from living cells.
Wolbachia is an obligate intracellular bacterium that can alter reproduction of its arthropod hosts, often through a mechanism called cytoplasmic incompatibility (CI). In CI, uninfected females ...fertilized by infected males yield few offspring, but if both are similarly infected, normal embryo viability results (called “rescue”). CI factors (Cifs) responsible for CI are pairs of proteins encoded by linked genes. The downstream gene in each pair encodes either a deubiquitylase (CidB) or a nuclease (CinB). The upstream gene products, CidA and CinA, bind their cognate enzymes with high specificity. Expression of CidB or CinB in yeast inhibits growth, but growth is rescued by expression of the cognate CifA protein. By contrast, transgenic Drosophila male germ line expression of both cifA and cifB was reported to be necessary to induce CI-like embryonic arrest; cifA expression alone in females is sufficient for rescue. This pattern, seen with genes from several Wolbachia strains, has been called the “2-by-1” model. Here, we show that male germ line expression of the cinB gene alone, from a distinct clade of cif genes from wNo Wolbachia, is sufficient to induce nearly complete loss of embryo viability. This male sterility is fully rescued by cognate cinAwNo expression in the female germ line. The proteins behave similarly in yeast. CinBwNo toxicity depends on its nuclease active site. These results demonstrate that highly divergent CinB nucleases can induce CI, that rescue by cognate CifA factors is a general feature of Wolbachia CI systems, and that CifA is not strictly required in males for CI induction. IMPORTANCE Wolbachia bacteria live within the cells of many insects. Like mitochondria, they are only inherited from females. Wolbachia often increases the number of infected females to promote spread of infection using a type of male sterility called cytoplasmic incompatibility (CI): when uninfected females mate with infected males, most embryos die; if both are similarly infected, embryos develop normally, giving infected females an advantage in producing offspring. CI is being used against disease-carrying mosquitoes and agricultural pests. Wolbachia proteins called CifA and CifB, which bind one another, cause CI, but how they work has been unclear. Here, we show that a CifB protein singly produced in fruit fly males causes sterility in crosses to normal females, but this is rescued if the females produce the CifA partner. These findings clarify a broad range of observations on CI and will allow more rational approaches to using it for insect control.
The SuFEx‐based polycondensation between bisalkylsulfonyl fluorides (AA monomers) and bisphenol bis(t‐butyldimethylsilyl) ethers (BB monomers) using Ph3P=N−PPh3+HF2− as the catalyst is described. The ...AA monomers were prepared via the highly reliable Michael addition of ethenesulfonyl fluoride and amines/anilines while the BB monomers were obtained from silylation of bisphenols by t‐butyldimethylsilyl chloride. With these reactions, a remarkable diversity of monomeric building blocks was achieved by exploiting readily available amines, anilines, and bisphenols as starting materials. The SuFEx‐based polysulfonate formation reaction exhibited excellent efficiency and functional group tolerance, producing polysulfonates with a variety of side chain functionalities in >99 % conversion within 10 min to 1 h. When bearing an orthogonal group on the side chain, the polysulfonates can be further functionalized via click‐chemistry‐based post‐polymerization modification.
The sulfur(VI) fluoride exchange (SuFEx)‐based polycondensation reaction between bisalkylsulfonyl fluorides and bisphenol bis(t‐butyldimethylsilyl) ethers using Ph3P=N−PPh3+HF2− as the catalyst was developed. Polysulfonates synthesized via this method can be further functionalized using click chemistry based transformations orthogonal to SuFEx.
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