Facile preparation of bimetallic Au-Cu nanoclusters as fluorescent nanoprobes for sensitive detection of Cr3+ and S2O82- ions.

Metallic nanoclusters (NCs) have attracted special attention from researchers due to their interesting optical properties. In this experiment, we proposed a facile one-step method for the synthesis of bimetallic gold-copper nanoclusters (AuCuNCs). The prepared AuCuNCs were characterized by fluorescence spectroscopy (FL), UV-vis absorption spectrum, transmission electron microscopy (TEM), etc. The emission peak of the prepared AuCuNCs was located at 455 nm and showed blue luminescence under the excitation of 365 nm UV light. Furthermore, after the addition of Cr3+ and S2O82- ions, the FL emission intensity of AuCuNCs was significantly reduced at 455 nm and there was a color change of diminished blue luminescence under UV lamp. The AuCuNCs exhibited excellent linearity and sensitivity for the detection of Cr3+ and S2O82- ions. The limits of detection (LOD) for the Cr3+ and S2O82- ions were calculated to be 1.5 and 0.037 µM, respectively. Finally, the recoveries of Cr3+ and S2O82- ions in Runxi Lake and tap water were measured by standard addition recovery test and were 96.66 âˆ¼ 116.29 %, 95.75 âˆ¼ 119.4 %.

How do government subsidies and consumers' low-carbon preference promote new energy vehicle diffusion? A tripartite evolutionary game based on energy vehicle manufacturers, the government and consumers.

At present, the diffusion and trading volume of new energy vehicles (NEVs) account for only a small part of the automobile market. How to effectively promote the production of energy vehicle manufacturers and the purchase of consumers for NEVs has become a key and urgent problem to be solved. Our research builds an evolutionary game model including government, consumers and energy vehicle manufacturers from the perspective of supply chain research, and discusses the participants' evolutionary stability strategy and portfolio stability strategy. In addition, the method of simulated moments is used to assign values to the model data, and MATLAB software is used for simulation verification and analysis. Through analysis, it is found that: (1) The government, energy vehicle manufacturers and consumers influence each other in their strategic choices, but to different degrees. (2) The difference of government subsidy objects will not affect the evolution direction and result of the diffusion game model of NEVs, but will affect the stable speed of strategic behavior and the change direction of strategic choice of consumers and energy vehicle manufacturers. And in the case of moderate subsidies, subsidies to energy vehicle manufacturers can promote the NEV diffusion. (3) Improving the environmental friendliness of NEVs and improving consumers' low-carbon preference for NEVs have about the same effect on the replicative power system. And compared with other key factors, they are the most favorable way to promote NEVs diffusion. At last, suggestions are put forward according to the research conclusions.

A novel fluorescent nanoprobe based on potassium permanganate-functionalized Ti3C2 QDs for the unique "turn-on" dual detection of Cr3+ and Hg2+ ions.

Titanium carbide quantum dots (Ti3C2 QDs) were synthesized by ammonia-assisted hydrothermal method. We also synthesized potassium permanganate (KMnO4)-functionalized Ti3C2 QDs (Mn-QDs) by modifying Ti3C2 nanosheets with KMnO4 and then cutting the functional nanosheets into Mn-QDs. The Ti3C2 QDs and Mn-QDs were characterized by fluorescence spectroscopy (FL), Fourier transform infrared spectroscopy (FTIR), UV-vis spectrophotometry (UV-vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Furthermore, the modified Mn-QDs have strong luminescence ability and good dispersion stability, which can be used for Cr3+ and Hg2+ double ion detection with enhanced fluorescence specificity. Cr3+/Hg2+ and negatively charged Mn-QDs are bound together by electrostatic interactions. Meanwhile, the surface of Mn-QDs is rich in functional groups, which interacts with Cr3+/Hg2+ to modify the surface traps, leading to defect passivation and exhibiting photoluminescence enhancement. For the dynamic quenching produced by the interaction of Mn-QDs with Hg2+ within 50 µM, it may be caused by the complex formation of Hg2+ trapped by the amino group on the surface of Mn-QDs. The detection limits for Cr3+ and Hg2+ were 0.80 µM and 0.16 µM, respectively. The recoveries of Cr3+ and Hg2+ ions in real water samples were 93.79-105.10% and 93.91-102.05%, respectively, by standard addition recovery test. In this work, the application of Mn-QDs in Cr3+ and Hg2+ ion detection was researched, which opens a new way for its application in the field of detecting heavy metal ions.

Eu doped Ti3C2 quantum dots to form a ratiometric fluorescence platform for visual and quantitative point-of-care testing of tetracycline derivatives.

Antibiotic residues have become a public health issues, the fast detection of tetracycline (Tc) in the environment is urgently required. In this work, Ti3C2 quantum dots (Ti3C2 QDs) and Europium ions jointly constructed a ratiometric fluorescence (FL) platform for the detection of Tc, based on synergistic impact of the Foster Resonance Energy Transfer (FRET) from Ti3C2 QDs to Eu3+ ions and the Antenna Effect (AE) between Tc and Eu3+ ions. And we proposed a ratiometric FL platform for detecting Tc with good linear response range (100-1000 uM) and low detection limit (48.79 nM). Meanwhile, we applied this platform to detect a serious of ß-diketone ligands of Eu3+ ions, demonstrating the platform's versatility for this category of chemical. Furthermore, based on the color changes of QDs@Eu3+ from blue to red at 365 nm ultraviolet light, an intelligent detection smart device was built for the visual semi-quantitative detection of Tc in actual samples. We proved the applicability of the device in complicated samples and the potential for rapid, sensitive, intuitive and point-of-care detection in the field of environment, food, pharmaceutical and agriculture.

Yttrium vanadates based ratiometric fluorescence probe for alkaline phosphatase activity sensing.

Alkaline phosphatase (ALP) is an important biomarker for diagnosis, and the abnormal level of serum ALP is closely related to a variety of diseases. In present work, a ratiometric fluorescence probe based on hybrid nanoparticles CDs@YVO4: Dy3+ nanoparticle is introduced for alkaline phosphatase (ALP) activity determination. The CDs@YVO4: Dy3+ probe is constructed by the carbon dots (CDs) and YVO4: Dy3+ through a simple mixing method, in which the blue emission of CDs at 405 nm acts as the calibrated signal, the green emission of YVO4: Dy3+ at 574 nm decreased with the increasing targets ALP, and used as the output signal. In addition, the Cu2+ and pyrophosphate (PPi) were also employed in this strategy to utilize the excellent fluorescnece quenching efficiency of Cu2+ to the Dy3+ ions emission of CDs@YVO4: Dy3+, as well as the strong affinity of PPi for Cu2+. In the presence of analyts ALP, ALP catalyzes the hydrolysis of PPi, causing the release of Cu2+, resulting in the Dy3+ ions emission quenched, while the CDs emission at 405 nm retained unchanged, based on this, we designed the off-on-off ratiometric fluorescence platform for ALP sensing. The experiment result shows that the ratio of F574/F405 is linear to the concentration of ALP in arange of 0.05∼3000 U/L with a detection limit of 0.04 U/L, which is comparable or better than those reported fluorescence probe, especially the calibrated signal introduction of CDs can eliminate the background interference, improve the accuracy of proposed probe greatly. Furthermore, the discrimination of ALP enzyme inhibitor with the IC50 of 26 µM, and ALP concentration in real human serum sample has also demonstrated the applicability of CDs@YVO4: Dy3+ fluorescence sensor well.

[Changing trends of etiologic characteristics of cardiovascular diseases among inpatients in Shanghai: a retrospective observational study from 1948 to 1999].

OBJECTIVE: To investigate the trends in the change of etiologic types of cardiovascular disease among inpatients in Shanghai area from 1948 to 1999. METHODS: The retrospective estimate was based on the data survey in two major general hospitals of Shanghai. Descriptive statistics were provided for all patients meeting the inclusion criteria. Trend of percentage change was compared using linear regression. Diagnoses were categorized using the International Classification of Diseases, 9th Revision. RESULTS: (1) A total of 37 086 admissions with different etiologic types of heart diseases from 1948 to 1999 was reviewed. The percentage of heart diseases among the inpatients in medical wards was significantly increased during this period, being 9.89%, 15.69%, 20.91%, 23.54% and 24.24% (P < 0.05) for each decade respectively and reaching a peak in 1990s. (2) Patterns of different etiologic types of heart diseases changed markedly from 1948 to 1999. The percentage of coronary heart disease increased from 6.78% in 1940s to 39.19% in 1990s (P < 0.05), cardiac dysrhythmias from 0.63% to 18.84% (P < 0.05), cardiomyopathy from 0.05% to 5.01% (P < 0.05) and endocarditis from 0.02% to 0.69% (P < 0.05). The percentage of rheumatic heart disease decreased from 50.30% to 10.25% (P < 0.05). The percentage of hypertensive heart disease, myocarditis and congenital heart disease remained unchanged. (3) From 1948 to 1999 the overall in-hospital mortality of heart diseases in different decades decreased from 17.91%, 11.51%, 14.07%, 7.35% to 2.39% (P < 0.05). (4) Patients were slightly younger in 1950s (39.7 +/- 5.5) years than those in 1990s (60.1 +/- 12.7) years (P < 0.05). (5) The percentage of male patients increased (ranging from 50.7% in 1940s to 62.4% in 1990s, P < 0.05). CONCLUSIONS: Hospitalization patterns of heart diseases have changed dramatically in the second half of the last century in Shanghai. Coronary heart disease is the most frequent condition requiring hospitalization nowadays and the rates of many age-related heart diseases are increasing and this has been paralleled by a substantial increase of the rates in the community survey. More attention should be paid to these heart diseases in Shanghai and in this century.