A spiropyran-based polymer with a stimulus response to water temperature and water content.

Temperature-responsive spiropyran-functionalized polymers usually require a thermo-sensitive polymer. However, their temperature response range is limited by the lower critical solution temperature (LCST) of the thermo-sensitive polymer, which does not exceed 37 °C. In this work, a hydrophilic polymer (PHEA-SP) sheet was prepared by photo-initiated copolymerization of hydroxyethyl acrylate (HEA) and a spiropyran crosslinking agent (SP). In water, swelling and hydrogen bonding can increase the ring-opening isomerization probability of spiropyran at the PHEA-SP crosslinking point, thus amplifying the discoloration of spiropyran induced by temperature change. PHEA-SP is very responsive to water temperature in the range of 25-55 °C, due to the amplification of spiropyranoid discoloration described above. This method avoids the dependence of the temperature responsive spiropyran-functionalized polymer on a thermo-sensitive polymer and additional UV light, while increasing the upper limit of the water temperature response to 55 °C. In addition, PHEA-SP also shows responsivity to water content in ethanol solution from 0.3% to 100%.

SERS-Active Composites with Au-Ag Janus Nanoparticles/Perovskite in Immunoassays for Staphylococcus aureus Enterotoxins.

The accurate detection of Staphylococcus aureus enterotoxins (SEs) is vital for food safety owing to their high pathogenicity, which may be performed with surface-enhanced Raman scattering (SERS) if SERS-active nanostructures are used. Herein, a Au-Ag Janus nanoparticle (NPs)/perovskite composite-engineered SERS immunoassay was developed for SEC detection. Plasmonic Au-Ag Janus NPs demonstrated inherent SERS activity from the 2-mercaptobenzoimidazole-5-carboxylic acid ligands. CsPbBr3@mesoporous silica nanomaterials (MSNs) were prepared and transformed into CsPb2Br5@MSNs in the aqueous phase. Paired SEC antibody-antigen-driven plasmonic Au-Ag Janus NP-CsPb2Br5@MSN composites were prepared. They showed amplified SERS activity, attributed to the depressed plasmonic decay due to electromagnetic field enhancement and the electron transfer mechanism. A positive relationship was established between SERS signals of composites and the SEC concentration. An additive-free SERS immunoassay was developed for simple, sensitive, and reproducible SEC detection. This study will be extended to develop multiple additive-free SERS-active plasmonic NP/perovskite composites that will open up the possibility of exploring more SERS detection probes for food safety monitoring.

A novel photothermal, self-healing and anti-reflection water evaporation membrane.

For the solar water evaporation system, there are no reports on the self-healing support, which is crucial for the sustainable use of solar evaporation membrane. In this work, a self-healing hydrogel is prepared via free radical copolymerization with covalent cross-linking and coordination cross-linking and is used as a photothermal water evaporation support. The photothermal material is then introduced into the hydrogel by physically doping acetylene carbon black. At the same time, inverted micro-pyramids are fabricated on the surface of the hydrogel by soft imprint to increase the utilization efficiency of incident light. The water evaporation rate of the composite membrane can reach 1.58 kg m-2 h-1, and the breaking elongation is 1580%. It can self-heal after it is completely broken, and can still be stretched 3 times its original length. The design of this self-healing photothermal membrane will provide a new idea for its application in a harsh outdoor environment.

"Add on" Dual-Modal Optical Immunoassay by Plasmonic Metal NP-Semiconductor Composites.

Staphylococcus aureus enterotoxins (SEs, involving SEA, SEB, SEC, SED, and SEE) are considered to be the common toxins causing food poisoning and are not allowed to be detected in food. Accurate and anti-interfering SE detection in a complex food matrix is urgently required for food safety. Dual-modal optical sensors are able to avoid mutual interference of optical signals and possess the advantages of high accuracy and sensitivity. Herein, Au nanobipyramids (Au NBPs) and persistent luminescence ZnGeGaO:Cr,Er,Yb nanoparticle (ZGGO NP) nanocomposites are fabricated using the SEC antibody/antigen as templates, which display enhanced persistent luminescence (PL) and surface-enhanced Raman scattering (SERS) strength. The enhanced PL of Au NBP-ZGGO NP nanocomposites is ascribed to plasmon-enhanced radiative transitions. It is first found that ZGGO NPs display unique upconversion fluorescence, which can be absorbed by Au NBPs and that they largely excite the intensive electromagnetic field for SERS enhancement. Dual-model optical immunoassay achieved anti-interfering and specific SEC detection with a limit of detection of 7.5 pg/mL for the PL signal and 8.9 pg/mL for the SERS signal in the range of 10 pg/mL-100 ng/mL. Depending on the plasmon-enhanced PL mechanism and upconversion fluorescence-enhanced SERS principle, plasmonic NP-semiconductor composites show potential prospects in the establishment of multimodal optical biosensors for the quantitative and accurate evaluation of analytes in a complex food matrix.

Light-Trapping SERS Substrate with Regular Bioinspired Arrays for Detecting Trace Dyes.

Recently, few studies have focused on the light-trapping surface-enhanced Raman scattering (SERS) substrate combined with Si micropyramids and Ag (or Au). However, the Si micropyramids possess no ordered period, which not only affects the repeatability of the SERS signal but also affects the theoretical exploration. Here, the ordered micropyramids with strong light-trapping capability were fabricated by utilizing unconventional nanosphere lithography and anisotropy wet etching technique. Then, the Ag nanobowls were assembled on the ordered micropyramids to form the SERS substrate with bioinspired compound-eyes structure by utilizing the liquid-solid interface self-assembly and transfer technique. Especially, the evidence for the contribution of antireflective Si micropyramids to Raman enhancement was first presented. For this bioinspired SERS substrate, the lowest concentration of R6G that can be detected is 10-13 M with the level of a single molecule, and the relative standard deviation (RSD) is 3.68%. Meanwhile, the quantitative analysis and qualitative analysis can be realized. Especially, simultaneous trace detection of four common dyes (R6G, CV, MG, and MB) in food can be realized, suggesting that this SERS substrate will have a good application prospect in the field of optical sensors.

Ratiometric persistent luminescence aptasensors for carcinoembryonic antigen detection.

NIR-emitted ZnGa2O4:Cr3+ persistent luminescence nanoparticles (ZGC NPs) coated with polydopamine (ZGC@PDA NPs) were designed featuring internal reference and quenching ability. Sr-doped Zn2GeO4 persistent luminescence nanorods (ZGO:Sr NRs) served as detection probes, which exhibited blue emission. The decay times and intensity of luminescence of ZGO:Sr NRs were optimized to acquire desired luminescence properties. An aptamer-guided ratiometric persistent luminescence sensor with the LOD (0.46 pg mL-1) was established to detect carcinoembryonic antigen (CEA). This developed ratiometric aptasensor based on persistent luminescence nanomaterials (PLMs) does not only use the afterglow properties of nanomaterials to avoid the interference of autofluorescence but also precludes the interference of certain factors in the detection environment on the luminescence intensity due to the introduction of a reference signal, and is suitable for early screening of tumor markers in serum samples. Moreover, the optimization of luminescence properties, especially for luminescence decay times, provides a way for the fabrication of multiple persistent luminescence materials in the application of time-resolved fluorescence technology. Graphical abstract Construction of ZGO:Sr NR- and ZGC@PDA NP-driven ratiometric aptasensor for CEA detection.

Seasonal variation in the frequency of venous thromboembolism: An updated result of a meta-analysis and systemic review.

OBJECTIVE: Venous thromboembolism, including deep vein thrombosis and pulmonary embolism, is likely to cause the death of both medical and surgical patients. Despite some evidence of seasonal variation in the incidence of venous thromboembolism, the existing studies obtain contradictory results. A temporal pattern for pulmonary embolism is known, but data on deep vein thrombosis are inconclusive. The purpose of this study is to make a meta-analysis and systematically review the literature about seasonal variations of pulmonary embolism and/or deep vein thrombosis in order to objectively diagnose venous thromboembolism. METHODS: According to dichotomous data, risk ratios (RRs) and 95% confidence intervals (CIs) were used to compare the incidence of venous thromboembolism in different seasons. The research was classified according to pulmonary embolism mortality, pulmonary embolism/deep vein thrombosis incidence, latitude/elevation/climatic types, and monthly incidence for four subgroup comparisons. There were a total of 23 eligible studies, in which 40,309 patients with venous thromboembolism were compared. RESULTS: The pooled total venous thromboembolism incidence was 27.2% in winter, 23.1% in spring, 24.6% in summer, and 25.1% in autumn. According to the results of pooled analysis, the incidence of venous thromboembolism in winter was much higher than that in summer (RR = 1.12, 95% CI: 1.01-1.24, adjusted P = .04), especially deep vein thrombosis. Moreover, the incidence of venous thromboembolism in summer and autumn was lower than that in winter in low-latitude (<200 m) areas and median low-latitude (0-50°-N) areas. Interestingly, the frequency of pulmonary embolism mortality was the largest in spring and smallest in summer (spring > winter ≈ autumn > summer). For monthly data, a statistically significantly lower incidence of venous thromboembolism was observed in May and July than in October. CONCLUSIONS: The study revealed a significantly higher incidence of venous thromboembolism and deep vein thrombosis in winter than in summer. Pulmonary embolism mortality occurred more frequently in spring than during other seasons. A statistically significantly lower incidence of venous thromboembolism was observed in May and July compared with that in October.

[Characteristics of the Size Distribution of Water Soluble Inorganic Ions in Sanya, Hainan].

Size-resolved filter samples were collected in Sanya every other week from June 2012 to May 2014. The mass concentrations of water-soluble inorganic ions, including anions (Cl-, NO3-, SO42-) and cations (Na+, NH4+, K+, Mg2+, Ca2+) were measured by ion chromatography. The results showed that the total concentrations of measured water-soluble inorganic ions were (8.91±7.27) and (11.34±9.37) µg·m-3 in PM2.1 and PM2.1-9, respectively. In PM2.1, SO42- and NH4+ comprised 72.2% of all water-soluble inorganic ions, while in PM2.1~9, Cl-, Ca2+ and Na+ comprised 67.6% of all water-soluble inorganic ions. In PM2.1, the total concentrations of water-soluble inorganic ions had highest concentrations in winter and lowest concentrations in summer. In PM2.1~9, the total concentrations of water-soluble inorganic ions presented the highest concentrations in summer. SO42- and NH4+ showed bimodal size distributions and the peaks in the fine mode shifted from 0.43-0.65 µm in spring, summer and autumn to 0.65-1.1 µm in winter. NO3-, Na+, Cl-, Ca2+ and Mg2+ were unimodal with the peaks in the coarse mode of 4.7-9.0 µm. K+ showed bimodal size distribution with the fine mode at 0.43-0.65 µm and the coarse mode at 4.7-5.8 µm. PCA analysis showed that water-soluble inorganic ions were mainly affected by the secondary formation, sea salt and soil particles or falling dust.

[Concentrations and Size Distributions of Water-soluble Inorganic Ions in Aerosol Particles in Taiyuan, Shanxi].

Size-resolved filter samples were collected in Taiyuan every other week from June 2012 to May 2014. The mass concentrations of water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO3- and SO42-) were measured by ion chromatography. The results showed that the total concentrations of measured water-soluble ions were (15.39±9.91), (21.10±15.49) and (36.34±18.51) µg·m-3 in PM1.1, PM2.1 and PM9, respectively. In PM1.1 and PM2.1, secondary water-soluble ions (SO42-, NO3- and NH4+) comprised 87.59% and 86.30% of all water-soluble ions, respectively, while in PM9, SO42- and Ca2+ comprised 32.78% and 28.54% of all water-soluble ions, respectively. SO42- and NH4+ had higher concentrations in winter and summer, and lower in spring and autumn. NO3-, K+and Cl- presented similar seasonal variation with a descending order of winter >autumn >spring >summer, and Ca2+ and Mg2+ followed the sequence of spring >winter >autumn >summer. SO42- and NH4+ showed a unimodal size distribution and the peak in the fine mode shifted from 0.43-0.65 µm in spring and autumn to 0.65-1.1 µm in summer. NO3- showed a bimodal size distribution. NO3- and NH4+ were dominated by the fine mode peaking at 0.43-2.1 µm in winter, and NO3- was dominated by the coarse mode peaking at 4.7-5.8 µm in summer. K+, Na+and Cl- also showed a bimodal size distribution with the fine mode at 0.43-1.1 µm and the coarse mode at 4.7-5.8 µm. Ca2+, Mg2+ and F- were unimodal with the peak in the coarse mode of 4.7-5.8 µm. On heavily polluted days, the mass concentrations of secondary water-soluble ions and Cl- accumulated, and secondary water-soluble ions were unimodal with the peak in the fine mode of 1.1-2.1 µm. However, on clear days, secondary water-soluble ions showed a bimodal size distribution with the fine mode at 0.43-0.65 µm and the coarse mode at 4.7-5.8 µm. The peak of secondary water-soluble ions in the fine mode shifted. PCA analysis showed that the sources of water-soluble ions were dominated by the secondary formation, coal combustion, industrial emission, biomass burning, and soil particles or falling dust.

[Characteristics of Water-soluble Inorganic Ions in Atmospheric Aerosols in Shenyang].

To investigate the levels and seasonal variation of water soluble inorganic components in ambient aerosol in Shenyang, 25 samples were collected with Andersen cascade sampler from Jun. 2012 to May. 2013 and nine water-soluble ions in samples were analyzed by IC. The different characteristics of aerosols between clean and pollution days in winter were discussed based on these samples. The results showed that the annual concentrations of total water soluble inorganic ions were 22.30 µg·m-3 and 14.29 µg·m-3 in fine and coarse particles, and SO42- and Ca2+ were the most abundant ions, respectively. The ratio of mass concentration between SO42- and NO3- was 2.28 and the NH4+ existed in the form of (NH4)2SO4 and NH4NO3 in fine particles. The concentrations of total water soluble ions in fine particles were higher in winter and spring compared with those in summer and autumn, and they varied significantly between different seasons. The fossil fuel consumption led to the maximum values of secondary inorganic ions in fine particles during winter. The concentrations of total water soluble ions in coarse particles varied slightly though they were higher in autumn and lower in winter, and the wind-drifting sand was responsible for the higher concentration of Ca2+ in autumn in coarse particles. The concentration of SO42-, NO3-, NH4+ accounted for 80% of total water soluble inorganic ions during clean days and rose to 94% during pollution days. The ions were mostly concentrated in the size ranges of 0.43-0.65 µm and 0.43-2.1 µm respectively during clean and pollution days in fine mode. The peaks of SO42-, NO3-, NH4+ in fine mode shifted from 0.43-0.65 µm to 1.1-2.1 µm, which meant these ions were transformed from condensing mode to droplets mode during pollution days. The air mass produced at Lake Baikal and transported through high altitude to the sampling point caused clean days, however the air mass transported through industrial areas might bring pollutions to the sampling point then caused pollution days.

A new p-metal-n structure AgBr-Ag-BiOBr with superior visible-light-responsive catalytic performance.

A novel visible-light-driven AgBr-Ag-BiOBr photocatalyst was synthesized by a facile hydrothermal method. Taking advantage of both p-n heterojunctions and localized surface plasmon resonance, the p-metal-n structure exhibited a superior performance concerning degradation of methyl orange under visible-light irradiation (λ>420 nm). A possible photodegradation mechanism in the presence of AgBr-Ag-BiOBr composites was proposed, and the radical species involved in the degradation reaction were investigated. HO2(⋅)/(⋅)O2(-) played the same important role as (⋅)OH in the AgBr-Ag-BiOBr photocatalytic system, and both the electron and hole were fully used for degradation of organic pollutants. A dual role of metallic Ag in the photocatalysis was proposed, one being surface plasmon resonance and the other being an electron-hole bridge. Due to the distinctive p-metal-n structure, the visible-light absorption, the separation of photogenerated carriers and the photocatalysis efficiency were greatly enhanced.

[Size distributions of water-soluble inorganic ions in atmospheric aerosols in Fukang].

To investigate the levels and size distributions of water soluble inorganic components, samples were collected with Andersen cascade sampler from Feb. 2011 to Feb. 2012, in Fukang, and were analyzed by IC. The variation trend, concentration level, composition, sources and size distribution of major ions during non-heating period were compared with heating period. Based on the specific samples, ionic compositions and size distributions were analyzed during heavy pollution, straw burning and spring planting periods. The results showed that inorganic components in Fukang were severely affected by heating. The total water soluble ions in fine and coarse particles during non-heating and heating periods were 11.17, 12.68 microg x m(-3) and 35.98, 22.22 microg x m(-3), respectively. SO4(2-) was mainly from saline-alkali soil, NO3(-) and NH4(+) were from resuspension of farmland soil during non-heating period, while SO4(2-), NO3(-) and NH4(+) were all from the fossil fuel consumption during the heating period. All ions were bimodal distribution during non-heating and heating periods. During the heating period, the particle size growth of SO4(2-), NO3(-) and NH4(+) in fine mode was found, SO4(2-) and NH4(+) peaked at 3.3-4.7 microm in coarse particles. Secondary pollutions were serious during heavy pollution days with high levels of secondary ions between 1.1 and 2.1 microm. Biomass burning obviously affected the size distribution of ions during the straw burning period and ions focused on smaller than 0.65 microm, while there were more soil dusts during spring planting periods and ions concentrated in larger than 3.3 microm.

[Water-soluble inorganic salts in ambient aerosol particles in Tangshan].

To investigate the levels, seasonal variation and size distributions of water soluble inorganic components, samples were collected with an Andersen cascade sampler in Tangshan from Sep. 2010 to Aug. 2011, and were analyzed by IC. The results showed that the secondary inorganic components (SO4(2-), NO3(-) and NH4(+)) were the major contributors to PM9 and PM2.1, accounting for 68% and 77% of the total water soluble salts in PM9 and PM2.1, respectively. The total concentrations of these three ions in spring, summer, autumn, and winter were 35.0, 84.7, 67.3 and 61.6 microg x m(-3) in PM9, and 23.2, 64.8, 52.7 and 49.6 microg x m(-3) in PM2.1. About 70%, 75% and 94% of SO4(2-), NO3(-) and NH4(+) were found in the fine mode of aerosol, respectively. Ca2+ and Mg2+ were unimodal and mostly concentrated in the coarse mode. Those results indicated that the pollution caused by atmospheric particles is serious in Tangshan. It is urgent to control the anthropogenic emissions sources, such as vehicle emission, coal and biomass burning. Meanwhile, it is necessary to strengthen the greening and reinforce the management of the road construction.