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The aim of this study was to assess the imaging features of urethral and peri-urethral masses on transvaginal or transperineal ultrasound (US) in a cohort of 95 women. In this retrospective study, medical records of 95 female patients with 98 asymptomatic or symptomatic urethral and peri-urethral masses were retrospectively reviewed. Data regarding patient demographic characteristics, symptoms, signs, imaging features on 2-D and 3-D transvaginal or transperineal US, diagnostic tests and physical and intra-operative findings were extracted. The US imaging features and clinicopathologic characteristics of each urethral or peri-urethral mass were compared. On ultrasound, 39 masses (in 39 patients) were diagnosed as urethral diverticula, which manifested mostly as complex cystic masses (24/39, 61.5%); 35 masses (in 33 patients) were diagnosed as para-urethral cysts, which manifested mostly as simple cystic masses (19/35, 54.3%); 13 hypo-echoic solid masses (in 12 patients) exhibiting blood flow signals on color Doppler imaging were diagnosed as urethral leiomyomas; hypo-echoic or heterogeneous solid masses (in 8 patients) exhibiting blood flow signals on color Doppler imaging were diagnosed as urethral caruncles, including one complicated by malignant transformation; solid masses with mixed echogenicity (in 2 patients) exhibiting blood flow signals on color Doppler imaging were diagnosed as urethral squamous cell carcinoma or adenocarcinoma, and a hypoechoic solid mass (in one patient) with blood-flow signals on color Doppler imaging was diagnosed as urethral condyloma associated with human papillomavirus infection. This study confirmed transvaginal or transperineal 2-D and 3-D ultrasonography to be a valid, non-invasive, cost-effective diagnostic modality for the differential diagnosis of urethral and periurethral masses. [ABSTRACT FROM AUTHOR]

• Single-phase Cu doped c -oriented ε -Fe 2–3 N films with manipulable magnetic and transport properties are synthesized. • The saturation magnetizations decrease with increasing Cu doping amount, which are attributed to the weaken of Fe-Fe ferromagnetic coupling by Cu doping. • The resistivity variations with changing temperature are weakened by Cu doping, which may be ascribed to the more hybridization of 3d states with N 2p states. c -oriented Cu doped ε -Fe 2 – 3 N films are fabricated on c -Al 2 O 3 by magnetron sputtering. It is found that the crystal constant c decreases with increasing Cu doping amount, which is due to the smaller radius of Cu atoms. The XPS peaks of Fe 2p and Cu 2p are confirmed with Fe-N and Cu-N binding energy determined. The saturation magnetizations decrease with increasing Cu doping amount, which are attributed to the weakening of Fe-Fe ferromagnetic coupling by Cu doping. Furthermore, the temperature dependences of (R T –R 300 K)/R 300 K indicate that the resistivity variations with changing temperature are weakened by Cu doping. The manipulable magnetic and transport properties by Cu doping may provide a new method of designing spintronic devices. [ABSTRACT FROM AUTHOR]

• A simple method to compare two liquors is developed. • The spectral distance was used to measure the differences of liquors quantitatively. • One method to predict years of finished Chinese liquors was presented. • The flavor of liquors can be considered without analysis of components in liquors. We propose a distance to measure differences of Chinese liquors quantitatively through comparing their three-dimensional fluorescence spectra. This distance can be easily computed with value ranges from 0 to 2. We use this distance to build a forecasting model to predict years of mixed liquors. The result shows that this model possesses high accuracy with the mean error around 0.3 year. Furthermore, since three-dimensional fluorescence spectra of Chinese liquors contain the information of all florescent substances inside of them, we suggest a method to classify flavors of original year Chinese liquors based on this distance. It gives a relatively correct classification on these samples in the sense of their flavors. [ABSTRACT FROM AUTHOR]

Rapid recruitment of small fish after biomanipulation in warm lakes may delay the reestablishment of submerged macrophytes, not least at high nutrient concentrations. Success has recently been obtained in controlling phosphorus (P) loading to many lakes, but nitrogen (N) inputs often remain high. To determine the interactive effects of N loading and the abundance of small-sized fish on the growth of the submerged macrophyte Vallisneria natans , we conducted an outdoor mesocosm experiment with a factorial design on the north shore of Lake Taihu, China. The experiment involved two densities of small crucian carp – low (10 g m − 2 ) and high (40 g m − 2 ) – crossed with two levels of N loading – present-day external nutrient loading (P: 5 μg L − 1 day − 1 , N: 130 μg L − 1 day − 1 ) and P: 5 μg L − 1 day − 1 with a three times higher N loading (N: 390 μg L − 1 day − 1 ). The results showed that nitrogen-fish interactions significantly hindered the growth of V. natans , particularly at the high N loading. At low N loading, high densities of fish decreased the relative growth rate, mean leaf length, leaf mass and root mass of V. natans by 16%, 5%, 8%, and 23%, respectively, compared with these measures at low fish densities. The effect of fish was even stronger when N loading was high, with decreases of 232%, 32%, 57%, and 47% for the respective plant growth measures. The stronger effect at high N loading was attributed to higher turbidity due to enhanced phytoplankton biomass and to increased consumption or damage of plants by the fish in response to the more nutrient-enriched plant tissue. Our results indicate that high abundance of small crucian carp in warm lakes may reduce the resilience of submerged macrophytes to external N loading, thereby lowering the chances of successful restoration by biomanipulation. [ABSTRACT FROM AUTHOR]

Reestablishment of submerged macrophytes is considered important when restoring shallow eutrophic lakes. To improve water clarity and consequently the growth conditions of macrophytes, removal of plankti-benthivorous fish has been used. In sub-tropical shallow lakes, however, rapid recruitment of small fish, especially benthivores during restoration, may hamper early reestablishment of submerged macrophytes. Crucian carp ( Carassius carassius ) and Vallisneria natans are common species dominated in sub-tropical shallow lakes. To investigate the effect of small benthivorous fish on the growth of Vallisneria natans , a 28-day outdoor controlled experiment was undertaken in 12 mesocosms with three densities of Carassius carassius − low (10 g m −2 ), high (40 g m −2 ) and no fish (all in four replicates). The results showed that the fish significantly increased chlorophyll- a concentrations and periphyton biomass in both fish treatments, most significantly at high density for Chl a . This concurs with an increase in nutrient concentrations, likely mediated by fish sediment disturbance and excretion, and a reduction of zooplankton biomass (less algal grazing). Increased concentrations of inorganic suspended solids with increasing fish density further enhanced turbidity, causing shading of the macrophytes. Accordingly, the relative growth rate, ramet number and root/leaf ratio of V. natans decreased significantly at low and high fish density compared with the controls, but the effects did not depend on fish density. However, mean leaf length rose with increasing fish density, likely to allow the plants to obtain more light. Overall, our results show that not only large-bodied carp, as demonstrated frequently, but also small-sized crucian carp posed a constraint on submerged macrophyte reestablishment, and we conclude that crucian carp may hamper restoration efforts in sub-tropical shallow lakes. Restoration by biomanipulation should therefore target also small-sized crucian carp. [ABSTRACT FROM AUTHOR]

[Display omitted] • The β-CD-AgNPs substrate can selectively combine with NFX. And the proposed method can be applied in the detection of real milk samples. • The "host–guest" interaction of NFX and β-CD-AgNPs was verified by the UV–Vis absorption spectroscopy, fluorescence spectroscopy, Zeta potential and DLS. • This developed SERS method is simple and sensitive, the LOD of NFX was 3.214 pmol/L in standard solution and 5.327 nmol/L in milk. The norfloxacin (NFX) residue in milk will increase human resistance to drugs and pose a threat to public health. In this work, a highly sensitive method for detection of NFX was developed based on surface enhanced Raman spectroscopy (SERS) using β-cyclodextrin functionalized silver nanoparticles (β-CD-AgNPs) as substrate. The unique spatial size and hydrophilicity of β-CD on the surface of AgNPs could selectively capture the target molecule (NFX) through some weak interactions, including hydrogen-bond interaction, electrostatic interaction, etc. The interactions were characterized by the UV–Vis absorption spectroscopy, fluorescence spectroscopy, Zeta potential and DLS. The Raman signal of NFX is largely enhanced when anchored by β-CD on the surface of AgNPs due to SERS effect. Through a series of experiments and analysis, the limit of detection (LOD) in standard solution and spiked milk were calculated to be 3.214 pmol/L and 5.327 nmol/L. The correlation coefficients (R2) were 0.986 and 0.984, respectively. For milk sample determination of NFX, the recovery was 101.29% to 104.00% with the relative standard deviation (RSD) from 2.986% to 9.136%. To sum up, this developed SERS strategy is sensitive and specific to detect NFX in milk, it has practical application value and prospects. [ABSTRACT FROM AUTHOR]

We define a (pseudo-)distance between graphs based on the spectrum of the normalized Laplacian. Since this quantity can be computed easily, or at numerically estimated, it is suitable for comparing in particular large graphs. Numerical experiments demonstrate that the spectral distance provides a practically useful measure of graph dissimilarity. The asymptotic behavior of the Laplacian spectrum furthermore yields a tool for classifying families of graphs in such a way that the distance of two graphs from the same family is bounded by O ( 1 / n ) in terms of size n of their vertex sets. [ABSTRACT FROM AUTHOR]

By assigning a probability measure via the spectrum of the normalized Laplacian to each graph and using L p Wasserstein distances between probability measures, we define the corresponding spectral distances d p on the set of all graphs. This approach can even be extended to measuring the distances between infinite graphs. We prove that the diameter of the set of graphs, as a pseudo-metric space equipped with d 1 , is one. We further study the behavior of d 1 when the size of graphs tends to infinity by interlacing inequalities aiming at exploring large real networks. A monotonic relation between d 1 and the evolutionary distance of biological networks is observed in simulations. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we try to propose a toy model, which follows the majority rule with the Fermi function, to uncover the role of the heterogeneous interaction between individuals in opinion formation. In order to do this, we define the impact factor , says individual , as the exponential function of its connectivity with the tunable parameter . also shows the public information that can be collected by individuals in the system. We realize our model in scale-free networks with mean connectivity . We find that much more public information ( ) and less public information ( ) cannot let either of the two opinions be the majority during the opinion formation. Furthermore, is a constant and equal to , and decreases as a power-law function of the mean connectivity of the network. Our work can provide some perspectives and tools to understand the diversity of opinion in social networks. [Copyright &y& Elsevier]

• The novel Ag-COF-COOH substrates provide huge SERS hot spots, EF = 9.72 × 106. • The SERS method in this work is sensitive and the LOD is 0.68 μg/L in milk. • The SERS method in this work requires only one step of pretreatment. Melamine, a nitrogen-containing organic molecule, has received widespread attention as it had been illegally added in dairy products to increase the content of nitrogen, leading to kidney stones in healthy people after long-term ingestion. Based on SERS technology and Covalent Organic Framework (COF) materials, we developed carboxyl-functionalized Ag-COF-COOH materials as SERS substrates for the detection of melamine adulteration. Using COF material as a ligand can effectively reduce the influence of interferents in milk. In addition, we investigated two causes of melamine SERS enhancement: the ordered arrangement of Ag NPs and the strong interaction between the substrate and the melamine. The linear range was 1–20 μg/L and the limit of detection (LOD) was 0.68 μg/L in liquid milk due to the high sensitivity and reliability of this method. The results show that this new SERS substrate has great potential for applications in the food surveillance industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • This is the first time that carbon dots have been synthesized using ammonium citrate and glutamic acid as precursors. • The fluorescence stability of carbon dots is fully explored, facilitating their use in real-world environments. • This method achieves high selectivity and sensitivity in the trace detection range. • Monitoring Cd2+ ions in tap water and lake water. In this study, fluorescent carbon dots were synthesized for the first time using ammonium citrate and glutamic acid as precursors via a one-pot hydrothermal method. The synthesized carbon dots emit blue fluorescence at 436 nm (excited at 320 nm) and demonstrate excellent photobleaching resistance and fluorescence stability in high salt environments. Within the range of 1–25 μM, the fluorescence of CDs gradually increases with the increasing concentration of Cd2+, reaching a limit of detection as low as 13 nM. This phenomenon could be ascribed to the chelation-enhanced fluorescence, a result of Cd2+ forming complexes with the abundant surface functional groups such as CN–, –COOH, –OH, –NH 2 in CDs. Furthermore, this turn-on fluorescent probe has been successfully used for the detection of Cd2+ in tap water and lake water, providing an efficient and sensitive method for the analysis of environmental metals. [ABSTRACT FROM AUTHOR]

[Display omitted] • COF (covalent-organic framework) capped with sliver nanoparticles (Ag NPs) were first developed as SERS substrate for detection of benzoic acid in liquid milk. • This detection method has high sensitivity and reliability that allows us to achieve LOD of 0.13μg/mL in milk and 0.00372μg/mL in water. • The proposed method can be applied in the detection of real milk samples. Benzoic acid, which has a pivotal role in food additive, is prohibited to add as a preservative in dairy products. China, Brazil, and other countries have proposed standard methods to detect the addition of benzoic acid in food. Surface-enhanced Raman scattering (SERS) is an upcoming spectral detection technique, which has been widely used in the field of material analysis with the advantages of non-invasive, fast detection speed and complex environment with little interference. To detect the illegal use of benzoic acid in dairy industry, we developed Ag-COF (covalent-organic framework) material as SERS substrate to detect benzoic acid in liquid milk. The great enhancement ability of Ag-COF substrate is controlled by the addition of acetic acid and complex interplay between COF material and benzoic acid. This detection method has high sensitivity and reliability that allows us to achieve limit of detection (LOD) of 0.13 μg/mL in milk and 0.00372 μg/mL in water by applying this method. In experiment on recovery rate of real samples, the detection time is less than 15 minutes and the relative standard deviation (RSD) ranged from 2.82% to 5.69%. Therefore, this method has practical significance of the detection of benzoic acid in dairy products. [ABSTRACT FROM AUTHOR]

In this paper, fluorescent carbon dots were prepared by hydrothermal method using 3,5-dihydroxybenzoic acid and l -Arginine as precursors. The synthesized CDs have excitation-dependent emission with emission peaks at 354 nm and 460 nm, corresponding to the optimal excitation wavelengths of 295 nm and 330 nm, respectively. CDs have good dispersion and resistance to photobleaching in aqueous solution, and can maintain stable fluorescence in highly concentrated salt environment. Based on the inner filter effect, Cr(VI) with strong absorption can shield the excitation light of CDs at 295 nm and absorb the emission fluorescence at 354 nm simultaneously. Due to the intermolecular electrostatic interaction, Hg(II) can coordinate with CDs surface groups and cause static quenching, which significantly reduces the fluorescence intensity of CDs emitted at 460 nm. The linear ranges were 0.1–2 μM and 0.4–5 μM for Cr(VI) and Hg(II) detection, respectively, and limits of detection were 0.024 μM and 0.084 μM. Additionally, the probe was successfully applied to tap water and lake water samples. With high sensitivity and spectral selectivity, this sensing strategy realized the detection of two heavy metal ions by a single fluorescent probe, demonstrating its great potential in the field of environmental metal analysis. [Display omitted] • First synthesis of carbon dots with spectral selectivity using 3,5-dihydroxybenzoic acid and l -arginine as precursors. • Separate detection of Cr(VI) and Hg(II) ions using the same carbon dots under different excitations. • This method achieves high selectivity and sensitivity in the trace detection range. • Monitoring Cr(VI) and Hg(II) ions in tap water and lake water. [ABSTRACT FROM AUTHOR]

• Ultrafast photo-physical properties of DASPA are studied by the TA spectra. • Simulated results suggest multiple binding locations between DASPA and protons. • TA results indicate a solvation relaxation rather than a state-to-state transition. • An energy model is proposed to demonstrate the relaxation mechanism. The ultrafast photophysical properties of dimethyl amino styryl pyridine acetonitrile (DASPA) were studied by the femtosecond transient absorption spectra (TA). The results show no evidence of state-to-state relaxation. The excited energy is released by the interaction between DASPA and solvent molecules. The solvation relaxation in protic solutions is faster than that in aprotic solutions, which results in a rapid decay of fluorescence. An energy diagram is finally proposed to interpret the relaxation mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • This paper presents a sensitive and label-free SERS method that requires no pre-derivatization and adjustment of pH for L-Hyp detection. • The mechanism of this work provides inspiration for detecting molecules with small Raman cross-section. • The proposed SERS method has a low LOD of 8.18 ng/mL in aqueous solution and 0.13 μg/mL in milk. The detection of non-protein nitrogen adulterants is a major challenge in dairy testing. As a marker molecule of animal hydrolyzed protein, the presence of non-edible L-hydroxyproline (L-Hyp) molecules can be used to identify low-quality milk containing components of animal hydrolyzed protein. However, it is still difficult to detect L-Hyp directly in milk. The Ag@COF-COOH substrate in this paper can be used to realize label-free L-Hyp sensitive detection based on the hydrogen bond transition mechanism. To explore the mechanism, the binding sites of hydrogen bond interaction have been verified experimentally and computationally, and the charge transfer process was also explained in terms of HOMO/LOMO energy level. In conclusion, the quantitative models for L-Hyp in an aqueous environment and in milk were developed. The limit of detection (LOD) of L-Hyp in an aqueous environment could reach 8.18 ng/mL, with R2 of 0.982. The linear range of quantitative detection in milk was 0.5–1000 μg/mL and the LOD was as low as 0.13 μg/mL. In this work, a hydrogen bond interaction based Surface-enhanced Raman spectroscopy (SERS) method for the label-free detection of L-Hyp was proposed, which complemented the application of SERS technology in the detection of dairy products. [ABSTRACT FROM AUTHOR]

Quinolone antibiotics have good antibacterial properties and are commonly used antibiotics in the dairy industry. Currently, the problem of excessive antibiotics in dairy products is very serious. As an ultra-sensitive detection technology, Surface-Enhanced Raman Scattering (SERS) was applied to the detection of quinolone antibiotics in this work. In order to classify and quantify three antibiotics (Ciprofloxacin, Norfloxacin, Levofloxacin) with highly similar molecular structures, a combination of magnetic COF-based SERS substrate and machine learning algorithms (PCA-k-NN, PCA-SVM, PCA-Decision Tree) was used. The classification accuracy of the spectral dataset could reach 100% and the results of LOD calculation were: CIP: 5.61 × 10−9M, LEV: 1.44 × 10−8M, NFX: 1.56 × 10−8M. This provides a new method for the detection of antibiotics in dairy products. [Display omitted] • This method realized the detection of three quinolone antibiotics with one SERS substrate. • This method can classify three quinolone antibiotics with highly similar molecular structures with 100% accuracy. • The proposed SERS method has low LODs in milk: CIP: 5.61 × 10−9M, LEV: 1.44 × 10−8M, NFX: 1.56 × 10−8M. [ABSTRACT FROM AUTHOR]

[Display omitted] • This is the first time that carbon dots were synthesized using cysteine and ethylenediamine as precursors. The synthesis method is green and simple, and the prepared N -CDs have good fluorescence stability. • The developed experimental conditions for the detection of Fe3+ using nitrogen-doped carbon dots as fluorescent probes have been fully optimized to significantly improve the sensitivity. • The method is simple, sensitive and highly feasible, with LOD as low as 0.069 μM in deionized water. And, linear models were also constructed in tap water and lake water with LOD of 0.21 μM and 0.59 μM, respectively. In this study, we synthesized stable nitrogen-doped carbon dots by a simple and economical one-step hydrothermal method using l -cysteine and anhydrous ethylenediamine as precursors. The prepared carbon dots have bright and stable blue light emission near 383 nm and can be used as fluorescent probes to detect the concentration of Fe3+ in environmental waters. It was demonstrated that due to intermolecular electrostatic interaction, a non-fluorescent complex N -CDs/Fe3+ is formed by coordination of Fe3+ with amino and carboxyl functional groups on the surface of carbon dots. Therefore, in combination with internal filtration effect, the fluorescence of carbon dots can be quenched in the presence of Fe3+, and the degree of quenching is linearly related to the concentration of Fe3+. The limit of detection in deionized water was as low as 0.069 μM with R2 of 0.998 and a linear range of 0.3 to 20 μM. In addition, satisfactory recoveries were achieved for the determination of Fe3+ in environmental water samples. The method is reliable, with highly sensitivity and selectivity, and has potential for practical applications in environmental metal analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The intermolecular hydrogen bonds in uric acid aqueous solution were studied. • The configuration search and geometry optimization of uric acid–water cluster were carried out. • Position and intensity of interaction are discussed by AIM and RDG analyses. Cluster structures that may be associated between uric acid molecules and different numbers of water molecules were studied in detail using density functional theory (DFT) at the B3LYP-D3(BJ)/6–31 + G (d, p) level. When the number of water molecules increases from one to three, the cluster configuration changes from planar single-ring structure to double-ring structure. At the same time, the weak interactions were analyzed by atomic analysis (AIM) and reduced density gradient (RDG) methods. Finally, the theoretical Raman spectra show that the N–H Raman peak in the uric acid molecule is redshifted and the hydrogen bond interaction is enhanced. [ABSTRACT FROM AUTHOR]

[Display omitted] • The AgNPs-4MPBA composite structure was first designed as SERS substrate for detection of fructose in urine. • This method achieve the LOD of fructose to be 0.535 µmol/L in urine. • This method realizes rapid fructose detection in less than 10 min. The accurate detection of fructose in human urine can help prevent and screen for diseases such as fructokinase deficiency and hereditary fructose intolerance. Surface-enhanced Raman spectroscopy (SERS) is an analytical technique with selectivity and high sensitivity, which has been widely applied to the detection of targets with complex backgrounds. In this work, 4-mercaptophenylboronic acid (4-MPBA) was modified on the surface of silver nanoparticles (AgNPs) under mild conditions to obtain a boronic acid-functionalized SERS substrate for the detection of fructose in artificial urine. The detection mechanism was based on the deboronization reaction of 4-MPBA on the surface of AgNPs, which was induced by fructose, and the Raman signal of the generated thiophenol (TP) molecules was significantly enhanced by the silver nanoparticles, with a linear increase in SERS peak intensity at 1570 cm−1. We achieved the detection limits of 0.084 µmol/L in water and 0.535 µmol/L in urine by this method. The relative standard deviation (RSD) in the recovery experiments of urine ranged from 1.01 % to 2.22 %, and the whole detection time was less than 10 min, which indicated that this method is highly reliable for fructose detection and has a good prospect in bioassay and clinical medicine. [ABSTRACT FROM AUTHOR]

Cavitation is a common phenomenon in diesel injector and has a strong influence on the internal flow. However, studies so far have focused on cavitation characteristics inside the nozzle. Its influence on the flow during control valve opening remains still unclear. In the paper, a computational study focused on the flow and cavitation phenomena within control valve has been reported and the effects of control valve’s structure parameters (including rounded edge, seal cone angle and outflowing control-orifice structure) on the flow and cavitation characteristics have been investigated in detail. Firstly the 3D model has been validated in terms of single injection quantity and fuel injection duration, showing a good consistency. And then, the development from sheet cavitation to cloud cavitation and the relationship between cavitation, pressure and velocity has been discussed. Based on the numerical results obtained, it is shown that not only the variation of pressure but also the velocity is the important factor which affects cavitation. The increase of the flow velocity reduces the pressure within the flow field which can aggravate the development of cavitation. As cavitation region increases, the fuel flow is hindered and the flow velocity decreases. However, the decrease of flow velocity has suppressed the development of cavitation. All of those variations form a cyclical process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon nanodots (CNDs) were synthesized through a facile microwave method. • The fluorescence of CNDs was selectively quenched by gold nanoparticles (AuNPs). • Once introduced, thiourea triggered the reversion of quenched fluorescence. • Effective applications in environmental water and compound fruit-vegetable juice. Illegal abuse results in the presence of thiourea (TU) in soil, wastewater, and even fruits, which is harmful for the environment and human health. It has urgent practical significance to design an efficient and reliable probe for TU detection. Herein, a sensitive fluorescent probe with off–on response for harmful TU was reported. The probe was designed with fluorescent carbon nanodots (CNDs) and gold nanoparticles (AuNPs) based on fluorescence resonance energy transfer (FRET) effect. Firstly, the CNDs were pre-combined with AuNPs and the fluorescence of CNDs was quenched due to the FRET effect. Upon addition of TU, the fluorescence of CNDs recovered due to the unbinding of CNDs and AuNPs, since the coordination interaction between TU and AuNPs is stronger than the electrostatic interaction among CNDs and AuNPs. Under the optimum parameters, a linear relationship was found between the relative fluorescence intensity of the probe and the concentration of TU in the range of 5.00 × 10-8-1.00 × 10-6 M (R2 = 0.9958), with the limit of detection (LOD) calculated to be 3.62 × 10-8 M. This proposed method is easy to operate and has excellent selectivity and sensitivity for TU, which can be effectively applied in environmental water and compound fruit-vegetable juice. [ABSTRACT FROM AUTHOR]

The detection of glucose in drinks (especially for sugar-free drinks) is of great practical significance. The traditional method for the detection of glucose was based on an enzymatic reaction using glucose oxidase, which takes a long time. Herein, a TMB-AgNPs@COF based SERS probe was designed for the rapid detection of glucose in drinks. The SERS probe was fabricated using silver nanoparticles loaded covalent organic frameworks (COFs) as substrate, 3,3',5,5'-Tetramethylbenzidine (TMB) was introduced as a signal molecule to solve the problem of weak SERS signal of glucose. The fabricated SERS probe is denoted as TMB-AgNPs@COF. The detection mechanism was based on the competitive binding of TMB and glucose with AgNPs@COF substrate. Glucose was more likely to bond with the substrate which was verified by Gaussian theory simulation. The SERS signal of TMB gradually decreased when glucose was introduced. The interaction between the substrate and glucose can also be demonstrated by SERS spectroscopy. By applying this method, we could achieve the detection limit of 0.096 μg/mL in drinks. The relative standard deviations were 2.63 %− 4.89 % in the recovery experiments of drinks. The whole detection time was less than 5 min and the substrate had good reproducibility. Therefore, the method was confirmed with a high potential for the detection of glucose in drinks. [Display omitted] • The TMB-AgNPs@COF was first designed as SERS probe for detection of glucose in drinks. • This method can be applied in the detection of real drink samples without pretreatment procedures. • This method realizes rapid glucose detection in less than 5 min. [ABSTRACT FROM AUTHOR]

Sodium thiocyanate (NaSCN) is normally used as a kind of food preservative in daily life, but using excessive NaSCN in milk would cause the low absorption of iodine in human body, and then would make the normal secretion of thyroid hormone disorder. In this study, we developed a method combines AgNPs and MIL-101(Fe) which is a kind of Metal organic frameworks materials as a kind of composite Surface Enhanced Raman Scattering (SERS) substrate and achieved the determination of NaSCN in spiked milk. The characteristic peak of NaSCN at 2110 cm−1 showed obvious SERS enhancement and has good linearity with the concentration of NaSCN in milk. Through the simple and rapid detection, the limit of detection in water and milk was calculated as 18.5 μg/L and 96.3 μg/L with the correlation coefficient of 0.991 and 0.988 respectively. This work provides a new method to detect NaSCN in milk and expands the application of SERS in food detection. [ABSTRACT FROM AUTHOR]

Rice as a paddy field crops, iron-containing materials application could induce its iron plaque formation, thereby affecting cadmium (Cd) transportation in the rhizosphere and its uptake in root. In this study, a hydroponic experiment was conducted to investigate the effects of three exogenous iron materials, namely nano-Fe 3 O 4 -modified biochar (BC–Fe), chelated iron (EDTA-Fe), and ferrous sulfate (FeSO 4), on the iron plaque formation on the surface of rice root, and to investigate the effects of formed iron plaque on the absorption, migration, and transportation of Cd and Fe in rice plant. The results showed that yellow-brown and brown iron plaque was formed on surface cells of the Fe-treated rice root, and some black particles were embedded in the iron plaque formed by BC-Fe. The proportion of crystallized iron plaque (31.8%–35.9%) formed by BC-Fe was much higher than that formed by EDTA-Fe and FeSO 4. The Cd concentrations in the crystallized iron plaque formed by BC-Fe were 7.64–13.0 mg·kg−1, and increased with the increasing of Fe concentrations in the plaque. The Cd translocation factor from root to stem (TF r-s) and the Cd translocation factor from stem to leaf (TF s-l) with BC-Fe treatment decreased by 84.7% and 80.0%, respectively. The results demonstrated that application BC-Fe promoted the formation of iron plaque and enhanced the sequestration of Cd and Fe in roots, thus reduced the transportation and accumulation of Cd in aerial rice tissues. [Display omitted] • BC-Fe promoted iron plaque formation and raised the proportion of crystallized iron plaque. • BC-Fe resulted in some black particles were embedded in iron plaque and outer root cells. • BC-Fe enhanced the sequestration of Cd and Fe level in rice root. • BC-Fe reduced the transportation and accumulation of Cd in aerial rice tissues. [ABSTRACT FROM AUTHOR]