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There is a growing interest in the use of flexible substrates for label-free and in situ Surface-enhanced Raman Spectroscopy (SERS) applications. In this study, a flexible SERS substrate was prepared using self-assembled Au/Ti3C2 nanocomposites deposited on a cellulose (CS) paper. The Au/Ti3C2 nanocomposites uniformly wrapped around the cellulose fibers to provide a three-dimensional plasma SERS platform. The limit of detection (LOD) of CS/Au/Ti3C2 was as low as 10−9 M for 4-mercaptobenzoic acid(4-MBA) and crystal violet (CV), demonstrating good SERS sensitivity. CS/Au/Ti3C2 was used for in situ SERS detection of thiram on apple surfaces by simple swabbing, and a limit of detection of 0.05 ppm of thiram was achieved. The results showed that CS/Au/Ti3C2 is a flexible SERS substrate that can be used for the detection of thiram on apple surfaces. These results demonstrate that CS/Au/Ti3C2 can be used for the non-destructive, rapid and sensitive detection of pesticides on fruit surfaces. [ABSTRACT FROM AUTHOR]

A multifunctional surface-enhanced Raman scattering (SERS) platform integrating sensitive detection and drug resistance analysis was developed for Gram-positive bacteria. The substrate was based on self-assembled Ti3C2Tx@Au NPs films and capture molecule phytic acid (IP6) to achieve specific capture of Gram-positive bacteria and different bacteria were analyzed by fingerprint signal. It had advantages of good stability and homogeneity (RSD = 8.88%). The detection limit (LOD) was 102 CFU/mL for Staphylococcus aureus and 103 CFU/mL for MRSA, respectively. A sandwich structure was formed on the capture substrate by signal labels prepared by antibiotics (penicillin G and vancomycin) and non-interference SERS probe molecules (4-mercaptobenzonitrile (2223 cm−1) and 2-amino-4-cyanopyridine (2240 cm−1)) to improve sensitivity. The LOD of Au NPs@4-MBN@PG to S. aureus and Au NPs@AMCP@Van to MRSA and S. aureus were all improved to 10 CFU/mL, with a wide dynamic linear range from 108 to 10 CFU/mL (R2 ≥ 0.992). The SERS platform can analyze the drug resistance of drug-resistant bacteria. Au NPs@4-MBN@PG was added to the substrate and captured MRSA to compare the SERS spectra of 4-MBN. The intensity inhomogeneity of 4-MBN at the same concentrations of MRSA and the nonlinearity at the different concentrations of MRSA revealed that MRSA was resistant to PG. Finally, the SERS platform achieved the determination of MRSA in blood. Therefore, this SERS platform has great significance for the determination and analysis of Gram-positive bacteria. [ABSTRACT FROM AUTHOR]

• A switchable and tunable multi-wavelength EDFL based on single STS filter is proposed and experimentally demonstrated. • The STS filter has a comb spectrum with obvious envelope and uniform fluctuation. • By adjusting the PC, the fiber laser can work in adjacent or non-adjacent multi-wavelength state. • The proposed multi-wavelength EDFL has the advantages of simple structure, low cost, easy adjustment and good stability. A novel switchable and tunable multi-wavelength erbium-doped fiber ring laser (EDFL) is proposed and experimentally demonstrated by using a single SMF-TMF-SMF (STS) structure filter. The STS filter, based on mode interference, is fabricated by sandwiching a section of two-mode fiber (TMF) between single mode fibers (SMF) through core-offset splicing, which has a comb spectrum with obvious envelope and uniform fluctuation. The transmission characteristics of the STS filter can be changed by adjusting the polarization controller (PC) wrapped on the TMF. Based on the cooperation of the STS filter and polarization dependent loss (PDL), the fiber laser can be individually switchable and widely tunable. By adjusting the PC, the outputs can be switched from single-wavelength to adjacent eight-wavelength and can be tuned in the range of 1528 ∼ 1561 nm. Furthermore, non-adjacent dual-, three- and four-wavelength with different intervals can also be achieved by appropriately adjusting the PC. With the assistance of four wave mixing (FWM) effect, the fiber laser has a stable output. The tuning and switching of the proposed multi-wavelength EDFL is simple and flexible. [ABSTRACT FROM AUTHOR]

We present a Monte Carlo model for optical coherence tomography (OCT) imaging of human tooth. The model is implemented by combining the simulation of a Gaussian beam with simulation for photon propagation in a two-layer human tooth model with non-parallel surfaces through a Monte Carlo method. The geometry and the optical parameters of the human tooth model are chosen on the basis of the experimental OCT images. The results show that the simulated OCT images are qualitatively consistent with the experimental ones. Using the model, we demonstrate the following: firstly, two types of photons contribute to the information of morphological features and noise in the OCT image of a human tooth, respectively. Secondly, the critical imaging depth of the tooth model is obtained, and it is found to decrease significantly with increasing mineral loss, simulated as different enamel scattering coefficients. Finally, the best focus position is located below and close to the dental surface by analysis of the effect of focus positions on the OCT signal and critical imaging depth. We anticipate that this modeling will become a powerful and accurate tool for a preliminary numerical study of the OCT technique on diseases of dental hard tissue in human teeth. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is one of the most common malignant tumours in the world. Recent reports have revealed natural products displayed inhibition on colon cancer potential by suppressing transforming growth factor‐β/Smads induced epidermal‐mesenchymal transition (EMT). In this article, 12 kinds of natural berberine analogues were screened for their effects on the inhibition of the colon cancer cells, the results showed that demethyleneberberine (DM‐BBR) exhibited an interesting and potential effect on inducing the apoptosis of HCT‐116 cells with drug concentrations of 6, 12 and 18 μM. Particularly, DM‐BBR reversed the EMT process by inhibiting the expression of p‐Smad2 and p‐Smad3 in the transforming growth factor‐β/Smads signal pathway, up‐regulated pro‐apoptotic protein cleaved caspase‐9, and blocked cell cycle at the S phase and increasing the expression of cyclin proteins P27 and P21. Taken together, these findings suggested that DM‐BBR could promote apoptosis and suppress TGF‐β/Smads induced EMT in the colon cancer cells HCT‐116. [ABSTRACT FROM AUTHOR]

CCD-based fluorescence tomography is widely used for small animal whole-body imaging. In this report, systematic signal-to-noise ratio (SNR) analyses of a fluorescence tomography imaging (FTI) system were performed, resulting in an easy-to-follow strategy to optimize hardware configurations and operational conditions for acquiring high-quality imaging data and for improving the overall system performance. Phantom experiments were conducted to demonstrate the performance improvement by these optimizations. The improved performance was further verified by imaging a tumor-bearing mouse in vivo. This report provides general and practical guidelines for setting up a high-performance electron multiplying charge coupled device based FTI system to achieve an optimized SNR, which can be useful for future FTI technology development. [ABSTRACT FROM AUTHOR]

We focus on the design of finite impulse response (FIR) multiple notch filters. To reduce the computational complexity and hardware implementation complexity, a novel algorithm is developed based on the mixture of the tuning of notch frequencies and the sparsity of filter coefficients. The proposed design procedure can be carried out as follow: first, since sparse FIR filters have lower implementation complexity than full filters, a sparse linear phase FIR single notch filter with the given rejection bandwidth and passband attenuation is designed. Second, a tuning procedure is applied to the computed sparse filter to produce the desired sparse linear phase FIR multiple notch filter. When the notch frequencies are varied, the same tuning procedure can be employed to render the new multiple notch filter instead of designing the filter from scratch. The effectiveness of the proposed algorithm is demonstrated through three design examples. [ABSTRACT FROM AUTHOR]

High performance platform for detecting ESBL-E. coil. [Display omitted] • Design of capture substrate to achieve stable, efficient capture of ESBL-E. coil. • Proposing of signal-enhancing structure and indirect method to detect ESBL-E. coil. • The platform has a good linear range and a detection limit of 10 CFU/mL. • A new method for the detection of ESBL-E. coil in milk. Drug-resistant bacteria is highly infectious and has been appearing in food in recent years threatening human health. Therefore, effective detection of drug-resistant bacteria is crucial. In this paper, an interference-free surface-enhanced Raman scattering (SERS) platform was developed for the detection of extended-spectrum β-lactamase E. coil (ESBL-E. coil). 4-mercaptomethylboronic acid (4-MPBA) was used as a capture molecule for drug-resistant bacteria, and self-assembled gold nanoparticles (Au NPs) were utilized to develop a high-performance SERS analytical platform for the detection of drug-resistant bacteria. Meanwhile, in order to obtain a lower detection limit and higher precision, Ti 3 C 2 T x , modified with 4-mercaptobenzonitrile (4-MBN) and Au NPs, was used for signal enhancement and indirect detection. The SERS platform detected signals from the Raman silent region, where there was no background signal from biological sources, eliminating the interference, a detection limit was 10 CFU/mL, with a wide dynamic linear range from 10-108 CFU/mL. Meanwhile, the stability, homogeneity and reproducibility were excellent. The precise quantification capability of the SERS platform was validated by the detection of ESBL-E. coil in milk. Therefore, the method holds great promise for the development of a stable and sensitive SERS platform for the detection of drug-resistant bacteria. [ABSTRACT FROM AUTHOR]

• Caffeine promoted growth and migration of paclitaxel-treated cancer cells. • Caffeine inhibited apoptosis in paclitaxel-treated cancer cells. • Caffeine down-regulated paclitaxel-induced α-tubulin acetylation in vitro and in vivo. • Caffeine decreased paclitaxel-induced inhibition of tumor growth. Caffeine (1,3,7-trimethylxanthine) is a xanthine alkaloid found in a number of dietary products consumed worldwide, such as coffee, tea, and soft beverages, and is known to act as a modifying agent for cytotoxic chemotherapeutic drugs. Studies have shown that caffeine reduces the cytotoxic effects of paclitaxel and inhibits paclitaxel-induced apoptosis; however, the underlying mechanism remains unclear. Here, we investigated whether caffeine inhibits the antitumor activity of paclitaxel via down-regulation of α-tubulin acetylation. In vitro studies, involving MTT assay, wound-healing assay, cell apoptosis assay, and western blotting analysis of A549 and HeLa cells, were performed. A549 and HeLa cell-based xenografts were established, and western blotting and immunohistochemical staining were performed for in vivo studies. The results showed that caffeine promoted the growth of cancer cells treated with paclitaxel. Additionally, caffeine enhanced migration ability, inhibited apoptosis, and decreased the acetylation of α-tubulin in paclitaxel-treated cancer cells. Furthermore, caffeine decreased the inhibitory effect of paclitaxel on tumor growth through down-regulation of α-tubulin acetylation in vivo. Taken together, these findings demonstrate that caffeine inhibits the anticancer activity of paclitaxel via down-regulation of α-tubulin acetylation, suggesting that patients receiving treatment with taxanes, such as paclitaxel, should avoid consuming caffeinated beverages or foods. [ABSTRACT FROM AUTHOR]

A novel composite material Nb 2 C-Au NPs can enhance electromagnetic resonance and charge transfer resonance by synergistic conjugation and exhibits good SERS enhancement of dye molecules and biomolecules adenine. [Display omitted] • Nb 2 C-Au NPs nanocomposite was synthesized by electrostatic self-assembly method. • Composite material can synergistically enhance multiple SERS mechanisms. • Nb 2 C-Au NPs exhibits good SERS detection performance for dye molecules and adenine. Recent years, two-dimensional transition metal carbonitrides (MXene) have attracted much attention in the field of surface-enhanced Raman scattering (SERS). However, the relatively low enhancement of MXene is a major challenge. Herein, Nb 2 C-Au NPs nanocomposites were prepared by electrostatic self-assembly method, which have a synergistically conjugated SERS effect. The EM hot spots of Nb 2 C-Au NPs are significantly enlarged and expanded, while the surface Fermi level is decreased. This synergistic effect could improve the SERS performance of the system. Consequently, for the dye molecules CV and MeB, the detection limits reach 10−10 M and 10−9 M, respectively, while for biomolecule adenine, the detection limit is as low as 5 × 10−8 M. The results also show the good concentration-dependent linearity, uniformity, reproducibility and stability of SERS substrate. Nb 2 C-Au NPs could be a fast, sensitive and stable SERS platform for label-free and non-destructive detection. This work may expand the application of MXene based materials in the field of SERS. [ABSTRACT FROM AUTHOR]

• A temperature measurement method with error suppression is performed by a dual-wavelength FRL with an intracavity Sagnac interferometer. • A dual-wavelength filter is formed by cascading two DWDMs. • The intensity difference of two peaks is measured by difference method. • Compared with single-wavelength configuration, the measurement error of dual-wavelength is reduced from 0.443% to 0.066%. The sensors based on intracavity intensity modulation of fiber ring laser (FRL) have shown excellent performance in sensing resolution and detection limit, but suffer from large measurement errors. The measurement errors mainly result from the power fluctuation of pump source and environmental interference. Therefore, the methods of error suppression are of great significance for FRL sensors. In this paper, a temperature measurement method with error suppression is performed by a dual-wavelength FRL with an intracavity Sagnac interferometer. The sensing principle of single- and dual-wavelength FRL sensors have been analyzed. By the sensing manner of intensity difference of two excited wavelengths, the measurement error has been decreased from 0.443% to 0.066% compared with the single-wavelength configuration. The temperature sensitivity and measurement stability have been further discussed. This method can be extended to similar FRL sensors to suppress measurement errors. [ABSTRACT FROM AUTHOR]