Fiber Bragg grating displacement sensor based on synchronous deformation sensing for real-time monitoring of a tunnel lining.

A fiber Bragg grating (FBG) displacement sensor based on synchronous sensing is developed for real-time monitoring of a tunnel lining. The sensing principle and mechanical structure of the proposed sensor are analyzed and simulated, and its sensitization effectiveness and temperature compensation are verified. Equivalent model tests show that the sensor has a good linear sensitivity of 19.48 pm/mm and an excellent precision of 5.13×10-2 m m in the displacement range of 0-25 mm, which is basically consistent with the simulation results. The key traffic parameters of the train were successfully obtained by real-time monitoring of the tunnel lining in a field trial, which shows the superior capability of micro-displacement measurement of the sensor. Furthermore, good stability and excellent creep resistance have also been demonstrated. Our results provide theoretical guidance for the fabrication and package of the FBG displacement sensor, which is valuable for structure health monitoring (SHM) in civil engineering applications.

Diffraction characteristics of radiated tilted fiber grating and its spectrometer application.

We have numerically and experimentally presented the diffraction characteristics of radiated tilted fiber grating (RTFG) in terms of the spectrum, bandwidth, degree of polarization, angular dispersion, and temperature crosstalk. The theoretical and experimental results have shown that the polarization property, bandwidth, and dispersion of RTFG highly depended on the tilt angle of RTFG, and the RTFG has ultra-low temperature crosstalk. We have simulated the transmission spectrum of the RTFG with different tilt angles (25°, 31°, 38°, 45°, and 54°), in which the results show that the larger tilt angle has the wider bandwidth. The RTFGs with the tilt angle of 25°, 31°, 38°, 45°, and 54° have the 3dB bandwidth of 110 nm, 144 nm, 182 nm, 242 nm, and 301 nm, respectively. Besides, the degree of polarization (DOP) of the radiated light from RTFG with the different tilt angles are 0.876, 0.944, 0.967, 0.998, and 0.970, respectively, and the RTFG has the maximum DOP at the tilt angle of 45°, which could be used as single-polarization diffraction device. The experimental results show that with further increase or decrease of the tilt angle, the DOP of radiated light of RTFG would decrease. Both the theoretical and experimental results show that the smaller tilt angle could greatly improve the diffraction angular dispersion of RTFG, in which the 25°, 31°, 38°, and 45° RTFG have the angular dispersion of 0.2288 °/nm, 0.1026 °/nm, 0.0714 °/nm, and 0.0528 °/nm, respectively. Due to the broad working bandwidth, the diffraction angles of RTFG have ultra-low temperature crosstalk, where -0.00042, -0.00054, -0.00064, and -0.00099 degree / °C at the tilt angle of 25°, 31°, 38°, and 45°. Finally, we have demonstrated a miniaturized spectrometer integrated by a 25° RTFG, which has a high spectral resolution of 0.08 nm. The proposed RTFG would be an ideal in-fiber diffraction device and widely applied in spectral analysis, space optical communication, and Lidar areas.

Wavelength-tunable noise-like fiber laser based on PbS quantum dot saturable absorber film.

A wavelength-tunable noise-like pulse (NLP) erbium-doped fiber laser incorporating PbS quantum dot (QD) polystyrene (PS) composite film as a saturable absorber (SA) is experimentally demonstrated. The wavelength tuning is implemented via a Lyot filter consisting of a segment of polarization-maintaining fiber (PMF) and a 45° tilted fiber grating. By adjusting the polarization state of the ring cavity, the laser can deliver NLP with a continuous wavelength-tunable range from 1550.21 to 1560.64 nm. During continuous wavelength tuning, the output power varies between a range of 30.88-48.8 mW. Worthwhile noting is that the output power of 48.8 mW is the reported highest output power for wavelength-tunable NLP operation in an erbium-doped fiber laser using composite film as a saturable absorber.

In-fiber duplex optical antenna and its programmable spectral filter application: publisher's note.

This publisher's note contains corrections to Opt. Lett.47, 4937 (2022)10.1364/OL.468940.

Intracavity birefringence-controlled GHz-tuning range passively harmonic mode-locked fiber laser based on NPR.

We experimentally demonstrate a harmonic-order controllable L-band Er-doped passively mode-locked fiber laser based on nonlinear polarization rotation (NPR). Distinct from all previous reports, we find that the intracavity birefringence is able to control the harmonic order of a passively mode-locked fiber laser. Experimentally, under a constant pump power of 704 mW, the harmonic order can be tuned from 113th to 39th monotonically by adjusting the polarization controller orientation only. The corresponding repetition rate changes from 2.21 to 0.77 GHz simultaneously. Remarkably, the super-mode suppression ratio of each harmonic order we observed is higher than 29 dB with a maximum of 36.5 dB. Simulated transmission spectra of NPR prove that the changed transmission plays an important role in controlling the harmonic order.

A novel reversed-phase and weak anion-exchange mixed-mode stationary phase based on horizontal polar-copolymerized approach for separation of small organic molecules and inorganic anions.

A novel silica-based reversed-phase/weak anion-exchange mixed-mode chromatography (MMC) stationary phase referred to as OTAS was synthesized based on the horizontal polar-copolymerized approach using trichlorooctadecylsilane (ODS) and (3-glycidyloxypropyl)trimethoxysilane (GPS) as ligands, and then followed by the reaction of epoxy group with diethylamine to introduce the tertiary ammonium functional group. The new stationary phase was characterized by instrumental analysis, and evaluated by separating the mixture of alkylbenzene homologues in reversed-phase mode and acidic organic compounds in ion-exchange chromatography mode, respectively. The results indicate that not only the baseline separation of 11 kinds of neutral and acidic organic compounds can be achieved successfully, but also 5 kinds of inorganic anions can be separated completely. The chromatographic property of OTAS column can be controlled by adjusting the molar ratio of ODS to GPS. Moreover, the OTAS column was used successfully to analyze the inorganic anions in the actual water samples. The good separation and selectivity of OTAS column suggests that the new MMC stationary phase can be used for the analysis of complex samples containing of neutral and acidic organic compounds or inorganic anions.

Preparation of a weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography stationary phase for protein separation using click chemistry.

In this study, 3-diethylamino-1-propyne was covalently bonded to the azide-silica by a click reaction to obtain a novel dual-function mixed-mode chromatography stationary phase for protein separation with a ligand containing tertiary amine and two ethyl groups capable of electrostatic and hydrophobic interaction functionalities, which can display hydrophobic interaction chromatography character in a high-salt-concentration mobile phase and weak anion exchange character in a low-salt-concentration mobile phase employed for protein separation. As a result, it can be employed to separate proteins with weak anion exchange and hydrophobic interaction modes, respectively. The resolution and selectivity of the stationary phase were evaluated in both hydrophobic interaction and ion exchange modes with standard proteins, respectively, which can be comparable to that of conventional weak anion exchange and hydrophobic interaction chromatography columns. Therefore, the synthesized weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography column can be used to replace two corresponding conventional weak anion exchange and hydrophobic interaction chromatography columns to separate proteins. Based on this mixed-mode chromatography stationary phase, a new off-line two-dimensional liquid chromatography technology using only a single dual-function mixed-mode chromatography column was developed. Nine kinds of tested proteins can be separated completely using the developed method within 2.0 h.

Ovarian tumor targeting of docetaxel-loaded liposomes mediated by luteinizing hormone-releasing hormone analogues. In vive distribution in nude mice.

Recent studies indicate that luteinizing hormone-releasing hormone (LHRH) analogues (LHRHa), like LHRH, are able to specifically bind to LHRH receptors which are highly expressed on the extracellular membrane of ovarian tumor cells. As a targeting moiety, LHRHa can mediate the ovarian tumor targeting of docetaxel-loaded liposomes. In our study, synthesized negatively charged cholesterol succinimide (CHS) was employed for the preparation of negatively charged docetaxel-loaded liposomes, with which the positively charged LHRHa is linked via electrostatic absorption. An HPLC-based assay for determination of docetaxel (CAS 114977-28-5, Doc) in vivo and the model of ovarian cancer xenograft were established to investigat the biodistribution of docetaxel, docetaxel liposomes (Doc-Lipo), and LHRHa mediated docetaxel-loaded liposomes (LHRHa-Doc-Lipo) in nude mice. Sixty minutes after administration of LHRHa-Doc-Lipo, the concentration of docetaxel in the ovarian tumor was 2.86 times that of Doc-Lipo and 9.02 times that of Doc in the nude mice bearing ovarian tumor. LHRHa-Doc-Lipo decreased the concentration of docetaxel in the liver and spleen by 57% and 34%, respectively, as compared with Doc-Lipo. Therefore, LHRHa-Doc-Lipo exhibits potentiality as an active targeting drug delivery system for chemotherapy of ovarian tumor.

[Research on thymopentin-loaded N-trimethyl chitosan nanoparticles administered through mouth].

OBJECTIVE: To prepare a peroral thymopentin-loaded N-trimethyl chitosan chloride-nanoparticle (Tp5-TMC-NP) ,and observe the pharmacodynamic action when the Tp5-TMC-NP is taken by way of the mouth. METHODS: N-trimethyl chitosan chloride was first synthesized, and then Tp5-TMC-NP was prepared with the formulation technology optimized by the Central Composite Design. The influence of Tp5-TMC-NP on the ratio of CD4+/CD8+ of T-lymphocytes were determined by flow cytometer. RESULTS: The regular global Tp5-TMC-NP prepared with the optimized formulation craft had the mean diameter of 110.6 nm and got the entrapment efficiency of 78.8%. The ratio of lymphocyte CD4+/CD8+ of Wistar rat administered with Tp5-TMC-NP perfusing stomach had 2.59 times higher than that with Tp5. CONCLUSION: Taken orally the Tp5-TMC-NP has much higher efficiency than Tp5.

Preparation of a TK/GCV administration system mediated by transferrin modified pro-cationic liposomes.

Transferrin modified pro-cationic liposomes were prepared and used to investigate the effect of targeting therapeutic genes to human hepatoma carcinoma cells in vitro. The main lipid CHETA, cholest-5-en-3beta-yl[2-[[4-[(carboxymethyl)dithio]-1-iminobutyl]amino]ethyl] carbamate (C36H61N3O4S2), was synthesized and used to prepare pro-cationic liposomes. The thymidine kinase (TK) gene loaded pro-cationic liposomes were prepared by first mixing the plasmid DNA and protamine together, and then incubating the resulted polyplexes with blank pro-cationic liposomes preformed by the thin film dispersion-sonication method. Transferrin (Tf) was adsorbed on the surface of pro-cationic liposomes via electrostatic interactions to form transferrin modified pro-cationic liposomes. Cellular association was measured by fluorimetry at excitation and emission wavelengths of 490 and 520 nm, respectively. The viability of TK gene infected cells following administration of ganciclovir (GCV) was investigated by MTT assay. The transferrin modified TK gene pro-cationic liposomes had a mean diameter of 240 +/- 12 nm and zeta potential of -24.10 +/- 2.5 mV (n = 3). The transmission electron microscopy image indicated that most of the liposomes were relatively regular and spherical with a condensed core inside. Cell-associated fluorescence of Tf-liposomes and unmodified liposomes (without transferrin) was 7.8 x 10(6), and 3.2 x 10(6) per milligram protein, respectively. Compared to Lipofectamine 2000 (Invitrogen, USA) the pro-cationic liposomes and transferrin modified pro-cationic liposomes had less cytotoxicity to cells. The transduced TK gene HepG2 cells were more sensitive to GCV than the un-transduced TK gene ones and the human normal Chang liver cells were not affected by the TK/GCV system mediated by procationic liposomes.

[Preparation and gene expression of transferrin modified gene loaded procationic liposomes].

A novel transferrin modified non-viral gene delivery system Tf-PLPD was developed and the related characteristics was investigated. Blank procationic liposomes were prepared by film dispersion-filteration method. PLPD was prepared as follows by first mixing the plasmid DNA and protamine together, then the resulted polyplexes were incubated for 10 min at room temperature, followed by addition of preformed blank procationic liposomes. Transferrin was adsorbed at the surface of PLPD via electrostatic interactions to form Tf-PLPD. Central composite design (CCD) was employed to optimize the formulation. The HepG2 cells were transfected using lacZ as reporter gene and characteristics such as the morphology, the mean particle size, the zeta potential and the transfection efficiency in HepG2 cells were further investigated by different methods. The resulting PLPD had a regular spherical surface with an average size of (228. 9 +/- 8. 0) nm (polydispersity index, PDI = 0. 122 +/- 0. 02, n = 3) , a zeta potential of ( - 25. 08 +/-2. 50) mV (n = 3) and a transfection efficiency of (12. 18 +/- 3. 80) mU x mg(-1) (protein). The Tf-PLPD had an average size of (240 +/- 12) nm (polydispersity index, PDI = 0. 150 +/- 0. 03, n = 3), a zeta potential of ( - 24. 10 +/- 2. 50) mV ( n = 3) and a transfection efficiency of (24. 26 +/- 2. 60) mU x mg(-1) (protein) , 20 times greater than that of the naked plasmid DNA. The presence of serum didn' t affect the tansfection activity of PLPD or Tf-PLPD. Compared to one kind of cationic liposomes (liposome-protamine-DNA, LPD), the PLPD and Tf-PLPD had much less cytotoxicity to three hepatic cell lines (including HepG2, SMMC7721 and Chang' s normal hepatocyte). The results indicated that the Tf-PLPD is a perspective non-viral vector for gene delivery systems.

Preparation and characterization of a novel nonviral gene transfer system: procationic-liposome-protamine-DNA complexes.

Procationic-liposome-protamine-DNA (PLPD) vector, a novel nonviral gene delivery system, that may further adsorb transferrin (Tf) at its surface via electrostatic interactions to form Tf-PLPD, was prepared from soybean phosphatidylcholine (PC), cholesterol (Chol), and a kind of cholesterol derivative, CHETA(cholest-5-en-3-ol(3beta)-[2-[[4-[(carboxymethyl)dithio]-1-iminobutyl] amino] ethyl] carba- mate) containing disulfide bond by film dispersion-filteration method. Central composite design was used to optimize the formulation. The presence of serum did not affect the transfection activity of PLPD or Tf-PLPD and the cell viability was not affected significantly when the cells were incubated with the complexes for 4 hr at 37 degrees C. Compared with one kind of cationic liposomes(liposome-protamine-DNA), the PLPD had much less cytotoxicity to three hepar cell lines(including HepG2, SMMC7721, and Chang's normal heptocyte). The procationic lipoplex described here, combining the condensing effect of protamine and the targeting capability of Tf, was a perspective nonviral vector for gene delivery system.

Characterization of transferrin-modified procationic-liposome protamine-DNA complexes.

We developed a novel transferrin modified non-viral gene delivery system, transferrin-modified procationic-liposome-protamine-DNA complexes (Tf-PLPD) and investigated its characteristics. Blank procationic liposomes were prepared using the film dispersion filter method. Protamine was used to condense plasmid DNA to form protamine-DNA complexes and the complexes were further incubated with blank procationic liposomes to form PLPD. Transferrin was adsorbed onto the surface of PLPD via an electrostatic interaction, and thus Tf-PLPD was produced. Characteristics such as stability in rat serum, morphology, average particle size, zeta potential, and transfection efficiency in HepG2 cells were further investigated. The results indicated that the procationic liposomes remained stable in rat serum for 24 h. Tf-PLPD protected plasmid DNA from enzymatic degradation even after lyophilization. The size distribution of Tf-PLPD was in the range of 240+/-12 nm and the zeta potential was -24.10+/-2.5 mV (n=3), respectively. The transfection efficiencies of Tf-PLPD were 24.26+/-2.6 mU beta-galactosidase/mg protein. Lyophilization and the presence of serum did not affect the transfectivity of Tf-PLPD and the procationic liposomes also had low cytotoxicity to cells.

Characteristics comparison before and after lyophilization of transferrin modified Procationic-Liposome-Protamine-DNA complexes (Tf-PLPD).

A novel non-viral gene delivery system, Procationic-Liposome-Protamine-DNA complexes (PLPD) which could further adsorb transferrin on the surface as a targeting ligand to form Tf-PLPD, was prepared and characterized before and after lyophilization. The size distribution of Tf-PLPD was in the range of 240 +/- 12 nm and the zeta potential was -24.10 +/- 2.5 mV. The transfection efficiencies of PLPD and Tf-PLPD were 12.18 +/- 3.8 and 24.26 +/- 2.6 mU beta-galactosidase/mg protein respectively. The lyophilization and the presence of serum didn't affect the tansfectivities of PLPD or Tf-PLPD. Compared to Lipofectamine 2000 (Invitrogen, U.S.A.), the procationic liposomes had less cytotoxicity to cells. In summary the procationic lipoplex described here, combining the condensing effect of protamine and the targeting capability of Tf, was a perspective non-viral vector for gene delivery system.

Research on thymopentin loaded oral N-trimethyl chitosan nanoparticles.

Peptides, although high efficacy and specificity in their physiological function, usually have low therapeutical activities due to their poor bioavailability when administrated orally. Nanoparticles have been regarded as a useful vector for targeted drug delivery system because they can protect drug from being degraded quickly and pass the gastrointestinal barriers. Here we described a novel oral N-trimethyl chitosan nanoparticles formulation containing thymopentin (Tp5-TMC-NP). N-trimethyl chitosan (TMC) was synthesized and then used to prepare Tp5-TMC-NP by ionotropic gelation. A three-factor, five-level CCD (Central Composite Design) design was used in the optimization procedure, with HPLC as the analyzing method. The resulting Tp5-TMC-NP had a regular spherical surface and a narrow particle size range with a mean diameter of 110.6 nm. The average entrapment efficiency was 78.8%. The lyophilized Tp5-TMC-NP formulation was stable in 4 degrees C or -20 degrees C after storage of 3 months without obvious changes in morphology, particle size, pH and entrapment ratio. The results of the flow cytometer determination showed that the ratio of CD4+/CD8+ of Wistar female rat givenTp5-TMC-NP (ig) was 2.59 time that of the group given Tp5 (ig).

[Determination of trace bismuth in traditional Chinese medicines by hydride generation atomic fluorescence spectrometry].

A method is reported for the determination of trace bismuth in traditional chinese medicine by hydride generation atomic fluorescence spectrometry. The effect of different means of digestion, the medium amounts of acid and reducing agent on the determination of Bi is investigated. In the given conditions, the linear range of determination is 0.1-200 microg x L(-1), and the detection limit is 0.0946 microg x L(-1). The instrumental relative standard deviation is about 0.55% and the recovery is about 94%-107%. The method is accurate, rapid and convenient with satisfactory results.