Fluorescence-based temperature sensing using erbium-doped optical fibers with 1.48 μm pumping

Temperature sensing using 1.54 μm fluorescence at the transition between the energy levels⁴I_15/2 (ground state) and⁴I_13/2 generated in an erbium-doped fiber with 1.48 μm pumping is proposed. The fluorescence has a peculiar spectral profile that possesses two peaks around 1.530 μm and 1.552 μm wavelengths. The temperature-dependent fluorescence is investigated in the temperature range between -50°C and 90°C. The power ratio between the two peaks increases with an increase in temperature. The sensitivity of the ratio is 0.007/°C on average in the measured temperature range. The total fluorescence power and the absorption loss at λ = 1480 nm in the fiber decrease as the temperature increases. Optical fiber temperature sensing immune from the fluctuation in pumping power can be performed using the peak power ratio and/or the absorption loss.     

Binding enhancements of nicotinic acid to water-soluble zinc porphyrins based on triple attractions of coordination, Coulomb, and CH-pi interactions

The binding of amines to artificial zinc-porphyrin receptors 1-4 was examined in basic aqueous solutions. For nicotinic acid and 3,5-dicarboxypyridine, substantial binding enhancements were observed compared to other amines with no pi system or carboxyl group. This observation suggested that interligand attractions of Coulomb and CH-pi interactions in addition to N-atom coordination can act effectively as recognition factors. The differences in the Coulomb interaction between carboxylate and sulfonate anions were also discussed.     

Synthesis and evaluation of fluorogenic reagents for simultaneous detection of peptides and proteins by HPLC in two different samples

To find the pairs of fluorogenic reagents having similar retention times in HPLC but with different fluorescent characteristics, six fluorogenic reagents bearing benzoxadiazole or benzoselenadiazole skeletons were synthesized. The resultant derivatives obtained from the reaction of peptides and proteins with reagents which have a benzoselenadiazole skeleton showed different fluorescence characteristics from those with a benzoxadiazole skeleton. Since each corresponding derivatives of trypsin inhibitor and BSA with DAABD-Cl and 7-fluoro-N-[2-(diethylamino)ethyl]-2,1,3-benzoselenadiazole-4-sulfonamide (DEAEABSeD-F) have similar retention times, the pair of reagents was adopted for the sensitive simultaneous detection of proteins in two different samples. When the soluble fraction of mouse hippocampus was divided into the two samples (A and B), each was reacted with DEAEABSeD-F for A and DAABD-Cl for B, respectively. The two reaction solutions were combined and subjected to HPLC analysis with two fluorescent detectors in series (excitation and emission at different wavelengths for A and B, respectively). The resultant two chromatograms had quite similar patterns for each other. The new pair of fluorogenic reagents (DAABD-Cl and DEAEABSeD-F) would be applicable to proteomics studies using the previously reported FD-LC-MS/MS method.     

Kinetics of the dehydrochlorination of poly(vinyl chloride) in the presence of NaOH and various diols as solvents

The dehydrochlorination of PVC in the presence of NaOH was investigated in different diols. Diethylene glycol (DEG), triethylene glycol (TEG), and propylene glycol (PG) were found to be effective in accelerating the dechlorination of PVC. The dehydrochlorination was promoted in the order TEG > DEG > PG, which was in agreement with the compatibility between PET and the diol. Compatibility resulted in an improved penetration of the PVC particle by the solvent, leading to the acceleration of the dehydrochlorination. The dehydrochlorination of PVC in NaOH/diol followed first-order kinetics, confirming the progress of the reaction under chemical reaction control. The apparent activation energies were 82 kJ mol⁻¹, 109 kJ mol⁻¹, and 151 kJ mol⁻¹ for TEG, DEG, and PG, respectively. The lower the activation energy became the faster the dehydrochlorination of PVC proceeded.     

Laser spectroscopic study on the conformations and the hydrated structures of benzo-18-crown-6-ether and dibenzo-18-crown-6-ether in supersonic jets

The laser-induced fluorescence spectra of jet-cooled benzo-18-crown-6 (B18C6) and dibenzo-18-crown-6 (DB18C6) exhibit a number of vibronic bands in the 35 000-37 000 cm(-1) region. We attribute these bands to monomers and hydrated clusters by fluorescence-detected IR-UV and UV-UV double resonance spectroscopy. We found four and two conformers for bare B18C6 and DB18C6, and the hydration of one water molecule reduces the number of isomers to three and one for B18C6-(H(2)O)(1) and DB18C6-(H(2)O)(1), respectively. The IR-UV spectra of B18C6-(H(2)O)(1) and DB18C6-(H(2)O)(1) suggest that all isomers of the monohydrated clusters have a double proton-donor type (bidentate) hydration. That is, the water molecule is bonded to B18C6 or DB18C6 via two O-H[dot dot dot]O hydrogen bonds. The blue shift of the electronic origin of the monohydrated clusters and the quantum chemical calculation suggest that the water molecule in B18C6-(H(2)O)(1) and DB18C6-(H(2)O)(1) prefers to be bonded to the ether oxygen atoms near the benzene ring.     

Optically transparent superhydrophobic TEOS-derived silica films by surface silylation method

Optically transparent silica films were prepared at room temperature (~27°C) by keeping the molar ratio of TEOS:MeOH:H₂O (0.001 M NH₄F) constant at 1:19.29:6.20, respectively. A surface chemical modification of the films was done with alkylchlorosilanes at different concentrations from 0 to 1 vol. % and aging times varied from half to 2 h. The DMCS and TMCS surface modified silica films showed the static water contact angle of 146° and 162°, respectively. When the DMCS and TMCS modified films were cured at temperatures higher than 240 and 275°C, respectively, the films became superhydrophilic. Further, the humidity study was carried out at a relative humidity of 90% at 30°C temperature over 60 days. We characterized the water repellent silica films by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, % of optical transmission, humidity tests and contact angle measurements.