CREB/Wnt10b mediates the effect of COX-2 on promoting BMP9-induced osteogenic differentiation via reducing adipogenic differentiation in mesenchymal stem cells.

Bone morphogenetic protein 9 (BMP9) is one of the most potent osteogenic factors, which may be a potential candidate for bone tissue engineering. However, the osteogenic capacity of BMP9 still need to be further enhanced. In this study, we determined the effect of Wnt10b on BMP9-induced osteogenic differentiation in mesenchymal stem cell (MSCs) and the possible mechanism underlying this process. We introduced the polymerase chain reaction (PCR), Western blot analysis, histochemical stain, ectopic bone formation, and microcomputed tomography analysis to evaluate the effect of Wnt10b on BMP9-induced osteogenic differentiation. Meanwhile, PCR, Western blot analysis, chromatin immunoprecipitation, and immunoprecipitation were used to analyze the possible relationship between BMP9 and Wnt10b. We found that BMP9 upregulates Wnt10b in C3H10T1/2 cells. Wnt10b increases the osteogenic markers and bone formation induced by BMP9 in C3H10T1/2 cells, and silencing Wnt10b decreases these effects of BMP9. Meanwhile, Wnt10b enhances the level of phosphorylated Smad1/5/8 (p-Smad1/5/8) induced by BMP9, which can be reduced by silencing Wnt10b. On the contrary, Wnt10b inhibits adipogenic markers induced by BMP9, which can be decreased by silencing Wnt10b. Further analysis indicated that BMP9 upregulates cyclooxygenase-2 (COX-2) and phosphorylation of cAMP-responsive element binding (p-CREB) simultaneously. COX-2 potentiates the effect of BMP9 on increasing p-CREB and Wnt10b, while silencing COX-2 decreases these effects. p-CREB interacts with p-Smad1/5/8 to bind the promoter of Wnt10b in C3H10T1/2 cells. Our findings suggested that Wnt10b can promote BMP9-induced osteogenic differentiation in MSCs, which may be mediated through enhancing BMP/Smad signal and reducing adipogenic differentiation; BMP9 may upregulate Wnt10b via the COX-2/p-CREB-dependent manner.

[Study of rotator phase and phase transition of short-chain alkane by means of Raman spectroscopy].

Raman spectroscopy was used to investigate the phase transition of n-hexacosane for real-time cooling run. In the cooling process, the n-hexacosane experienced the melt phase --> rotator phase --> monoclinic crystal phase transition. The changes in band intensity and frequency in the CH2 bending, CH2 twisting, skeletal C-C stretching, and CH3 rocking regions were mainly analyzed in order to know the changing sequence and process of these vibrational modes, and to reflect the relationship between these vibrational modes and molecular structure. Besides, the changes in band intensity and frequency revealed both transitions, particularly when using band components related to gauche bonds. Our research shows that Raman spectroscopy is an effective tool to monitor the phase transition of n-alkanes or even long-chain polymers. In addition, by analyzing the Raman peaks in 800-1 500 cm(-1) in the cooling process of n-hexacosane, the temperature range of rotator phase was obtained, proving that Raman spectroscopy can be used to observe the rotator phase occurring during the phase transition of paraffin.

[Low-temperature-dependent Raman study on A1 (LO) mode of 6H-SiC].

Variable temperature method was lent for low temperature Raman study on bulk monocrystal 6H-SiC in the temperature range from 80 to 320 K. Some Raman folding modes of 6H-SiC were assigned in the spectrum. The peak position and line width of optical phonon A1 (LO) versus temperature mainly below RT was focused on by 3-phonon and 4-phonon models. The result showed that as the temperature decreased the line width decreased, while the peak position shifted to high wave number. It was found that as the temperature varied below 160 K, the change in peak position and line width was little, different from it was at RT, revealing that the line type of A1 (LO) mode was mainly decided by the phonon characteristics and the effect of temperature could be ignored when it was below 160 K. It was showed that 4-phonon model was closer to the experiment data for fitting. Both the third and forth anharmonic vibration contributed to the spectrum, while the former was the main process. Moreover, the phonon lifetime became longer when the temperature fell because of the decrease in the atomic thermal motion.

[Research on AlInGaN quaternary alloys as MQW barriers in GaN-based laser diodes].

InGaN/GaN, InGaN/InGaN and InGaN/AlInGaN multi-quantum-well (MQW) laser diodes (LDs) were grown on (0001) sapphire substrate by metalorganic chemical vapor deposition (MOCVD). The GaN (0002) synchrotron X-ray diffraction (XRD), electroluminescence (EL) and optical power-current (L-I) measurement reveal that AlInGaN quaternary alloys as barriers in MQWs can improve the crystal quality, optical emission performance, threshold current and slope efficiency of the laser diode structure to a large extent compared with other barriers. The relevant mechanisms are that: 1. The Al component increases the barrier height of the MQWs so that more current carriers will be caught in. 2. The In component counteracts the strain in the MQWs that decreases the dislocations and defects, thereby the nonradiative recombination centers are decreased. 3. The In component decreases the piezoelectric electric field that makes the electrons and the holes recombine more easily.

[Study of reference and order parameter of Raman spectroscopy research on alkane phase transition].

Raman spectroscopy was used to investigate the order-disorder phase transition of n-eicosane for real-time cooling run. At the phase transition temperature, the integrated intensity of the 1 300 cm(-1) spectra range changes greatly, which requires further consideration of 1 300 cm(-1) as a reference in the research on polymer and biomembrane using Raman spectroscopy. The experiment support was provided for doubt about order parameter based on 1 130 cm(-1) that it did not refer to generally accepted interpretation of an order parameter and it proved that the order definition could just be used as a relative measure method for disorder.

[A Raman study of ZnO powders with ZnO2 as precursor].

Raman spectra of ZnO powders prepared by firing ZnO2 precipitate were reported in detail for the first time. By comparing the spectra with that of the sample fabricated by another method and analyzing frequency difference between the focused-laser irradiated samples with different firing temperature in preparation, it was concluded that the -333 cm(-1) peak is ascribed to E2 (high)-E2 (low) and the -661 cm(-1) peak to its overtone. In addition, a new interpretation for the observed Raman peaks between 400 and 500 cm(-1) in ZnO2 powders was presented based on the IR data and ab initio calculation.

[Effect of the film of gold nanowire arrays on surface enhanced Raman scattering].

Metal nanowire arrays as surface-enhanced Raman scattering substrate, could bring high enhancement effect. According to the electromagnetic enhancement theory, the high enhancement factors come from the strong electromagnetic coupling between nanowires in the arrays. Gold nanowire arrays and gold nanobrushes were prepared by electro-deposition of gold into alumina template coated with gold film, then chemically etching alumina directly or rubbing gold film and chemically etching alumina. SEM showed the nanowires around 60 nm in diameter with length around 600 nm in the nanobrushes. In the gold nanobrushes, local nanowires collect in bundles after complete dissolution of alumina matrix due to the transverse tension during drying in the air. The two kinds of samples are different in structure. But optical transmission measurements of the two samples in the direction perpendicular to the substrate both showed plasma-enhanced absorption around 640-650 nm. The authors choose 4-mercaptopyridine (4-MP) as the probe molecules because 4-MP chemically adsorb on Au nanowires tightly by monolayer and align perpendicular to Au surface. SERS experiments were performend with a 632.8 nm laser. SERS signals come from the back scattering of the incident light propagating perpendicular to the Au substrates. And the Raman spectra were collected at morethan 10 different points on each sample. A strong, locally inhomogeneous surface-enhanced Raman spectrum of 4-MP adsorbed on Au nanobrushes with enhancement factor as high as 1 x 10(6) was observed. At the same time, SERS of 4-MP from the gold nanowire arrays under the same experiment conditions showed the enhancement factor around 10(2). Considering the optical transmission measurements of the two samples, the enhancement factors both come from resonance field enhancement. According to the difference of the two kinds of samples, the higher enhancement factors of gold nanobrushes are related with the gold film. According to the localization theory of electromagnetic field, the field around the upper part of the nanowires of the nanobrushes is far stronger than that of the bottom part and on the film. So the gold film introduced higher enhancement factors in SERS The spectrum of 4-MP also showed that the CT mechanism affects the enhancement factors.

[Temperature-dependent optical activity and birefringence study of D-alanine single crystal].

The measurement of the anisotropy of optical acitivity and birefringence is one of the most important clues to studying physical properties of a biaxial crystal of D-alanine. In order to investigate a second-order phase transition predicted by A. Salam between two states of D-alanine, the behavior of birefringence and optical activity is useful for the phenomenological approach to the transition mechanism. The optical activity as a peculiar quantity can respond to the modulation of the crystal lattice and to the change in the bonding nature of constituent atoms. In the present paper, the authors use the PEM-90 photoelastic modulator to study the conformation change of D-alanine at the temperature ranging from 220 to 290 K. The temperature dependence of I(2f)/I(dc) showed that the conformation of D-alanine molecule in single crystal changed around 250 K. The obtained results provide an obvious evidence of optical rotation phase transition predicted by Salam.

[Raman spectra and photoluminescence spectra of InGaN/GaN multiquantum wells annealed].

InGaN/GaN multiquantum well, grown by MOCVD on a sapphire substrate and annealed under the conditions of 700 and 900 degrees C x (20 min)(-1), was studied by means of mirco-Raman spectroscopy and photoluminescence. The Raman peak of E2, A1 showed red shift after multiquantum were wells annealed, and the HWHM of Raman peakdecreased imperceptibly. Moreover,the photoluminescence peak of the sample annealed under the condition of 700 degrees x (20 min)(-1) showed a red shift, then appeared a blue shift under the condition of 900 degrees C x (20 min)(-1). These results clearly showed that the sample annealed induced strain stress relief that could explain Raman peak shift, but the piezoelectric field induced the quantum-confined Stark effect, which can't agree with the photoluminescence experiment. Sample annealed could change the width of quantum well and InGa phase segregated; these factors influencing structure of quantum well could explain the results of photoluminescence spectra.

[A high transmittance material in UVc band].

Spectral characteristics of an organic material in acid with different concentrations were investigated in the solution of a proper acid concentration. The results showed that at 252 nm the transmittance T = 56.5%, but at 290 nm the material had a strong absorption peak (epsilon > 10(4) L. (mol.cm)-1). The absorbance A280-298 nm > 8, i.e. T280-298 nm < 10(-8). The band width was about 16 nm. Therefore, this material has conspicuous characteristics such as high transmittance and deep cutoff in the background in ultraviolet-c band. The transmission peak can be shifted in the range of 251-260 nm by changing the pH value of the solution and selecting solution with a different polarity. By analyzing the spectra of the material in acid we found that the two original absorption peaks disappeared, and a new strong absorption peak appeared at 290 nm. Moreover, it seems to be some relation between the two absorption peak intensity and the new peak, which needs to be further studied. Using this result, we can produce high quality UV-filters of this material with traditional coating and colour glass technology.

[The luminescence character of Eu complexes with derivatives of benzoic acid and different second ligands].

Synthesize eight rare earth europium complexes with derivatives of benzoic acid and different second ligands. We obtained luminescence spectra of these complexes. Although their Eu3+ have about local surrounding symmetry, luminescent intensities are different each other. Because of matching of energy level the complexes with phen is better than with bipy and through the variety structure of spectra show the complexity of Eu3+ hypersensitive transition.