Amorphous Calcium Phosphate (ACP) is an essential mineral phase formed in mineralized tissues and the first commercial product as artificial hydroxyapatite. ACP is unique among all forms of calcium phosphates in that it lacks long-range, periodic atomic scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at 25 degree 2 theta, and no other different features compared with well-crystallized hydroxyapatite. Under electron microscopy, its morphological form is shown as small spheroidal particles in the scale of tenths nanometer. In aqueous media, ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystalline. It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo. Moreover, it can increase alkaline phosphatase activities of mesoblasts, enhance cell proliferation and promote cell adhesion. The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration. ACP may also be a potential remineralizing agent in dental applications. Recently developed ACP-filled bioactive composites are believed to be effective anti-demineralizing/remineralizing agents for the preservation and repair of tooth structures. This review provides an overview of the development, structure, chemical composition, morphological characterization, phase transformation and biomedical application of ACP in dentistry.

Background/Aims: Diabetic cardiomyopathy (DCM) represents the major cause of morbidity and mortality among diabetics. Exercise has been reported to be effective to protect the heart from cardiac injury during the development of DCM. However, the potential cardioprotective effect of exercise in advanced DCM remains unclear. Methods: Seven-week old male C57BL/6 wild-type or db/db mice were either subjected to a running exercise program for 15 weeks or kept sedentary. Cardiac function, myocardial apoptosis and fibrosis, and mitochondrial biogenesis were examined for evaluation of cardiac injury. Results: A reduction in ejection fraction and fractional shortening in db/db mice was significantly reversed by exercise training. DCM induced remarkable cardiomyocyte apoptosis and increased ratio of Bax/Bcl-2 at the protein level. Meanwhile, DCM caused slightly myocardial fibrosis with elevated mRNA levels of collagen I and collagen III. Also, DCM resulted in a reduction of mitochondrial DNA (mtDNA) replication and transcription, together with reduced mtDNA content and impaired mitochondrial ultrastructure. All of these changes could be abolished by exercise training. Furthermore, DCM-associated inhibition of PGC-1α and Akt signaling was significantly activated by exercise, indicating that exercise-induced activation of PGC-1α and Akt signaling might be responsible for mediating cardioprotective effect of exercise in DCM. Conclusion: Exercise preserves cardiac function, prevents myocardial apoptosis and fbrosis, and improves mitochondrial biogenesis in the late stage of DCM. Exercise-induced activation of PGC-1α and Akt signaling might be promising therapeutic targets for advanced DCM.

Intrigued by the initial report of an extended lumiosity distribution perpendicular to the disk of the edge-on Sc galaxy NGC 5907, we have obtained very deep exposures of this galaxy with a Schmidt telescope, large-format CCD, and intermediate-band filters centered at 6660Å and 8020Å. These two filters, part of a 15-filter set, are custom-designed to avoid the brightest (and most variable) night sky lines. As a result, our images are able to go deeper, with lower sky noise than those taken with broad-band filters at similar effective wavelengths: e.g., 0.6 e − arcsec −2 sec −1 for our observations vs. 7.4 e − arcsec −2 sec −1 for the R-band measures of Morrison et al. In our assessment of both random and systematic errors, we show that the flux level where the errors of observation reach 1 mag arcsec −2 are 29.00 mag arcsec −2 in the 6660Å image (corresponding to 28.7 in R-band) and 27.4 mag arcsec −2 in the 8020Å image (essentially on the I-band system).As detailed in Shang et al., our observations show NGC 5907 has a luminous ring around it that most plausibly is due to the tidal disruption of a dwarf spheroidal galaxy by the much more massive spiral. Here we show that, fainter than 27th R mag arcsec −2 , the surface brightness around NGC 5907 is strongly asymmetric, being mostly brighter on NW (ring) side of the galaxy midplane. This asymmetry rules out a halo for the origin of the faint surface brightness we see.We find this asymmetry is likely an artifact owing to a combination of ring light and residual surface brightness at faint levels from stars that our star-masking procedure cannot completely eliminate. The possible existence of an optical face-on warp in NGC 5907, suggested by our VLA HI observations, is too confused with foreground star contamination to be independently studied. Good agreement with the surface photometry of NGC 5907 by Morrison et al. and other workers lead us to conclude that their data are similarly affected at faint levels by ring light and residual effects from their star masking procedures. Inspection of the images published by Morrison et al. and Sackett et al. confirm this to be the case. Thus, we conclude that NGC 5907 does not have a faint, extended halo.In this paper we present the details of our deep surface photometry of this galaxy, this time paying close attention to the issue of the faint luminosity distribution around this galaxy. Section 2 presents our observations, including details of the data reduction process, which are important for the reader to be able to critically assess the accuracy of our method. In Section 3 we study the faint luminosity distribution around NGC 5907 as it appears in our images, including how the ring, foreground stars, and a possible face-on warp can influence what we see. Our results are compared to those previously published in Section 4, in which we also reassess the likelihood of a halo existing around this galaxy. Section 5 summarizes the main results of this paper. OBSERVATIONS AND DATA REDUCTIONThe phases of data reduction that con...

We report on a new Be/X‐ray pulsar binary located in the Wing of the Small Magellanic Cloud (SMC). The strong pulsed X‐ray source was discovered with the Chandra and XMM–Newton X‐ray observatories. The X‐ray pulse period of 1062 s is consistently determined from both Chandra and XMM–Newton observations, revealing one of the slowest rotating X‐ray pulsars known in the SMC. The optical counterpart of the X‐ray source is the emission‐line star 2dFS 3831. Its B0‐0.5(III)e+ spectral type is determined from VLT‐FLAMES and 2dF optical spectroscopy, establishing the system as a Be/X‐ray binary (Be‐XRB). The hard X‐ray spectrum is well fitted by a power law with additional thermal and blackbody components, the latter reminiscent of persistent Be‐XRBs. This system is the first evidence of a recent supernova in the low‐density surroundings of NGC 602. We detect a shell nebula around 2dFS 3831 in Hα and [O iii] images and conclude that it is most likely a supernova remnant. If it is linked to the supernova explosion that created this new X‐ray pulsar, its kinematic age of (2–4) × 104 yr provides a constraint on the age of the pulsar.

In this paper, we present a multi-color photometric study of the nearby spiral galaxy M81, using images obtained with the Beijing Astronomical Observatory 60/90 cm Schmidt Telescope in 13 intermediate-band filters from 3800 to 10000Å. The observations cover the whole area of M81 with a total integration of 51 hours from February 1995 to February 1997. This provides a multi-color map of M81 in pixels of 1 ′′ .7 × 1 ′′ .7. Using theoretical stellar population synthesis models, we demonstrate that some BATC colors and color indices can be used to disentangle the age and metallicity effect. We compare in detail the observed properties of M81 with the predictions from population synthesis models and quantify the relative chemical abundance, age and reddening distributions for different components of M81. We find that the metallicity of M81 is about Z = 0.03 with no significant difference over the whole galaxy. In contrast, an age gradient is found between stellar populations of the central regions and of the bulge and disk regions of M81: the stellar population in its central regions is older than 8 Gyr while the disk stars are considerably younger, ∼ 2 Gyr. We also give the reddening distribution in M81. Some dust lanes are found in the galaxy bulge region and the reddening in the outer disk is higher than that in the central regions.

We report the serendipitous discovery with XMM-Newton that 3XMM J185246.6+003317 is an 11.56 s X-ray pulsar located 1 ′ away from the southern boundary of supernova remnant Kes 79. The spin-down rate of 3XMM J185246.6+003317 is < 1.1 × 10 −13 s s −1 , which, together with the long period P = 11.5587126(4) s, indicates a dipolar surface magnetic field of < 3.6×10 13 G, a characteristic age of > 1.7 Myr, and a spin-down luminosity of < 2.8 × 10 30 erg s −1 . Its X-ray spectrum is bestfitted with a resonant Compton scattering model and can be also adequately described by a blackbody model. The observations covering a seven month span from 2008 to 2009 show variations in the spectral properties of the source, with the luminosity decreasing from 2.7 × 10 34 erg s −1 to 4.6 × 10 33 erg s −1 , along with a decrease of the blackbody temperature from kT ≈ 0.8 keV to ≈ 0.6 keV. The Xray luminosity of the source is higher than its spin-down luminosity, ruling out rotation as a power source. The combined timing and spectral properties, the non-detection of any optical or infrared counterpart, together with the lack of detection of the source in archival X-ray data prior to the 2008 XMM-Newton observation, point to 3XMM J185246.6+003317 being a newly discovered transient low-B magnetar undergoing an outburst decay during the XMM-Newton observations. The nondetection by Chandra in 2001 sets an upper limit of 4 × 10 32 erg s −1 to the quiescent luminosity of 3XMM J185246.6+003317. Its period is the longest among currently known transient magnetars. The foreground absorption toward 3XMM J185246.6+003317 is similar to that of Kes 79, suggesting a similar distance of ∼ 7.1 kpc.

We describe in detail the extinction correction procedures used for the Beijing-Arizona-Taiwan-Connecticut Sky Survey (BATC Survey). The survey covers the spectral range 3200È9900 by Ó utilizing a set of 15 intermediate-band Ðlters. These Ðlters are speciÐcally designed to exclude most of the bright and variable night-sky emission lines. We also present extinction coefficients for the Ðlter passbands for typical photometric nights at the Xinglong Observing Station, Beijing Astronomical Observatory (where the observations of the survey are being carried out). Time-dependent, low-amplitude (D1%), nightly extinction variation has been observed. Such variation is demonstrably independent of Ðlter bandpass and air mass, with amplitudes ranging from D0.01 to D0.03 mag. The variation is plausibly caused by slowly varying (at D1%) atmospheric extinction, possibly related to changes in air pressure/temperature/humidity that occur during the night. An iterative Ðtting scheme has been developed to take this time-varying component into account. We conclude that the survey can achieve its stated observational goal, namely, an absolute photometric calibration that is tied to the system to an accuracy of 1% in all Ðlters. AB l ÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈ

We demonstrate here that the enhancement of optical transmission originates not only from surface plasmons ͑SPs͒ but also from the coupling of SPs in the Ag/ SiO 2 multilayer with a periodic array of subwavelength holes. The multilayer film is constructed by repeating a building block, which contains two layers: one is a silver film with periodic array of subwavelength holes and the other is a film of SiO 2 . The multilayers were fabricated by magnetron sputtering, and the array of holes was milled with focused-ion-beam facility. The measured optical transmission properties reasonably agree with our numerical calculations. It is shown that the coupling of SPs strongly depends on the detailed structure, and in our system, the coupled SPs can be characterized by using an effective-permittivity model. In the sandwiched structure with nanostructured silver, the coupling of SPs leads to the shift of transmission peaks, while in a nanostructured Ag/ SiO 2 multilayer, the coupling of SPs yields a new resonant mode with increased quality factor of the transmission peak, which originates from multiple scatterings and the coupling of electromagnetic waves on the interfaces of the multilayers. These properties may be utilized to tune electromagnetic wave in subwavelength optics.