Calcium (Ca) and silica (Si) ions have attracted intense interest in biomedical applications. The two ions are directly involved in many biological processes; for instance, Ca plays a key role in regulating cellular responses to bioceramics, promoting cell growth, and differentiation into osteoblasts. Si plays a significant role in bone calcification and is helpful for bone density improvement and inhibiting osteoporosis. Calcium silicate ceramics including a large group of trace metal containing calcium silicate‐based compounds are involved in biomedical applications such as repairing hard tissue texture, bone scaffolds, bone cements, or implant coatings. The aim of the study is to provide a comprehensive overview of developments in research on calcium silicate‐based ceramics, such as wollastonite (CaSiO3), diopside (CaMgSi2O6), akermanite (Ca2MgSi2O7), bredigite (Ca7Mg(SiO4)4), merwinite (Ca3MgSi2O8), monticellite (CaMgSiO4), hardystonite (Ca2Zn(Si2O7), and baghdadite (Ca3ZrSi2O9), including degradation, apatite mineralization, and mechanical properties. Finally, the biological in vitro and in vivo presentation for bone tissue repair are summarized, which show promise with regard to application of calcium silicate‐based ceramics as bone repair and replacement materials.

Abstract:In this paper, a simple and cheap method to prepare porous ZnO by using zinc nitrate, ethanol and triethanolamine (TEA) is reported. The as-prepared sample consisted of nano and micro pores. The sample was calcined at 300 ℃, 400 ℃ and 500 ℃ with different heating rates. At 500 ℃, the nano pores disappeared but the sample maintained its micro porosity. Field emission scanning electron microscopy (FE-SEM) pictures confirmed that the size and growth of ZnO nanoparticles depended on the heating conditions. The infrared (IR) absorption peak of Zn-O stretching vibration positioned at 457 cm 1 was split into two peaks centered at 518 cm 1 and 682 cm 1 with the change of morphology. These results confirmed that Fourier transform infrared (FT-IR) spectrum was sensitive to variations in particle size, shape and morphology. The photoluminescence (PL) spectrum of porous ZnO contained five emission peaks at 397 nm, 437 nm, 466 nm, 492 nm and 527 nm. Emission intensity enhanced monotonously with increase of temperature and the change was rapid between temperatures of 300 ℃ and 500 ℃. This was due to the elimination of organic species and improvement in the crystallanity of the sample at 500 ℃.

No abstract

No abstract

No abstract

No abstract

The optical energy gap of amorphous Se powder has been determined by a photoacoustic method and has been found to be 1.99 ? 0.02 eV. On annealing, the gap decreases linearly as a function of annealing temperature towards that of the crystalline selenium.

No abstract