Accuracy of duplex stainless steel feature generated by electrical discharge machining (EDM)

The present paper studies different types of errors generated on the feature (cylindrical holes) which was fabricated by the wire EDM of 2205 duplex stainless steel. Different experimental parameters such as, pulse on time, pulse off time and wire tension on the feature as well as the contribution of these parameters on cylindricity error, circularity error and diameter error were explored. Moreover, interactions among the input parameters were also considered. It was found that the total contributions of interactions between different parameters are reasonably high for all the cases which make the modelling process very complex for cylindricity, circularity and diameter errors in term of the range of parameter considered in this investigation. Wire tension has highest contribution on cylindricity error which is lowest at high value wire tension. Pulse on time has minor contribution on the cylindricity error and it increases with the increase of pulse on time. Pulse of time does not have any influence on the cylindricity error. The circularity error was lowest at medium pulse off time and medium wire tension; and those two parameters have almost similar and highest contributions. The pulse on time has around 14% contribution on circularity error and the medium value of it minimizes the circularity error. The input parameters such has pulse on time, pulse off time and wire tension have around 13%, 16% and 7% contributions respectively on diameter error which is minimized at medium pulse on time, and low pulse off time and low wire tension

Impact of B2O3 and La2O3 addition on structural, mechanical and biological properties of hydroxyapatite

In this study, hydroxyapatite-B2O3-La2O3 composites (with ≤ 20 wt.% B2O3 and ≤ 2 wt.% La2O3) were synthesized via wet precipitation method and calcined at 1100 °C for 1 h. X-ray diffraction (XRD) analysis revealed the existence of the pure hydroxyapatite (HA) phase with high crystallinity. Characteristic absorption bands of HA were also observed in Fourier transform infrared spectra. Furthermore, scanning electron microscopy images demonstrated that the addition of B2O3 and La2O3 into HA enhanced the particle growth. Mechanical properties of the composites were studied by diametral tensile test and the results showed that incorporation of 10 wt.% B2O3 and 2 wt.% La2O3 led to a 39% increase in tensile strength (compared to the pure HA). In vitro cytocompatibility of HA-B2O3-La2O3 composites was investigated using Osteosarcoma Cell Lines (Saos-2). Incorporation of B2O3 and La2O3 into HA had no toxic effect towards the cells. Based on its tensile strength properties and biological response, composite of 88 wt.% HA, 10 wt.% B2O3 and 2 wt.% La2O3 was suggested as a promising composite for bone tissue engineering applications

Apoptotic mechanism of lantadene A from lantana camara leaves against prostatic cancer cells

Lantadene A (LA) which is one of the major pentacyclic triterpenoids in Lantana camara leaves was reported to exhibit anticancer property. However, the detail mechanism of LA inhibition against prostate cancer cells is still remained unknown. Hence, this study aimed to extract LA which was then used to treat LNCaP cells for the prediction of its apoptotic mechanism. A serial of separation techniques including maceration, solvent partition, crystallization and column chromatography was applied to recover LA. Approximately, 0.45%w/w LA was obtained from the plant leaves with 87.16% purity. The results found that the viability of LNCaP cells decreased with the increase of LA concentration with the IC50 of 208.4 μg/mL. High content screening showed the nucleuses of intact cells were started to collapse at the LA concentration more than 12.5 μg/mL, whereas the breakage of mitochondrial membrane was observed together with the release cytochrome C into cytosols. The activities of caspases -3/7 and -9 was found to increase in a dose dependent manner. Cell cycle arrest was happened during the (G0/G1) phase at the concentration of LA more than 50 μg/mL. As a conclusion, LA was effective to inhibit the growth of LNCaP cells without any cytotoxic effects to RWPE-1 cells. The inhibitory action of LA followed the intrinsic pathway of mitochondria dependent mechanism

Structural characterization, optical properties and in vitro bioactivity of mesoporous erbium-doped hydroxyapatite

We report the successful synthesis of mesoporous erbium doped hydroxyapatite (Er-HA, Ca10-xEr2x/3?x/3(PO4)6(OH)2) by using a rapid and efficient microwave assisted wet precipitation method. Characterization techniques like X-ray diffraction (XRD), Fourier transform infra-red (FTIR), X-ray fluorescence spectrometer (XRF), Brunauer, Emmett and Teller (BET) and transmission electron microscopy (TEM) were used to determine lattice parameters, particle size, degree of crystallinity, elemental composition, surface area and morphology of Er-HA. Results confirmed the formation of crystalline Er-HA having crystallite size of 25 nm with spherical and rod like morphology, while the TEM analysis confirmed the mesoporous nature of the particles. Optical spectra of Er-HA contained seven electron transitions, whereas blue shift in the energy band gap (Eg) was observed upon increase in Er3+ content. The photoluminescence (PL) spectra contained green and red emissions. In vitro bioactivity study conducted in SBF revealed that the incorporation of Er3+ ions into HA structure lead to the faster discharge of Er3+ ions resulting in intense growth of apatite grains on the surface of the Er-HA pellets with Ca/P ratio of 1.72

A review of synthesis methods, properties and use of monetite cements as filler for bone defects

The major objective of the current review is to highlight the prime importance of bone cements particularly monetite cement as filler to treat various bone defects which may result due to osteoporosis, some accidents, some trauma disease or any other orthopedic surgical disorders. Previous studies showed that polymethyl methacrylate (PMMA), calcium phosphate cements (CPCs), dicalcium phosphate (DCP) cement and acrylic polymer cements have been employed to improve the bone defects, but these materials have a certain issue of insitu setting. To overcome these problems, concentration was swiftly diverted towards monetite cement which revealed better results. Therefore, in this review, more focus has been given to the monetite cement. In this work, a brief but very productive discussion has also been inducted about the various synthetic routes to synthesize monetite cement and its properties which will help the readers to get key information about the growing significance of monetite cement as a bone filler and its future use and importance. The main theme of this review is to highlight the tremendous achievements achieved in the monetite cementing materials and their further scope in the near future as to upgrade their properties and use in the biomedical field

Co-doped hydroxyapatites as potential materials for biomedical applications

Hydroxyapatite (HA) is a synthetic biomaterial resembling the composition of mammalian hard tissue and thus, it is widely employed as a bone graft material, hard tissue engineering scaffold and coating layer for metallic substrates. Biological apatite is non-stoichiometric in nature. It is composed of small crystals and characterized by poor crystallinity and relatively high solubility with respect to stoichiometric HA. Chemical compositions of these crystals consist of Ca, P and trace amounts of various ions, such as Mg2+, Zn2+, Sr2+, Ag+, Cl- and F- which are more prominent as dopants or adsorbed on the crystal surface. However, these ions play an important role in the metabolism of hard tissues. Synthetic HA is a stoichiometric material with a Ca/P ratio of 1.67, which lacks the presence of valuable trace ions regularly present in natural hard tissue. Thus, the structure of synthetic HA is partially incorporated by these ions to mimic the chemical composition of the biological apatite structure. Ionic substitutions have been planned as a tool to enhance the biological role of HA based materials. As single dopant frameworks have indicated great outcomes, it makes sense that various dopants can be utilized to further build the valuable impacts of each, within the constraints of the material stability of HA. This review is focused on co-ionic substitutions in HA system and their combined effects on related biomedical characteristics

Antibacterial polylactic acid/chitosan nanofibers decorated with bioactive glass

In this study, we have presented the structural and in vitro characterization of electrospun polylactic acid (PLA)/Chitosan nanofibers coated with cerium, copper or silver doped bioactive glasses (CeBG/CuBG/AgBG). Bead-free, smooth surfaced nanofibers were successfully prepared by using electrospinning technique. The nanocomposite fibers were obtained using a facile dip-coating method, their antibacterial activities against E. coliE. coli (ATCC 25922 strains) were measured by the disk diffusion method after 24 h of incubation at 37 °C. CeBG and CuBG decorated PLA/Chitosan nanofibers did not develop an inhibition zone against the bacteria. On the other hand, nanofibers coated with AgBG developed an inhibition zone against the bacteria. The as-prepared nanocomposite fibers were immersed in SBF for 1, 3 and 7 days in Simulated Body Fluid (SBF) for evaluation of in vitro bioactivity. All samples induced the formation of crystallites with roughly ruffled morphology and the pores of fibers were covered with the extensive growth of crystallites. Energy Dispersive X-ray (EDX) composition analysis showed that the crystallites possessed Ca/P ratio close to 1.67, confirming the good in-vitro bioactivity of the fibers