In vitro study of the SBF and osteoblast-like cells on hydroxyapatite/chitosan–silica nanocomposite

Hydroxyapatite/chitosan–silica (HApCSi) nanocomposites were synthesized by co-precipitated method and their potential application as filler materials for bone regeneration were investigated in simulated body fluid (SBF). To study their biocompatibility, they were cultured with rat osteoblast-like UMR-106 cells for 3, 7, 14, and 21 days. Studies of the silica contents in chitosan matrix showed the presence of silinol (Si–OH) groups in CSi hybrid and their decrease after being composited with calcium phosphate (CaP) which is desirable for the formation of the apatite. XRD and TEM studies showed that the HAp formed in the CSi matrix were nanometer (20–40 nm) in size. Nanocomposites of HApCSi20 processed with 20%v/v silica whisker showed a micro hardness of 84.7 ± 3.3 MPa. Mineralization study in SBF showed the formation of apatite crystals on the HApCSi surface after being incubated for 7 days. In vitro biocompatibility, cell morphology, proliferation, and cell adhesion tests confirmed the osteoblast attachment and growth on the HApCSi20 surface. The density of cells and the production of calcium nodules on the substrate were seen to increase with increasing cultured time. The mechanical evaluation and in vitro experiment suggested that the use of HApCSi composite will lead to the formation of new apatite particles and thus be a potential implant material.     

Substitution of manganese and iron into hydroxyapatite: Core/shell nanoparticles

The bioceramics, hydroxyapatite (HAP), is a material which is biocompatible to the human body and is well suited to be used in hyperthermia applications for the treatment of bone cancer. We investigate the substitution of iron and manganese into the hydroxyapatite to yield ceramics having the empirical formula Ca_9.4Fe_0.4Mn_0.2(PO₄)₆(OH)₂. The samples were prepared by the co-precipitation method. The formation of the nanocrystallites in the HAP structure as the heating temperatures were raised to obtain a glass–ceramic system are confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and electron spin resonance (ESR). TEM images show the core/shell structure of the nanoparticles, with the core being formed by the ferrites and the shell by the hydroxyapatite. The ED patterns indicate the nanoparticles formed at 500 °C have an amorphous structure while the nanoparticles formed at 1000 °C are crystalline. ESR spectroscopy indicated that the Fe³⁺ ions have a g-factor of 4.23 and the Mn²⁺ ions have a g-factor of 2.01. The values of the parameters in the spin Hamiltonian which describes the interaction between the transition metal ions and the Ca²⁺ ions, indicate that the Mn²⁺ ion substitute into the Ca²⁺ sites which are ninefold coordinated, i.e., the Ca(1) sites.     

The effect of cetyl palmitate crystallinity on physical properties of gamma-oryzanol encapsulated in solid lipid nanoparticles

This present study was aimed at investigating the effect of the crystallinity of cetyl palmitate based solid lipid nanoparticles (SLNs) on the physical properties of γ-oryzanol-loaded SLNs. SLNs consisting of varying ratios of cetyl palmitate and γ-oryzanol were prepared. Their hydrodynamic diameters were in the range 210-280?nm and the zeta potentials were in the range -27 to -35?mV. The size of SLNs increased as the amount of cetyl palmitate decreased whereas no significant change of zeta potentials was found. Atomic force microscopy pictures indicated the presence of disc-like particles. The crystallinity of SLNs, determined by differential scanning calorimetry and powder x-ray diffraction, was directly dependent on the ratio of cetyl palmitate to γ-oryzanol and decreased with decreasing cetyl palmitate content in the lipid matrix. Varying this ratio in the lipid mix resulted in a shift in the melting temperature and enthalpy, although the SLN structure remained unchanged as an orthorhombic lamellar lattice. This has been attributed to a potential inhibition by γ-oryzanol during lipid crystal growth as well as a less ordered structure of the SLNs. The results revealed that the crystallinity of the SLNs was mainly dependent on the solid lipid, and that the crystallinity has an important impact on the physical characteristics of active-loaded SLNs.     

Optimal cutting condition determination for desired surface roughness in end milling

CNC end milling is a widely used cutting operation to produce surfaces with various profiles. The manufactured parts’ quality not only depends on their geometries but also on their surface texture, such as roughness. To meet the roughness specification, the selection of values for cutting conditions, such as feed rate, spindle speed, and depth of cut, is traditionally conducted by trial and error, experience, and machining handbooks. Such empirical processing is time consuming and laborious. Therefore, a combined approach for determining optimal cutting conditions for the desired surface roughness in end milling is clearly needed. The proposed methodology consists of two parts: roughness modeling and optimal cutting parameters selection. First, a machine learning technique called support vector machines (SVMs) is proposed for the first time to capture characteristics of roughness and its factors. This is possible due to the superior properties of well generalization and global optimum of SVMs. Next, they are incorporated in an optimization problem so that a relatively new, effective, and efficient optimization algorithm, particle swarm optimization (PSO), can be applied to find optimum process parameters. The cooperation between both techniques can achieve the desired surface roughness and also maximize productivity simultaneously.     

Influence of manganese substitution into the A-site of perovskite type Ca1−xMnxTiO3 ceramic

Ca_1−xMn_xTiO₃ (x = 0–1.0) perovskite ceramics were prepared by conventional solid state reaction. XRD was used to confirm the microcrystalline nature of the Ca_1−xMn_xTiO₃ crystals. For the x = 0 composition, the XRD patterns were those of a single orthorhombic perovskite while for x = 0.2–0.8, the XRD spectra were those of two orthorhombic perovskite phases: CaTiO₃ and MnTiO₃. For x = 1, XRD pattern was that of the MnTiO₃ phase only. The morphology and particle size of the grains of the different composition were observed using SEM. The size of the particles increased from 0.2 μm to 2–3 μm as x increased from 0 to 0.6. The room temperature dielectric constant at the frequency of 110 kHz for the x = 0.2 and x = 1.0 ceramics were ∼3.41 × 10⁴ and ∼4.99 × 10³, respectively. The ESR linewidth of samples increased with increasing manganese content due to the formation of magnetic cluster. Our ESR studies indicate that the manganese ions are in the Mn⁴⁺ state.     

Vitamin A stability in triple fortified extruded,artificial rice grains containing iron,zinc and vitamin A

Multi‐micronutrient‐fortified rice could be an effective and sustainable approach to combat micronutrient deficiencies. We produced hot‐extruded artificial rice grains fortified with 10 mg iron (as micronised ground ferric pyrophosphate), 5 mg zinc (as oxide, sulphate or carbonate) and 750 μg vitamin A/g [as retinyl palmitate (RP)] and measured RP stability. The rice was designed to be mixed 1:200 with natural rice. Mean RP losses were 5.3% during extrusion, 28.5% during storage and 9.8% during cooking. Storage losses after 18 weeks at 30 °C in plastic packages exposed to light were ca 40% with iron and zinc causing no further losses. In aluminium packages (no light), mean RP losses were ca 20%. Iron, but not zinc, increased RP degradation. Zinc sulphate increased the negative effect of iron. The relatively good stability of RP during hot extrusion can be explained by the closed surface and dense nature of the artificial grain protecting RP from oxidation.     

Effect of synthesis time on morphology of CeO_2 nanoparticles and Au/CeO_2 and their activity in oxidative steam reforming of methanol

Ceria(CeO_2)supports,synthesized by hydrothermal treatment with different synthesis time(CeO_2-X h,where X is the synthesis time in h)in the presence of the surfactant cetyltrimethyl ammonium bromide,were used as supports for gold(Au)catalysts.The synthesis time significantly affects the morphological structure and crystallite size of CeO_2,where CeO_2-2 h has the smallest crystallite size with coexisting nanorods and nanoparticles.Transmission electron microscopy analysis confirms the morphology of CeO_2 with distinctive(110),(100)and(111)planes,in agreement with interplanar spacings of 0.19,0,27 and 0.31,respectively.However,the morphology of CeO_2-8 h and CeO_2-48 h is mainly a truncated octahedral with crystal planes(111)and(100)accompanied by an interplanar spacing of 0.31 and0.27 nm,respectively.The CeO_2-X h supports and those with a 3 wt%Au loading(Au/CeO_2-X h)were investigated in the oxidative steam reforming of methanol at temperatures between 200 and 400 ℃.The Au/CeO_2-2 h gave the highest methanol conversion level and hydrogen yield at a low temperature of 250 ℃.This superior catalytic performance results from the good interaction between the metal and support and the well-distributed Au species on the CeO_2 support.     

Nanogold‐based immunochromatographic strip test for rapid detection of clinical and environmental strains of Vibrio cholerae

A nanogold‐based immunochromatographic strip test (VCG strip test) for the detection of all 70 isolates of Vibrio cholerae including O1, O139, and non‐O1/O139 (NVCs) was developed using two monoclonal antibodies (MAbs), namely VC‐63 and VC‐201, which bound specifically to 10 and 15 kDa proteins. Direct detection of V. cholerae in experimentally spiked fresh seafood samples such as shrimp, blood clam, mussel, and oyster could be achieved with sensitivities of 10⁷ CFU/ml, which was similar to that of the dot blotting test using each MAb. The detection sensitivity could be improved to 10³ or 10 or 1 CFU/ml of original bacterial content after preincubation of the sample in alkaline peptone water for 6, 12, and 24 hr consecutively. However, the detection sensitivities were also dependent on the content of other bacteria in the sample that might compete or inhibit the growth of V. cholerae during the preenrichment step. Due to its broad specificity, simplicity and rapid result generation, the VCG strip test can be used for the preliminary detection of V. cholerae at point of care for both environmental and clinical strains to assist appropriate decision or epidemiological surveillance of virulent V. cholerae strains (including NVC strains), which are ubiquitous in the environment and seafood.     

Food properties of egg white protein modified by rare ketohexoses through Maillard reaction

d ‐psicose (Psi), a rare ketohexose, improves food properties of proteins through the Maillard reaction (MR) much more than d ‐fructose (Fru). This encouraged us to investigate the improvement of food properties of proteins through MR with various rare ketohexoses (d ‐psicose, Psi; d ‐tagatose, Tag; and d ‐sorbose, Sor). The food properties of egg white protein (EWP) after reaction with Psi, Tag, Sor and Fru were studied. Psi‐EWP (43.3 μmol TE g^?1) and Tag‐EWP (43.4 μmol TE g^?1) had the highest antioxidant activity, followed by Sor‐EWP (38.4 μmol TE g^?1) and Fru‐EWP (38.9 μmol TE g^?1). MR enhanced the breaking stress of heat‐induced EWP gels by 224–267%. The breaking stress was higher in Psi‐EWP (81.1 kN m^?2), Tag‐EWP (80.0 kN m^?2) and Sor‐EWP (77.8 kN m^?2) than in Fru‐EWP (71.6 kN m^?2). Furthermore, the foaming capacity was highest in Psi‐EWP and Sor‐EWP. Rare ketohexoses improved food properties of EWP more than Fru. Overall, Psi offered the greatest functional improvement.     

Effect of d‐Psicose Used as Sucrose Replacer on the Characteristics of Meringue

Excessive intake of sugar‐rich foods leads to metabolic syndrome. d ‐Psicose (Psi) not commonly found in nature, is noncalorie sweetener with a suppressive effect on the blood glucose level. Thus, Psi has the potential to be utilized as a sucrose (Suc) replacer in sugar‐rich foods, including meringue‐based confectionery (MBC). In this study, we investigated the effect of Psi on the physical and chemical properties of meringue. Meringue was made by whipping egg white and Suc (at a weight ratio of 1:1) and baking at 93 °C for 2 h. Thirty percent of the total weight of Suc was replaced with d ‐ketohexoses such as Psi, d ‐fructose, d ‐tagatose, and d ‐sorbose. The meringues containing d ‐ketohexoses had higher specific volume than the meringue not containing d ‐ketohexoses (Ct‐meringue). Baking of meringue caused differences between Psi and the other d ‐ketohexose meringues. Meringue containing Psi (P30‐meringue) had the highest breaking stress (7.00 × 10⁵ N/m²) and breaking strain (4.40%), resulting in the crunchiest texture. In addition, P30‐meringue also had the highest antioxidant activity (491.84 μM TE/mg‐meringue determined by ABTS method) and was the brownest due to a Maillard reaction occurring during baking. The replacement of Suc with Psi improved the characteristics of baked meringue. Thus, Psi was found to be useful in modifying the physical and chemical properties of MBC.