A systematic study on the use of ultrasound energy for the synthesis of nickel-metal organic framework compounds.

A nickel metal-organic framework (Ni-MOF) was successfully synthesized using ultrasound irradiation. Further to this, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and nitrogen adsorption [i.e. Brunauer-Emmett-Teller (BET) Surface Area Analysis] techniques were used to characterize the synthesized Ni-MOF. In addition, the effect of sonication on the surface area, pore diameter and pore volume of the final product was systematically studied using Taguchi technique. The experiments ascertained that manufacturing of the Ni-MOF by means of the ultrasonic-assisted technique is feasible at a relatively shorter time compare to the conventional methods. The final product showed more uniform shape distribution and improved BET properties. The obtained results offered that the synthesized Ni-MOF samples could be used in several applications.

Respiratory diseases in agate grinding workers in Iran.

BACKGROUND: Agate is a hard silica stone with bands of various colors, which is used in jewelry. The agate grinding workers are exposed to silica dust. OBJECTIVE: To determine the prevalence of respiratory diseases in agate grinding workers and the associated factors. METHODS: In this cross-sectional study, 170 agate grinding workers from Mashhad, northeastern Iran, were examined. Medical and occupational history for respiratory illnesses was taken using respiratory questionnaire of the national program of silicosis control, lung examination, spirometry and chest radiography. Chest x-rays were interpreted according to the International Labor Office (ILO) classification system, 2000. RESULTS: The mean±SD of age and work duration of the participants were 31.2±10.1 and 13±8.2 years, respectively. The prevalence of silicosis among agate workers was 12.9% (95% CI: 7.9%-18.0%); 18 workers had simple and 4 had complicated silicosis. There was a significant (p<0.05) relationship between contracting silicosis and exposure duration. 20 (11.7%) workers had symptoms consistent with chronic bronchitis and 8 (4.7%) showed asthma and asthma-like symptoms. The most frequent disorder observed in spirometry was the restrictive pattern (n=43, 30%). In the agate grinders, clinical and spirometry findings did not match with radiological findings. CONCLUSION: Agate grinding workers are at increased risk for respiratory diseases, specifically for silicosis and chronic bronchitis. The disease is related to silica dust exposure, poor ventilation and inappropriate personal protection.

The use of carbon nanotubes to reinforce 45S5 bioglass-based scaffolds for tissue engineering applications.

Bioglass has been used for bone-filling material in bone tissue engineering, but its lean mechanical strength limits its applications in load-bearing positions. Carbon nanotubes (CNTs), with their high aspect ratio and excellent mechanical properties, have the potential to strengthen and toughen bioactive glass material without offsetting its bioactivity. Therefore, in this research, multiwall carbon nanotube (MWCNT)/45S5 Bioglass composite scaffolds have been successfully prepared by means of freeze casting process. 45S5 Bioglass was synthesized by the sol-gel processing method. The obtained material was characterized with X-ray powder diffraction (XRD). The mechanical properties of the scaffolds, such as compression strength and elastic modulus, were measured. Finally, compared with the scaffolds prepared by 100% 45S5 Bioglass powders, the addition of 0.25 wt.% MWCNTs increases the compressive strength and elastic modulus of 45S5 Bioglass scaffolds from 2.08 to 4.56 MPa (a 119% increase) and 111.50 to 266.59 MPa (a 139% increase), respectively.