Preparation of hierarchical mesoporous CaCO3 by a facile binary solvent approach as anticancer drug carrier for etoposide

To develop a nontoxic system for targeting therapy, a new highly ordered hierarchical mesoporous calcium carbonate nanospheres (CCNSs) as small drug carriers has been synthesized by a mild and facile binary solvent approach under the normal temperature and pressure. The hierarchical structure by multistage self-assembled strategy was confirmed by TEM and SEM, and a possible formation process was proposed. Due to the large fraction of voids inside the nanospheres which provides space for physical absorption, the CCNSs can stably encapsulate the anticancer drug etoposide with the drug loading efficiency as high as 39.7 wt.%, and etoposide-loaded CCNS (ECCNS) nanoparticles can dispersed well in the cell culture. Besides, the drug release behavior investigated at three different pH values showed that the release of etoposide from CCNSs was pH-sensitive. MTT assay showed that compared with free etoposide, ECCNSs exhibited a higher cell inhibition ratio against SGC-7901 cells and also decreased the toxicity of etoposide to HEK 293 T cells. The CLSM image showed that ECCNSs exhibited a high efficiency of intracellular delivery, especially in nuclear invasion. The apoptosis test revealed that etoposide entrapped in CCNSs could enhance the delivery efficiencies of drug to achieve an improved inhibition effect on cell growth. These results clearly implied that the CCNSs are a promising drug delivery system for etoposide in cancer therapy.     

Separation of copper from cobalt in sulphate solutions by using CaCO3

Lime neutralization is widely used to precipitate heavy metals including copper and cobalt from wastewater. Limestone (calcium carbonate: CaCO₃) is too stable to be used directly for this purpose. Grinding of CaCO₃ in the solutions of copper and cobalt sulphate was conducted to raise its reactivity. During the mechanochemical activation, CaCO₃ reacted with copper sulphate but not significantly with cobalt sulphate and this phenomenon allowed an easy separation of copper from cobalt. The residual of Cu(II) ions in solution could be controlled at less than 0.1%, meanwhile more than 90% of the Co(II) ions remained in aqueous solution.     

Optimization of Synthesis Parameters for Mesoporous Shell Formation on Magnetic Nanocores and Their Application as Nanocarriers for Docetaxel Cancer Drug

In this work, Fe₃O₄@SiO₂ nanoparticles were coated with mesoporous silica shell by S⁻N⁺I⁻ pathway by using anionic surfactant (S⁻) and co-structure directing agent (N⁺). The role of co-structure directing agent (CSDA) is to assist the electrostatic interaction between negatively charged silica layers and the negatively charged surfactant molecules. Prior to the mesoporous shell formation step, magnetic cores were coated with a dense silica layer to prevent iron oxide cores from leaching into the mother system under any acidic circumstances. However, it was found that both dense and mesoporous coating parameters affect the textural properties of the produced mesoporous silica shell (i.e., surface area, pore volume and shell thickness). The synthesized Fe₃O₄@SiO₂@m-SiO₂ (MCMSS) nanoparticles have been characterized by low-angle X-ray diffraction, transmission electron microscopy (TEM), and N₂ adsorption-desorption analysis, and magnetic properties. The synthesized particles had dense and mesoporous silica shells of 8–37 nm and 26–50 nm, respectively. Furthermore, MCMSS possessed surface area of ca. 259–621 m²·g⁻¹, and pore volume of ca. 0.216–0.443 cc·g⁻¹. MCMSS showed docetaxcel cancer drug storage capacity of 25–33 w/w% and possessed control release from their mesochannels which suggest them as proper nanocarriers for docetaxcel molecules.     

Studies of Thermal Conductivity of Nano CaCO3/HIPS Composites by Unsteady State Technique and Simulation with Nielsen's Model

Differential scanning calorimeter (DSC) and thermal conductivity meter were used for measurement of thermal conductivity by unsteady state technique of the high impact polystyrene (HIPS) composites filled with 0.5, 1.5, and 2.5 wt.% of CaCO₃ nano particles. A comparison of experimental and theoretical values of (K _c /K _m) was done using MATLAB software fitting in Nielsen's model of thermal conductivity for polymers containing low limit of volume fraction. The packing fraction (Φ _max) and geometry and orientation dependent parameter (A) of the nanofiller were assumed as 0.10 and 100, respectively, which are most fitted for this model. The effect of nanosize on thermal conductivity was well predicted by plotting different values of thermal conductivity at various source temperatures. The violation of the theoretical values because of local molecular vibration at higher temperature is highlighted promisingly in the plots.     

Studies on Structure and Properties of HDPE Functionalized Through Ultraviolet Irradiation and Its Blends with CaCO3

Abstract

The structure and properties of high-density polyethylene (HDPE) functionalized through ultraviolet irradiation in air and its blends with CaCO₃ were studied by Fourier transfer infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), contact angle measurement, Molau test, and mechanical properties test. The experimental results reveals that oxygen-containing groups such as C = O and C - O were introduced onto the molecular chains of HDPE through ultraviolet irradiation in air, and the groups' concentration increases with irradiation time. After irradiation, the water contact angle of HDPE becomes smaller, showing that the hydrophilicity of irradiated HDPE increases. Compared with those of HDPE/CaCO₃ blend, the dispersion of CaCO₃ particles in irradiated HDPE/CaCO₃ blend, the interface interaction between CaCO₃ particles and irradiated HDPE matrix, and the mechanical properties of irradiated HDPE/CaCO₃ blend are improved due to the introduction of polar groups.     

Studies on scaling of membranes in desalination by direct contact membrane distillation: CaCO3 and mixed CaCO3/CaSO4 systems

Scaling of membranes by CaCO₃ and CaSO₄-CaCO₃ is of considerable concern in membrane desalination processes. It is particularly relevant for porous crossflow hollow fiber-based membrane distillation (MD) processes which can achieve high water recovery and can encounter heavy precipitation of scaling salts. Therefore an analysis of the scaling potential for CaCO₃ and mixed CaSO₄-CaCO₃ systems is presented first in terms of the saturation index profiles throughout the crossflow hollow fiber membrane module as a function of the location in the module for feed solutions resulting from high water recovery. Scaling experiments during DCMD with tap water, CaCO₃ and mixed CaSO₄/CaCO₃ were conducted over a wide range of values of saturation index (SI) (10<SI_calcite<64, 1.1<SI_Gypsum<1.5) using porous fluorosilicone coated crossflow hollow fiber membrane desalination modules. The effects of flow rates, flow patterns (cross vs. parallel flow) and the nature of the membrane surface on possible scaling scenarios were further investigated for the scaling salt CaSO₄. Experimental results at high saturation indices show that even when the precipitation rate was fast in the CaCO₃ system at elevated temperatures or high concentrations, no significant loss in water vapor permeation was observed suggesting no effect of scaling on membrane flux. However, for a few of the mixed CaSO₄-CaCO₃ systems, the water vapor flux dropped somewhat. Possible explanations have been provided and a method to solve this problem has been illustrated. Fast feed flow rate resulted in a shortened induction period. Crossflow flow pattern and the nature of the hydrophobic porous coating on the membrane surface were proven to be helpful in developing the resistance to scaling. Results of modeling show that concentration polarization effects are far more important than temperature polarization effects.     

Fabrication and characterization of WO3 flocky microspheres induced by ethanol

The novel tungsten trioxide flocky microspheres induced by ethanol were successfully obtained via a simple and convenient hydrothermal route. The as-prepared products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, BET surface area measurement and UV-Vis diffuse reflectance spectroscopy. WO₃ powder prepared with volume ratio (v_ethanol/v_water) of 40% revealed a complete flocky microsphere structure with particle size of 3.0-4.0 μm and exhibited good photochromic property. The possible formation mechanism of the flocky microspheres was proposed and the improved photochromic properties were also investigated.     

Effects of grinding and firing conditions on CaAl2Si2O8 phase formation by solid-state reaction of kaolinite with CaCO3

The effects of grinding and firing conditions on CaAl₂Si₂O₈ phase formation by solid-state reaction of kaolinite with CaCO₃ were investigated by differential thermal analysis (DTA)–thermogravimetry (TG), X-ray powder diffraction (XRD) and ²⁹Si and ²⁷Al MAS NMR. Unground and ground samples showed similar crystallization behavior at about 850 °C, and the crystallizing temperature was relatively unaffected by grinding. On the other hand, the crystalline products were strongly influenced by the grinding. Gehlenite (Ca₂Al₂SiO₇) was the dominant phase in the unground samples but layer-structured CaAl₂Si₂O₈ was dominant in the ground samples, together with a small amount of anorthite, which is the stable phase. The amount of anorthite gradually increased with higher firing temperature, the sample fired at 1000 °C being almost completely anorthite. Grinding treatment before firing was effective in accelerating the decomposition of CaCO₃ and extending the temperature range for the formation of CaAl₂Si₂O₈, a phase with local structure similar to that of layered CaAl₂Si₂O₈.     

TiN/Si3N4复合材料的磁控溅射制备及其电性能研究

利用直流反应磁控溅射法在Si3N4陶瓷基体上制备了TiN导电薄膜。采用X射线衍射仪(XRD)、扫描电镜(SEM)和电子能谱(EDS)对薄膜的物相组成以及表面形貌进行分析,表明TiN薄膜均匀,且与基体有较强的附着力。采用SZ82型四探针测试仪对薄膜进行了方阻随厚度变化的分析,表明薄膜的厚度对薄膜的电性能有很大的影响。     

Ultrasound and water-mediated synthesis of bis-thiazoles catalyzed by Fe(SD)3 as Lewis acid-surfactant-combined catalyst

Preparation of bis-aminothiazoles under different conditions including synthesis in EtOH under ultrasound irradiation and also in water in the presence of Fe(SD)₃ as Lewis acid-surfactant-combined catalyst (LASC) under ultrasound irradiation has been studied. The results were compared with the traditional reflux method. Also, the results confirmed the efficiency of the synthesis in water and under ultrasound irradiation technique. Moreover, the antibacterial activity of products was investigated using the well-diffusion method against bacterial strains including Micrococcus luteus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis. All of the products showed good antibacterial activity against M. luteus and E. coli. Most of the products showed antibacterial activity higher than erythromycin against M. luteus, E. coli, and B. subtilis.     

The Preparation of Molybdenum Oxynitride by Hydrazine Reduction of MoO3 at Moderate Temperature and Its Application in the Selective Hydrogenation of Long-Chain Linear Alkadienes

Molybdenum oxynitride was prepared by hydrazine reduction of MoO₃ at moderate temperatures. The anhydrous condition was favorable to production of amorphous molybdenum oxynitride, and the presence of hydrogen favored the reduction of Mo⁶⁺ and Mo⁴⁺ species to Mo ⁺ (0 < < 4) species. These molybdenum oxynitrides exhibited activity for hydrogenation which depended on the amount of Mo ⁺ (0 < < 4) species produced under reaction conditions. The amorphous molybdenum oxynitride MoO_1.83N_0.36 catalyst showed a good catalytic activity, selectivity, and resistance to poisoning of H₂S for liquid-phase hydrogenation of longer-chain alkadienes.     

Acidity of sulfated zirconia as studied by FTIR spectroscopy of adsorbed CO and NH3 as probe molecules

The acid properties of pure and sulfated zirconias were studied by FTIR spectroscopy of adsorbed CO and NH₃ as probe molecules. Whereas pure monoclinic zirconia shows only Lewis acidity, sulfation of tetragonal and monoclinic zirconia creates new bridging OH groups. Two types of Brønsted-acidic centers and two types of Lewis-acidic centers with enhanced acid strength were identified. A communication between the different types of Lewis-acidic sites and the related adsorbed sulfate molecules could be shown. The coordination of basic molecules such as CO onto Lewis-acid sites induces a decrease of the intrinsic Brønsted-acidity of the bridging OH groups. These effects are discussed on the basis of a model of the acidic centers that was previously proposed.On leave from Department of Chemistry, Faculty of Science, Minia University, El-Minia, Egypt.