Synthesis,characterization, photocatalytic evaluation,and toxicity studies of TiO2–Fe3+ nanocatalyst

Based on our previous work on the green preparation of Ag–TiO₂ photocatalyst with bactericidal activity under visible light, we extended our studies to the synthesis of TiO₂–Fe³⁺ materials with enhanced photocatalytic activity for the degradation of recalcitrant organic pollutants in water. TiO₂–Fe³⁺ nanopowders were synthesized using a robust, environmentally friendly procedure. Established amounts of Fe(NO₃)₃·9H₂O and titanium tetraisopropoxide (TTIP) were mixed using glacial acetic acid as solvent. Hydrolysis of TTIP–Fe³⁺ was accomplished using a 30 % (W/V) Arabic gum aqueous solution. TiO₂–Fe³⁺ nanopowders were obtained by thermal treatment at 400 °C. In order to elucidate the structure of these photocatalysts, microscopic and spectroscopic characterization techniques were applied. The high resolution transmission electron microscopy (HRTEM) analysis indicated the presence of uniformly distributed particles with average particle size of about 9 nm. According to the HRTEM lattice fringes, ring pattern, and selected area electron diffraction pattern, the crystalline part of the samples consists of anatase (PDF 01-086-1157 with the lattice constant of 3.7852, 9.5139 Å and 90°) as dominant phase. X-ray photoelectron spectroscopy (XPS) was applied to determine the oxidation state of iron. The XPS provides evidence for Fe³⁺ surface species in the TiO₂–Fe³⁺ composite. Complete degradation of aqueous solutions (20 ppm) of methylene blue and/or methyl orange was accomplished after 4 h of treatment using 150 mg of TiO₂–Fe³⁺/150 mL of dye solution. The in vitro toxicity of the materials was tested. The materials showed no toxicity against human red blood cells.     

Schiff base-assisted surface patterning of polylactide–zinc oxide films: generation,characterization and biocompatibility evaluation

A novel route for obtaining ordered microporous polylactide films has been explored using zinc oxide and a Schiff base. The SEM images reveal that the water vapor condensation near the surface of a polylactide solution containing a synthesized Schiff base and zinc oxide results in well-dispersed water droplets, which upon subsequent evaporation can assist breath figure patterning. The generation of ordered micropores at the film surface is attributed to the interaction between the surface +ve charge of well-dispersed zinc oxide particles and the δ-bearing water droplets from moisture. The potential for biocompatible applications has been revealed for the membranes by the cell viability assay against mice fibroblast (L929) cells and the hemocompatibility assay. The findings suggest an efficient route for the development of porous biodegradable polylactide membranes for various applications, typically for wound dressing.     

Preparation,characterization, biological activity,and transport study of polystyrene based calcium–barium phosphate composite membrane

Calcium–barium phosphate (CBP) composite membrane with 25% polystyrene was prepared by co-precipitation method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and Thermogravimetric analysis (TGA) were used to characterize the membrane. The membrane was found to be crystalline in nature with consistent arrangement of particles and no indication of visible cracks. The electrical potentials measured across the composite membrane in contact with univalent electrolytes (KCl, NaCl and LiCl), have been found to increase with decrease in concentrations. Thus the membrane was found to be cation-selective. Transport properties of developed membranes may be utilized for the efficient desalination of saline water and more importantly demineralization process. The antibacterial study of this composite membrane shows good results for killing the disease causing bacteria along with waste water treatment.     

Thermal expansion and theoretical density of 2,2′,4,4′,6,6′-hexanitrostilbene

The linear coefficient of thermal expansion (CTE) and the theoretical density are important for energetic materials. To obtain the CTE and theoretical density of 2,2′,4,4′,6,6′-hexanitrostilbene (HNS), X-ray powder diffraction (XRD) together with Rietveld refinement was employed to estimate the dimension and density change at a crystal lattice level, in the range of temperature 30–240 °C. The CTE of a-, b-, c-axis and volume were obtained as 7.6719 × 10⁻⁵/°C, 6.8044 × 10⁻⁵/°C, 1.1192 × 10⁻⁵/°C and 16.725 × 10⁻⁵/°C, respectively. Also, the possible reasons for the expansion property of HNS have been discussed by comparing its structure with 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Based on the refined lattice parameters, the theoretical densities of HNS at various temperatures were obtained. By extrapolation of linear fitting the theoretical density of HNS at 20 °C was gotten as 1.7453 g/cm³. Furthermore, a good thermal resilience of HNS has also been observed when the temperature returned from 240 to 30 °C.     

Synthesis of β-cyclodextrin hydrogel nanoparticles for improving the solubility of dexibuprofen: characterization and toxicity evaluation

Objective: This study was aimed to enhance aqueous solubility of dexibuprofen through designing β-cyclodextrin (βCD) hydrogel nanoparticles and to evaluate toxicological potential through acute toxicity studies in rats.

Significance: Dexibuprofen is a non-steroidal analgesic and anti-inflammatory drug that is one of safest over the counter medications. However, its clinical effectiveness is hampered due to poor aqueous solubility.

Methods: βCD hydrogel nanoparticles were prepared and characterized by percent yield, drug loading, solubilization efficiency, FTIR, XRD, DSC, FESEM and in-vitro dissolution studies. Acute oral toxicity study was conducted to assess safety of oral administration of prepared βCD hydrogel nanoparticles.

Results: βCD hydrogel nanoparticles dramatically enhanced the drug loading and solubilization efficiency of dexibuprofen in aqueous media. FTIR, TGA and DSC studies confirmed the formation of new and a stable nano-polymeric network and interactions of dexibuprofen with these nanoparticles. Resulting nanoparticles were highly porous with 287?nm in size. XRD analysis revealed pronounced reduction in crystalline nature of dexibuprofen within nanoparticles. Release of dexibuprofen in βCD hydrogel nanoparticles was significantly higher compared with dexibuprofen tablet at pH 1.2 and 6.8. In acute toxicity studies, no significant changes in behavioral, physiological, biochemical or histopathologic parameters of animals were observed.

Conclusions: The efficient preparation, high solubility, excellent physicochemical characteristics, improved dissolution and non-toxic βCD hydrogel nanoparticles may be a promising approach for oral delivery of lipophilic drugs.     

Safety evaluation of nanodiamond-doxorubicin complexes in a Na?ve Beagle canine model using hematologic,histological,and urine analysis

While doxorubicin(DOX)is one of the most common chemotherapeutic drugs for treating cancer,use of DOX must be managed carefully due to dose-related toxicity.Nan...     

A fuzzy AHP evaluation model for buyer–supplier relationships with the consideration of benefits,opportunities, costs and risks

With increasingly fierce global competition, firms in various industries need to build a cooperative buyer–supplier relationship to survive and to acquire reasonable profit. Even though the literature on various types of collaboration between firms is abundant and the works on supplier selection models are numerous, the research that provides a mathematical model for the selection of the most appropriate form of buyer–supplier relationship is very limited. Existing buyer–supplier evaluation models usually only consider the benefits from the relationship, but not the opportunities, costs and risks that may need to be confronted. The main objective of this study is to propose an analytical approach to evaluate the forms of buyer–supplier relationship between a manufacturer and its supplier. A fuzzy analytic hierarchy process (AHP) model, which applies fuzzy set theory and the benefits, opportunities, costs and risks (BOCR) concept, is constructed to deal with uncertainty and to consider various aspects of alternatives. Multiple factors that affect the success of the relationship are analysed by incorporating experts’ opinions on their priority of importance, and a performance ranking of the buyer–supplier forms is obtained. A case study of selecting the most appropriate buyer–supplier form between a TFT-LCD manufacturer and its colour filter supplier is presented, and the proposed model is applied to facilitate the decision process. The proposed model is a general form that can be tailored and applied by firms that are making decisions on buyer–supplier relationship.     

Synthesis and study of complexes of Pu(V) and Np(V) propionates with α,α′-bipyridine

New complexes of Np(V) and Pu(V) with α,α′-bipyridine of the composition AnO₂(bipy) · OOCC₂H₅·H₂O (An = Np, Pu) were synthesized. They are isostructural to each other; however, they differ essentially in the structure and characteristics from the similar complexes of An(V) formates and acetates. The new compounds were characterized by powder X-ray diffraction, thermal analysis, electronic absorption spectroscopy, and IR spectroscopy.     

Synthesis, characterization and hydrolytic degradation study of polyetheresteramide copolymers based on ε-caprolactone, 6-aminocaproic acid, and poly(ethylene glycol)

In this paper, a new kind of biodegradable aliphatic polyetheresteramide copolymers (PEEA) based on -caprolactone, 6-aminocaproic acid, and poly(ethylene glycol) (PEG) were synthesized by melt polymerization method. The obtained copolymers were characterized by ¹H-NMR. The thermal properties of PEEA copolymers were studied by DSC and TGA/DTA under nitrogen atmosphere. The water absorption and hydrolytic degradation behavior was also studied in detail. With the increase in PEG content or the decrease in caprolactone content, the water absorption of the copolymers increased accordingly. For the hydrolytic degradation behavior, with the increase in PEG content or caprolactone content, the degradation rate increased then.     

Synthesis,characterization r）oly [LA-co-（GIc-alt-Lys）] for and biological evaluation of nerve regeneration scaffold

A novel nerve repairing material poly [LA-co.（GIc-alt-Lys）] （PLGL） was synthesized. The viability and growth of Schwann cells （SCs） co-cultured With poly （D, L- lactic acid） （PDLLA） films （control group） and PLGL films were evaluated by MTT assay and SEM observation. Then, contact angle measurement, histological assessment and enzyme-linked immunosorbent assay （ELISA） testing on inflammatory-related cyto- kines such as IL-10 and TGF-β1 were performed. The results showed that, compared with PDLLA, PLGL films possesses better hydrophilicity, biocompatibility, degradation property and less inflammatory reaction. The present study indicated that PLGL scaffolds would meet the requirements of artificial nerve scaffold and have a potential application in the fields of nerve regeneration.     

Size-controlled model Co nanoparticle catalysts for CO₂ hydrogenation: synthesis, characterization, and catalytic reactions

Model cobalt catalysts for CO(2) hydrogenation were prepared using colloidal chemistry. The turnover frequency at 6 bar and at 200-300 °C increased with cobalt nanoparticle size from 3 to 10 nm. It was demonstrated that near monodisperse nanoparticles in the size range of 3-10 nm could be generated without using trioctylphosphine oxide, a capping ligand that we demonstrate results in phosphorus being present on the metal surface and poisoning catalyst activity in our application.     

Electrochemical,optical, and magnetic properties of Ni x InSe (0 < x ≤ 1) intercalation compounds

We have studied the electrochemical, optical, and magnetic properties of nickel-intercalated InSe single crystals. The energy position of the excitonic maximum and the full width at half maximum of the excitonic band in the Ni _x InSe intercalation compounds have been shown to be nonmonotonic functions of nickel concentration. Nickel-intercalated InSe possesses ferromagnetic properties: the dependence of its magnetic moment on magnetic field has the form of a hysteresis loop, characteristic of hard-magnetic ferromagnets.     

Structural disorder of ball-milled,nanosized, Fe-doped SnO<Subscript>2</Subscript>: X-ray diffraction and Mössbauer spectroscopy characterization

Structural characterization of nanosized Fe-doped semiconducting oxide SnO₂ is reported. Samples of Sn_1?x Fe _x O_2?y (with x ranging from 0.11 to 0.33) were processed in a planetary ball mill, subsequently HCl-washed to eliminate metallic iron impurities introduced by the milling tools, and characterized by X-ray diffraction and Mössbauer spectroscopy. Results showed that Fe enters the host matrix randomly replacing Sn in octahedral sites regardless of iron concentration. It has been found the presence of oxygen deficient iron sites attributed to the stoichiometric unbalance of precursor materials used in the milling process. It is known that structural features like particle size and residual microstrain are highly affected by the milling process. Values of average particle sizes as calculated by Scherrer’s method alone decreased with increasing Fe concentration. This result was shown, by means of the Williamson-Hall correction method, to be misleading as a large degree of microstrain is expected for mechanically milled powders. In fact, corrected values of average particle sizes turned out to be reasonably homogeneous regardless of iron content and milling time with no consistent trend. Residual microstrain, on the other hand, was found to increase with iron content giving way to the conclusion that broadening of diffraction peaks are mostly due to increasing microstrain as a function of iron doping and milling time. Williamson-Hall analysis also showed a large degree of particle size inhomogeneity. Milling of undoped SnO₂ showed that this inhomogeneity is due mostly to doping as opposed to milling.     

A calorimetric study of S′ and θ′ precipitation in Al2O3 particle-reinforced AA2618

Differential scanning calorimetry (DSC) was used to study the kinetics of S and precipitation in AA2618 and its composite containing 15 vol % Al₂O₃ particles . The unreinforced alloy and the composite were fabricated by a proprietary casting method, followed by extrusion. The DSC studies were carried out on as-quenched samples of the test materials. The precipitation of the S and phases in both materials was found to be kinetically controlled and obey the modified Avrami-Johnson-Mehl equation. The growth mechanisms for S and formation in AA2618 seemed unaffected by the addition of Al₂O₃ particles. The growth parameters obtained for the precipitation of these phases in the matrix alloy and the composite were not significantly different.     

Comparative study of synthesis and characterization of Pr ：YAG nanoparticles using different precipitator by co-precipitation method

分别采用碳酸氢铵和尿素为沉淀剂用沉淀法制备了Pr掺杂的YAG纳米粉体。并利用XRD、FT-IR、TEM等方法对样品进行了成分、粒度和形貌等性能分析,讨论了不同沉淀剂的反应机理。结果表明,碳酸氢铵沉淀法能够在较低温度下制备颗粒均匀、分散性良好的YAG纳米粉体;而尿素沉淀法所制备的粉体需要较高的煅烧温度,粉体粒径大、团聚较为严重。此外,Pr∶YAG纳米粉体的荧光强度随粉体粒径的增大而加强。     

A study of the geogrid–subballast interface via experimental evaluation and discrete element modelling

This paper presents a study of the interface of geogrid reinforced subballast through a series of large-scale direct shear tests and discrete element modelling. Direct shear tests were carried out for subballast with and without geogrid inclusions under varying normal stresses of \(\sigma _n =6.7\) to \(45\hbox { kPa}\). Numerical modelling with three-dimensional discrete element method (DEM) was used to study the shear behaviour of the interface of subballast reinforced by geogrids. In this study, groups of 25–50 spherical balls are clumped together in appropriate sizes to simulate angular subballast grains, while the geogrid is modelled by bonding small spheres together to form the desired grid geometry and apertures. The calculated results of the shear stress ratio versus shear strain show a good agreement with the experimental data, indicating that the DEM model can capture the interface behaviour of subballast reinforced by geogrids. A micromechanical analysis has also been carried out to examine how the contact force distributions and fabric anisotropy evolve during shearing. This study shows that the shear strength of the interface is governed by the geogrid characteristics (i.e. their geometry and opening apertures). Of the three types of geogrid tested, triaxial geogrid (triangular apertures) exhibits higher interface shear strength than the biaxial geogrids; and this is believed due to multi-directional load distribution of the triaxial geogrid.     

X-ray and thermochemical studies of phase transitions in crystalline host–guest compounds of 1,1′–binaphthyl–2,2′–dicarboxylic acid with ethanol and acetone

The crystal structures of two 1:2 and 1:1 host–guest compounds between BNDA and acetone have been determined by single crystal X-ray diffraction and are comparatively discussed with reference to recently reported BNDA/ethanol clathrates of different composition. Simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC) in combination with the X-ray powder diffraction (XRD) method reveal that the thermal degradation of the BNDA/ethanol 1:2 α–form clathrate takes place in two steps with the intermediate formation of the 2:1 β–form clathrate. On the other hand, desolvation of the BNDA/acetone 1:2 α–form clathrate gives no indication for the formation of any intermediate phase in the TG–DSC traces unlike the XRD studies showing the existence of the β–form during desolvation. A possible explanation of this latter property is the very similar thermal decomposition temperature of both phases. The TG–DSC results for the isothermal inclusion of vaporous ethanol and acetone indicate that this process takes place in a single step with the formation of the 1:2 BNDA/ethanol and 1:1 BNDA/acetone clathrates, respectively.     

Synthesis and characterization of sol–gel derived (Ba,Ca)(Ti,Zr)O<Subscript>3</Subscript> nanoparticles

A citrate precursor method was employed to synthesize lead-free perovskite 0.5Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ (BZT-0.5BCT) crystallites. Powders and gels were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, thermal analysis and transmission electron microscopy. It was indicated that BZT-0.5BCT transparent gel can be obtained via the chelation of citric acid with metal ions. Gels transformed into crystalline powders with single-phase perovskite structure when heat-treated above 650 °C, significantly lower than that in a solid-state reaction method. The primary particle size of the powders increased from 30 to 60 nm as the decomposition temperature was raised from 600 to 750 °C.     

Electrochemical DNA analysis with a supramolecular assembly of naphthalene diimide, ferrocene, and β-cyclodextrin

Naphthalene diimide 1 bearing ferrocene and β-cyclodextrin (β-CD) was prepared. Its half-wave potential at 420 mV shifted 40-50 mV upon addition of an excess of adamantylamine, suggesting that the ferrocene of 1 is included in the cavity of β-CD intramolecularly to form a pseudocyclic structure. This unique architecture is retained even where 1 is bound to calf thymus DNA to give rise to a catenane-like structure. Morphology of the DNA complex with 1 was further explored by atomic force microscopy to reveal that the DNA strand tends to bend as the amount of 1 on it increases. Presumably, intermolecular, yet intrastrand, inclusion of ferrocene into β-CD is responsible for this phenomenon. The resulting globular structure reverted partially by the addition of adamantylamine. At a low ratio of 1 to DNA, a novel reduction peak appeared at 320 mV in the differential pulse voltammograms of 1 at the expense of the 420 mV peak. The peak current of the former was proportional to the DNA concentration, thereby enabling quantitation of DNA in a signal-on way. Likewise, a polymerase chain reaction (PCR) product of 754 bp was analyzed successfully with a detection limit of 13 nM.