Narrow Results

The gold nanoparticles (Au NPs) are always recognized as vital and important for human life from the ancient era. But it is very difficult to synthesize the Au NPs in the oxidizing atmosphere for the intended purpose. The innovative flame reduction method utilizing the N, N-Dimethylformamide (DMF) as a solvent was successfully used for the synthesis of precious metal Au NPs. The synthesized Au NPs are bare, so they can be directly used without any further processing as catalyst materials. The Au NPs were synthesized by burning their salt in DMF as solvent and fuel using a simple lamp. The prepared nanoparticles were found readily dispersible in water and DMF giving stable sols. In this paper, we report the synthesis of bare metal nanoparticles using the flame reduction method for the first time. The prepared NPs were collected on the glass surface and used for routine characterization techniques viz., UV-Visible, XRD, HR-TEM and electron diffraction. The Au NPs were 15nm in size and showed characteristic absorption peak at 550nm. The characteristic peaks observed in XRD of synthesized nanoparticles demonstrated the cubic phase of Au NPs. The formation mechanism of the prepared nanoparticles in open-air flame synthesis has been discussed in detail in this paper.

Nanocrystalline cerium oxide (CeO₂) particles prepared by the novel two-stage precipitation method were used for the catalysis of CO oxidation. Firstly, two shapes, i.e. particulate (P-) and needle-like (N-), CeO₂ nanoparticles were formed via proposed temperature-arranged routes. The crystalline structure, morphology, particle size, and surface area of samples were characterized by using XRD, TEM, HRTEM, and BET techniques. Furthermore, the morphological effect of the CeO₂ samples on the catalytic activity of CO oxidation was investigated. From the experimental results, it indicated that the prepared samples were all nonporous and fcc-structured CeO₂. The CeO₂ particles, as precipitating at 90°C for 5 min and then aging at 90°C, were particulate, whereas they were needle-like by aging at 0°C. The CO oxidation reaction showed that the catalytic activity of N-CeO₂ nanoparticles was higher than that of P-CeO₂, attributing from the exposed higher-energy {100} and {110} facets for N-CeO₂ nanoparticles. Moreover, the calcined samples with higher degree of crystallinity showed further promotion in catalytic activity. It was also worthy to note, that by replacing the CeO₂ catalyst by Pd/CeO₂, a large increase in the CO conversion was found, especially catalyzed by Pd/N-CeO₂.

SINGAPORE – Human Heart Tissue Grown from Stem Cells Improves Drug Testing.

UNITED STATES – Bioengineered Human Livers Mimic Natural Development.

UNITED STATES – New Cellular Target May Put the Brakes on Cancer’s Ability to Spread.

UNITED STATES – Does Consuming Low-Fat Dairy Increase the Risk of Parkinson’s Disease?

UNITED STATES – Memory Loss and Other Cognitive Decline Linked to Blood Vessel Disease in the Brain.

AUSTRALIA – Fabricating High Performance Nanohybrid Catalysts.

TAIWAN – US FDA Approves Zhaohe Cao-based Botanical Drug as an Investigational New Drug for Cancer Therapy.

KOREA – Distinguished Professor Sang Yup Lee Elected to the NAS.

Fe(II) pyridinebisimine complexes activated with trialkylaluminium or modified methylaluminoxane (MMAO) as catalysts were employed for the polymerization of butyl methacrylate (BMA). Polymer yields, catalytic activities and molecular weights as well as molecular weight distributions of BMA can be controlled over a wide range by varying the reaction parameters such as cocatalyst, Al/Fe molar ratio, monomer/catalyst molar ratio, monomer concentration and reaction temperature used in the polymerization. The catalytic activity of Fe(II) complex was 11.1 kg_polym/mol_Fe·h and the highest yield could reach 99.1% under optimum condition.

Two multi-nuclear titanium complexes [Ti(η⁵–Cp*)Cl(μ–O)]₃(1) and [(η⁵–Cp*TiCl)(μ–O)₂(η⁵–Cp*Ti)₂(μ–O)(μ–O)₂]₂Ti (Cp* = C₅Me₅)(2) have been investigated as the precatalysts for syndiospecific polymerization of styrene. In the presence of modified methylaluminoxane (MMAO) as a cocatalyst, complexes 1 and 2 display much higher catalytic activities towards styrene polymerization, and produce the higher molecular weight polystyrenes with higher syndiotacticities and melting temperatures (T_m) than the mother complex Cp*TiCl₃ does when the polymerization temperature is above 70°C and the Al/Ti molar ratio is in the low range especially.

A series of titanium complexes Ar[O, E]Cp*TiCl (Cp* = C₅Me₅, Ar = 1,2-phenylene, E = NH (1a); Ar = 1,2-phenylene, E = O (1b); Ar = 2,2′-diphenylene, E = O (1c); Ar = 2,2′-dinaphthalene, E = O (1d)) has been prepared by the reaction of corresponding phenol derivatives with Cp*TiCl₃ in the presence of excessive triethylamine. Under the conditions of low Al/Ti molar ratio (e.g. 500) and high reaction temperatures (≥ 70°C), all the titanium complexes display higher catalytic activities towards the syndiospecific polymerization of styrene, in the presence of modified methylaluminoxane (MMAO) as a cocatalyst, than their mother complex Cp*TiCl₃. The catalyst activities and polymer yields as well as polymer properties are considerably affected by the steric and electronical effects of the bidentate ligands.

The tremendous potential for the manifold applications of porphyrins, porphyrazines, and phthalocyanines derives from their photophysical and electrochemical properties, their remarkable stability, and their predictable and rigid structure. These applications include nonlinear optics, catalysts, sensors, actuators, molecular sieves, and therapeutics. All of these properties are modulated by appending various chemical moieties onto the macrocycles, by choice of metallo derivative, and by the choice of environment. In multichromophoric systems, furthermore, the relative orientation of the chromophores, the nature of the linker, and the size of the system also dictate the properties. The synthesis of multichromophoric systems – both via covalent and noncovalent linkers – is driven by the desire to make new materials and to understand biological processes such as the various aspects of photosynthesis. Though electron and energy transfer processes continue to drive the synthesis of ever more complex systems, more recent focus has shifted toward other applications and functionalities of these structures. The focus of this perspective is on four recent developments in formation and characterization of functional, porphyrinic materials and devices: (1) self-assembly and self-organization of porphyrin arrays and aggregates into phototransistors and photonic devices; (2) self-assembled porphyrin squares for sensors, sieves, and catalysts; (3) covalently bound arrays of different chromophores as photonic materials; and (4) spatially separated arrays of metalloporphyrins as cross-reactive sensors.

The influence of free bases of meso-tetrakis(3,5-di-tert-butyl-4-hydroxy-phenyl)porphyrins and meso-tetraphenylporphyrins and their complexes of Co, Ni, Cu, Pt upon the radical chain oxidation of oleic acid as model substrates for lipid peroxidation has been studied. It was shown that the introduction of the antioxidative phenolic fragment into the porphyrin ring leads to the dual activity of phenolic porphyrins when compared with their tetraphenyl substituted analogues in substrate oxidation. Free base phenolic porphyrins and their nickel, copper, platinum complexes demonstrate acute inhibitory effect upon oleic acid peroxidation due to the key role of 2,6-di-tert-butylphenol moities, whereas cobalt porphyrin exhibits dual activity associated with the presence of both the redox active metal center and phenolic group.

(Ionic liquids) ILs have unique properties compared with conventional solvents, opening a wide range of application as solvents and catalysts. ILs' cytotoxicity extend their application in biomedicine by acting as antimicrobial and anticancer agents. This article reviews the current research advances of ILs' biomedical application from the following four aspects: solvents, catalysts, antimicrobial and anticancer agents. By introducing ILs' interesting structures and their corresponding unique properties, this review concludes the current state-of-art of ILs biomedical applications. We also try to point out the ILs issues and solutions for more potential applications in biomedicine.

Multi-walled carbon nanotubes (MWCNTs) were synthesized onto a series of individual and bimetallic catalysts by the chemical vapor deposition (CVD) of acetylene at low temperature (600${}^{\circ }$C). The catalysts were prepared by two methods, i.e., precipitation and sol–gel, with two different carriers – MgO and Al₂O₃. The catalysts were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric (TG) analysis, low-temperature adsorption of nitrogen. The yield of the MWCNTs was calculated in two ways, while the highest yield of 800% was achieved onto the two-component NiO/Co₂O₃/MgO catalyst, SEM and transmission electron microscopy (TEM) results confirm that uniform tube-like structure MWCNTs with the yield of 410% were obtained onto Co₂O₃/Al₂O₃ catalyst. These MWCNTs are smooth and pointing in the same direction. Their tube diameter is about 20nm, which is the smallest around all observed MWCNTs. Moreover, nonuniform curved bamboo-like MWCNTs with nozzles in the yield of 760% were obtained onto NiO/V₂O₃/MgO catalyst. Their diameter ranges from 25nm to 50nm. Results show that single-component catalyst promotes the growth of uniform and smaller nanotubes. Among the as-grown nanotubes, their specific surface area increases and average pores diameter reduces after the treatment with concentrated nitric acid at reflux and washing condition. The largest specific surface area (305m²/g) and average pores diameter (26m²/g) are processed to MWCNTs grown onto the NiO/Co₂O₃/MgO catalyst. MWCNTs with such large structural adsorption characteristics and purity of more than 99% obtained with yield 800% show potential use for preparation of nanocomposites as anode materials in lithium ion batteries.

The development of low-cost and high-efficiency catalysts is very important to promote carbon dioxide reduction reaction (CO₂RR). Metal phosphides (MPs) are promising catalysts for CO₂ reduction because of their excellent electrical conductivity, good stability, high activity and selectivity. In this review, we summarize the latest progress of MPs in CO₂RR from chemocatalysis, electrocatalysis and photocatalysis, and discuss in detail their advantages and catalytic mechanism. In the end, we provide some potential challenges and inspiring outlooks to serve as guidance for future research and practical applications of MPs in catalytic CO₂ reduction.

Modern humans are heavily dependent on chemicals and have constantly looked for improved molecular designs with better efficiency and simple ways to get them. This is why catalysis, the method of getting upgraded chemicals through modern processes using a suitable catalyst, is an important area of research. At least one catalytic step is involved in 90% of the manufacturing of chemical products nowadays. Since chemical processes are always associated with a potential environmental hazard, the behavior of the catalyst used is of specific significance concerning environmental resistance. Therefore, the used catalysts should be explored for complete restoration even in the case of 100% efficiency. Zeolites are a group of materials with the characteristics of thermal and chemical stability and can be regenerated by calcination. Because of these crucial features, these types of materials have been widely used in various catalytic reactions and large-scale petrochemical procedures. The gas-phase reactions in zeolite have been intensively studied to develop zeolite as acid–base and redox catalysts to generate fine chemicals. Furthermore, the encapsulation of different metal complexes within the zeolite pores makes them attractive catalytic materials to contribute as a potential component for various industrial organic transformation processes.

X-ray absorption fine structure (XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials, environmental sciences, and so on. In this chapter, we introduce the XAFS principles, including its basic theory, data analysis and experiment, from the view point of practical use. To show its strength as a local structure probe, applications of XAFS in various functional materials are introduced, covering nanoparticles and catalysts, magnetic semiconductors, thin film materials, complex compounds, in situ probing of the nucleation and growth processes of nanomaterials, as well as operando study of catalysts under working conditions.

In addition, we also briefly introduce some relatively new XAFS-related techniques, such as time-resolved and space-resolved XAFS techniques.