Synthesis and electrochemical characterization of Li2MnO3–LiNixCOyMnzO2 cathode for lithium battery using co-precipitation method

The Li_xNi_0.23Co_0.12Mn_0.65O₂ electrode system with various compositions (x = 1.19, 1.33, 1.46, 1.58) was synthesized from a metal oxide precursor synthesized by co-precipitation method. The XRD patterns of the prepared powders revealed a hexagonal α-NaFeO₂ structure (space group: R-3m, 166) and the existence of a Li₂MnO₃ phase in the composite structure. In particular, the low Li content sample shows a three integrated structure (spinel, Li₂MnO₃, LiMO₂) for a Li/Metal(Ni/Co/Mn) mol ratio of 1.2. Scanning electron microscopy showed that all the synthesized samples contained spherical agglomerates with a size of 8–10 μm. Among the samples tested, Li_1.46Ni_0.23Co_0.12Mn_0.65O₂ shows relatively high charge and discharge capacity for the first cycle is 287, 192.9 mA h g^?1, respectively. Also, charge transfer resistance was also significantly improved compare with other samples.     

A Generalized Crystallographic Description of All Tellurium Nanostructures

Despite tellurium being less abundant in the Earth's crust than gold, platinum, or rare‐earth elements, the number of industrial applications of tellurium has rapidly increased in recent years. However, to date, many properties of tellurium and its associated compounds remain unknown. For example, formation mechanisms of many tellurium nanostructures synthesized so far have not yet been verified, and it is unclear why tellurium can readily transform to other compounds like silver telluride by simply mixing with solutions containing silver ions. This uncertainty appears to be due to previous misunderstandings about the tellurium structure. Here, a new approach to the tellurium structure via synthesized structures is proposed. It is found that the proposed approach applies not only to these structures but to all other tellurium nanostructures. Moreover, some unique tellurium nanostructures whose formation mechanism are, until now, unconfirmed can be explained.     

Characteristics of nano-sized (Pb, La)TiO3 powder synthesized at room temperature

We synthesized nano-sized (Pb, La)TiO3 powder using a high energy mechano-chemical technique at room temperature. By the results, nano-sized (Pb, La)TiO3 powder with perovskite structure was successfully synthesized from an oxide mixture using a high energy mechano-chemical technique without any post-annealing. The mechanically-synthesized (Pb, La)TiO3 powder consisted of nanometer sized particles and had very high homogeneity. According to increase of milling time, source phases such as Pb oxides and TiO2 disappeared and the perovskite PLT phase was formed by chemical reaction and the release of OH group.     

Semi-transparent thin film solar cells by a solution process

Easily processed, low cost, and highly efficient solar cells are desirable for photovoltaic conversion of solar energy to electricity. We present the fabrication of precursor solution processed CuInGaS2 (CIGS) thin film solar cells on transparent indium tin oxide (ITO) substrates. The CIGS absorber film was prepared by a spin-coating method, followed by two successive heat treatment processes. The first annealing process was on a hot plate at 300 °C for 30 min in air to remove carbon impurities in the film; this was followed by a sulfurization process at 500 °C in an H₂S(1%)/Ar environment to form a polycrystalline CIGS film. The absorber film with an optical band-gap of 1.52 eV and a thickness of about 1.1 µm was successfully synthesized. Because of the usage of a transparent glass substrate, a bifacial CIGS thin film device could be achieved; its power conversion efficiency was measured to be 6.64% and 0.96% for front and rear illumination, respectively, under standard irradiation conditions.     

State of the Art: The Immunomodulatory Role of MSCs for Osteoarthritis

Osteoarthritis (OA) has generally been introduced as a degenerative disease; however, it has recently been understood as a low-grade chronic inflammatory process that could promote symptoms and accelerate the progression of OA. Current treatment strategies, including corticosteroid injections, have no impact on the OA disease progression. Mesenchymal stem cells (MSCs) based therapy seem to be in the spotlight as a disease-modifying treatment because this strategy provides enlarged anti-inflammatory and chondroprotective effects. Currently, bone marrow, adipose derived, synovium-derived, and Wharton’s jelly-derived MSCs are the most widely used types of MSCs in the cartilage engineering. MSCs exert immunomodulatory, immunosuppressive, antiapoptotic, and chondrogenic effects mainly by paracrine effect. Because MSCs disappear from the tissue quickly after administration, recently, MSCs-derived exosomes received the focus for the next-generation treatment strategy for OA. MSCs-derived exosomes contain a variety of miRNAs. Exosomal miRNAs have a critical role in cartilage regeneration by immunomodulatory function such as promoting chondrocyte proliferation, matrix secretion, and subsiding inflammation. In the future, a personalized exosome can be packaged with ideal miRNA and proteins for chondrogenesis by enriching techniques. In addition, the target specific exosomes could be a gamechanger for OA. However, we should consider the off-target side effects due to multiple gene targets of miRNA.     

Pyrolysis characteristics of Oriental white oak: Kinetic study and fast pyrolysis in a fluidized bed with an improved reaction system

The kinetic parameters for the pyrolysis of Oriental white oak were evaluated by thermogravimetric analysis (TGA). The white oak was pyrolyzed in a fluidized bed reactor with a two-staged char separation system under a variety of operating conditions. The influence of the pyrolysis conditions on the chemical and physical characteristics of the bio-oil was also examined. TGA showed that the Oriental white oak decomposed at temperatures ranging from 250 to 400 °C. The apparent activation energy ranged from 160 to 777 kJ mol^− 1. The optimal pyrolysis temperature for the production of bio-oil in the fluidized bed unit was between 400 and 450 °C. A much smaller and larger feed size adversely affected the production of bio-oil. A higher fluidizing gas flow and higher biomass feeding rate were more effective in the production of bio-oil but the above flow rates did not affect the bio-oil yields significantly. Recycling a part of the product gas as a fluidizing medium resulted the highest bio-oil yield of 60 wt.%. In addition, high-quality bio-oil with a low solid content was produced using a hot filter as well as a cyclone. With exception of the pyrolysis temperature, the other pyrolysis conditions did not significantly affect the chemical and physical characteristics of the resulting bio-oil.     

MECHANISMS OF ICE CRYSTALLIZATION AND RECRYSTALLIZATION IN ICE CREAM: A REVIEW

This review article focuses on the mechanisms of ice crystallization and recrystallization and factors that influence them in ice creams. Ice crystallization is an important factor that determines ice cream's final quality. The smaller the ice crystal size is in the final product, the better the quality is. Large ice crystals cause a coarse, grainy, and icy texture in ice cream. The initial ice crystals are formed in the freezer barrel and then grow in size during hardening and storage. Recrystallization during storage is influenced by various factors, including total solids, initial freezing temperature, unfrozen water, stabilizer type, sweetener type, and storage temperature. The roles of these factors, especially stabilizers, are discussed.     

Synthesis and characterization of novel hybrid polyoxazoline‐grafted multiwalled carbon nanotubes

The novel hybrid polyoxazoline‐grafted multiwalled carbon nanotubes (POZO‐grafted MWNTs) were synthesized by the reaction of partially hydrolyzed polyoxazolines (Hydrolyzed‐POZO) and MWNTs having carboxylic acid groups (MWNT‐COOH) in the presence of DCC as a condensing agent. Hydrolyzed‐POZO (degree of hydrolysis, 20.2 mol % by ¹H‐NMR) were produced from the hydrolysis of polyoxazolines in an aqueous NaOH solution at reflux for 72 h. MWNT‐COOH were prepared by acid treatment of pristine MWNTs. The composition, structure, thermal property, and surface morphology of the novel hybrid POZO‐grafted MWNTs were fully characterized by FT‐IR, Raman, ¹H‐NMR, DSC, TGA, SEM, and TEM. The obtained POZO‐grafted MWNTs are well soluble in various organic solvents and water. It was observed that the glass transition temperature (T_g) of POZO‐grafted MWNTs was lower than that of Hydrolyzed‐POZO due to the absence of hydrogen bonding interactions between Hydrolyzed‐POZO itself caused by the incorporation with MWNTs. It was also found that Hydrolyzed‐POZO was homogeneously attached to the surfaces of MWNTs through the “grafting‐to” method. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Improvement in CO2 absorption and reduction of absorbent loss in aqueous NH3/triethanolamine/2-amino-2-methyl-1-propanol blends

Changes in the CO₂ absorption rates and capacities of the absorbent 2-amino-2-methyl-1-propanol (AMP), blended with NH₃ and other additives, were investigated toward performance improvement. The NH₃-blended absorbent removed CO₂ more efficiently than the AMP absorbent alone. However, absorbent loss through NH₃ evaporation was observed under these conditions. A second absorbent, the tertiary amine triethanolamine (TEA), which has a low vapor pressure, was selected and blended with the NH₃/AMP system to reduce NH₃ evaporation. Its effects on NH₃ loss and the absorption rate and capacity of the NH₃/AMP system were investigated, and the optimum blending ratios were determined. In addition, the absorbent blend at the optimum blending ratio was compared to AMP alone and the commercially available absorbent monoethanolamine at the same weight ratio. The thermal stabilities of the absorbents, under conditions used in the CO₂ absorption process, were compared by thermogravimetric analysis.     

The absorption rate of CO2/SO2/NO2 into a blended aqueous AMP/ammonia solution

The Inter-governmental Panel on Climate Change (IPCC) reported that human activities result in the production of greenhouse gases (CO₂, CH₄, N₂O and CFCs), which significantly contribute to global warming, one of the most serious environmental problems. Under these circumstances, most nations have shown a willingness to suffer economic burdens by signing the Kyoto Protocol, which took effect from February 2005. Therefore, an innovative technology for the simultaneously removal carbon dioxide (CO₂) and nitrogen dioxide (NO₂), which are discharged in great quantities from fossil fuel-fired power plants and incineration facilities, must be developed to reduce these economical burdens. In this study, a blend of AMP and NH₃ was used to achieve high absorption rates for CO₂, as suggested in several publications. The absorption rates of CO₂, SO₂ and NO₂ into aqueous AMP and blended AMP+NH₃ solutions were measured using a stirred-cell reactor at 293, 303 and 313 K. The reaction rate constants were determined from the measured absorption rates. The effect of adding NH₃ to enhance the absorption characteristics of AMP was also studied. The performance of the reactions was evaluated under various operating conditions. From the results, the reactions with SO₂ and NO₂ into aqueous AMP and AMP+NH₃ solutions were classified as instantaneous reactions. The absorption rates increased with increasing reaction temperature and NH₃ concentration. The reaction rates of 1, 3 and 5 wt% NH₃ blended with 30 wt% AMP solution with respect to CO₂/SO₂/NO₂ at 313 K were 6.05～8.49×10^?6, 7.16–10.41×10^?6 and 8.02～12.0×10^?6 kmol m^?2s^?1, respectively. These values were approximately 32.3–38.7% higher than with aqueous AMP solution alone. The rate of the simultaneous absorption of CO₂/SO₂/NO₂ into aqueous AMP+NH₃ solution was 3.83–4.87×10^?6 kmol m^?2s^?1 at 15 kPa, which was an increase of 15.0–16.9% compared to 30 wt% AMP solution alone. This may have been caused by the NH₃ solution acting as an alternative for CO₂/SO₂/NO₂ controls from flue gas due to its high absorption capacity and fast absorption rate.