Novel Ester-linked Anionic Gemini Surfactant: Synthesis,Surface-Active Properties and Antimicrobial Study

A novel anionic gemini surfactant containing an ester bond in the spacer group was synthesized using cardanol as the raw material and characterized by IR, ¹H NMR and ¹³C NMR. The surface properties of the gemini surfactant were investigated and compared with its corresponding single chain surfactant counterpart. It was found that this novel gemini surfactant exhibited a low critical micelle concentration value (1.9 mM) and good efficiency in reducing surface tension of water (33.6 mN/m). The gemini surfactant was found to have antimicrobial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa), Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacteria and fungi (Aspergillus niger, Aspergillus flavus, Candida albicans and Rhizopus stolonifer). The gemini as well as the corresponding single chain surfactant showed good antimicrobial activity against all pathogenic microorganisms studied and can be employed as an antimicrobial agent. The synthesized novel anionic gemini surfactant possesses an excellent wettability and low foamability.     

Conducting polyaniline based paints on low carbon steel for corrosion protection

Conducting polyaniline powder was synthesized chemically and paints containing conducting polyaniline powder were applied on low carbon steel samples. The conducting polyaniline powder was characterized by UV-Visible absorption spectroscopy and the morphology of paint coating on low carbon steel was studied by scanning electron microscopy. The corrosion protection performance of the coating was evaluated by using potentiodynamic polarization techniques and electrochemical impedance spectroscopy. It has been found that the 2 wt % polyaniline-hydrochloric acid based paint coating offers maximum corrosion protection to low carbon steel in chloride medium.     

The infrared infiltration and joining of advanced material

JOM - Infrared processing is a newly developed technique for materials processing. Key features include rapid processing, simplicity, and low cost. Because of the rapid processing, very little...     

Development of a generative CAPP system for axisymmetric components for a job shop environment

Process planning is a function in a manufacturing organization that selects the manufacturing processes and parameters to be used to transform a part from its initial state to the final form according to the design specifications. It is a bridge between product design and product manufacturing. The activities of process planning include understanding the part specifications or product design data, selection of job material and tool, setup planning, sequencing the operations within a setup, determination of process parameters for each operation, and generation of process sheets. This paper outlines a method to develop a generative computer-aided process planning system for axisymmetric components for a job shop environment. A decision support system is used to perform semi-structured tasks such as setup planning and establishing precedence relationship among various operations.     

Investigations on synthesis of HfB2 and development of a new composite with TiSi2

This paper presents the results of investigation carried out on synthesis and densification of monolithic HfB₂ and the effect of TiSi₂ as sinter additive. Pure phase HfB₂ was prepared by boron carbide reduction of HfO₂ and hot pressed to full density with the addition of TiSi₂. Isothermal oxidation study of this composite was carried out at 850 °C up to 64 h. Formation of HfB₂ was seen at 1200 °C but pure HfB₂ was formed at a much higher temperature of 1875 °C in vacuum. Hot pressing of HfB₂ at 1850 °C and 35 MPa pressure gave a compact of 80% TD. Addition of TiSi₂ helped in achieving a much higher density at a lower temperature of 1600 °C and a pressure of 20 MPa. A fully dense composite of HfB₂ and TiSi₂ was obtained with 15% TiSi₂. Hardness and fracture toughness of this composite were 27.4 ± 1.9 GPa and 6.6 ± 0.2 MPa m^1/2, respectively. Considerable deflection was observed in the crack propagation in composites. Oxidation studies indicated the formation of HfO₂, SiO₂, TiO₂ and HfSiO₄ with some glassy phase and the composite with 15% TiSi₂ was seen to be completely covered with a protective glassy layer.     

在表面活性剂存在下铬铁矿表土中镍的微生物萃取(英文)

加入表面活性剂吐温20,用Aspergillus niger对预处理过的印度Sukinda铬铁矿表土在摇瓶中生物浸取镍。考察添加表面活性剂吐温20对黑曲霉菌Aspergillus niger生长及浸镍效果的影响。结果表明,添加低浓度的表面活性剂吐温20对黑曲霉菌从预处理过的铬铁矿表土中提取镍是有利的。通常,Aspergillus niger利用培养基中的碳源来进行细胞代谢,产生有机代谢物,从而生物浸出矿。添加表面活性剂吐温20加速了黑曲霉菌对碳源的消耗,从而改善了镍浸出效果。在预处理矿浆浓度为2%和温度为30°C的条件下,添加表面活性剂吐温20的镍浸取率能达到39%,没有表面活性剂的镍浸取率只有24%。     

Essential Oil of <Emphasis Type="Italic">Artemisia scoparia</Emphasis> Inhibits Plant Growth by Generating Reactive Oxygen Species and Causing Oxidative Damage

We investigated the chemical composition and phytotoxicity of the essential oil extracted from leaves of Artemisia scoparia Waldst. et Kit. (red stem wormwood, Asteraceae). GC/GC-MS analyses revealed 33 chemical constituents representing 99.83% of the oil. The oil, in general, was rich in monoterpenes that constitute 71.6%, with β-myrcene (29.27%) as the major constituent followed by (+)-limonene (13.3%), (Z)-β-ocimene (13.37%), and γ-terpinene (9.51%). The oil and β-myrcene were evaluated in a dose–response bioassay under laboratory conditions for phytotoxicity against three weeds—Avena fatua, Cyperus rotundus, and Phalaris minor. A significant reduction in germination, seedling growth, and dry matter accumulation was observed in the test weeds. At the lowest treatment of 0.07 mg/ml Artemisia oil, germination was reduced by 39%, 19%, and 10.6% in C. rotundus, P. minor, and A. fatua, respectively. However, the inhibitory effect of β-myrcene was less. In general, a dose-dependent effect was observed and the growth declined with increasing concentration. Among the three weeds, the inhibitory effect was greatest on C. rotundus, so it was selected for further studies. We explored the explanation for observed growth inhibition in terms of reactive oxygen species (ROS: lipid peroxidation, membrane integrity, and amounts of conjugated dienes and hydrogen peroxide)-induced oxidative stress. Exposure of C. rotundus to Artemisia oil or β-myrcene enhanced solute leakage, indicating membrane disintegration. There were increased levels of malondialdehyde and hydrogen peroxide, indicating lipid peroxidation and induction of oxidative stress. We conclude that Artemisia oil inhibits plant root growth through generation of ROS-induced oxidative damage.     

Wilkinson's salt: A flame retardant for poly(methyl methacrylate)

Poly(methyl methacrylate) reacts with RhCI(PPh₃)₃ at 260°C in a sealed tube to produce a material which is insoluble in common solvents. The infrared spectrum and CP/MAS ¹³C-NMR spectrum indicate the presence of anhydrides. Differential scanning calorimetry shows that the transition temperature has increased by 15°C. Thermogravimetric analysis indicates that 25% of the material is not volatilized at 600°C. The oxygen index of the mixture of the rhodium compound with PMMA increases from 14 to 20 (bottom ignition).     

Influence of surfactant properties on thermal behavior and sol–gel transitions in surfactant‐HPMC mixtures

Four surfactants, namely, sodium n‐decyl sulfate (SDeS), sodium n‐hexadecyl sulfate (SHS), sodium n‐dodecyl sulfate (SDS), and Triton X‐100, were used as additives to study thermal behavior and sol–gel transformations in dilute aqueous hydroxypropyl methyl cellulose (HPMC)/surfactant mixtures using micro‐differential scanning calorimetry. The influence of anionic surfactant, SDS on the gelation varied with SDS concentration where the sol–gel transition started at a higher temperature. Shape of the thermograms changed from single mode to dual mode at the SDS concentration of 6 mM and higher. SDeS and SHS, however, resulted in “salt‐in” effect of a different magnitude during gelation. Triton X‐100, being a non‐ionic surfactant, showed a minor “salt‐out” effect on the thermo‐gelation process. On the basis of different thermal behavior of anionic and non‐ionic surfactant/HPMC systems, a mechanism is proposed explaining how the chemical structure and electro‐charge of the surfactants affect the polymer/surfactant binding and polymer/polymer aggregation because of hydrophobic interaction during the sol–gel transition. © 2009 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2009