Synergistic antioxidant and antibacterial activity of rosemary plus butylated derivatives

Antioxidant and antibacterial activity of a methanol rosemary extract (RE) containing 30% carnosic acid (CA), 16% carnosol (COH) and 5% rosmarinic acid (RA) was studied in vitro alone and in combination with the antioxidant food additives butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). The antioxidant efficiency of the extract, CA, and RA, was determined by a kinetic analysis of the 2,2-diphenyl-2-picrylhydrazyl hydrate radical (DPPH·) scavenging activity. RE showed two different rate slopes in the reduction of DPPH· vs. time curve, which correlated with the distinct behaviours of RA and CA; pure RA reached the plateau more rapidly than CA. A synergistic antioxidant effect between RE and BHT was demonstrated by isobolographic analysis and a synergistic interaction of RE with BHA to inhibit Escherichia coli and Staphylococcus aureus growth was observed. Therefore, rosemary not only enhances the antioxidant efficiency of BHA and BHT, but also the antibacterial effect of BHA; allowing a decrease from 4.4 to17 folds in the amounts of the synthetic compounds used.     

二(2-乙基己基)二硫代磷酸对镅和稀土元素协同萃取的研究

研究了二(2-乙基己基)二硫代磷酸(DEHDTP)和三辛基氧磷(TOPO)、4,7-二苯基-1,10-邻二氮菲(DPPHEN)、三辛基硫磷(TOPS)三种协萃剂对Am^3 、Nd^3 、Eu^3 、Tm^3 的协同(混合)萃取行为。TOPO和DPPHEN有很强的协萃能力,并提高了镅和稀土元素之间的分离系数,前者β(Am/Eu)=3．9,后者β(Am/Eu)=2,而TOPS几乎没有协萃作用。在常量稀土离子存在时分离系数进一步提高,TOPO的β(Am/Eu)=71,DPPHEN的β(Am/Eu)=3。     

Physicochemical Properties and Phase Behavior of Didecyldimethylammonium Chloride/Alkyl Polyglycoside Surfactant Mixtures

Mixed surfactant systems, used in many formulations, have aroused great attention and interest from researchers and industry due to the possibility of synergism. Alkyl polyglycoside (APG) and didecyldimethylammonium chloride (DDAC) mixtures combine the excellent properties of pure surfactants and play an important role in the development of multi‐functional washing products. To study the synergism between APG and DDAC, the physicochemical properties of different mixed systems have been investigated. The critical micelle concentration (CMC) is about 180 mg·L^?1 and the surface tension at the CMC is about 26.0 mN·m^?1 at a mass fraction of 40 % DDAC (ω_DDAC40 %). The values are significantly lower than pure surfactants. The foaming property shows the best performance at ω_DDAC20 %. When the mass fraction of DDAC is 80 %, the mixture exhibits better wetting and emulsifying properties. Synergism was observed in surface tension, foaming and emulsifying properties, while the wetting ability and detergency exhibited no such effects. Phase behavior of the APG/DDAC/water ternary system has also been carried out by polarized optical microscope. The phase diagram is characterized by a micellar phase, a region where lamellar and micellar phases coexist and a lamellar phase.     

Response of phosphine-resistant mixed-age cultures of lesser grain borer,Rhyzopertha dominica (F.) to different phosphine-carbon dioxide mixtures

Mixed-age cultures of a phosphine-resistant strain of lesser grain borer, Rhyzopertha dominica (F.) were exposed to various concentrations of phosphine and phosphine plus 10, 20 and 30% carbon dioxide combinations (CO₂) for different time intervals at 25 °C to evaluate the comparative efficacy of admixtures of phosphine-CO₂. The mortality data of the mixed age cultures were recorded taking the adult count at weekly intervals for 8 weeks. Lethal concentrations were determined by probit analysis. Phosphine with carbon dioxide exerted significant synergistic effect on the mortality of mixed-age cultures at 4, 6 and 7 days of exposure, while individually phosphine or carbon dioxide did not show a raised increase in their response. The addition of 30% carbon dioxide to lower concentrations of phosphine over shorter exposures of 4 days showed better synergistic effect among the treatments. The present study revealed that CO₂ augmented the effect of phosphine thereby reducing the concentration and exposure time required to bring about significant mortality in the mixed-age cultures of R. dominica.     

Influence of halide ions on the adsorption of diphenylamine on iron in 0.5 M H2SO4 solutions

Halide ions are found to enhance the inhibition performance of amines due to enhanced adsorption of amines by the adsorbed halide ions on the metal surface. In this work, the synergistic action of halide ions on the corrosion inhibition of iron in 0.5 M H₂SO₄ by diphenylamine has been found out by electrochemical impedance and polarization methods. Analysis of impedance data has been made with equivalent circuit with constant phase angle element for calculation of double layer capacitance values. Experiments have been carried out in the concentration range of 100-1000 ppm of diphenylamine in the presence of 0.5-1.0 × 10⁻³ M of halide ions. Diphenylamine is found to be a cathodic inhibitor and the inhibition efficiency of about 65% is obtained at 1000 ppm. The anodic and cathodic Tafel slopes in the presence of diphenylamine alone and with halide ions are 65 ± 5 and 105 ± 5 mV, respectively. Diphenylamine inhibits corrosion by adsorption and the surface coverage values are increased considerably in the presence of halide ions. In the presence of iodide ions, the inhibition efficiency of diphenylamine at 100 ppm is increased to more than 90%. In the case of other halide ions, the inhibition efficiency of diphenylamine in increased to 80% at 1000 ppm. The order of synergism of halide ions is I⁻ ? Br⁻ > Cl⁻. The highest synergistic effect of iodide ions is due to chemisorption with metal surface due to its larger size and ease of polarizability.     

Montmorillonite/graphene oxide nanocomposite as superior adsorbent for the adsorption of Rhodamine B and Nickel ion in binary system

A series of montmorillonite reduced graphene oxide (MrGO) composites were synthesized using different ratios (5, 10, 15 and 20) of montmorillonite (MMt) to GO. The synthesized composites were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, surface area analyzer (BET), and Fourier transform- infrared spectroscopy. The adsorption capacity and efficiency of the synthesised composites were examined towards removal of Rhodamine B (RhB) and Nickel ion (Ni²⁺). The results were compared with that of GO and commercial MMt clay. The kinetic sorption models were evaluated, and it was observed that sorption follows the pseudo-second-order kinetics. Adsorption isotherm was best fit into the Langmuir model (R²?=?0.996 for RhB & 0.957 for Ni²⁺). Among all the synthesized composites, MrGO-2, a composite of GO and montmorillonite with (1:10) ratio, showed maximum activity towards the adsorption of Rhodamine B and Ni²⁺ calculated to be 625?mg/g and 178?mg/g respectively at neutral pH condition. From the calculated ΔG⁰ (?3.99 & ?0.71?kJ?mol^?1), ΔH (28.6 & 4.61?kJ?mol^?1) and ΔS (?107.5 & ?17.8?J?mol^?1 K) values for RhB & Ni²⁺ respectively, it can be unambiguously inferred that the adsorption process was feasible, endothermic and exhibiting least randomness, respectively. The prepared MrGO composites showed good adsorption capacity towards efficient removal of RhB and Ni²⁺ in single as well as binary system.     

MNA-TBP从盐酸介质中萃取Ir(Ⅳ)

对ＭＮＡ－ＴＢＰ从盐酸介质中萃取Ｉｒ（Ⅳ）作了研究．结果表明：ＭＮＡ－ＴＢＰ对Ｉｒ（Ⅳ）萃取有协同效应．当ＭＮＡ和ＴＢＰ在正辛烷中的浓度各为０．４５ｍｏｌ／Ｌ，待萃液中ＨＣｌ总浓度为４ｍｏｌ／Ｌ，铱浓度为１７３．１３μｇ／ｍｌ，相比为１时，协萃系数Ｒ为２．３３，协萃合物的组成为（ＭＮＡＨ）＋．ＩｒＣｌ＄２－６．（ＨＴＢＰ）＋．     

Zinc Corrosion in Acidic Solutions Containing Single and Mixed Surfactants

The influence of surfactant synergism on Zn corrosion inhibition in 0.1-M HCl aqueous solutions has been determined at room temperature. Solutions of single and mixed surfactants consisting of sodium dodecylsulfate (SDS) and N,N-dimethyldodecan-1-amine oxide (DDAO) in water and in 0.1-M HCl were also prepared at room temperature. Critical micelle concentration (CMC) data were obtained through surface tension measurements as a function of mixing composition. A regular solution model was considered to analyze CMC values. The interaction parameter (β), the composition of mixed micelles (x) and the activity coefficients (f) were estimated by a regular solution model for all amphoteric–anionic mixed systems. β Vvalues showed synergism for the binary mixtures of these solutions in the absence and presence of 0.1-M HCl at all investigated compositions. Zinc corrosion in single and binary SDS/DDAO mixed solutions at 5-mM total surfactant concentrations in the presence of 0.1-M HCl was also investigated at static and dynamic conditions. The weight loss data revealed corrosion inhibition activity obeyed the following order: binary (0.75 DDAO + 0.25 SDS) > binary (0.50 DDAO + 0.50 SDS) > single DDAO > single SDS, suggesting an enhancement in the corrosion inhibition activity of DDAO in the presence of a proper amount of SDS. Conductivity time measurements show a similar trend as that obtained by a weight loss method at (0.50 DDAO + 0.50 SDS). The results were illustrated on the basis of synergistic interaction between the mixed surfactants.     

Ni//Mo synergism via hydrogen spillover,in pyridine hydrodenitrogenation

The pyridine hydrodenitrogenation (HDN) over physically separated stacked Ni//Mo beds was investigated using a continuous-flow high pressure (3 MPa) stainless steel microreactor. Results prove the existence of synergism between physically separated beds of Ni-/γ-Al₂O₃ and Mo/γ-Al₂O₃ catalysts for the pyridine hydrodenitrogenation reaction. This synergism is explained by the formation of hydrogen spillover. Product analysis of the pyridine hydrodenitrogenation over Ni//Mo stacked beds suggested that the hydrogen spillover modified the active sites of the MoS₂ by increasing the hydrogenation sites.