The degradation of 4-chloro-3-methylphenol（PCMC）using zeolite-encapsulated iron（III）,nickel（II）,and copper（II）complexes of N,N’-disalicylidene-1,2-phenylenediamine as catalysts,in a heterogeneous Fenton-like ...The degradation of 4-chloro-3-methylphenol（PCMC）using zeolite-encapsulated iron（III）,nickel（II）,and copper（II）complexes of N,N’-disalicylidene-1,2-phenylenediamine as catalysts,in a heterogeneous Fenton-like advanced oxidation process,was studied.The physicochemical properties of the catalysts were determined using powder X-ray diffraction,thermogravimetric analysis,Brunauer–Emmett–Teller surface area analysis,Fourier-transform infrared spectroscopy,elemental analysis,and scanning electron microscopy.The effects of four factors,namely initial H2O2 concentration,catalyst dosage,temperature,and pH,on the degradation of a model organic pollutant were determined.The results show that at low acidic pH,almost complete removal of PCMC was achieved with the iron（III）,nickel（II）,and copper（II）catalysts after 120 min under the optimum reaction conditions：catalyst dosage 0.1 g,H2O2 concentration 75 mmol/L,initial PCMC concentration 0.35mmol/L,and 50 °C.The reusability of the prepared catalysts in PCMC degradation was also studied and a possible catalyst deactivation mechanism is proposed.The possible intermediate products,degradation pathway,and kinetics of PCMC oxidation were also studied.展开更多
Designing of new peptide materials for biomedical and protein engineering applications are important. In the present work an attempt has been made to study the effect of D-Leu in collagen like tetra peptide on the str...Designing of new peptide materials for biomedical and protein engineering applications are important. In the present work an attempt has been made to study the effect of D-Leu in collagen like tetra peptide on the structure and stability of peptide against enzymes and results are compared with its chiral counterpart L-form. Effect of replacement of L-Leu in Leu-Gly-Pro-Ala tetra peptide with D-Leu on structure has been studied using circular dichroic spectroscopy (CD). Our findings suggest that, D-Leu substitution leads to conformational changes in Leu-Gly-Pro-Ala secondary structure from β-sheet to turns. L → D-Leu Configurational changes in Leu-Gly-Pro-Ala owes to enhanced thermal stability which has been substantiated through CD and differential scanning calorimetry. Change in chirality of the leucine inhibits collagenolytic activity, which enables to design selective inhibition of proteases with greater specificity.展开更多
Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. Surfactants are effec-tive capping agents as they prevent the aggregation of nanoparticles during storage and use. However, ...Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. Surfactants are effec-tive capping agents as they prevent the aggregation of nanoparticles during storage and use. However, the biocompatibility of several of the surfactants is questionable. In this report, the use of thiosalicylic acid as both reducing and capping agent is reported. Compared to conventional synthesis, this methodology requires higher temperature for synthesis, which then is expected to result in aggregates of larger size. The ability of three different synthesis methodologies – direct heating, photochemical and microwave dielectric treatment were evaluated and assessed on the basis of the size, size distribution and stability of the particles. Microwave irradiation was found to be most suitable for achieving particles with a hydrodynamic diameter of 10 nm. Our studies indicate that -COO- group is involved in the reduction of Ag+ and –SH group of TSA is involved in the capping of the nanoparticles.展开更多
Increasing energy cost calls for exterior coatings with high near infra-red reflectance,so as to reduce heat absorption and in turn cost of air-conditioning.While modulations of substrate,use of white metal oxides as ...Increasing energy cost calls for exterior coatings with high near infra-red reflectance,so as to reduce heat absorption and in turn cost of air-conditioning.While modulations of substrate,use of white metal oxides as pigments or under-layers has been reported in past,reports on metal oxide or doped metal oxide pigments with high NIR reflectance is scarce.We report for the first time a blue colored cobalt aluminate type pigment prepared through doping of cerium,praseodymium or neodymium.CIELAB color measurements and calculation ofDE indicated that the Nd doped sample had crystal size of(36±1)nm,bandgap value of(2.4±0.2)eV and color coordinates similar to that of cobalt aluminate.The molar ratio as estimated by EDX was found to be Al:Cu:Co:Ce:Nd:O=2:0.06:0.06:0.012:0.00012:6.18.The pigment was found to have potential applications as a cool blue colorant,owing to changes in optical properties arising out of crystal chemistry changes.Incorporation of rare earth metal ions was found to enhance the NIR reflectance by 10%,when compared to a conventional cobalt aluminate pigment.The oxide has been well characterized and its performance as a pigment evaluated.We have proposed that changes in crystal lattice when neodymium enters into Ce4+sites enhance the NIR reflectance by about 9%as against the entry of praseodymium.展开更多
基金Leather Industry Development Institute(LIDI),Government of Ethiopia,Addis Ababa,for full financial support for his PhD studies under Twinning Program between Leather Industry Development Institute(LIDI),Addis Ababa University(AAU)and CSIR-Central Leather Research Institute(CLRI)
文摘The degradation of 4-chloro-3-methylphenol（PCMC）using zeolite-encapsulated iron（III）,nickel（II）,and copper（II）complexes of N,N’-disalicylidene-1,2-phenylenediamine as catalysts,in a heterogeneous Fenton-like advanced oxidation process,was studied.The physicochemical properties of the catalysts were determined using powder X-ray diffraction,thermogravimetric analysis,Brunauer–Emmett–Teller surface area analysis,Fourier-transform infrared spectroscopy,elemental analysis,and scanning electron microscopy.The effects of four factors,namely initial H2O2 concentration,catalyst dosage,temperature,and pH,on the degradation of a model organic pollutant were determined.The results show that at low acidic pH,almost complete removal of PCMC was achieved with the iron（III）,nickel（II）,and copper（II）catalysts after 120 min under the optimum reaction conditions：catalyst dosage 0.1 g,H2O2 concentration 75 mmol/L,initial PCMC concentration 0.35mmol/L,and 50 °C.The reusability of the prepared catalysts in PCMC degradation was also studied and a possible catalyst deactivation mechanism is proposed.The possible intermediate products,degradation pathway,and kinetics of PCMC oxidation were also studied.
文摘Designing of new peptide materials for biomedical and protein engineering applications are important. In the present work an attempt has been made to study the effect of D-Leu in collagen like tetra peptide on the structure and stability of peptide against enzymes and results are compared with its chiral counterpart L-form. Effect of replacement of L-Leu in Leu-Gly-Pro-Ala tetra peptide with D-Leu on structure has been studied using circular dichroic spectroscopy (CD). Our findings suggest that, D-Leu substitution leads to conformational changes in Leu-Gly-Pro-Ala secondary structure from β-sheet to turns. L → D-Leu Configurational changes in Leu-Gly-Pro-Ala owes to enhanced thermal stability which has been substantiated through CD and differential scanning calorimetry. Change in chirality of the leucine inhibits collagenolytic activity, which enables to design selective inhibition of proteases with greater specificity.
文摘Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. Surfactants are effec-tive capping agents as they prevent the aggregation of nanoparticles during storage and use. However, the biocompatibility of several of the surfactants is questionable. In this report, the use of thiosalicylic acid as both reducing and capping agent is reported. Compared to conventional synthesis, this methodology requires higher temperature for synthesis, which then is expected to result in aggregates of larger size. The ability of three different synthesis methodologies – direct heating, photochemical and microwave dielectric treatment were evaluated and assessed on the basis of the size, size distribution and stability of the particles. Microwave irradiation was found to be most suitable for achieving particles with a hydrodynamic diameter of 10 nm. Our studies indicate that -COO- group is involved in the reduction of Ag+ and –SH group of TSA is involved in the capping of the nanoparticles.
基金One of the authors(SPR)thanks the Department of Science and Technology,Government of India for the funding received under the WOS-A programFinancial assistance of the CSIR New Delhi under the XII Plan project is also acknowledged.
文摘Increasing energy cost calls for exterior coatings with high near infra-red reflectance,so as to reduce heat absorption and in turn cost of air-conditioning.While modulations of substrate,use of white metal oxides as pigments or under-layers has been reported in past,reports on metal oxide or doped metal oxide pigments with high NIR reflectance is scarce.We report for the first time a blue colored cobalt aluminate type pigment prepared through doping of cerium,praseodymium or neodymium.CIELAB color measurements and calculation ofDE indicated that the Nd doped sample had crystal size of(36±1)nm,bandgap value of(2.4±0.2)eV and color coordinates similar to that of cobalt aluminate.The molar ratio as estimated by EDX was found to be Al:Cu:Co:Ce:Nd:O=2:0.06:0.06:0.012:0.00012:6.18.The pigment was found to have potential applications as a cool blue colorant,owing to changes in optical properties arising out of crystal chemistry changes.Incorporation of rare earth metal ions was found to enhance the NIR reflectance by 10%,when compared to a conventional cobalt aluminate pigment.The oxide has been well characterized and its performance as a pigment evaluated.We have proposed that changes in crystal lattice when neodymium enters into Ce4+sites enhance the NIR reflectance by about 9%as against the entry of praseodymium.
