Influence of the Chemical Molar Ratio on the Copper Nanoparticles: Controlled-Surfactants, -Reducing Agents, and -Precursors

2016 ◽  
Vol 37 (5) ◽  
pp. 700-704
Author(s):  
Chang-Wan Kim ◽  
Hakyung Jeong ◽  
Youngwook Noh ◽  
Dongjin Lee ◽  
Chongmu Lee ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
Reducing Agents ◽  
Molar Ratio

scholarly journals Synthesis, characterization and evaluation of copper nanoparticles as agrochemicals against Phytophthora spp.

2019 ◽  
Vol 2 (6) ◽  
pp. 48-56
Author(s):  
Hoang Minh Hao ◽  
Cao Van Du ◽  
Duong Thi Ngoc Dung ◽  
Cao Xuan Chuong ◽  
Nguyen Thi Phuong Phong ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
Chemical Reduction ◽  
Trisodium Citrate ◽  
Molar Ratio ◽  
In Vitro Test ◽  
Weight Percentage ◽  
Phytophthora Spp ◽  
Transmission Electron ◽  
Xrd Techniques

By using water as a solvent, copper nanoparticles (CuNPs) have been synthesized from copper sulfate via chemical reduction method in the presence of trisodium citrate dispersant and polyvinylpyrrolidone (PVP) as capping agent. The effects of the experimental parameters such as the concentration of reducing agent (NaBH4), reaction temperature, molar ratio of citrate/Cu2+ and weight percentage ratios of Cu2+/PVP on the CuNP sizes were studied. The size of CuNPs in a range of 31 nm was obtained at NaBH4 concentration of 0.2 M, 50oC, citrate/Cu2+ molar ratio of 1.0 and Cu2+/PVP weight percentage of 5%. The colloidal CuNPs were characterized by using UV–Visible spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The colloidal solution of CuNPs (3±1 nm) was investigated the potential against Phytophthora spp. which cause economically crop diseases. Under in vitro test conditions, the inhibition of Phytophthora spp. mycelia growth at three concentrations of CuNPs (10, 20, 30 ppm) after 48 hours are 90.18%, 91.87% and 100%, respectively. These results provided a simple and economical method to develop the CuNPs-based-fungicide.  

scholarly journals Microemulsions as Nanoreactors for Preparation of Nanoparticles with Antibacterial Activity

2012 ◽  
Vol 25 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Sakhawat Hossain ◽  
Ummul K Fatema ◽  
Md Yousuf A Mollah ◽  
M Muhibur Rahman ◽  
Md Abu Bin Hasan susan
Keyword(s):  
Antibacterial Activity ◽  
Copper Nanoparticles ◽  
Copper Chloride ◽  
Sodium Dodecyl ◽  
Antibiotic Sensitivity ◽  
Chemical Society ◽  
Molar Ratio ◽  
Electron Microscopic ◽  
Sem Images ◽  
E Coli

Nanoparticles of silver and copper have been synthesized by reduction of aqueous silver  nitrate and copper chloride solutions with sodium borohydride in anionic water-in-oil  (w/o) microemulsions, sodium dodecyl sulphate (SDS)/1-pentanol/cyclohexane/water.  Scanning electron microscopic (SEM) images, energy dispersive spectra (EDX) and UVspectra  have been used to characterize the resultant nanoparticles. The average size of the  nanoparticles has been found to be influenced by the water to surfactant molar ratio (Wo)  in the microemulsions. Smaller particles are obtained at low Wo, while higher Wo yields  larger particles. The antibiotic sensitivity of silver and copper nanoparticles against  Escherichia coli (E. coli) was tested by zone inhibition method using nanoparticles in  ethanol suspension. Both silver and copper nanoparticles showed the potential for use as  antibacterial agents against E. coli with sensitivity as good as conventional antibiotics.  Silver nanoparticles show higher antibacterial activity against E. coli, compared to copper nanoparticles. As the amount of the nanoparticles in the suspension decreases, antibacterial activity decreases; however the concentration dependence on antibacterial  activity has been less pronounced. DOI: http://dx.doi.org/10.3329/jbcs.v25i1.11777 Journal of Bangladesh Chemical Society, Vol. 25(1), 71-79, 2012

scholarly journals COMPOSITES BASED ON CALCIUM PHOSPHATES AND COPPER NANOPARTICLES

2021 ◽  
pp. 320-328
Author(s):  
Ольга Николаевна Мусская ◽  
Валентина Константиновна Крутько ◽  
Анатолий Иосифович Кулак ◽  
Евгений Николаевич Крутько
Keyword(s):  
Polyethylene Glycol ◽  
Crystal Lattice ◽  
Optical Spectroscopy ◽  
Copper Nanoparticles ◽  
Colloidal Solution ◽  
Copper Ions ◽  
Calcium Phosphates ◽  
Molar Ratio ◽  
Mechanical Mixing ◽  
Polymer Stabilizers

Боргидридным методом с использованием полимерных стабилизаторов (полиэтиленгликоля, поливинилпирролидона) синтезированы наночастицы меди. Методом оптической спектроскопии установлено, что наибольшей стабильностью (до 1,5 месяца) обладают наночастицы меди, полученные при мольном соотношении Cu /полимер 1:3 - 6. Показано, что в отсутствии полимера либо при его небольшом содержании (мольное соотношение Cu /полимер 1:1) происходит агрегирование образующихся наночастиц и выпадение осадка, содержащего медь и ее оксиды (CuO, CuO). Механическим смешиванием аморфизированных фосфатов кальция (в порошковой и гелевой форме) и наночастиц меди (в виде коллоидного раствора) получен порошковый композит, содержащий фазы CaCuH(PO) и CuPOOH . Выявлено, что при совместном осаждении фосфатов кальция и наночастиц меди происходит встраивание ионов меди в кристаллическую решетку фосфатов кальция с образованием смешанных кислых и средних солей. Copper nanoparticles were synthesized by the borohydride method using polymer stabilizers (polyethylene glycol, polyvinylpyrrolidone). It was found by optical spectroscopy that copper nanoparticles obtained at a molar ratio Cu / polymer of 1: (3 - 6) have the highest stability (up to 1.5 months). It was shown that in the absence of polymer or at its low content (molar ratio Cu / polymer 1:1), the resulting nanoparticles aggregate and a precipitate forms containing copper and its oxides (CuO, CuO). By mechanical mixing of amorphized calcium phosphates (in powder and gel form) and copper nanoparticles (in the form of a colloidal solution), a powder composite containing CaCuH(PO) and CuPOOH phases was obtained. It was shown that during the coprecipitation of calcium phosphates and copper nanoparticles, copper ions are incorporated into the crystal lattice of calcium phosphates with the formation of mixed acidic and medium salts.

Achievements in the Synthesis of Elemental Silver Nanoparticles with Various Geometric Forms

2018 ◽  
Vol 15 (2) ◽  
pp. 112-128
Author(s):  
Oleg V. Mikhailov
Keyword(s):  
Silver Nanoparticles ◽  
Reducing Agents ◽  
Molar Ratio ◽  
Capping Agent ◽  
Elemental Silver ◽  
Methods Of Synthesis ◽  
Physicochemical Methods ◽  
Biological Methods ◽  
Specific Synthesis

Background:The data on the specific synthesis of elemental silver nanoparticles (Ag-NP) having the forms of various geometric bodies (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by various methods, have been systematized and generalized.Objective:It is noted that the forms and sizes of Ag-NP are greatly dependant on the conditions in which they are formed.Method:Comparison of the data of the characteristics of silver nanoparticles obtained by chemical, physicochemical and biological methods has been made.Results:It has been shown that form and size of produced Ag-NP depend strongly on the such factors as temperature, the concentration of silver(I) containing precursor, pH of the solution, the molar ratio between capping agent and silver(I) containing precursor, reducing agents etc., and, also, on the method used for Ag-NP synthesis (chemical, physicochemical or biological).It has also been noted that biological methods of synthesis of Ag-NP are generally more preferable in comparison with the chemical and physicochemical methods. The review covers mainly publications published in the last 20 years.

scholarly journals Surface-capped copper nanoadditive for improvement of base oil properties

2019 ◽  
Vol 54 (1) ◽  
pp. 1-10
Author(s):  
F Shaon ◽  
AA Rana ◽  
SM Masum ◽  
MA Ullah ◽  
MM Karim
Keyword(s):  
Copper Nanoparticles ◽  
Reduction Method ◽  
Chemical Reduction ◽  
Ultrasonic Method ◽  
Molar Ratio ◽  
Infrared Spectrometry ◽  
Carbon Chain Length ◽  
Chemical Reduction Method ◽  
Base Oil ◽  
Uniform Dispersion

Copper nanoparticles surface-capped by alkanethiol with long carbon chain length was prepared successfully by chemical reduction method. 1-dodecanethiol was used as the coating material for the desired smooth and protected surface. Various reaction parameters, like effect of pH, molar ratio of the reactants etc. had been tested experimentally to explore the most suitable and economical way of using the chemical reduction method. Uniform, smooth surface and spherical shaped copper nanoparticles, with particle size of about 40-60 nm had been produced successfully. Copper nanoparticles surface-capped by alkanethiol (C12S-Cu) was characterized by means of x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectrometry and ultraviolet-visible spectroscopy. Uniform dispersion of copper nanoadditive in base oil using ultrasonic method was investigated. The tribological behavior of C12S-Cu as an additive for base oil was evaluated. Viscosity, pour point, and flash point of nano lubricants at different concentrations of nanoadditive (0.2, and 0.5 wt %) were evaluated. Bangladesh J. Sci. Ind. Res.54(1), 1-10, 2019

Preparation and study of concentrated hydrosols of copper nanoparticles using of weak reducing agents

2015 ◽  
Vol 85 (8) ◽  
pp. 1793-1800 ◽  
Author(s):  
K. S. Murasheva ◽  
K. Yu. Kochmarev ◽  
S. A. Vorob’ev ◽  
S. V. Saikova
Keyword(s):  
Copper Nanoparticles ◽  
Reducing Agents

Lipid Polymorphism and Virus-Membrane Fusion as Observed in Vitrified Thin Films by Cryo-Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 492-493
Author(s):  
P.M. Frederik ◽  
K.N.J. Burger ◽  
M.C.A. Stuart ◽  
A.J. Verkleij
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Membrane Fusion ◽  
Film Formation ◽  
Molar Ratio ◽  
Influenza B ◽  
Complex Structures ◽  
Type Ii ◽  
Suspended Material ◽  
Cryo Electron Microscopy

Cellular membranes are often composed of phospholipid mixtures in which one or more components have a tendency to adopt a type II non-bilayer lipid structure such as the inverted hexagonal (H||) phase. The formation of a type II non-bilayer intermediate, the inverted lipid micel is proposed as the initial step in membrane fusion (Verkleij 1984, Siegel, 1986). In the various forms of cellular transport mediated by carrier vesicles (e.g. exocytosis, endocytosis) the regulation of membrane fusion, and hence of inverted lipid micel formation, is of vital importance.We studied the phase behaviour of simple and complex lipid mixtures by cryo-electron microscopy to gain more insight in the ultrastructure of different lipid phases (e.g. Pβ’, Lα, H||) and in the complex membrane structures arising after Lα < - > H|| phase changes (e.g. isotropic, cubic). To prepare hydrated thin films a 700 mesh hexagonal grid (without supporting film) was dipped into and withdrawn from a liposome suspension. The excess fluid was blotted against filter paper and the thin films that form between the bars of the specimen grid were immediately (within 1 second) vitrified by plunging of the carrier grids into ethane cooled to its melting point by liquid nitrogen (Dubochet et al., 1982). Surface active molecules such as phospholipids play an important role in the formation and thinning of these aqueous thin films (Frederik et al., 1989). The formation of two interfacial layers at the air-water interfaces requires transport of surface molecules from the suspension as well as the orientation of these molecules at the interfaces. During the spontaneous thinning of the film the interfaces approach each other, initially driven by capillary forces later by Van der Waals attraction. The process of thinning results in the sorting by size of the suspended material and is also accompanied by a loss of water from the thinner parts of the film. This loss of water may result in the concentration and eventually in partial dehydration of suspended material even if thin films are vitrified within 1 sec after their formation. Film formation and vitrification were initiated at temperatures between 20-60°C by placing die equipment in an incubator provided widi port holes for the necessary manipulations. Unilamellar vesicles were made from dipalmitoyl phosphatidyl choline (DPPC) by an extrusion method and showed a smooth (Lα) or a rippled (PB’.) structure depending on the temperature of the suspensions and the temperature of film formation (50°C resp. 39°C) prior to vitrification. The thermotropic phases of hydrated phospholipids are thus faithfully preserved in vitrified thin films (fig. a,b). Complex structures arose when mixtures of dioleoylphosphatidylethanol-amine (DOPE), dioleoylphosphatidylcholine (DOPC) and cholesterol (molar ratio 3/1/2) are heated and used for thin film formation. The tendency of DOPE to adopt the H|| phase is responsible for the formation of complex structures in this lipid mixture. Isotropic and cubic areas (fig. c,d) having a bilayer structure are found in coexistence with H|| cylinders (fig. e). The formation of interlamellar attachments (ILA’s) as observed in isotropic and cubic structures is also thought to be of importance in biological fusion events. Therefore the study of the fusion activity of influenza B virus with liposomes (DOPE/DOPC/cholesterol/ganglioside in a molar ratio 1/1/2/0.2) was initiated. At neutral pH only adsorption of virus to liposomes was observed whereas 2 minutes after a drop in pH (7.4 - > 5.4) fusion between virus and liposome membranes was demonstrated (fig. f). The micrographs illustrate the exciting potential of cryo-electron microscopy to study lipid-lipid and lipid-protein interactions in hydrated specimens.

A New Method for Plasminogen Standardization

1968 ◽  
Vol 20 (03/04) ◽  
pp. 548-554
Author(s):  
J Gajewski ◽  
G Markus
Keyword(s):  
Proteolytic Activity ◽  
Specific Activity ◽  
Molar Ratio ◽  
Sharp Transition ◽  
Equivalence Point ◽  
Constant Amount ◽  
Residual Level ◽  
Activity Measurements ◽  
Complete Saturation ◽  
Human Plasminogen

SummaryA method for the standardization of human plasminogen is proposed, based on the stoichiometric interaction between plasminogen and streptokinase, resulting in inhibition of proteolytic activity. Activation of a constant amount of plasminogen with increasing amounts of streptokinase yields linearly decreasing activities, as a function of streptokinase, with a sharp transition to a constant residual level. The point of transition corresponds to complete saturation of plasmin with streptokinase in a 1:1 molar ratio, and is therefore a measure of the amount of plasminogen present initially, in terms of streptokinase equivalents. The equivalence point is independent of the kind of protein substrate used, buffer, pH, length of digestion and, within limits, temperature. The method, therefore, is not subject to the variations commonly encountered in the usual determination based on specific activity measurements.

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