scholarly journals A rapid, high yield size-selective precipitation method for generating Au nanoparticles in organic solvents with tunably monodisperse size distributions and replaceable ligands

RSC Advances ◽  
2017 ◽  
Vol 7 (88) ◽  
pp. 55830-55834 ◽  
Author(s):  
Steven Gravelsins ◽  
Al-Amin Dhirani
Keyword(s):  
Organic Solvents ◽  
Au Nanoparticles ◽  
Precipitation Method ◽  
High Yield ◽  
Size Distributions ◽  
Selective Precipitation ◽  
Precipitation Procedure

A fast and robust size-selective precipitation procedure by non-solvent addition has been developed to fractionalize hydrophobic-ligated Au nanoparticles with tunable sizes and monodispersities.

Synthesis and Characterization of Different γ-Al2O3 Nanocatalysts for Methanol Dehydration to Dimethyl Ether

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Seyyed Ya'ghoob Hosseini ◽  
Mohammad Reza Khosravi Nikou
Keyword(s):  
Dimethyl Ether ◽  
Solid Acid Catalyst ◽  
Fixed Bed ◽  
Operating Parameter ◽  
Textural Properties ◽  
Ammonia Solution ◽  
Precipitation Method ◽  
High Yield ◽  
Methanol Dehydration ◽  
Adsorption Desorption

Abstract A simple co-precipitation method was utilized to synthesize γ-Al2O3 catalysts using aluminum nitrate nonahydrate as the source of aluminum cations for methanol dehydration to dimethyl ether (DME). Different precipitating agents comprising ammonium carbonate, ammonium bicarbonate and ammonia solutions were used for preparation of the samples. The catalysts were characterized by XRD, FTIR, SEM, NH3-TPD and N2 adsorption-desorption techniques. The sample prepared by ammonia solution had the highest acidity among the synthesized catalysts. Also, N2 adsorption-desorption results showed suitable textural properties for all of the synthesized samples. Vapor phase dehydration of methanol to DME was performed in the fixed bed micro reactor over the synthesized catalysts and commercial one for comparison purposes. The effects of different characteristics of catalysts such as surface area, acidity, sintering factor and temperature as an operating parameter on performance of catalysts were investigated. The catalyst prepared by ammonia solution showed best catalytic activity due to the suitable textural properties and high amount of acidic sites. Also, the results showed that only high acid strength can’t result high yield of DME for a solid acid catalyst.

scholarly journals A Novel Inulin-Mediated Ethanol Precipitation Method for Separating Endo-Inulinase From Inulinases for Inulooligosaccharides Production From Inulin

2021 ◽  
Vol 9 ◽  
Author(s):  
Xin Li ◽  
Qiannan Zhang ◽  
Wei Wang ◽  
Shang-Tian Yang
Keyword(s):  
Enzymatic Hydrolysis ◽  
Aspergillus Niger ◽  
Functional Food ◽  
Degree Of Polymerization ◽  
Precipitation Method ◽  
High Yield ◽  
Process Conditions ◽  
Food Ingredients ◽  
Ethanol Precipitation ◽  
Novel Method

Inulin is a kind of polysaccharide that can be obtained various biomass. Inulooligosaccharides (IOS), a kind of oligosaccharides that can be obtained from inulin by enzymatic hydrolysis using inulinases, have been regarded as the functional food ingredients. Commercially available inulinases produced by natural Aspergillus niger contained both endo- and exo-inulinase activities. For IOS production from inulin, it is desirable to use only endo-inulinase as exo-inulinase would produce mainly the monosacchairde fructose from inulin. In the present study, a simple inulin-mediated ethanol precipitation method was developed to separate endo- and exo-inulinases present in natural inulinases. IOS production from inulin using the enriched endo-inulinase was then optimized in process conditions including pH and temperature, achieving a high yield of ∼94%. The resultant IOS products had a degree of polymerization ranging from 2 to 7. The study demonstrated a novel method for obtaining partially purified or enriched endo-inulinase for IOS production from inulin in an efficient process.

Size-selective and High-yield Nanocrystal Growth of PbTe Compounds Using a Chemical Vapor Deposition Technique

2005 ◽  
Vol 886 ◽  
Author(s):  
B. Zhang ◽  
Nicholas Gothard ◽  
Jian He ◽  
Daniel Thompson ◽  
Terry M. Tritt
Keyword(s):  
Chemical Vapor ◽  
Good Control ◽  
Atomic Ratio ◽  
High Yield ◽  
Chemical Vapor Transport ◽  
Selective Precipitation ◽  
Lattice Constants ◽  
Nanocrystal Growth ◽  
Vapor Deposition Technique ◽  
Xrd Patterns

ABSTRACTThe nanocrystals of PbTe and related compounds (Pb1−xSnxTe, PbTe1−xSex), differing by size and composition, have been synthesized using a chemical vapor transport (CVD) technique. The size–selective precipitation mechanism relying on the variation of heating temperatures, Ar flow rates and admixture with Au particles, enables a relatively good control of particle size distribution. In addition, the doping ratios of those nanocrystals are readily modified by changing the atomic ratio in the raw starting materials. Subsequently, a yield of hundreds of milligrams of nanocrystals which exhibit narrow size distributions at 100 nm, 300 nm and 600 nm and controllable composition have been obtained. XRD patterns taken on the PbTe samples show sharp, which indicate good crystallinity of samples. According to the shift of the Bragg reflections, the lattice constants of (Sn / Se) doped PbTe change with the variation of the doping ratios.

Hemicelluloses Separation from Black Liquor

2012 ◽  
Vol 518-523 ◽  
pp. 589-593
Author(s):  
Yu Xin Liu ◽  
Bing Sun ◽  
Yong Zhu ◽  
Tong Zai Li
Keyword(s):  
Organic Solvents ◽  
Black Liquor ◽  
Precipitation Method ◽  
Separation System ◽  
Ft Ir ◽  
Charge Temperature ◽  
Mixed Alcohols

The black liquor from NaOH-AQ pulping of bagasse was treated by conventional alcohol precipitation method to separate hemicelluloses. In the system of alcohol/methanol, some parameters which may affect the hemicelluloses precipitation were discussed, such as mixed alcohols charge, temperature, pH and time. The obtained hemicelluloses were analyzed by FT-IR. The results showed that compared with conventional separation system of hemicelluloses by alcohol, when the Valcohol: Vmethanolwas 5:5 and pH was 4.5 at 45°C, the consumption of alcohols was decreased by 17% to 30%. Moreover, the addition of flocculants of PAC/A PAM in the process of hemicelluloses separation, the consumption of organic solvents would be further decreased.

Nucleic acid related compounds. 38. Smooth and high-yield iodination and chlorination at C-5 of uracil bases and p-toluyl-protected nucleosides

1982 ◽  
Vol 60 (5) ◽  
pp. 554-557 ◽  
Author(s):  
Morris J. Robins ◽  
Philip J. Barr ◽  
Jerzy Giziewicz
Keyword(s):  
Nucleic Acid ◽  
Organic Solvents ◽  
High Yield ◽  
Iodine Monochloride ◽  
High Yields ◽  
Related Compounds

Treatment of uracil bases and protected nucleosides with iodine monochloride (ICl) gave the corresponding 5-iodouracil products in over 95% purified yields. Analogously facile chlorination was effected with iodobenzene dichloride (PhICl2). Protection of the nucleosides as p-toluyl esters provided reactants that were soluble in organic solvents and crystallized readily in high yields.

Distribution of thiobarbituric acid-reactive substances in lipoproteins and proteins in serum.

1989 ◽  
Vol 35 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
D Bonnefont ◽  
A Legrand ◽  
J Peynet ◽  
J Emerit ◽  
J Delattre ◽  
...  
Keyword(s):  
Apolipoprotein B ◽  
Thiobarbituric Acid ◽  
Precipitation Method ◽  
High Density Lipoproteins ◽  
Separation Procedure ◽  
Serum Lipoproteins ◽  
Thiobarbituric Acid Reactive Substances ◽  
Selective Precipitation ◽  
Acid Reaction

Abstract We assessed the distribution of malondialdehyde (MDA) in lipoproteins and proteins in serum after using two procedures to separate the lipoproteins: sequential ultracentrifugation or selective precipitation with a sodium phosphotungstate and magnesium chloride reagent followed by ultracentrifugation of the supernate. MDA concentrations were determined by the thiobarbituric acid reaction and quantified by fluorometry. We found that 43% of the thiobarbituric acid-reactive substances (TBARS) was bound to the lipoproteins--27% to very-low- and low-density lipoproteins (VLDL-LDL) and 16% to high-density lipoproteins (HDL)--and from 11.5% to 15.8% to proteins, depending on the separation procedure. Residual unbound TBARS were located in the ultracentrifugation layers that contained no lipoproteins or proteins. The TBARS concentration in serum lipoproteins containing apolipoprotein B (i.e., VLDL-LDL) was the same after ultracentrifugation or selective precipitation. We therefore consider the precipitation method more suitable for routine TBARS determination in these lipoproteins, because it is easier to handle and faster. However, for determination of TBARS in HDL, selective precipitation requires subsequent ultracentrifugation at a density of 1.21 kg/L.

Quantification of high-density-lipoprotein cholesterol by precipitation with phosphotungstic acid/MgCl2.

1983 ◽  
Vol 29 (12) ◽  
pp. 2026-2030 ◽  
Author(s):  
G Assmann ◽  
H Schriewer ◽  
G Schmitz ◽  
E O Hägele
Keyword(s):  
High Density Lipoprotein ◽  
High Performance ◽  
Phosphotungstic Acid ◽  
Density Lipoprotein ◽  
High Density ◽  
Precipitation Method ◽  
Lipoprotein Subfractions ◽  
Precipitation Procedure ◽  
High Density Lipoprotein Subfractions ◽  
Layer Chromatography

Abstract We evaluated the use of a modified phosphotungstic acid/MgCl2 precipitation procedure for the precipitation of apolipoprotein B-containing lipoproteins. Precipitation of these lipoproteins [very-low- and low-density lipoproteins, and lipoprotein (a)] is complete, with negligible coprecipitation of high-density lipoprotein subfractions (HDL1, HDL2, HDL3), even in hypertriglyceridemic sera. In comparison with ultracentrifugation, the precipitation method yields, on the average, values that are 0.17 mmol/L lower for cholesterol values but almost identical for apolipoprotein A-I and phosphatidylcholine. Looking for delta 3,5-cholestadiene formed from cholesterol in the precipitation residue, we used "high-performance" liquid chromatography and "high-performance" thin-layer chromatography and found none.

Biogenic Synthesized Ag/Au Nanoparticles: Production, Characterization, and Applications

2018 ◽  
Vol 14 (2) ◽  
pp. 82-94 ◽  
Author(s):  
Nelson Duran ◽  
Amedea B. Seabra
Keyword(s):  
Au Nanoparticles ◽  
Cost Effective ◽  
Industrial Applications ◽  
Shell Structures ◽  
Size Distributions ◽  
Biological Applications ◽  
Biogenic Synthesis ◽  
Au Nps ◽  
Potential Applications ◽  
Scientific Attention

Background: Bimetallic silver-gold nanoparticles (Ag/Au NPs) with different structures have recently gained scientific attention due to their new and superior properties in comparison with metallic NPs made from a single metal. Ag/Au NPs (alloy or core-shell structures) have been applied to several biomedical, technological, and environmental applications. The potential applications of Ag/Au NPs are widespread yet poorly investigated in comparison with monometallic NPs. Besides traditional chemical and physical routes to synthesize bimetallic Ag/Au NPs, biogenic protocols are considered cost-effective, simple, and environmentally friendly. Despite their simplicity, biogenic routes to synthesize Ag/Au NPs are less explored than traditional synthetic protocols. Methods: In this context, we present a review and discuss recent progress in the preparation of bimetallic Ag/Au NPs with different morphologies, structures, and size distributions using biogenic synthetic protocols. Results: Biogenic synthesis using plant extracts, algae, bacteria, fungi, and other biological agents are presented and discussed. The characterization and potential applications of biogenically synthesized Ag/Au NPs in the different areas of medicine and biological applications, such as antibacterial, anticandidal, anticancer, antidiabetes, and as sensors for clinical diagnosis are presented and discussed. Conclusion: Finally, challenges and drawbacks in the biological routes for the preparation of Ag/Au NPs for industrial applications are also discussed.

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