On the development of a continuous methodology to fractionate microfibriallated cellulose

AbstractThe focus of this study is the development of a methodology to mechanically separate or fractionate micro-fibrillated fibre suspensions (MFC) into different size classes. We extend the principle outlined by Madani et al. (2010) and create a continuous separation in an annular gap undergoing spiral Poiseuille flow (solid body rotation superimposed on pressure driven flow). Achieving hydrodynamic stability of this flow was the main scientific challenge for scale-up. This work is presented in two different studies. In the first study, we perform a series of batch-wise centrifugation tests to develop the criteria for motion of the individual classes of particles which compose a Eucalyptus MFC suspension. Here, we suspend the MFC in a weak gel and demonstrate a linear reduction in average particle size with increasing centrifugal force; motion is initiated in heavier particles before the lighter ones. In the second study, we use this batch-wise data to design a continuous prototype and we successfully demonstrate a continuous separation with performance similar to that achieved in the batch-wise tests.

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Azithromycin nanosuspension preparation using evaporative precipitation into aqueous solution (EPAS) method and its comparative dissolution study

Current Pharmaceutical Analysis ◽

10.2174/1573412917999200909145745 ◽

2020 ◽

Vol 17 ◽

Author(s):

Mohammad Hossain Shariare ◽

Tonmoy Kumar Mondal ◽

Hani Alothaid ◽

Md. Didaruzzaman Sohel ◽

MD Wadud ◽

...

Keyword(s):

Aqueous Solution ◽

Particle Size ◽

Dissolution Rate ◽

Average Particle Size ◽

Scale Up ◽

Average Particle ◽

Total Drug ◽

Residual Solvent ◽

Dissolution Study ◽

Drug Content

Aim: EPAS (evaporative precipitation into aqueous solution) was used in the current studies to prepare azithromycin nanosuspensions and investigate the physicochemical characteristics for the nanosuspension batches with the aim of enhancing the dissolution rate of the nanopreparation to improve bioavailability. Methods: EPAS method used in this study for preparing azithromycin nanosuspension was achieved through developing an in-house instrumentation method. Particle size distribution was measured using Zetasizer Nano S without sample dilution. Dissolved azithromycin nanosuspensions were also compared with raw azithromycin powder and commercially available products. Total drug content of nanosuspension batches were measured using an Ultra-Performance Liquid Chromatography (UPLC) system with Photodiode Array (PDA) detector while residual solvent was measured using gas chromatography (GC). Results: The average particle size of azithromycin nanosuspension was 447.2 nm and total drug content was measured to be 97.81% upon recovery. Dissolution study data showed significant increase in dissolution rate for nanosuspension batch when compared to raw azithromycin and commercial version (microsuspension). The residual solvent found for azithromycin nanosuspension is 0.000098023 mg/ mL or 98.023 ppb. Conclusion: EPAS was successfully used to prepare azithromycin nanoparticles that exhibited significantly enhanced dissolution rate. Further studies are required to scale up the process and determine long term stability of the nanoparticles.

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Synthesis and characterization of the aluminium phosphates modified with ammonium, calcium and molybdenum by hydrothermal method

Polish Journal of Chemical Technology ◽

10.1515/pjct-2016-0040 ◽

2016 ◽

Vol 18 (2) ◽

pp. 131-139

Author(s):

Kinga Łuczka ◽

Barbara Grzmil ◽

Bogumił Kic ◽

Krzysztof Kowalczyk

Keyword(s):

Particle Size ◽

Physicochemical Parameters ◽

Average Particle Size ◽

Synthesis And Characterization ◽

Average Particle ◽

Influence Of Process Parameters ◽

Molar Ratios ◽

Aluminum Phosphates ◽

The Individual

Abstract Synthesis and characterization of the aluminum phosphates modified with ammonium, calcium and molybdenum were conducted. The influence of process parameters (reactive pressure and molar ratios) in the reaction mixture were studied. The contents of the individual components in the products were in the range of: 10.97–17.31 wt% Al, 2.65–13.32 wt% Ca, 0.70–3.11 wt% Mo, 4.36–8.38 wt% NH3, and 35.12–50.54 wt% P2O5. The materials obtained in the experiments were characterized by various physicochemical parameters. The absorption oil number was in the range from 67 to 89 of oil/100 g of product, the surface area was within the range of 4–76 m2/g, whereas the average particle size of products reached 282–370 nm. The Tafel tests revealed comparable anticorrosive properties of aluminum phosphates modified with ammonium, calcium, molybdenum in comparison with commercial phosphate.

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Zeta Potential Studies of Titanium Dioxide and Silver Nanoparticle Composites in Water-Based Colloidal Suspension

Multifunctional Nanocomposites ◽

10.1115/mn2006-17072 ◽

2006 ◽

Cited By ~ 1

Author(s):

Assaf Azouri ◽

Ming Ge ◽

Kun Xun ◽

Klaus Sattler ◽

Joe Lichwa ◽

...

Keyword(s):

Zeta Potential ◽

Charge Exchange ◽

Colloidal Suspension ◽

Average Particle Size ◽

Effective Diameter ◽

Average Particle ◽

Tio2 Particles ◽

Ag Particles ◽

The Individual ◽

Ph Curve

We determine the zeta potential (ZP) by using electrophoretic laser light scattering and Laser Doppler Velocimetry (LDV). Particle sizes are measured by photon correlation spectroscopy (PCS). We studied the ZP for colloidal suspensions of TiO2 and Ag metal particles in order to determine the kinetic interaction and charge exchange between the particles. We investigated the natural tendency of the particles for aggregation and varied the pH of the solution. It was found that the ZP versus pH curve for the mixed TiO2/Ag did not behave as the average of the individual TiO2 and Ag curves as one would expect, and instead there was a slight horizontal shift towards higher pH values which implies that the particles in the mixed TiO2/Ag colloid are interacting with the result of charge exchange. The average particle size was measured in terms of effective diameter, for the TiO2, Ag and the mixed TiO2/Ag particles. The results indicated an increase of approximately 100 nm in the effective diameter of the mixed TiO2/Ag particles size compared to the size of the individual TiO2 particles. This can be explained as the fact that 50 nm Ag particles are adsorbed on the surface of the TiO2 particles.

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Development and Characterization of Polyphenon 60 and Caffeine Microemulsion for Enhanced Antibacterial Activity

BioMed Research International ◽

10.1155/2014/932017 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

Sonal Gupta ◽

Rakhi Bansal ◽

Javed Ali ◽

Reema Gabrani ◽

Shweta Dang

Keyword(s):

Antibacterial Activity ◽

Mammalian Cells ◽

Average Particle Size ◽

Natural Compounds ◽

Average Particle ◽

Tem Analysis ◽

E Coli ◽

Vero Cell Line ◽

Effective Delivery ◽

The Individual

Green tea catechins and caffeine have exhibited antibacterial activity; however, their use is limited by lack of stability and effective delivery systems. Polyphenon 60 (P60) and caffeine were encapsulated in a single microemulsion (ME) formulation with an objective to lower the minimum inhibitory concentrations (MICs) of the individual agents against selected pathogens (S. epidermidisandE. coli). Combination of two natural compounds would advocate two different mechanisms on the bacterial growth thereby providing for better antibacterial activity. Thermodynamically stable ME was developed and characterized with an average particle size of 17.58 nm, further confirmed by TEM analysis. Antibacterial studies included chequerboard microdilution assay to determine the MIC and fractional inhibitory concentration (FIC) of both the natural compounds individually and in combination. MIC and FIC results indicated that the combination of the above two natural compounds was proficient in lowering the MICs of individual agents. Results of DPPH assay indicated that ME system preserved the long term antioxidative potential of P60 and caffeine. The cytotoxicity of the optimized formulation on Vero cell line by MTT assay was found to be nontoxic to mammalian cells.

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The Influence of Nanofiller Shape and Nature on the Functional Properties of Waterborne Poly(urethane-urea) Nanocomposite Films

Polymers ◽

10.3390/polym12092001 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2001

Author(s):

Milena Špírková ◽

Jiří Hodan ◽

Rafał Konefał ◽

Luďka Machová ◽

Pavel Němeček ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Particle Size ◽

Average Particle Size ◽

Degradation Process ◽

Nanocomposite Films ◽

Chain Extension ◽

Hydroxyl Groups ◽

Average Particle ◽

Internal Arrangement ◽

The Individual

A series of waterborne polycarbonate-based poly(urethane-urea) nanocomposite films were prepared and characterized. An isocyanate excess of 30 mol% with respect to the hydroxyl groups was used in the procedure, omitting the chain-extension step of the acetone process in the dispersion preparation. The individual steps of the synthesis of the poly(urethane-urea) matrix were followed by nuclear magnetic resonance (NMR) spectroscopy. The nanofillers (1 wt% in the final nanocomposite) differed in nature and shape. Starch, graphene oxide and nanocellulose were used as representatives of organic nanofillers, while halloysite, montmorillonite, nanosilica and hydroxyapatite were used as representatives of inorganic nanofillers. Moreover, the fillers differed in their shape and average particle size. The films were characterized by a set of methods to obtain the tensile, thermal and surface properties of the nanocomposites as well as the internal arrangement of the nanoparticles in the nanocomposite film. The degradation process was evaluated at 37 °C in a H2O2 + CoCl2 solution.

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Biogenic Synthesis of Silver Nanoparticles Mediated by the Consortium Comprising the Marine Fungal Filtrates of Penicillium Oxalicum and Fusarium Hainanense Along With Their Antimicrobial, Antioxidant and Larvicidal Potency

10.21203/rs.3.rs-1115139/v1 ◽

2021 ◽

Author(s):

Rashmi Thakor ◽

Harsh Mistry ◽

Hitesh Patel ◽

Himanshu S Bariya

Keyword(s):

Silver Nanoparticles ◽

Radical Scavenging Activity ◽

Average Particle Size ◽

Radical Scavenging ◽

Penicillium Oxalicum ◽

Average Particle ◽

Fungal Isolates ◽

Ability To Act ◽

The Individual ◽

Cell Free Filtrate

Abstract The silver nanoparticles were biosynthesized using fungal isolates as well as their mixed cell free filtrate acting as a consortium namely, DS-2 (Penicillium oxalicum), DW-8 (Fusarium hainanense) and DSW-28, respectively. The UV-Visible spectra determined the surface plasmon resonance at 438, 441 and 437 nm for the silver nanoparticles synthesized by DS-2, DW-8 and DSW-28, respectively. The Tauc’s plot analysis disclosed the band gap energy between 2.21 eV to 2.24 eV which depicted their ability to act as a semiconductor. The TEM imaging revealed the spherical shape along with the average particle size of DS-2 as 11.14 ± 2.39 nm and DW-8 as 7.59 ± 1.31 nm whereas that of DSW-28 as 5.73 ± 0.4 nm. Thus, the silver nanoparticles synthesized by DSW-28 were smaller in size than the individual isolates. The XRD pattern of the silver nanoparticles exhibited the crystalline structure corresponding to their peaks. The FTIR spectra indicates the presence of different functional groups on the surface of the synthesized silver nanoparticles. The broad-spectrum antimicrobial activity was exhibited by silver nanoparticles synthesized by DSW-28 against Gram positive, Gram negative bacteria and plant pathogen Fusarium oxysporum than the individual fungal isolates. The DSW-28 synthesized silver nanoparticles also acts as an effective antioxidant by depicting their radical scavenging activity against DPPH. Moreover, the silver nanoparticles synthesized by DSW-28 also inhibited the growth of 4th instar larvae of Aedes aegypti and Culex quinquefasciatus more efficiently than DS-2 and DW-8 in a dose-dependent method. The impressive bioactivity of the silver nanoparticles synthesized by the mixture of cell free filtrate of various fungi acting as a consortium recommends their prospective use in agriculture as well as in biomedical as an antimicrobial, antioxidant and larvicidal agents in future.

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Production of fine zinc borate in industrial scale

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq120224031c ◽

2012 ◽

Vol 18 (4-1) ◽

pp. 547-553 ◽

Cited By ~ 6

Author(s):

Gaye Çakal

Keyword(s):

Particle Size ◽

Average Particle Size ◽

Scale Up ◽

Lag Time ◽

Pilot Scale ◽

Zinc Borate ◽

Industrial Scale ◽

Process Conditions ◽

Average Particle ◽

Scale Production

In this study, zinc borate production in an industrial scale batch reactor was carried out at the optimum process conditions determined in the previous studies performed at the laboratory and pilot scale reactors. The production was done via the heterogeneous reaction of boric acid and zinc oxide. The samples were characterized by chemical analysis, XRD, TGA, SEM and particle size distribution. The final product which was obtained in the industrial scale reactor was 2ZnO.3B2O3.3H2O. The kinetic data for the zinc borate production reaction fit to a modified logistic model where the lag time was taken into account. As observed, the reaction time was influenced by scaling up. There was a lag time of 120 min for the industrial scale production and thus, the reaction completion time was 70 min longer compared to pilot scale. It should be emphasized that the specific reaction rate, k; as well as the average particle size and the hydration temperature of zinc borate are unaffected by scale up.

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Development of Semiliquid Ingredients from Grape Skins and Their Potential Impact on the Reducing Capacity of Model Functional Foods

Journal of Food Quality ◽

10.1155/2018/1969680 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9

Author(s):

Milan Stojanovic ◽

Laura Marinoni ◽

Giovanni Cabassi ◽

Malisa Antic ◽

Vera Lavelli

Keyword(s):

Functional Foods ◽

Average Particle Size ◽

High Energy ◽

Average Particle ◽

Phenolic Contents ◽

Freeze Dried ◽

Grape Skins ◽

The Individual ◽

Reducing Capacity

Grape skins (GS), which can be considered as reusable coproducts of winemaking, were processed to develop semiliquid ingredients for functional foods, as an alternative to powdered GS, which needs high energy input for drying. Processing of semiliquid GS ingredients included blanching, dilution to obtain dispersions with 2% or 10% of dry solids, milling, homogenization, and pasteurization. The individual phenolic contents and in vitro ferric ion reducing capacity (FRAP) of semiliquid GS ingredients were compared with those of air-dried and freeze-dried GS. With respect to freeze-dried GS, the recovery of FRAP values was ~75% for both air-dried GS and 2% GS dispersion and 59% for 10% GS dispersion. The average particle size diameters of solids in semiliquid GS ingredients were similar to those observed in commercial apple skin products. Possible applications of GS semiliquid ingredients to increase the reducing capacity of food 10 times include formulation into beverages and ice-type desserts and use in bakery products.

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Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽

10.1557/adv.2020.370 ◽

2020 ◽

Vol 5 (57-58) ◽

pp. 2961-2972

Author(s):

P.C. Meléndez-González ◽

E. Garza-Duran ◽

J.C. Martínez-Loyola ◽

P. Quintana-Owen ◽

I.L. Alonso-Lemus ◽

...

Keyword(s):

Catalytic Activity ◽

Anion Exchange ◽

Average Particle Size ◽

Synthesis Method ◽

Alkaline Media ◽

High Catalytic Activity ◽

Average Particle ◽

Carbon Spheres ◽

Hollow Carbon ◽

Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

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A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

MRS Proceedings ◽

10.1557/proc-721-e3.7 ◽

2002 ◽

Vol 721 ◽

Author(s):

Monica Sorescu

Keyword(s):

Room Temperature ◽

Average Particle Size ◽

Direct Determination ◽

Average Particle ◽

Lattice Method ◽

Recoilless Fraction ◽

Single Room ◽

Magnetite Particles ◽

Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

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