scholarly journals Optimization of the synthesis parameters of nanocomposites based on bacterial nanocellulose/Fe3O4

Tehnika ◽  
2021 ◽  
Vol 76 (3) ◽  
pp. 273-278
Author(s):  
Aleksandra Janićijević ◽  
Aleksandra Sknepnek ◽  
Miljana Mirković ◽  
Vladimir Pavlović ◽  
Suzana Filipović
Keyword(s):  
Scientific Community ◽  
Time Interval ◽  
Iron Salt ◽  
Bacterial Nanocellulose ◽  
Synthesis Conditions ◽  
Structure And Morphology ◽  
Synthesis Parameters ◽  
Acetic Fermentation ◽  
Engineering And Technology ◽  
The Matrix

Development in many areas of engineering and technology are closely linked to the development of new or improvement of existing materials. Having in mind wide use of bacterial nanocellulose (BNC) in various areas of everyday life, from biomedicine, ecology to electronics, BNC-based composites are becoming widely used and attracting the attention of the scientific community. It is especially important to examine in detail the synthesis parameters that affect the changes in the crystal structure and morphology of the obtained composites, having in mind that these changes have a crucial influence on their final functional properties. In this paper, a composite material based on bacterial nanocellulose BNC (as the matrix) and ferromagnetic Fe3O4 was studied. BNC was obtained by the activity of acetic fermentation bacteria after 7 days of growth in a suitable medium. The research is aimed to optimization of the Fe3O4 precipitation conditions. It's especially considering the time interval of BNC films spend in the iron salt solution. The influence of the performed synthesis conditions was considered by the SEMEDS, FTIR and XRD methods.

scholarly journals Residue-Residue Mutual Work Analysis of Retinal-Opsin Interaction in Rhodopsin: Implications for Protein-Ligand Binding

2019 ◽  
Author(s):  
Wenjin Li
Keyword(s):  
Virtual Work ◽  
Interaction Matrix ◽  
Time Interval ◽  
Transition Path ◽  
Transition Path Sampling ◽  
Decomposition Approach ◽  
Work Analysis ◽  
Nmr Study ◽  
The Matrix ◽  
Dynamics Simulations

AbstractEnergetic contributions at single-residue level to retinal-opsin interaction in rhodopsin were studied by combining molecular dynamics simulations, transition path sampling, and a newly developed energy decomposition approach. The virtual work at an infinitesimal time interval was decomposed into the work components on one residue due to its interaction with another residue, which were then averaged over the transition path ensemble along a proposed reaction coordinate. Such residue-residue mutual work analysis on 62 residues within the active center of rhodopsin resulted in a very sparse interaction matrix, which is generally not symmetric but anti-symmetric to some extent. 14 residues were identified to be major players in retinal relaxation, which is in excellent agreement with an existing NMR study. Based on the matrix of mutual work, a comprehensive network was constructed to provide detailed insights into the chromophore-protein interaction from a viewpoint of energy flow.

scholarly journals SINTEZA I STRUKTURA BAKTERIJSKE CELULOZE PRIMENOM BAKTERIJA SIRĆETNOG VRENJA

2021 ◽  
Author(s):  
Aleksandra Janicijevic ◽  
◽  
Suzana Filipovic ◽  
Vladimir B. Pavlovic ◽  
Aleksandra Sknepnek ◽  
...  
Keyword(s):  
Ftir Spectroscopy ◽  
Everyday Life ◽  
Bacterial Cellulose ◽  
Food Industry ◽  
Cellulose Fibers ◽  
Time Intervals ◽  
Structure And Morphology ◽  
Synthesis Parameters ◽  
Naoh Treatment

As one of the most common biopolymers on Earth, cellulose has found an important role in food industry, biomedicine andbiotechnology. The process of obtaining cellulose fibers is often followed with the presence of the byproduct, whose removal is required procedure. From that reason, the process of obtaining material on a bacterial cellulose (BC) basis,finds wide application in everyday life. Having in mind her many features, we have investigated the change in structure and morphology of BC depending on the synthesis parameters. The influence of the medium volume and different time intervals of NaOH treatment relative to different BCN yields and structure. The mentioned changes were examined by XRD, FTIR spectroscopy, as well as SEM and EDS analyzes.

Effect of Catalyst Synthesis Parameters on the Performance of CO2 Hydrogenation to Methanol over SBA-15 Supported Cu/ZnO-Based Catalysts

2020 ◽  
Vol 400 ◽  
pp. 159-169
Author(s):  
Sara F.H. Tasfy ◽  
Noor Asmawati Mohd Zabidi ◽  
Maizatul Shima Shaharun ◽  
Duvvria Subbarao
Keyword(s):  
Surface Area ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bet Surface Area ◽  
Methanol Production ◽  
Synthesis Conditions ◽  
Metal Loading ◽  
Synthesis Parameters ◽  
Metal Support Interaction ◽  
Active Metal

Bimetallic Cu-ZnO-based catalyst were systematically prepared via impregnation technique under controlled synthesis conditions of active metal loading, ratio of active metal Cu:Zn and synthesis pH. The effect of the synthesis condition on the performance of the Cu-ZnO supported catalysts with respect to the hydrogenation of CO2 to methanol in micro-activity fixed-bed reactor at 250°C, 2.25 MPa, and 75% H2/25%CO2 ratio. The synthesized catalysts were characterized by transmission electron microscopy (TEM) and temperature programmed desorption, reduction, oxidation and pulse chemisorption (TPDRO) and the surface area determination was also performed. The results demonstrate that the catalytic structure, activity, and methanol selectivity was strongly affected by the synthesis parameters. Increasing of synthesis pH from 1 to 7 shows better metal particles distribution, Cu desperation of 29%, higher BET surface area as well as Cu surface area, while further increasing on pH revealed on particles agglomeration and weak metal-support interaction. In addition, increasing of the active metal loading from 5 to 15 % resulted in dramatic increase in the conversion of CO2 and methanol production while further increase caused lower catalytic performance. Moreover, catalyst with total loading of 15%, Cu:Zn ratio of 70:30 synthesized at pH of 7 exhibit higher catalytic activity of 14%, methanol selectivity of 92%, and TOF of 1.24×103 s-1 compared with other catalyst prepared under various conditions

Effect of the Sol-Gel Synthesis Parameters on the Incorporation of an Anti-inflammatory Drug in a Ceramic Material

2007 ◽  
Vol 1007 ◽  
Author(s):  
Aracely Hernandez ◽  
Patricia Esquivel-Ferriño ◽  
Idalia Gomez ◽  
Lucia Cantu
Keyword(s):  
Ceramic Material ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Molar Ratio ◽  
Inflammatory Drug ◽  
Synthesis Conditions ◽  
Synthesis Parameters ◽  
Anti Inflammatory ◽  
Drug Incorporation ◽  
Sol Gel Synthesis

ABSTRACTIn the present work, sol-gel method was used to incorporate in a ceramic material a non steroidal anti-inflammatory drug (piroxicam) as model drug. The incorporation of the drug in the SiO2 network was carried out at different sol-gel synthesis parameters, such as pH (3 and 5) and the alkoxide/water ratio (1:6 and 1:8). The biomaterial obtained was analyzed by thermal analysis TGA-DTA, infrared spectroscopy (FTIR), Scanning Electronic Microscopy (SEM) and X-ray diffraction (XRD); specific surface area and porosity were analyzed from nitrogen adsorption isotherm. Better drug incorporation into the material was achieved at the synthesis conditions of pH 5 and 1:6 alkoxide/water molar ratio.

An Assessment of Chemical Vapor Deposition Synthesis of SnO2 Nanowires by Statistical Design

2016 ◽  
Vol 701 ◽  
pp. 52-56 ◽  
Author(s):  
Maisara Azad Mat Akhir ◽  
Khairudin Mohamed ◽  
Sheikh Abdul Rezan ◽  
Hooi Ling Lee ◽  
Siti Suhaila M. Izah
Keyword(s):  
Chemical Vapor Deposition ◽  
Flow Rate ◽  
Vapor Deposition ◽  
Deposition Time ◽  
Statistical Design ◽  
Chemical Vapor ◽  
Synthesis Conditions ◽  
Synthesis Parameters ◽  
Cvd Synthesis ◽  
Temperature Deposition

This paper studies the chemical vapor deposition (CVD) synthesis conditions for tin oxide (SnO2) nanowires (NWs) by using statistical design of experiment (DOE). The influences of synthesis parameters (growth temperature, deposition time and flow rate of argon) on SnO2 NWs diameter were studied. From perturbation analysis with DOE, it was found that temperature gave the most significant effect to the diameter of SnO2 NWs via CVD method followed by flowrate of argon and deposition time. Furthermore, based on the cube graph, the smallest SnO2 NWs (~18 nm) can be obtained at temperature of 850 °C with argon flow rate of 100 sccm using a deposition time of 60 min. On the other hand, the largest SnO2 NWs (~248 nm) can be produced at 900 °C.

Renormalization of the transformation operators of quantum electrodynamics

1954 ◽  
Vol 227 (1168) ◽  
pp. 94-102
Keyword(s):  
Quantum Electrodynamics ◽  
Matrix Theory ◽  
Transformation Operator ◽  
Time Interval ◽  
Matrix Elements ◽  
Finite Time Interval ◽  
Time Intervals ◽  
Starting Point ◽  
The Matrix ◽  
Long Time

The transformation operator of electrodynamics for a finite time interval with uncertain boundaries is represented by a continuous switching on and off of the charge. It is shown that its divergencies are the same as those appearing in the S matrix theory, and a covariant procedure is given for isolating their infinite parts. Provided Gupta’s renormalized Lagrangian is used as a starting point all the infinities may be removed. The coefficients of the counter terms are power series in the time-dependent charge with coefficients that are independent of the time interval being considered. The practice of approximating the matrix elements of the transformation operators for long time intervals by matrix elements of the S matrix is discussed and justified. In an appendix the extension of these results to the renormalizable meson theories is discussed.

scholarly journals The effect of magnetite nanoparticles synthesis conditions on their ability to separate heavy metal ions

2017 ◽  
Vol 43 (2) ◽  
pp. 3-9 ◽  
Author(s):  
Magdalena Bobik ◽  
Irena Korus ◽  
Lidia Dudek
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Magnetite Nanoparticles ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Average Crystallite Size ◽  
Iron Oxide Particles ◽  
Synthesis Conditions ◽  
Synthesis Parameters ◽  
Co Precipitation

Abstract Magnetite nanoparticles have become a promising material for scientific research. Among numerous technologies of their synthesis, co-precipitation seems to be the most convenient, less time-consuming and cheap method which produces fine and pure iron oxide particles applicable to environmental issues. The aim of the work was to investigate how the co-precipitation synthesis parameters, such as temperature and base volume, influence the magnetite nanoparticles ability to separate heavy metal ions. The synthesis were conducted at nine combinations of different ammonia volumes - 8 cm3, 10 cm3, 15 cm3 and temperatures - 30°C, 60°C, 90°C for each ammonia volume. Iron oxides synthesized at each combination were examined as an adsorbent of seven heavy metals: Cr(VI), Pb(II), Cr(III), Cu(II), Zn(II), Ni(II) and Cd(II). The representative sample of magnetite was characterized using XRD, SEM and BET methods. It was observed that more effective sorbent for majority of ions was produced at 30°C using 10 cm3 of ammonia. The characterization of the sample produced at these reaction conditions indicate that pure magnetite with an average crystallite size of 23.2 nm was obtained (XRD), the nanosized crystallites in the sample were agglomerated (SEM) and the specific surface area of the aggregates was estimated to be 55.64 m2·g-1 (BET). The general conclusion of the work is the evidence that magnetite nanoparticles have the ability to adsorb heavy metal ions from the aqueous solutions. The effectiveness of the process depends on many factors such as kind of heavy metal ion or the synthesis parameters of the sorbent.

Production of Zirconium Aluminides by Self-Propagating High-Temperature Synthesis

2018 ◽  
Vol 769 ◽  
pp. 66-71 ◽  
Author(s):  
Oleg Yu. Dolmatov ◽  
Daniil K. Kolyadko ◽  
Nikita O. Pimenov ◽  
Stanislav S. Chursin
Keyword(s):  
Matrix Material ◽  
Chemical Processes ◽  
Optimal Parameters ◽  
Synthesis Conditions ◽  
High Temperature Synthesis ◽  
The Matrix ◽  
Basic Characteristics ◽  
Physical And Chemical ◽  
The Impact ◽  
Shs Method

This work presents the possibility of carrying out the SH-synthesis of materials based on intermetallic zirconium-aluminium compounds. This material can be used as the matrix material of dispersion nuclear fuel. As the result of experiments on the synthesis of zirconium aluminide by the SHS-method, the technological features and basic characteristics of physical and chemical processes have been identified. During the synthesis, the temperature distributions along the volume of samples and the impact of synthesis conditions on the phase composition of finished product were analyzed. Also, the optimal parameters for the production of specific phases of zirconium aluminides have been stated. In this paper, a material with a content of intermetallic Al2Zr and Al3Zr of more than 90 percent was obtained.

Correlations Between Conditions of Synthesis, Phase Composition and Luminescent Properties of Eu - Polytantalate

2003 ◽  
Vol 796 ◽  
Author(s):  
Vladimir Vasilyev ◽  
Alvin Drehman ◽  
Lionel Bouthillette
Keyword(s):  
Phase Composition ◽  
Luminescent Properties ◽  
Luminescent Materials ◽  
Temperature Dependent ◽  
Sintered Ceramic ◽  
X Ray ◽  
Synthesis Conditions ◽  
Ceramic Thin Films ◽  
Synthesis Parameters ◽  
Temperature Dependent Photoluminescence

ABSTRACTCorrelations between synthesis conditions, phase composition, and spectral properties of the sintered ceramic, thin films and single crystals of EuTa7O19 phosphors have been studied using x-ray diffractometry and temperature dependent photoluminescence (PL) spectroscopy at temperatures between 18 K and 650 K. From the PL spectra of Eu3+, one can obtain information about the area of homogeneity of phases, their temperature transformations, and changes in the bonding character in the neighborhood of the luminescent ion. As a result, this information helps to optimize the synthesis parameters for luminescent materials.

Reanalysis of Some CLUSTER Bow-Shock Crossings With an Optimized Timing Method

2020 ◽  
Author(s):  
Gérard M. Chanteur
Keyword(s):  
Condition Number ◽  
A Priori ◽  
Time Lag ◽  
Bow Shock ◽  
Time Interval ◽  
Normal Vector ◽  
Time Lags ◽  
The Matrix ◽  
Pseudo Inverse

<p>When a shock is moving through a cluster of spacecraft, the normal N to the shock and the velocity of the shock along N can be determined from the crossing times of the different spacecraft assuming that the shock is planar and moves without deformation or rotation during the time interval of the encounter. For a cluster of four spacecraft there are six pairs of spacecraft, each one giving raise to a scalar equation relating the vector position R from the first to the second spacecraft, the normal vector N and the time lag Dt : R.N=VDt. This over-determined system of six equations is solved by computing the pseudo inverse of the matrix M acting on the normal vector on the lhs of the equation. Thus the system is modified by attributing a priori a positive weight to each equation (wj, j=1 to 6) the sum being constrained to 1. Then a statistical ensemble of 6-uplets (wj, j=1 to 6) is built ; for each element of this ensemble we compute the condition number of matrix M and we look for the 6-uplet giving the lowest condition number. This procedure warrants the best accuracy of the pseudo-inverse of M and hence the best estimate of the normal vector N. Adding random perturbations to M and to the time lags allows to estimate the uncertainties on N and V through simulations. This optimized timing method is applied to reanalyze some crossings of the terrestrial bow-shock by CLUSTER and the results are compared to the results obtained by the standard method using the reciprocal vectors defined in the ISSI report SR-008 « Multi-Spacecraft Analysis Methods Revisited » published in 2008. A similar method has been applied to the determination of wave vectors of chorus elements observed by MMS in the inner magntosphere.</p>

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