Influence Of Preparation Procedure Research Articles

Study on the surface performance strengthening of AlCrN coated cemented carbide by micro-texture laser preparation process

The combined application of coating and surface texture technology on the material surface can enhance its performance. However, the two procedure and their joint mechanism have not been fully revealed. Therefore, this paper takes the micro-textured coated cemented carbide as the research object, and focuses on the influence of preparation procedure and process parameters on surface characteristics and friction behavior. The results show that compared with the coating textured (XT) sample, the textured coating (XW) sample has more advantages in micro-hardness, microstructure and wear degree. The Rockwell hardness of the XT sample is better. Compared with the single coating sample, the coating micro-hardness of the XW sample is increased by 10 %, the Rockwell hardness is reduced by 2 %, the average grain size is reduced by 7.9 %, and the friction force is reduced by 6.2 %. Additionally, within a certain range, the increase of Al content will increase the sample hardness, reduce friction, and inhibit the Cr content and the growth of CrN phase grains. Complete process parameter optimization based on the ideal solution.

Influence of Preparation Procedure on Physicochemical and Antibacterial Properties of Titanate Nanotubes Modified with Silver

Silver nanoparticles (NPs) are effective antibacterial agents; however, aggregation of NPs and uncontrolled release of Ag+ affect their efficiency and may pose a risk to the environment. To overcome these disadvantages, immobilization of Ag onto titanate nanotubes (TNTs) was investigated. This paper describes the physicochemical and antibacterial properties of silver incorporated titanate nanotubes (Ag/TNTs) prepared using five procedures and containing different Ag amounts (0.11–30.85 wt.%). The methods were (i) sol-gel followed by a hydrothermal process; (ii) photodeposition under ambient conditions; (iii) photodeposition under an inert atmosphere; (iv) NaBH4 reduction; and (v) electroless deposition after activation of TNTs with Sn2+. Depending on the synthesis procedure, the presence of metallic Ag NPs, AgO or AgCl was observed. The electroless method led to an additional deposition of SnO2 NPs. The antibacterial properties of Ag/TNTs were analyzed as a function of Ag content and released against Escherichia coli and Staphylococcus epidermidis. The best bactericidal properties exhibited Ag/TNTs prepared through the photodeposition process due to the higher interaction of exposed Ag NPs with bacteria. An increase of Ag loading resulted in improvement of antibacterial activity of Ag/TNTs although no direct correlation between silver content or release and inhibition of bacterial growth was found.

Influence of preparation procedures on the phenolic content, antioxidant and antidiabetic activities of green and black teas

The influence of common tea preparation procedures (temperature, infusion time, consumption time interval and tea bag/loose-leaf) and the type of water used, on the total phenolic content (TPC), the radical scavenging activity and the α-glucosidase inhibitory activity were assessed. Higher TPC and antioxidant activity were obtained when using lower mineralized waters. Tea bags also evidenced higher antioxidant activity than loose-leaf samples. Under the same conditions (90 oC and five minutes of infusion time) green tea contains almost twice the quantity of polyphenols and the free radical scavenging ability of black tea. In the α-glucosidase assay all infusions were active (97-100 %). Furthermore, HPLC allowed to identify some of the polyphenols present in both teas and to monitor their composition change with time. After twenty-four hours, the antioxidant activity was maintained without significant changes, but a small decrease in enzyme inhibition was observed, although this activity was still very high.

Influence of preparation procedure and ferric oxide nanoparticles addition on transport properties of homogeneous cation-exchange SPPO/SPVC membrane

Homogeneous cation-exchange membranes were prepared through evaporation and phase inversion methods using sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) and sulfonated polyvinylchloride as binders. The effect of polymers blend’s ratio and preparation method on structure and electrochemical properties of the prepared membranes were evaluated. The microstructures of the membranes were investigated by scanning electron microscopy (SEM) and the sulfonation of polyvinylchloride was confirmed by elemental analyses. Moreover, the membranes performance was evaluated by ion-exchange capacity (IEC), fixed ion concentration, membrane potential, transport number, permselectivity, areal resistance, ionic permeability, flux of ions, current efficiency, membrane oxidative stability, mechanical properties and water content tests. The results indicated that IEC and water content were affected by the SPPO content and microstructures of the membranes. The results showed increased efficiency and suitable electrochemical properties for membranes prepared by the evaporation method in comparison with others. Also, \(\hbox {Fe}_{2}\hbox {O}_{3}\) nanoparticles were synthesized at room temperature by a simple sonochemical reaction between ferric chloride and NaOH. The results revealed that the addition of different amounts of \(\hbox {Fe}_{2}\hbox {O}_{3}\) nanoparticles to the polymeric matrix could affect the hydrophilicity and transport properties of ion-exchange membranes.

Influence of preparation procedure on catalytic activity of PdBEA zeolites in aqueous phase hydrodechlorination of 1,1,2-trichloroethene

Pd-loaded BEA zeolites containing 1 wt % of Pd were prepared by a two-step postsynthesis method (PdSiBEA and PdSiAlBEA) and a conventional wet impregnation (PdHAlBEA). Modification of BEA zeolite resulted in the introduction of Pd ions into zeolite framework as pseudo-tetrahedral Pd(II) and extra-framework octahedral Pd(II) evidenced by XRD, DR UV–vis and TPR measurements. Calcination of as prepared zeolites in air at 773 K for 3 h and then reduction in 10% H2/Ar flow at 873 K for 3 h led to obtain red-C-PdSiBEA, red-C-PdSiAlBEA and red-C-PdHAlBEA zeolites with different Pd nanoparticles size distributions showed by TEM. These zeolite materials were found to be active catalysts in aqueous-phase hydrodechlorination of 1,1,2-trichloroethene (TCE). The conducted catalytic reactions have demonstrated that the rate and course of TCE hydrodechlorination depend on the catalysts preparation method and Pd nanoparticles size.

The Influence of Preparation Procedures on Hydrogenation CO<sub>2</sub> to Formic Acid over Supported Ru Catalysts

A series of catalysts made of ruthenium loaded on γ-Al2O3 nanorods were prepared to study the effects of preparation procedure on their catalytic performances for hydrogenation CO2 to formic acid. The catalysts are characterized by XRD, nitrogen adsorption measurement and H2-TPR in detail. The results reveal that the catalytic activity is determined by the structure of supported ruthenium oxide species. The dispersion of RuOx is influenced by the preparation procedures. Optimal activity of catalyst for the hydrogenation of CO2 to formic acid is achieved over a γ-Al2O3 nanorods supported 2.0 wt% ruthenium catalyst, which is prepared by calcinations at 573 K in flowing air for 6h.

Preparation and thermal properties of chitosan/bentonite composite beads

Due to their biodegradable and nontoxic nature, biopolymer composites are often used as remarkable adsorbents in treatment of wastewater. In this study chitosan/bentonite composite beads were obtained by addition of clay into the polymer using solution process. Before the composite preparation, bentonite was modified with surfactant cetyltrimethyl ammonium bromide (CTAB). The morphology of beads was examined by scanning electron microscopy (SEM). Thermal properties of the composite beads were studied by simultaneous thermogravimetry coupled with differential scanning calorimetry (SDT) and differential scanning calorimetry (DSC). TG results showed that the complex decomposition mechanism of the composites depends on the preparation procedure. It was observed that the concentration of NaOH used for composites precipitation affects the final structure of beads. The influence of preparation procedure on the glass transition temperature Tg of chitosan/bentonite samples was not found (Tg values for all samples were about 144 ?C).

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ChemInform Abstract: Hybrid and Biohybrid Silicate Based Materials: Molecular vs. Block‐Assembling Bottom‐Up Processes

AbstractReview: 341 refs.

Host reaction against empty alginate-polylysine microcapsules. Influence of preparation procedure.

Microcapsules, prepared with alginate and polylysine, were injected intraperitoneally into mice and the number of peritoneal leucocytes as well as the cells sticking to the capsule wall were counted after 4-28 days. A significant increase in host reaction was observed when the microcapsules contained an outer layer of polylysine as compared with calcium alginate beads without polylysine or microcapsules coated with an outer layer of alginate. The alginate sources influenced the host reaction significantly. After an intraperitoneal residence of 4 days, the microcapsules were mainly surrounded by macrophages. After 28 days, several cell layers surrounded the microcapsules; macrophages, multinucleate giant cells, fibroblasts and mesothelial cells.

Hybrid and biohybrid silicate based materials: molecular vs. block-assembling bottom–up processes

This critical review introduces a discussion on the influence of preparative procedures (nanofabrication) of nanostructured hybrids and biohybrids, comparing their structural and textural characteristics that determine the properties of the resulting materials. Selected examples of silicate-based hybrids of analogous compositions prepared by both molecular and blocks-assembly bottom-up strategies are discussed to show advantages and inconveniences of each methodology (341 references).

Influence of the preparation procedure and chitosan type on physicochemical properties and release behavior of alginate–chitosan microparticles

Background: The potential for use of chitosan-treated alginate microparticles as a vehicle for oral phenytoin delivery has not been thoroughly exploited. Aim: We studied the influence of preparation procedure and chitosan type on physicochemical properties and release behavior of alginate-chitosan microparticles. Method: The total number of 24 microparticles formulations prepared by varying contents of calcium gelling ions and varying contents and type of chitosan was examined. As an additional variable, two different hardening times (1 and 24 hours) were employed. Possible interactions of components, surface morphology of microparticles as well as release profile of phenytoin were studied. Results: Both series of formulations with regard to hardening times, irrespective of the chitosan type and/or concentration employed appeared to be highly loaded with the model drug (above 90%). The drug release studies showed that the kinetics of phenytoin cannot be straightforwardly predicted based on the molecular weight of chitosan alone. On the other hand, prolonging the hardening time from 1 to 24 hours had significantly improved phenytoin kinetics, and gave rise to a formulation with the liberation half-time of about 2.5 hours. Conclusion: This study showed that the latter formulation is eligible for further modifications aimed at improving the regularity of phenytoin absorption.

Influence of preparation procedure on the conductivity and transparency of SWCNT-polymer nanocomposites

Nanostructuring of polymers has opened up new perspectives for multi-functional materials. In this paper we report on the feasibility of preparing transparent and conducting polymer nanocomposites based on poly(ethylene terephthalate) (PET) and single wall carbon nanotubes (SWCNT) as additive. Polymer nanocomposites were prepared by two different methods, direct mixing in the melt (DM) and in situ polymerization (I-SP). Samples prepared by DM show a low percolation threshold for electric conductivity, ϕ c = 0.024 wt.% of SWCNT, and are more transparent to light than samples prepared by I-SP. Particularly, a DM composite with composition just above ϕ c exhibits a conductivity of ∼10 −8 S/cm and about 70% of transmittance to visible light. Better electrical and optical properties of nanocomposites prepared by DM in relation to those prepared by I-SP can be explained by assuming that a certain level of aggregation of SWCNT favors the formation of electrical pathways and reduces the number of scatters of light, hence favoring the transmittance of the visible light through these materials.

Silica–zirconia mixed oxide samples by an hybrid materials based innovative preparation procedure: Influence of preparation procedure and composition on active sites

Abstract In this work, the interaction of amorphous silica–zirconia mixed oxide samples obtained from inorganic–organic silica-based hybrid materials with pyridine and CO2 was studied to investigate their acid/base character. Several silica–zirconia mixed oxide powders characterized by different [Zr/Si] atomic ratios were prepared and treated at increasing temperatures both in a conventional muffle and with microwave technology. The powder samples were characterized with Diffuse Reflectance Infrared Fourier Transform (DRIFT) and X-ray Photoelectron (XP) spectroscopies. The surface acidic and basic active sites were investigated (with DRIFT spectroscopy) by chemisorbing probe molecules (pyridine, carbon dioxide). The obtained results revealed the presence of both Lewis and Bronsted acidic sites on the amorphous silica–zirconia mixed oxide powder surfaces. Several acidic sites characterized by different strength were observed; the acidic sites distribution is markedly influenced by the sample composition and by the heat treatment: more numerous acidic sites form on the surface of the samples treated with microwaves with respect to the muffle treated ones; the increment of the temperature and the decrease of the zirconium content cause a significant decrement of the acidic sites. No basic sites were revealed.

Diclofenac nanosuspensions: Influence of preparation procedure and crystal form on drug dissolution behaviour

The aim of this paper was to ascertain the role of drug crystalline form and preparation procedure in nanosuspension formulations in order to optimise dissolution properties of lipophilic, poorly soluble drugs, thus improving their oral bioavailability. The non-steroidal anti-inflammatory drug diclofenac acid (DCF), which is known to exist in different crystal forms, was chosen as a model drug. To this purpose, the influence of homogenization technique was studied by preparing several nanosuspensions with two different crystalline forms of the drug (DCF1 and DCF2). Particle size and size distribution, morphology, microstructure, and thermal behaviour of the different formulations were studied by photon correlation spectroscopy (PCS), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC). Solubility studies of the bulk drug crystalline forms and dissolution experiments of nanosuspensions in comparison with different controls (bulk drug, physical mixtures, coarse suspensions) were carried out in different media: distilled water, simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Besides well known factors capable of affecting drug nanoparticle dissolution, results showed that drug dissolution rate in nanosuspensions is strongly affected by the drug solubility, which depends on the crystal form, and preparation procedure (high pressure homogenization process). Results demonstrated that this process partially transformed DCF2 in DCF1 while it did not have any effect on the DCF1 crystals.

Influence of Preparative Procedures on Assay of Platelet Function and Apparent Effects of Antiplatelet Agents

Previous studies have shown that anticoagulants alter platelet reactivity and the apparent effects of antiplatelet agents. This study was conducted to identify the impact of methods of preparation of blood samples on an assay of platelet function and the effects of antiplatelet agents. The activation of platelets was identified with the use of flow cytometry in response to thrombin (1 and 10 nmol/L), adenosine diphosphate (0.2 and 1 micromol/L), platelet activating factor (1 nmol/L), and convulxin (1 and 10 ng/ml). Antiplatelet effects were assessed after the addition in vitro of tirofiban (50 ng/ml) and cangrelor (10 nmol/L). Results were compared in whole blood and platelet-rich plasma (PRP) anticoagulated with corn trypsin inhibitor (32 microg/ml, a specific inhibitor of factor XIIa). The fraction of young platelets was quantified with thiazole orange, which identifies ribonucleic acid. The activation of platelets was consistently less in PRP compared with whole blood. Activation in PRP was 23 +/- 15% that in whole blood for thrombin, 65 +/- 26% for adenosine diphosphate, 40 +/- 20% for platelet activating factor, and 49 +/- 25% for convulxin (p <0.01 for each comparison). The fraction of young platelets in PRP was 39 +/- 11% that in whole blood (p <0.001). The effects of antiplatelet agents varied with agonist and antiplatelet agent but were generally greater in PRP compared with whole blood (p <0.05). In conclusion, platelet reactivity is lower and the effects of antiplatelet agents are greater and potentially misleading in PRP compared with whole blood. The accuracy of platelet function testing may be improved by performance in whole blood.

The influence of ionic strength, electrolyte type and preparation procedure on formation of weak polyelectrolyte complexes

The influence of ionic strength, electrolyte type and preparation procedure on formation of weak polyelectrolyte complexes formed by mixing aqueous solutions of poly(dimethylaminoethyl methacrylate) (PAMA) and poly(acrylic acid) (PAA) was investigated. For that purpose, nephelometric, electrokinetic and microcalorimetric measurements were performed. The influence of preparation procedure on formation of polyelectrolyte complexes was much more pronounced at lower ionic strength (50 mmol dm −3) than at higher ionic strength (200 mmol dm −3). The effect of KCl, NaNO 3 and phosphate buffer on weak polyelectrolyte complex formation is discussed. The obtained results are compared with earlier studies of effects of electrolyte type and ionic strength on multilayers formed by alternate adsorption of PAMA and PAA at silica surface. It has been shown that the formation of polyelectrolyte multilayers on metal oxide surface is largely governed by the phase behaviour of polyelectrolyte complexes in solutions and that the presence of different salts influences in similar manner both polyelectrolyte complex formation and polyelectrolyte multilayer formation process.

The influence of preparation procedures and tungsten loading on the metathesis activity of ethene and 2-butene over supported WO 3 catalysts

A series of catalysts composed of WO 3, γ-Al 2O 3 and HY were prepared to study the effects of preparation procedure and tungsten loading on their catalytic performances for the metathesis between ethene and 2-butene to propene. The catalysts are characterized by X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH 3-TPD), temperature-programmed reduction of hydrogen (H 2-TPR), N 2 adsorption, UV–vis and UV resonance Raman techniques. The results reveal that the catalytic activity is determined by the structure of supported tungsten oxide species. Based on the correlation between the activity and structure of tungsten oxide species, the isolated tetrahedral oxide species are suggested to be the active sites precursors, which exhibit characteristic Raman band at 970 cm −1.

Influence of preparation procedure on the surface chemistry and catalytic characteristics of FeZSM-5 zeolite in selective oxidation of benzene to phenol

The influence of preparation procedure on the nature of active centers, surface chemistry, and catalytic characteristics of FeZSM-5 zeolite in selective oxidation of benzene to phenol using N2O as an oxidizing agent was studied.

Influence of preparation procedure on polymer composition: synthesis and characterisation of polymethacrylates bearing β-D-glucopyranoside and β-D-galactopyranoside residues

Methacrylate derivatives bearing β-D-glucopyranoside and β-D-galactopyranoside residues are synthesised by glycosylation of 2-hydroxyethyl methacrylate (HEMA) with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide and 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide, respectively. β-Selectivity in the glycosylation reactions is ensured by neighbouring-group participation of acetyl groups at O-2 in the glycosyl donors. 2-(2′,3′,4′,6′-tetra-O-acetyl-β-D-glucosyloxy)ethyl methacrylate (AcGlcEMA, 1a) was obtained as a crystalline solid and its crystal structure was determined by single-crystal X-ray diffraction. Deprotected polymers are synthesised in two parallel ways; either polymerisation of the protected monomers and subsequent deacetylation of the resulting polymers, or polymerisation of the previously deprotected monomers. The number- and weight-average relative molecular masses of both the protected and deprotected polymers are determined by size exclusion chromatography (SEC). Absolute molecular masses are obtained using the previously estimated refractive-index increments, dn/dc. It is found that polymerisation of deprotected monomers leads to polymers of well-defined composition, in contrast to the deacetylation of protected polymers.