Effect Of Preparation Technique Research Articles

Porous biochar derived from tea saponin for supercapacitor electrode: Effect of preparation technique

Biochar is widely employed as an electrode of supercapacitor. In this work, one-step pyrolysis and chemical activation method were introduced to prepare porous biochars from tea saponin (TS). The performance differences of biochars prepared by two methods were studied. On this basis, further researches were carried out to explore the influence of the mass ratio of KOH/pre-carbonized precursor on the structure and electrochemical performance of the biochars. All samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Raman spectra, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results revealed that KOH could effectively increase the specific surface area of biochar. The specific area of ACTS-1.0 prepared with a KOH/pre-carbonized precursor mass ratio of 1:1, is up to 1550.03 cm2/g with a pore volume of 0.9076 cm3/g, and the structure was highly amorphous and disordered. The FT-IR and XPS results showed that there are various functional groups on the ACTS-1.0 biochar surface. These structural and compositional advantages lead to a higher specific capacitance (278 F/g) of ACTS-1.0 in an aqueous electrolyte and a high energy density of 27.01 Wh/kg at an organic electrolyte. Meanwhile, the as-prepared ACTS-1.0 has excellent cycling stability over 10,000 cycles in various electrolytes.

Effect of preparation techniques on BaWO4: structural, morphological, optical and electron density distribution analysis

The scheelite BaWO4 materials were prepared by co-precipitation and molten salt method. The crystallographic structure, optical behavior, morphology, and electronic charge distributions of the prepared BaWO4 were studied by various spectroscopic techniques such as X-ray power diffraction, photoluminescence spectroscopy, UV–Visible absorption spectroscopy, scanning electron microscopy and electron density distribution analysis, respectively. The micron-sized rock-like structured BaWO4 particles were obtained in the surface morphology. These structured BaWO4 exhibited intense blue emission peak at 430 nm when excited at 375 nm. The synthesized material revealed the high intense blue emission which attributed to the intrinsic transitions of [WO4]2− tetrahedrons.

Effect of Preparation Technique on the Performance of Ni and Ce Incorporated Modified Alumina Catalysts in CO2 Reforming of Methane

Performances of modified sol–gel alumina (MSGA) based catalysts, synthesized in an inert atmosphere and activated by Ni and Ce were investigated in CO2 reforming of methane. Two different incorporation methods were used to dope Ce into the structure of the catalysts: (i) simultaneous impregnation of Ce together with Ni (Ni–Ce@MSGA), (ii) one-pot synthesis of Ce incorporated alumina support material (Ni@Ce-MSGA). In the second case Ni was impregnated on the Ce-MSGA support. Synthesized catalysts were characterized using TPR, XRD, N2 adsorption/desorption, pyridine adsorbed DRIFT, CO2-TPD techniques. These analyses showed that the synthesized catalysts possessed reduced Ni particles, as well as mesoporous structure, Lewis acid sites and moderate basicity. The modified sol–gel alumina and modified sol–gel Ce-MSGA supported catalysts showed stable activity in CO2 reforming of methane. Ce incorporation improved catalytic activity of the synthesized catalysts and reduced the occurrence of reverse water gas shift reaction. Ni–Ce@MSGA catalyst decreased the CO2/CH4 conversion ratio much higher than Ni@Ce-MSGA catalyst. Coke analysis were determined using TGA/DTA, XRD, and SEM analysis. Especially, simultaneous impregnation of Ce and Ni catalyst inhibited coke deposition significantly due to lattice oxygen of ceria. However, coke deposition over Ni@Ce-MSGA catalyst was higher than Ni@MSGA catalyst since Ni@Ce-MSGA catalyst has higher nickel crystal size than that of Ni@MSGA catalyst.

Effect of Preparation Technique on Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration Sample Adequacy: 3 Years of Experience from a Single Center.

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is increasingly used to sample mediastinal lymph nodes and lesions. However, the methodological details of an optimal preparation technique for aspirated material have not yet been clearly determined. This study was an evaluation of the effect of 2 preparation techniques on the adequacy of aspirated specimens. A retrospective analysis was performed of EBUS-TBNA samples obtained at the institution over a total of 36 months. Two periods were examined. Almost all of the aspirated material was smeared onto slides and fixed with 95% alcohol in the first period of the study. Subsequently, to improve diagnostic ability, a pair of slides was prepared from each needle pass: the first was air-dried, and the second was fixed in 95% alcohol. The remainder of the aspirate was kept for cell block analysis. In total, 462 samples were obtained from 260 patients. The overall sampling adequacy was 74% in the first and 81.1% in the second period (p < 0.05). Approximately 14% of the specimens included a sufficient number of cells for immunohistochemical cell block evaluation in the first period and 42% in the second period (p < 0.001). Histological subtyping of non-small cell lung carcinoma was determined in 18 (56.3%) and the primary origin of a tumor was determined based on morphological and immunohistochemical properties in 32 (84.2%) of the patients in the first and second periods, respectively. The access to a sufficient EBUS-TBNA sample and the ability to perform the appropriate preparation can impact the specific diagnosis and treatment of patient with a single procedure.

The Use of Organophilic Bentonite in the Removal Phenol from Aqueous Solution: Effect of Preparation Techniques

This study focuses on the investigation of the capability of surfactant-modified bentonite for removal of phenol from aqueous solution. Calcium bentonite was beneficiated by means of ion exchange method using sodium trioxocarbonate (IV) resulting into sodium exchanged bentonite (SEB) and modified using ion exchange method, impregnation method, mechanical mixing methods using quaternary hexadecyltrimethylammonium bromide (HDTMABr). Fourier Transform Infra-Red Spectroscopy (FTIR) technique was used to study the vibrational bands of the sodium exchanged bentonite and modified SEB respectively. The effects of contact time, pH and initial concentration were studied on SEB and surfactant-modified SEB. The result reveals that the removal of phenol using SEB and surfactant-modified bentonite has optimum pH, contact time and equilibrium adsorption capacity of 6.0, 60 mins and 22.4 mgg-1 respectively. The result further shows that the surfactant-modified bentonite produced by impregnation method gave better experimental and calculated adsorption capacities of 6.4 mgg-1 and 10.5 mgg-1 respectively. The kinetic data obtained fitted well with pseudo second-order equation with correlation coefficient (R2) value of 0.999. This study therefore recommends that surfactant-modified bentonite obtained by means of impregnation is a potential adsorbent for the removal of phenol from aqueous solution and subsequently waste water.

Effects of preparation technique and lanthana doping on Ni/La2O3-ZrO2 catalysts for hydrogen production by CO2 reforming of coke oven gas

A series of Ni/La2O3-ZrO2 catalysts were prepared by homogeneous precipitation, template or sol-gel technique and used for hydrogen production from coke oven gas by CO2 reforming. The catalysts were characterized by BET, XRD, TPR, TPH, TEM and TG–DSC. A study is also carried out to observe the effect of lanthana loading on the reforming reaction. TPH results indicated the presence of more than two types of carbonaceous species on the used catalysts, which are categorized based on temperature difference. The low-temperature carbon species could be considered as the active sites for the reforming reaction. Experiments and TG-DSC results revealed that all of the catalysts present good catalytic performance and excellent anti-carbon property. The test results showed that the catalysts prepared by sol-gel method exhibited the highest catalytic activity due to their suitable pore size distribution. The Ni/La2O3-ZrO2 catalyst with 8wt% lanthanum oxide loading provides the best catalytic activity, which will be promising application on catalytic CO2 reforming of COG in the future.

Cationic PEGylated polycaprolactone nanoparticles carrying post-operation docetaxel for glioma treatment.

Background: Brain tumors are the most common tumors among adolescents. Although some chemotherapeutics are known to be effective against brain tumors based on cell culture studies, the same effect is not observed in clinical trials. For this reason, the development of drug delivery systems is important to treat brain tumors and prevent tumor recurrence. The aim of this study was to develop core–shell polymeric nanoparticles with positive charge by employing a chitosan coating. Additionally, an implantable formulation for the chemotherapeutic nanoparticles was developed as a bioadhesive film to be applied at the tumor site following surgical operation for brain glioma treatment. To obtain positively charged, implantable nanoparticles, the effects of preparation technique, chitosan coating concentration and presence of surfactants were evaluated to obtain optimal nanoparticles with a diameter of less than 100 nm and a net positive surface charge to facilitate cellular internalization of drug-loaded nanoparticles. Hydroxypropyl cellulose films were prepared to incorporate these nanoparticle dispersions to complete the implantable drug delivery system.Results: The diameter of core–shell nanoparticles were in the range of 70–270 nm, depending on the preparation technique, polymer type and coating. Moreover, the chitosan coating significantly altered the surface charge of the nanoparticles to net positive values of +30 to +50 mV. The model drug docetaxel was successfully loaded into all particles, and the drug release rate from the nanoparticles was slowed down to 48 h by dispersing the nanoparticles in a hydroxypropyl cellulose film. Cell culture studies revealed that docetaxel-loaded nanoparticles cause higher cytotoxicity compared to the free docetaxel solution in DMSO.Conclusion: Docetaxel-loaded nanoparticles dispersed in a bioadhesive film were shown to be suitable for application of chemotherapeutics directly to the action site during surgical operation. The system was found to release chemotherapeutics for several days at the tumor site and neighboring tissue. This can be suggested to result in a more effective brain tumor treatment when compared to chemotherapeutics administered as an intravenous bolus infusion.

Effect of preparation techniques on structural and electrical properties of PZT/PVDF composites

Effect of preparation techniques on structural and electrical properties of PZT/PVDF composites

A comparative study of physical properties in Fe3O4 nanoparticles prepared by coprecipitation and citrate methods

AbstractMagnetite exhibits unique structural, electronic, and magnetic properties in extreme conditions that are of great research interest. In this work, the effects of preparation technique on X‐ray peak broadening, magnetic and elastic moduli properties of Fe3O4 nanoparticles prepared by coprecipitation (FcP‐NPs) and citrate (FC‐NPs) methods have been investigated. The structural characterization of the samples is evidence for a cubic structure with Fd‐3m space group. The Williamson‐Hall analysis was used to study crystallite sizes and lattice strain of the samples and also stress and energy density. In addition, the crystallite sizes are compared with the particle sizes and the magnetic core sizes obtained from TEM and VSM methods, respectively. In addition, the cation distribution obtained from calculated inversion parameter indicate that in the smaller particles, more amount of Fe2+ on the tetrahedral sites can be related to higher stress induced in the FcP‐NPs compared to the FC‐NPs. The saturation magnetization of the FcP‐NPs is almost two times bigger than the saturation magnetization of the FC‐NPs. It could be attributed to the decrease in the negative interaction on the octahedral site and also the magnetic moment on the tetrahedral site of the FcP‐NPs. The increase in force constants of the FC‐NPs determined by infrared spectra analysis compared to FcP‐NPs suggests the strengthening of their interatomic bonding. The values of shear and longitudinal wave velocities obtained from force constants have been used to determine the values of Young's modulus, rigidity modulus, bulk modulus, and Debye temperature. By comparison of the elastic results of FC‐NPs with the FcP‐NPs, we can observe that the elastic properties of the F‐NPs have been improved by synthesis method, while Poisson's ratio almost remains constant. In addition, using the values of the compliance sij obtained from elastic stiffness constants, the values of Young's modulus and Poisson's ratio along the oriented direction [hkl] have been calculated for the samples.

Effect of Preparation Technique on Microstructure and Hydrogen Storage Properties of LaNi3.8Al1.0Mn0.2 Alloys

LaNi 3.8 Al 1.0 Mn 0.2 alloy was prepared by vacuum induction melting and melt-spinning. The effects of different preparation techniques of the as-cast, cast then annealed, as-spun and spun then annealed alloys on the microstructure and hydrogen storage properties were investigated. The results indicated that the non-CaCu 5 phases in the alloy became tinier and more dispersive after annealing or melt-spinning compared to those of the as-cast one. But in the spun then annealed alloy, the non-CaCu 5 phases disappeared and only a single-phase with CaCu 5 type structure was found. For all the alloys, the cell volume was increased in an order of as-cast

Effect of preparation technique on the selected characteristics of Zn1−xCoxO nanocrystalline thin films deposited by sol–gel and magnetron sputtering

We have investigated structural, optical and magnetic properties of Zn1−xCoxO (0⩽x⩽0.2) nanocrystalline thin films deposited on glass substrates by sol–gel dip coating and reactive radio-frequency magnetron sputtering technique. The effects of the preparation technique and Co doping concentration on the ZnO thin films have been examined. The results reveal that the sol–gel prepared thin films are less c-axis oriented than those of magnetron sputtered thin films. None of the prepared thin films contained secondary phases. With the increase of Co doping concentrations, the crystallite size and orientation degree of the films change in both of the film deposition techniques. The film surfaces with both deposition techniques are homogeneous and dense; the grains on the surface is randomly scattered. Grain size decreases with increasing Co content. With both film deposition techniques, the band gap energy of the films decreases with increasing Co doping ratio and film thickness except for the 9.1at.% Co doped ZnO magnetron sputtering films. It is found that Co has the valance state of 2+in ZnO lattice. Considering the magnetic properties, it has been observed that there is a paramagnetic behavior and no ferromagnetic signals over temperature range of 5–300K for the samples prepared by both of the sol–gel dip coating and magnetron sputtering techniques.

Preparation and drug release behavior of pH-responsive bovine serum albumin-loaded chitosan microspheres

A novel inverse emulsion-ionic crosslinking approach was adopted to prepare pH-responsive chitosan microspheres and effect of preparation technique, such as chitosan concentration, emulsifier concentration, water/oil ratio and homogenization speed, on the morphology and property of the microspheres were investigated. The chitosan microspheres with spherical in shape, smooth surface, high productivity and promising pH responsiveness were obtained. On this basis, bovine serum albumin (BSA)-loaded chitosan microspheres was prepared to test the drug release behavior in buffers with different pH values. BSA-chitosan microspheres with particle sizes in range from 5 to 10μm released BSA slowly in neutral medium and released rapidly in acidic medium, and exhibited obviously pH-responsive release behavior. Korsmeyer–Peppas model can be used for describing BSA release kinetics from chitosan microspheres, which corresponded with a Fickian release behavior, and the diffusion through the swelling of chitosan microspheres was the main factor in controlling BSA release.

Preparation and characterization of waterborne epoxy latexes and epoxy/(silica sol) composites

A series of waterborne epoxy latexes was synthesized, and epoxy/(silica sol) composite latexes were prepared. The effects of functional monomer methacrylic acid (MAA) and silica sol on the latex particle size, morphology, and stability were investigated. With increasing amounts of MAA, the conversion rate increased, the particle size reduced, and the viscosity of the epoxy latexes increased. The epoxy latexes had storage stability and could be stored at room temperature for more than 6 months with a solid content variation of less than 1%. For the (silica sol)‐modified waterborne epoxy latexes, the effects of preparation techniques and silica sol content on the latexes and latex films were investigated. When the silica sol content increased, the particle size of the composite latexes decreased. The morphology investigation showed that when the silica sol content increased, the uneven surface level of the latex films was increased. The increase of elemental silica on the surface was in accord with the improvement of the water resistance of the composite latex films. The heat resistance of these films was improved as well, and their overall performance was better than that of the epoxy latex films. J. VINYL ADDIT. TECHNOL., 20:57–64, 2014. © 2014 Society of Plastics Engineers

Aripiprazole-cyclodextrin binary systems for dissolution enhancement: effect of preparation technique, cyclodextrin type and molar ratio.

The aim of this work was to investigate the effect of the natural and the chemically modified form of cyclodextrins namely; β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) respectively on the solubility and dissolution rate of aripiprazole; an antipsychotic medication showing poor aqueous solubility. Phase solubility of aripiprazole with the studied CDs and the complexation efficiency values (CE) which reflect the solubilizing power of the CDs towards the drug was performed. Solid binary systems of aripiprazole with CDs were prepared by kneading, microwave irradiation and freeze-drying techniques at 1:1 and 1:2 (drug to CD) molar ratios. Drug-CD physical mixtures were also prepared in the same molar ratios for comparison. The dissolution of aripiprazole-binary systems was carried out to select the most appropriate CD type, molar ratio and preparation technique. Phase solubility study indicated formation of higher order complexes and the complexation efficiency values was higher for HP-β-CD compared to β-CD. Drug dissolution study revealed that aripiprazole dissolution was increased upon increasing the CD molar ratio and, the freeze-drying technique was superior to the other studied methods especially when combined with the HP-β-CD. The cyclodextrin type, preparation technique and molar ratio exhibited statistically significant effect on the drug dissolution at P≤ 0.05. The freeze-dried system prepared at molar ratio 1:2 (drug: CD) can be considered as efficient tool for enhancing aripiprazole dissolution with the possibility of improving its bioavailability.

Thermal Properties and Crystallisation Behaviour of Thermoplastic Natural Rubber (TPNR) Nanocomposites

The effect of preparation technique on the crystallisation behavior and thermal properties of TPNR filled nanoclay nanocomposites was investigated. The nanocomposites were prepared via melt blending method using internal mixer (Haake 600P). Two types of nanocomposites preparation technique were employed which is method A and B. In method A, the nanoclay was pre-mixed with liquid natural rubber (LNR) before it was charged into the other materials. For method B, the nanoclay was directly charged into the molten TPNR matrix. The result shows, preparation methods were significantly affect the crystallinity and thermal properties of TPNR nanocomposites. DSC thermogram revealed that nanocomposites crystallinity was increased when prepared by method A but decreased with method B. An increment in polypropylene crystallinity was attributed by the nanoclay which is believed to be as a nucleating agent. DMA thermogram suggested that the preparation method has affected the storage modulus and tan δ but not the glass transition temperature (tg).

Effects of preparation techniques on root canal shaping assessed by micro-computed tomography

BackgroundRoot canal shaping without any procedural error is of the utmost preference. Therefore, the purpose of this study was to use micro-computed tomography to evaluate and compare the root canal shaping efficacy of ProTaper rotary files and standard stainless steel K-files.Material/MethodsSixty extracted upper second premolars were selected and were divided into 2 groups of 30. Before preparation, all samples were scanned by micro-CT. Then, 30 teeth were prepared with stainless steel files and the remaining 30 with ProTaper rotary files. Canal transportation and centering ability before and after root canal shaping were assessed using micro-CT. The amount and direction of canal transportation and the centering ratio of each instrument were determined in the coronal, middle, and apical parts of the canal. The 2 groups were statistically compared using one-way ANOVA.ResultsProTaper rotary files gave less transportation (p<0.001) and better centering ability (p<0.00001) compared with stainless steel files.ConclusionsThe manual technique for preparation of root canals with stainless steel files produces more canal transportation, whereas rotary files remain more centered in the canal.

Effect of preparation techniques on infrared emissivities of Zn0.9Co0.1O powders

Zn0.9Co0.1O powders were prepared by chemical solution deposition, solid-state reaction and sol–gel route at different calcination temperatures. The structure and morphologies of samples were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The infrared absorption spectra and infrared emissivities in the range of 8–14μm were investigated by Fourier transform infrared spectroscopy and IR-2 dual-band infrared emissometer. XRD patterns confirmed the hexagonal wurtzite structure of as-synthesized samples but the peaks of the secondary phase, ZnCo2O4, were observed below 1000°C. Scanning electron micrographs showed large grain sizes of the samples prepared by solid-state reaction and sol–gel processing. The infrared emissivities of samples fabricated by chemical solution deposition and sol–gel route decreased with increasing temperature. Powders obtained using solid-state reaction showed the lowest emissivities, with a minimum value (0.755) at 1150°C.

Effect of Preparation Technique on Methyl Orange Sorption Behavior of Exfoliated Graphite

Three natural graphite flakes (35, 50 and 80 mesh) were used as raw material. Exfoliated graphite (EG) was prepared by rapidly heating expandable graphite to 1000 °C in a muffle and by irradiating it in a microwave oven with a power of 280 W for 40 s, respectively. The EG samples were used for removing methyl orange (MO) from aqueous solution. The effect of preparation technique of EG (particle size of natural graphite and exfoliation method of expandable graphite) on MO removal properties was investigated, and a higher removal rate was achieved.

Effect of preparation techniques on the properties of curcumin liposomes: Characterization of size, release and cytotoxicity on a squamous oral carcinoma cell line

Curcumin, a chemopreventive agent, was incorporated into liposomes using different preparation techniques and characterized for parameters such as drug loading efficiency, size, in vitro release and in vitro cytotoxicity on a squamous carcinoma cell line. Liposomes were prepared with different methods – thin layer evaporation, ethanol injection and sonication methods, respectively, obtaining, multilamellar vesicles (MLVs) and small unilamellar vesicles (SUVs). The preparation techniques influenced the size, encapsulation efficiency, in vitro release and cytotoxicity profiles. Encapsulation efficiency increased with decrease in drug to lipid ratio in the following rank order – MLVs > SUVs > ethanol injection vesicles. In vitro release and in vitro cytotoxicity were a function of the size of vesicle, which varied depending on the preparation technique. Based on these results, it can be concluded that different liposomal formulations can be employed to achieve unique in vivo needs in cancer chemotherapy.

Effects of Preparation Techniques on the Thermoelectric Properties and Pressive Strengths of n-type Bi&lt;SUB&gt;2&lt;/SUB&gt;Te&lt;SUB&gt;3&lt;/SUB&gt; Based Materials

以商用区熔(ZM)n型Bi 2 Te 3 基材料为原料, 采用简单研磨结合放电等离子烧结技术(ZM+SPS)和熔体旋甩(MS)结合放电等离子烧结技术(MS+SPS)制备了n型Bi 2 Te 3 基块体热电材料. 对三种不同工艺制备出样品的微结构、热电性能和力学性能进行了研究. FESEM微结构表征结果表明: 区熔样品的晶粒粗大, 有较强的取向性; 经SPS烧结后, 晶粒细化, 取向性大为降低; 而区熔样品经MS+SPS后, 晶粒得到进一步细化, 且没有明显的取向性. 对三组样品进行的热电性能和抗压强度测试, 结果表明: 区熔原料最大 ZT 值为0.72(430K), 抗压强度仅为40MPa; 经SPS后, 样品的最大 ZT 值为0.68(440K), 抗压强度为110MPa, 相比区熔样品提高了175%; MS+SPS样品的最大 ZT 值为0.96(320K), 其室温 ZT 值相比区熔样品提高了64%, 抗压强度相比区熔样品提高了400%, 达到200MPa.