Improved Procedure For Synthesis Research Articles

Повышение термоэлектрической эффективности устройств преобразования энергии за счет использования наноструктурированных материалов

Background: Thermoelectric materials have received much interest because of their capacity to transform thermal energy into electrical power, providing a sustainable method for energy collecting. Despite substantial study, the actual use and effectiveness of these materials require more investigation as they move from laboratory to industrial settings. Objective: This study's objective is to provide a thorough analysis of the evolution of thermoelectric materials, from their fundamental theoretical underpinnings to their integration into devices, highlighting material science advances that improve their efficiency and applicability. Methods: We did a thorough review of current research that focused on new materials, improved synthesis procedures, and innovative design strategies to improve the thermoelectric figure of merit. Furthermore, we investigated the procedures of integrating these materials into devices, taking into account both performance measurements and scalability. Results: The findings show substantial advances in the fabrication of nanostructured thermoelectric materials, which significantly boost the Seebeck coefficient while preserving electrical conductivity. We also found essential solutions for optimising device architecture that simultaneously boost heat management and efficiency. Conclusion: Breakthroughs in material science and engineering are driving the fast integration of improved thermoelectric materials into practical systems. Future research should concentrate on the scalability of these technologies and their integration into a larger range of renewable energy systems, therefore improving their economic feasibility and environmental effect.

Synthesis and magnetic properties of single phase titanomagnetites

The focus of this paper is the study of cation distributions and resulting magnetizations in titanomagnetites (TMs), (1−x)Fe3O4−xFe2TiO4 solid solutions. TM remnant states are hypothesized to contribute to planetary magnetic field anomalies. This work correlates experimental data with proposed models for the TM pseudobinary. Improved synthesis procedures are reported for single phase Ulvöspinel (Fe2TiO4), and TM solid solutions were made using solid state synthesis techniques. X-ray diffraction and scanning electron microscopy show samples to be single phase solid solutions. M-H curves of TM75, 80, 85, 90, and 95 (TMX where X = at. % of ulvöspinel) were measured using a Physical Property Measurement System at 10 K, in fields of 0 to 8 T. The saturation magnetization was found to be close to that predicted by the Neel model for cation distribution in TMs. M-T curves of the remnant magnetization were measured from 10 K to 350 K. The remnant magnetization was acquired at 10 K by applying an 8 T field and then releasing the field. Experimental Neel temperatures are reported for samples in the Neel model ground state.

Novel acidic ionic liquid as a catalyst and solvent for green synthesis of dihydropyrimidine derivatives

A novel acidic ionic liquid (AIL), 3-(2-carboxybenzoyl)-1-methyl-1H-imidazol-3-ium chloride {[Cbmim]Cl}, was synthesized and used as an efficient and green catalyst for the Biginelli reaction under solvent-free conditions. The present study aims to develop an improved synthesis procedure, based on a one-pot Biginelli condensation reaction, by using different aldehydes, β-dicarbonyl compounds, and urea or thiourea. This method, in comparison with the classical Biginelli reaction, has several advantages, including high yield, short reaction time and experimental simplicity.

Relationship between structure, magnetism, and thermoelectricity in CePd3Mx alloys

A series of CePd3Mx compounds (M = Na, Mg, Ca, B, Al, Ga, Si, Ge, S, Te, In, and Sn) has been synthesized and their structural, magnetic, and thermoelectric properties measured. The formation of an ordered CePd3M0.125 phase appears to be a gradual transition for elements from rows 2-4 of the periodic table while a miscibility gap appears to exist in the pseudo binary CePd3-CePd3M0.125 phase diagram for M elements from row 5. We report for the first time the existence of alloys with M = Te and S synthesized through a novel precursor approach, with the S-filled compounds showing an unusual contraction of the unit cell. The average valence of the Ce ions in CePd3Mx appears to be strongly correlated with both the electron count and filling fraction of the M elements, while the thermal conductivity reduction achieved through partial filling appears to saturate for M elements with masses above ∼25 amu and at filling levels above ∼5%. The combination of these effects results in a modest enhancement in the thermoelectric figure of merit from 0.07 to 0.11 at 100 K for samples filled with Mg and Ca at a nominal filling level of x = 0.02. Further modest increases may be possible using this approach if improved synthesis procedures can be developed.

Improved Syntheses for the Compounds [(1,5-COD)M(μ-O2C8H15)]2 (M = Ir, Rh)

An improved synthesis procedure is reported for the compounds [(1,5-COD)M(μ-O2C8H15)]2 (COD = cyclooctadiene, M = Ir (1), Rh (2), O2C8H15 = 2-ethylhexanoate); that procedure provides a more effective method of product isolation resulting in easier crystallization, and 76% and 85% yields of pure, crystalline 1 and 2, respectively. The improved synthesis and simplified crystallization of high-purity 1 and 2 are significant, not only because 1 is useful as a model for industrial Ziegler-type hydrogenation precatalysts, but also because 1 and 2 are potentially useful in a variety of other areas.

An Improved Synthesis of Borazine with Aluminum Chloride as Catalyst

AbstractBorazine is an excellent precursor for boron nitride. However the existing synthetic methods for the preparation of borazine have drawbacks such as relatively high reaction temperatures, side reactions, long reaction times, and low yields. An improved synthesis procedure was disclosed, which involved the use of aluminum chloride as a catalyst in the reaction of sodium borohydride with ammonium sulfate. The aluminum chloride catalyst brought the reaction temperature down from 120–140 °C to 45 °C. Improved yields of borazine were obtained in comparison to the reaction without a catalyst. In addition, the reaction process was investigated in detail by 11B NMR spectroscopy and Fourier transform infrared spectroscopy (FTIR). It was found that aluminum borohydride formed in very small quantity when aluminum chloride was introduced, which plays an important role in the reaction.

Synthesis of Slot Arrays on Integrated Waveguides

An improved synthesis procedure is presented in this letter for the design of waveguide slot arrays directly integrated on the substrate of the exciting microstrip line. To take into account the smallness of the waveguide height, the standard shunt-admittance model usually adopted for the single radiating slot is properly modified into an improved T-network model. Accordingly to this choice, a two-step synthesis procedure is developed to accurately determine the radiating slots' parameters. Experimental validations are discussed for the design of an 8-GHz linear array with a -20-dB Taylor pattern.

Improved multivariable quantitative feedback design for tracking error specifications

An improved design procedure for multi-input/multi-output (MIMO) quantitative feedback theory (QFT) problems involving tracking error specifications (TESs) has been presented. Appropriate transformation of the MIMO system to a series of equivalent single-input/single-output (SISO) problems is presented that motivates an improved synthesis procedure using feedback compensator and pre-filter transfer function matrices (TFMs). The key features of the procedure are that, for each equivalent SISO problem, (i) interactions and the effects of uncertainty are treated as an output disturbance, and (ii) sufficient conditions can be determined that assure desired levels of robust performance within the bandwidth region at a transformation cost that can be computed a priori. This paper also considers how the individual elements of the pre-filter TFM can be designed for MIMO QFT problems with a reduced level of conservatism and over-design using existing SISO methods. A benchmark quadruple-tank process is considered to illustrate the benefits of the new design paradigm.

An improved synthesis algorithm for reflectarrays design

An improved synthesis procedure is presented in this letter for the design of microstrip reflectarray antennas. The iterative projection based algorithm is modified to include the effect of different incidence angles on the reflectarray elements in the evaluation of the design curve. Experimental results on an X-band prototype of unequal microstrip patch elements are reported.

Fujitsu to license photocatalyst

Crystalline titanium silicalites with the MFI structure and high titanium content (Si/Ti=10) have been prepared using improved synthesis procedures. The monoclinic lattice symmetry of silicalite-1 changes to orthorhombic on introduction of titanium. The titanium silicalites retain their orthorhombic symmetry even after calcination in air. On progressive incorporation of titanium, (i) the unit cell dimensions and volume (from XRD) increase linearly, (ii) the crystal size decreases progressively, (iii) the intensity of the framework IR band at 960 cm−1 increases, (iv) a band around 47000 cm−1 appears in the electronic spectra due to charge transfer transitions involving Ti(IV) sites, (v) the hydrophilicity of the zeolite (from water adsorption measurements) increases, (vi) the adsorption capacity for cyclohexane increases, (vii) the 29Si MAS NMR lines exhibit progressive broadening, and finally (viii) the catalytic activity in the hydroxylation of phenol to catechol and hydroquinone also increases markedly. Based on these observations, it is concluded that a significant fraction of titanium in these samples is situated in framework positions. The catalytic properties of these well-defined titanium-modified zeolites will be described in more detail in the subsequent parts of this series.

Synthesis of deuterated volatile lipid degradation products to be used as internal standards in isotope dilution assays. 1. Aldehydes.

The isotopically labeled compounds [5,6-(2)H(2)]hexanal (d-I), [2, 3-(2)H(2)]-(E)-2-nonenal (d-II), [3,4-(2)H(2)]-(E,E)-2,4-nonadienal (d-III), and [3,4-(2)H(2)]-(E,E)-2,4-decadienal (d-IV) were prepared in good yields using new or improved synthesis procedures. Labeling position, chemical purity, and isotopic distribution of the compounds were characterized by various MS and NMR techniques. These molecules are used as internal standards in quantification experiments based on isotope dilution assay. Synthesis of d-I, d-III, and d-IV has not yet been reported in the literature.

Synthesis of Deuterated Volatile Lipid Degradation Products To Be Used as Internal Standards in Isotope Dilution Assays. 2. Vinyl Ketones

The isotopically labeled compounds [5,6-(2)H(2)]-(Z)-1, 5-octadien-3-one (d-I) and [1-(2)H(1;2),2-(2)H(1;1)]-1-octen-3-one (d-II), as well as the unlabeled reference compound (Z)-1, 5-octadien-3-one (I) were prepared by improved synthesis procedures. Labeling position, chemical purity, and isotopic distribution of the compounds were characterized by various MS and NMR techniques. These molecules are used as internal standards in quantification experiments based on isotope dilution assay. The newly prepared compound d-II was synthesized in a simple two-step procedure, and formation of the main isotopomers was studied in model systems.

An improved method for TS-1 synthesis: 29Si NMR studies

It is possible to incorporate up to eight Ti ions per unit cell, which is probably the maximum, into the MFI structure (TS-1) using our improved synthesis procedure; 29Si NMR studies have helped in evolving the sysnthesis route.

Catalytic properties of crystalline titanium silicalites I. Synthesis and characterization of titanium-rich zeolites with MFI structure

Crystalline titanium silicalites with the MFI structure and high titanium content (Si/Ti=10) have been prepared using improved synthesis procedures. The monoclinic lattice symmetry of silicalite-1 changes to orthorhombic on introduction of titanium. The titanium silicalites retain their orthorhombic symmetry even after calcination in air. On progressive incorporation of titanium, (i) the unit cell dimensions and volume (from XRD) increase linearly, (ii) the crystal size decreases progressively, (iii) the intensity of the framework IR band at 960 cm −1 increases, (iv) a band around 47000 cm −1 appears in the electronic spectra due to charge transfer transitions involving Ti(IV) sites, (v) the hydrophilicity of the zeolite (from water adsorption measurements) increases, (vi) the adsorption capacity for cyclohexane increases, (vii) the 29Si MAS NMR lines exhibit progressive broadening, and finally (viii) the catalytic activity in the hydroxylation of phenol to catechol and hydroquinone also increases markedly. Based on these observations, it is concluded that a significant fraction of titanium in these samples is situated in framework positions. The catalytic properties of these well-defined titanium-modified zeolites will be described in more detail in the subsequent parts of this series.