Input Molar Ratio Research Articles

In Situ Formation of Iodide Precursor for Perovskite Quantum Dots with Application in Efficient Solar Cells.

Perovskite quantum dots (PQDs) become a kind of competitive material for fabricating high-performance solar cells due to their solution processability and outstanding optoelectronic properties. However, the current synthesis method of PQDs is mostly based on the binary-precursor method, which results in a large deviation of the I/Pb input ratio in the reaction system from the stoichiometric ratio of PQDs. Herein, a ternary-precursor method with an iodide source self-filling ability is reported for the synthesis of the CsPbI3 PQDs with high optoelectronic properties. Systematically experimental characterizations and theoretical calculations are conducted to fundamentally understand the effects of the I/Pb input molar ratio on the crystallographic and optoelectronic properties of PQDs. The results reveal that increasing the I/Pb input molar ratio can obtain ideal cubic structure PQDs with iodine-rich surfaces, which can significantly reduce the surface defects of PQDs and realize high orientation of PQD solids, facilitating charge carrier transport in the PQD solids with diminished nonradiative recombination. Consequently, the PQD solar cells exhibit an impressive efficiency of 15.16%, which is largely improved compared with that of 12.83% for the control solar cell. This work provides a feasible strategy for synthesizing high-quality PQDs for high-performance optoelectronic devices.

Resistive Heating Catalytic Micro-Reactor for Process Intensified Fuel Reforming to Hydrogen

Abstract Process intensification of fuel reforming using micro-reactors has become crucial for feed flexibility in H2 production for fuel cells. In the literature on microreactors, energy supply for these endothermic reactions has faced limitations, relying on external heating, or autothermal operation. This paper explores a novel approach using a thin-film catalytic heater to develop micro-reactors. The study focuses on dry methane reforming in a simplified micro-reactor where thermal energy is supplied through electric resistive heating of a thin carbon sheet with a catalyst applied to its surface. The thin catalytic heated layer inside the reactor minimizes energy losses and the reactor footprint. Power input was varied from 90-225 W to understand its impact on the reactor temperature, CH4 conversion, H2 and CO yields. Fast thermal response times were achieved using the carbon paper as thin film for heating. Ni/MgO impregnated onto carbon paper was utilized as the catalytic heating element which resulted in CH4 conversions greater than 60% at temperature above750 K. Influence of operating conditions such as the input molar ratio of CO2/CH4, and gas hourly space velocity (GHSV) were also investigated to understand the scope of the catalyst in this setup. High GHSVs (592,885 and 948,617 mL/(hr.gcatalyst)) were tested to understand the throughput achievable using this setup. This approach demonstrates improved scope and feasibility for further intensification compared to conventionally heated microreactors. The research paves the way for efficient and compact micro-reactors for fuel reforming processes.

Sustainable assessment of an integrated energy system coupled with solar thermochemical cycle

The energy transition globally makes the development of carbon-free and low-carbon fuels obligatory as these fuels cannot only be utilized as energy carriers but also for long-term energy storage. This paper presents the energy, technoeconomic, and environmental assessment of a new hybrid renewable energy integrated system with a novel concept of the thermochemical cycle for methanol production. For this purpose, a thermochemical cycle based on CeO2/Ce2O3 oxides is integrated with the methanol synthesis system. It consists of two chemical steps: (1) oxygen carrier reduction step where metal oxide reduction Ce (IV) to Ce (III) (endothermic phase) is performed employing renewable thermal energy and chemical energy originated from ultra-high concentrated photovoltaics and fossil methane respectively and (2) waste gas dissociation step where oxidation of Ce(III) takes place with dissociation of water and carbon dioxide (exothermic phase) and resulting syngas is converted to methanol. Plant design and simulation are performed in ASPEN plus commercial software. MATLAB was employed for the programming of thermal data to perform pinch analysis. The technical feasibility of the second step was investigated comprehensively in terms of temperature, input molar ratio and the potential operating conditions that were identified (TOXI = 900 °C and H2O/CO2 = 3.7) based on methanol production performance. Overall energy efficiency, solar-to-fuel efficiency and thermal efficiency are calculated to be 77.2%, 38% and 44.1% respectively. The findings of the environmental analysis show that carbon utilization of 20.85%, carbon storage of 79.14%, carbon capture of 100% and carbon avoidance of 19.6% are achieved. Economic analysis shows that the net project capital expenditure (CAPEX) and operating expenditure (OPEX) are estimated to be $186.49M and $218.67M. It was found that the best-case scenario of natural gas (NG) price is 40$/MWh, where the breakeven point is achieved during the 5th year of the project lifetime.

Efficient separation of IgG from IgM antibodies via conjugated surfactant micelles

Immunoglobulin-G (IgG) (∼150 kDa) antibodies confer longer term immunity against bacterial or viral infections than the heavier IgM’s (∼900 kDa), which are generally detectable in blood circulation in response to more recently acquired infections. There may be, however, a time overlap, which is problematic for diagnostic purposes, in the interests of which it is essential to separate IgM's from IgG’s. We describe a purification platform, functioning at pH 6.5, containing Tween-20, or Brij-O20, non-ionic detergent micelles, mixed with the sugar-rich detergent dodecyl maltoside (DDM), amino acid monomer tyrosine (Tyr), and conjugated by the amphiphilic complex [(bathophenanthroline)3: Fe2+]. Using conjugated Brij-O20 micelles, with input molar ratio IgG: IgM 9:1, IgG is recovered at 10 °C with 85–90% yield, (by SDS-PAGE densitometry) and ≥95% purity (also by SDS-PAGE), while IgM's are recovered at lower yields (28–34%) and contain small amounts of co-extracted IgG's. Addition of E. coli lysate as an artificial contamination background does not reduce the yield or purity of the recovered IgG. Tween-20/DDM/Tyr micelles lead to IgG purity ≥95% similar to that of Brij-O20, but with lower process yields (64–70%, by densitometry). Chromatographic separation with Protein A or Protein G resins leads to yields comparable to those obtained with Brij-O20 micelles, but with lower purity.

Facile Phase-Selectable Chemical Synthesis of Tin Selenide Nanosheets toward Nanostructured Materials for Energy-Related Applications

Here, we present a facile, phase-selectable, size-controllable chemical method for the synthesis of Sn-Se nanosheets (NSs). The resultant NSs were characterized using XRD, SEM, TEM, STEM, and EDS. Phase control was achieved by changing the input molar ratio of Sn:Se. At ratios of 1:1 and 1:2, pure-phase, rectangular SnSe NSs; at ratios of 1:6 and 1:10, pure-phase, hexagonal SnSe2 NSs; and at a ratio of 1:4, a mix of the two NSs were produced. The produced NSs were large (a few hundred nm in diameter) and thin (10–20 nm), although there was no significant increase in the optical band gap calculated from UV–vis–NIR spectroscopy, indicating an absence of quantum confinement effects. Size control of both phases was achieved by changing the amount of the ligand, trioctylphosphine oxide (TOPO). Increasing the amount of TOPO decreased the size of the SnSe NSs and increased the size of the SnSe2 NSs. Finally, the formation mechanism was investigated and it was found that the formation of metal-ion complexes, namely, Sn-TOPO and Se-oleylamine, played an important role in the phase selectivity and size distribution of the NSs by changing the effective ratio of Sn:Se and slowing the nucleation of the NSs.

A method for parallel microscale protein labeling and precise control over the average degree of labeling (aDoL)

A widely used approach for protein conjugation is through the lysine residues reacting with NHS- or other active esters. However, it is a challenge to precisely control the degree of labeling (DoL) due to the instability of active ester and variability of reaction efficiencies. Here, we provide a protocol for better control of aDoL using existing Copper-free Click Chemistry reagents. It is a two-step reaction with one purification in between. Briefly, proteins of interest were first activated with azide-NHS. After removing unreacted azide-NHS, the protein-N3 is then reacted with a limited amount of complementary click tag. Our studies have shown the click tag will fully react with the protein-N3 after 24 h’ incubation, and therefore does not require additional purification steps. As such, the aDoL is equal to the input molar ratio of the click tag and the protein. Furthermore, this approach offers a much simpler and more economical way to perform parallel microscale labeling. Once a protein is pre-activated with N3-NHS, any fluorophore or molecule with the complementary click tag can be attached to the protein by mixing the two ingredients. Quantities of the protein used in the click reaction can be at any desired amount. In one example, we labeled an antibody in parallel with 9 different fluorophores using a total of 0.5 mg of antibody. In another example, we labeled Ab with targeted aDoL value from 2 to 8. In a stability comparison study, we have found the conjugated fluorophore using the suggested click protocol stayed attached to the protein longer than with standard NHS-fluorophore labeling.

RETRACTED: Multi-attribute optimization of sustainable aviation fuel production-process from microalgae source

The aviation sector has been one of the most significant contributors to greenhouse gas (GHG) emissions; there is an urgent need to transition from traditional fossil-based jet fuel to sustainable aviation fuel to meet net-zero targets by 2030. The use of renewable aviation fuel may be regarded as the most effective option for reducing GHG emissions in the aviation sector while allowing for long-term growth. In this study, the microalgae oil was transformed to develop hydrocarbons with the boiling point range of jet fuel. Following the transesterification of algal oil fatty acids to algal oil methyl ester, fractional distillation was carried out. The Box-Behnken technique was used to design experiments for efficient resource utilization by minimizing the number of tests during transesterification. The quantitative relationship function between input (molar ratio of methanol to oil, catalyst concentration, and temperature) and % yield of methyl ester as an output of the process was developed using analysis of variance (ANOVA). The ANFIS (adaptive neuro-fuzzy inference system) was utilized to develop a prognostic model with good prediction effectiveness. MORSM (multi-objective response surface methodology) was also used to build a prediction model using correlations. A set of statistical indicators and Theil's U2 were used to examine the prediction efficacy and model uncertainty of ANFIS and MORSM. On both statistical indices and Theil's U2, the ANFIS-based model outperformed. To get the best results, the desirability approach was used to improve operating parameters. According to the desirability approach, the best operating parameters were catalyst concentration at 2.09%, methanol to oil ratio at 9.17%, and temperature at 60.49 °C, which resulted in the greatest yield of 91%.

Continuous production of isoamyl acetate from fusel oil under supercritical CO2: A mass transfer approach

Isoamyl acetate esters were synthesized under supercritical CO2 (SC-CO2) in a continuous packed-bed reactor (PBR) using immobilized lipase (Novozym 435) as the catalyst. A fractional factorial design (24−1) was applied to evaluate the effects of pressure (10–20 MPa), temperature (40–60 °C), substrates (fusel oil + acetic anhydride) flow rate (QS1/S2: 0.2–0.6 mL/min), and CO2 flow rate (QCO2: 0.4–1.2 L/min) on the isoamyl acetate conversion (X, %). Results showed that only the effects of QS1/S2 were statistically significant at the level of 5%. Mathematical modeling of the PBR was applied using the law of conservation of mass that resulted in two partial differential equations for fluid and enzymes. The model was solved using finite difference methods and successfully validated with the experimental data in terms of isoamyl alcohol concentration. Finally, the model was employed to examine the impact of the input molar ratio of fusel oil per acetic anhydride (IMFA) and the length per diameter ratio (L/D) of the PBR on its performance.

Thermodynamic calculations for the chemical vapor deposition of hexagonal boron nitride using triethylboron, ammonia, and hydrogen

The presence of C in B(C2H5)3 makes possible its incorporation into hexagonal boron nitride (h-BN) thin films grown during chemical vapor deposition (CVD) under select process conditions. A series of CVD phase diagrams that indicate the regions of stability of the phases of h-BN, C and B4C as a function of temperature and input mole ratio of reactants (N/B) under set pressures and H2 diluent-to-reactant mole ratios (H2/(B + N)) have been calculated and analyzed for the TEB/NH3/H2 system. The equilibrium calculations showed that within the total pressure range of 0.01-100 Torr, increasing the H2 content in the TEB/NH3/H2 gas mixture tends to suppress the stability of C throughout a 400–1600 °C temperature range, but it also suppresses the stability of h-BN at higher temperatures. Further, it was determined that increasing the total system pressure suppresses the occurrence of C as a second phase while expanding the stability of h-BN. The thermodynamic equilibrium results were compared to the results of experimental investigations involving the CVD synthesis of sp2-BN as a means to evaluate their usefulness as a guide for avoiding the co-deposition of C and B4C with h-BN.

InGaN気相成長における気相-固相関係に対する基板拘束の影響( ナノ構造・エピ成長分科会特集「窒化物半導体エピタキシャル成長における基板の役割」の再考)

InGaN気相成長における気相-固相関係に対する基板拘束の影響( ナノ構造・エピ成長分科会特集「窒化物半導体エピタキシャル成長における基板の役割」の再考)

Optimization of the Raw Material Input Molar Ratio on the Carbothermal Production of Solar-Grade Silicon

Optimization of the Raw Material Input Molar Ratio on the Carbothermal Production of Solar-Grade Silicon

Aminolysis of poly(ethylene terephthalate) waste with ethylenediamine and characterization of α,ω-diamine products

Bis(2-aminoethyl) terephthalamide (BAET, or trimer) and α,ω-aminoligo(ethylene terephthalamide) (AOET, or oligomers) were obtained from the reaction of poly(ethylene terephthalate) (PET) waste with excess amount of ethylenediamine (EDA). The structures of trimer BAET and oligomers AOET were confirmed by FTIR, NMR, HPLC-MS analysis. The influence of input molar ratio of reactants on oligomer yield was also investigated. The formation of oligomers competed with the formation of trimer even though EDA was used in excess amount. The melting points, thermal properties of BAET and AOET were determined by DSC, TGA techniques. The physical melting process and chemical transamidation of amino end capped BAET/AOET occurred concurrently before thermal decomposition.

Improvements in the crystalline quality of MOVPE-InN layers by facet controlling with hydrogen partial pressure

Facet control of InN was performed for the improvement of the crystalline quality of InN layers on GaAs (1 1 1)B by metalorganic vapor phase epitaxy (MOVPE). Growth mode of InN could be controlled by changing the input mole ratio of hydrogen in the carrier gas and growth temperature. When the input mole ratio of hydrogen in the carrier gas was 0 (N 2 ambient) and growth temperature was low, InN with a flat surface could be obtained. On the contrary, when a small amount of hydrogen was contained in the carrier gas (0.4% of H 2), InN islands having a (1 0 1¯ 2) facet were grown. It was also found that the crystalline quality of InN could be improved by employing a growth mode change during epitaxial growth from three dimensional (3D) to two dimensional (2D), indicating a reduction in dislocation density.

Simultaneous conversion of CHClF2 and CH3Br to CH2CF2

Gas phase reaction of CHClF(2) with CH(3)Br in an alumina tube reactor at 773-1123 K as a function of various input ratios of CH(3)Br to CHClF(2) is presented. The major products detected include C(2)F(4), CH(2)CF(2), and CH(4). Minor products include CH(3)Cl, CHF(3), C(2)H(4), C(2)H(2), CH(2)CF-CF(3), and C(2)H(3)F. The reaction produces a high yield of CH(2)CF(2) (53% based on CHClF(2) feed) at 1123 K and an input molar ratio of CH(3)Br to CHClF(2) of 1.8, suggesting that the reaction potentially can be developed as a process to convert two ozone depleting substances (CHClF(2) and CH(3)Br) to a highly valuable chemical, CH(2)CF(2). The reaction of CHClF(2) with CH(3)Cl and CH(3)I was also investigated under similar reaction conditions, to assist in understanding the reaction chemistry involved in the reaction of CHClF(2) with CH(3)Br.

Morphology and optical properties of GaAs layers grown on (1 1 1)A GaAs substrates in N2ambient by metalorganic chemical vapor deposition

Using tertiary-butyl arsine as a group V precursor, GaAs epitaxial layers have been grown on both (1 1 1)A- and (1 0 0)-oriented GaAs substrates in N2 ambient using the atmospheric metalorganic chemical deposition technique. The surface morphology and optical properties of the GaAs homoepitaxial layers were studied in detail. It is found that both the surface morphologies and optical properties of GaAs layers on (1 1 1)A GaAs substrates depend much more strongly on the combination of growth temperature and V/III input molar ratio, compared to the epitaxial layers on (1 0 0) plane GaAs. The photoluminescence (PL) emission efficiency increases with increasing growth temperature in the region 550–650 °C for both (1 1 1)A and (1 0 0) GaAs epitaxial layers. At room temperature, the PL emission intensity of the (1 1 1)A GaAs epilayer grown under optimum growth conditions is 67 times as strong as that of the same run-grown (1 0 0) GaAs epilayer.

Influence of lattice constraint from InN and GaN substrate on relationship between input mole ratio and solid composition of InGaN during MOVPE

Thermodynamic analyses incorporating the contribution of lattice constraint from the substrates were carried out to understand the relationship between input In mole ratio and solid composition of stress-free InGaN, InGaN on GaN and InGaN on InN during metalorganic vapour phase epitaxy. The calculated results suggest that a compositionally unstable region is found at the InN-rich region for InGaN on GaN at high temperatures, while that for InGaN on InN can be seen at the GaN-rich region due to the lattice constraint from the substrate. These results imply that incorporating the contribution of lattice constraint is indispensable to predict the thermodynamic properties of such materials.

Thermodynamic study on compositional instability of InGaN/GaN and InGaN/InN during MBE

Thermodynamic analyses were carried out to understand influence of lattice constraint from GaN and InN substrates on relationship between solid composition x of In x Ga 1− x N films and input mole ratio R In (= P In 0/( P In 0+ P Ga 0) where P i 0 is the input partial pressure of element i) during molecular beam epitaxy. The calculated results suggest that compositional unstable region is found at small R In region for InGaN on InN while that for InGaN on GaN can be seen at large R In region at higher temperatures. This implies that InN-rich thin films are possible to form on InN substrate though it is difficult to form on GaN substrate.

Application of a modified version of Habeeb's trinitrophenylation method for the characterization of hapten–protein conjugates in a reversed micellar medium

We describe here a protocol for determining the epitope density of hapten–carrier conjugates at the nanomolar level. Conjugates of bovine serum albumin (BSA) and hen egg albumin (OVA) were prepared with two model haptens: 4-acetyl benzoic acid (ABA) as a chromophoric carboxylic hapten and cholesterol hemisuccinate (Chol HS) as a carboxylic derivative of a nonchromophoric hydroxylated hapten. Small-scale but valuable haptenization of carriers was achieved (≈4.3 nmol with an input molar ratio of hapten to carrier within the range from 50:1 to 100:1) that proved yet compatible with immunogenicity and antibody detection. We used a modified version of the amide bond-generating mixed anhydride method of Erlanger performed in a reversed micellar medium. Microsample aliquots of the coupling reaction (carriers plus activated haptens) or control experiment (carriers plus nonactivated haptens) mixtures were directly subjected to trinitrophenylation in the reversed micellar medium. The results for carrier substitution were strongly correlated ( r 2=0.94; n=12) with those obtained by other methods such as UV analysis (for ABA) and chromatographic determination (for Chol HS). This method was found directly applicable to other hapten–carrier conjugates coupled by the same procedure, provided that the haptens do not absorb at about 335 and 420 nm (absorption peaks of trinitrophenyl groups). With this simple, rapid, reproducible and low-cost analysis method, the separation of uncoupled hapten and conjugate is unnecessary. This facilitates the optimization of reaction conditions. Finally, using this procedure, kinetic studies of conjugate formation can be carried out in a very simple manner.

Quasi-thermodynamic analysis of MOVPE growth of Ga xAl yIn 1− x− yN

A quasi-thermodynamic model of metalorganic vapor phase epitaxy (MOVPE) growth of Ga x Al y In 1− x− y N alloys has been proposed. In view of the complex growth behavior of Ga x Al y In 1− x− y N, we focus our attention on the gallium-rich quaternary alloys that are lattice matched to GaN, In 0.15Ga 0.85N or Al 0.15Ga 0.85N, which are widely used in the GaN-based optoelectronic devices. The relationship between GaAlInN alloy composition and input molar ratio of group III metalorganic compounds at various growth conditions has been calculated. The influence of growth temperature, nitrogen fraction in the carrier gas, input partial pressure of group III metalorganics, reactor pressure, V/III ratio and the decomposition rate of ammonia on the composition of deposited alloys are studied systematically. Based on these calculated results, we can find out the appropriate growth conditions for the MOVPE growth of Ga x Al y In 1− x− y N alloy lattice matched to GaN, In 0.15Ga 0.85N or Al 0.15Ga 0.85N.

Pd(II) and Pt(II) Complexes of 2-Phenyl- and 2-Benzyl-imidazoline: Synthesis, Structural Characterization, DNA Modification andin vitro Antileukaemic Activity

In this paper we describe the synthesis and chemical characterization of three new Pd(II)–imidazoline complexes: [PdCl2 (C6H5–CH2–C3H5N2)2] (2), [PdCl(SEt2) (C6H4-C3H5N2)] (5) and [Pd(C6H4-C3H5N2) (μ-Br)]2 (6). We have also analyzed the DNA modifications and in vitro antileukaemic activity of these compounds and of their previously reported analogs [Pd Cl2 (C6H5–C3H5N2)2] (1), [Pd (C6H4–C3H5N2) (μ-OAc)]2 (3), [Pd (C6H4–C3H5N2) (μ-Cl)]2 (4) and [Pt(C6H4–C3H5N2)(μ-Cl] (7). All these compounds modify the DNA secondary structure since they alter the melting temperature (Tm) of the DNA. Circular dichroism spectra indicated, moreover, that compounds 3, 5 and 6 induced higher modification on the double helix than compounds 1, 2 and 4. While compounds 1, 2 and 5 seem to induce slight changes in the electrophoretic mobility of the open and covalently closed circular forms of pUC8 DNA at high ri (input molar ratio of Pd or Pt to nucleotides), compounds 3, 6 and 7 do not modify at any ri the tertiary structure of the plasmid DNA. Antileukaemic tests suggest that compounds 1, 4 and 7 exhibit important cytotoxic activity since their IC50 values against HL-60 human leukaemic cells were below 10 μg ml−1. © 1997 John Wiley & Sons, Ltd.