Components Of Solution Research Articles

Multi-Walled Carbon Nanotubes Improve the Development of Chrysanthemum × morifolium (Ramat.) Hemsl. ‘Jinba’ Inflorescences

The application of cut flower preservation technology can significantly enhance both the ornamental and economic value of fresh-cut flowers. Research on vase solutions has become a concentrated area in current studies on cut flower preservation. Multi-walled carbon nanotubes (MWCNTs), as a type of carbon nanomaterial with bactericidal and membrane-penetrating properties, can be used as a component in vase solutions. This supplementation of energy substances aims to improve antioxidant enzyme activity, thereby enhancing the postharvest quality of cut chrysanthemums. In this study, deionized water and a standard preservative solution were employed as control groups to compare the effects of MWCNTs applied at different concentrations, combined with common preservatives such as sugar and 8-hydroxyquinoline, on the postharvest flowering and preservation of Chrysanthemum × morifolium ‘Jinba’. By observing the distribution of MWCNTs in the tissues surrounding the cut and changes in water content, carbon sources, osmoregulatory substance levels, and the expression of relevant key genes, a formulation with excellent postharvest treatment effects was identified. Preliminary investigations into its action and mechanism were also conducted. The results indicated that the combined treatment with 5 mg L−1 MWCNTs, 30 g L−1 sucrose, and 0.2 g L−1 8-hydroxyquinoline effectively promoted water and sugar uptake in chrysanthemum flowers, accelerating bud opening, maintaining larger inflorescence diameter, and extending the vase life. Ultimately, this enhanced the ornamental value of cut chrysanthemums. These research findings provide theoretical and experimental foundations for the application of multi-walled carbon nanotubes as auxiliary additives to improve the ornamental quality of cut flowers.

Nutritional profile and risk assessment of inorganic elements in enteral and parenteral nutrition formulas

The contents of essential (Ca, Fe, K, Na, P, and Zn) and potentially toxic inorganic elements (As, Al, Cd, Cr, Cu, Mn, and Pb) in enteral and parenteral nutrition formulas were evaluated by inductively coupled plasma optical emission spectrometry (ICP OES) and graphite furnace atomic absorption spectrometry (GFAAS). A total of 30 enteral formulas, 23 parenteral solution components, and 3 parenteral solutions were analyzed. The elements Ca and K presented the higher contents (72–2918 mg L−1 and 235–2760 mg L−1) while the lowest concentration levels were found for As and Cd (<0.68 µg L−1 and <0.01–0.62 µg L−1) in the studied samples. The validated analytical methods presented an accuracy of 75–116% and RSD values lower than 9.8%. Calcium gluconate and magnesium sulfate, which are used as raw materials in parenteral solution, are potential sources of Al and Mn contamination. A Hazard Quotient (HQ) >1 was obtained for Al (27 ± 1 µg L−1) in one of the parenteral samples, whereas the established limit is 25 µg L−1. Enteral samples were considered safe for consumption regarding the Al, As, and Cd levels. One healing-specific and pediatric formula contained Pb at levels above 0.25 µg kg-day−1, too high for safe consumption. The enteral formulas (pediatric, diabetes-specific, renal-specific, healing-specific, and standard formula with addition of fiber) presented risks in relation to the consumption of Cr and Mn (>250 µg day−1 and >11 mg day−1). The results indicate the need for strict monitoring, considering that these formulations are often the single patient’s food source.

An empirical model for branding oriented by the environmental sustainability of the Amazon Rainforest: a hybrid structural equation modeling with fsQCA approach

Utilizing the Theory of Planned Behavior, a meaningful connection between an organization and its consumers can be established, transcending mere appearances and delving into emotions, relationships, and brand experiences. In line with these principles, this study aims to present an empirical model grounded in factual evidence derived from the perspectives of entrepreneurs and consumers of environmentally sustainable brands in the Brazilian Amazon. The proposed model adopts a mixed-modeling approach, utilizing data analysis techniques such as fuzzy-set qualitative comparative analysis (fsQCA). Two independent data sets were collected: one from 8 companies operating in the Amazon rainforest and another from 535 potential consumers. By analyzing these datasets, consumer motivations for the consumption of sustainable brands, entrepreneurial practices, and the role of traditional communities and the forest environment in shaping brand perceptions were identified. The results reveal that, from the consumer’s perspective, the key factors influencing a positive inclination to purchase sustainable brands include the brand’s engagement with traditional com munities, perceived product quality, brand innovation, and a transparently communicated positioning strategy. These constructs form the core components of the main solution. This article provides valuable information for entrepreneurs operating sustainable brands in tropical forests as well as for policymakers in community-based entrepreneurship. It is also of interest to researchers and individuals involved in brand management as a strategy for empowering small businesses engaged in sustainable practices and community collaboration. The study’s findings and recommendations have the potential to foster more sustainable and socially responsible business practices, thereby enhancing local economies and contributing to environmental preservation.

Detergent-induced quantitatively limited formation of diacyl phosphatidylinositol dimannoside in Mycobacterium smegmatis

Mycobacterial plasma membrane, together with the peptidoglycan-arabinogalactan cell wall and waxy outer membrane, creates a robust permeability barrier against xenobiotics. The fact that several antituberculosis drugs target plasma membrane-embedded enzymes underscores the importance of the plasma membrane in bacterial physiology and pathogenesis. Nevertheless, its accurate phospholipid composition remains undefined, with conflicting reports on the abundance of phosphatidylinositol mannosides (PIMs), physiologically important glycolipids evolutionarily conserved among mycobacteria and related bacteria. Some studies indicate cardiolipin, phosphatidylethanolamine, and phosphatidylinositol as dominant structural phospholipids. Conversely, some suggest PIMs dominate the plasma membrane. A striking example of the latter is the use of reverse micelle extraction, showing diacyl phosphatidylinositol dimannoside (Ac2PIM2) as the most abundant phospholipid in a model organism, Mycobacterium smegmatis. Our recent work reveals a rapid response mechanism to membrane-fluidizing stress in mycobacterial plasma membrane: monoacyl phosphatidylinositol dimannoside and hexamannoside (AcPIM2 and AcPIM6) are converted to diacyl forms (Ac2PIM2 and Ac2PIM6). Given the dynamic nature of PIMs, we aimed to resolve the conflicting data in the literature. We show that unstressed M. smegmatis lacks an Ac2PIM2-dominated plasma membrane. Ac2PIM2 accumulation is induced by experimental conditions involving sodium docusate, a component of the reverse micellar solution. Using chemically synthesized PIMs as standards, we accurately quantified phospholipid ratio in M. smegmatis through liquid chromatography-mass spectrometry, revealing that mycobacterial plasma membrane is dominated by cardiolipin, phosphatidylethanolamine, and phosphatidylinositol. PIMs are quantitatively minor but responsive to environmental stresses in M. smegmatis. Our study paves the way for accurate modeling of mycobacterial plasma membrane.

Enhanced visible-light-driven peroxymonosulfate activation for antibiotic mineralization using electrosynthesized nanostructured bismuth oxyiodides thin films

The search for non-specific catalysts capable of removing a wide range of organic contaminants remains a key challenge given their increasing presence in aquatic environments. In this ongoing exploration, this work proposes the use of bismuth oxyiodides as activators of ecological oxidative radicals, wherein raw substances like peroxymonosulfate (PMS) gain prominence due to the valuable efficiency of the radicals they can generate. For BiOI, serving as a precursor to the photocatalysts, the effect of the electroactive solution components on its electrochemical preparation was analyzed using the voltamperometric technique. The compositional and structural characterization confirmed successful formation. Deposit annealing treatments result in new species such as Bi7O9I3 at 250ºC and, primarily, Bi5O7I at 420 or 520ºC—species that also exhibit visible light absorption, paving the way for their use under sunlight. Initially, a single tetracycline (TC) solution was employed to test the degradation and mineralization capability of the prepared films, assessing the impact of the solution's pH, the presence of PMS, light irradiation, and annealing temperature. The annealing temperature increases the catalytic effect. It is noteworthy that for all bismuth iodide films, the highest catalytic activity was observed when combining PMS and visible light irradiation, showcasing a synergistic improvement. This trend holds for multipollutant solutions as well. In a crucial role for the material's application, the results demonstrate that annealing temperatures below 450ºC promote films that reasonably maintain their activity and chemical stability after continuous reuse.

Assessment of the stabilization effect of ferrous sulfate for arsenic-contaminated soils based on chemical extraction methods and in vitro methods: Methodological differences and linkages

Stabilization of arsenic-contaminated soils with ferrous sulfate has been reported in many studies, but there are few stabilization effects assessments simultaneously combined chemical extraction methods and in vitro methods, and further explored the corresponding alternative relationships. In this study, ferrous sulfate was added at FeAs molar ratio of 0, 5, 10 and 20 to stabilize As in 10 As spiked soils. Stabilization effects were assessed by 6 chemical extraction methods (toxicity characteristic leaching procedures (TCLP), HCl, diethylenetriamine pentaacetic acid (DTPA), CaCl2, CH3COONH4, (NH4)2SO4), and 4 in vitro methods (physiologically based extraction test (PBET), in vitro gastrointestinal method (IVG), Solubility Bioaccessibility Research Consortium (SBRC) method, and the Unified Bioaccessibility Research Group of Europe method (UBM)). The results showed that the HCl method provides the most conservative assessment results in non-calcareous soils, and in alkaline calcareous soils, (NH4)2SO4 method provides a more conservative assessment. In vitro methods provided significantly higher As concentrations than chemical extraction methods. The components of the simulated digestion solution as well as the parameters may have contributed to this result. The small intestinal phase of PBET and SBRC method produced the highest and lowest ranges of As concentrations, and in the range of 127–462 mg/kg and 68–222 mg/kg when the FeAs molar ratio was 5. So the small intestinal phase of PBET method may provide the most conservative assessment results, while the same phase of SBRC may underestimate the human health risks of As in stabilized soil by 51 %(at a FeAs molar ratio of 5). Spearman correlation analysis indicated that the small intestinal phase of PBET method correlated best with HCl method (correlation coefficient: 0.71). This study provides ideas for the assessment of stabilization efforts to ensure that stabilization meets ecological needs while also being less harmful to humans.

Taking spontaneous plants as a natural strategy for vegetation restoration in construction and demolition waste landfills: a case study in Suzhou, China.

Construction and demolition waste (CDW) landfills around the city have caused serious damage to the ecological environment and menaced the public health. Restoration of closed CDW landfills is critical to compensate for the degraded ecosystem and ensure safety in further development and utilization. Vegetation restoration is an essential part of the restoration of CDW landfills, in which the use of spontaneous plants is the foundation of the nature-based strategy. In this study, Fenghuangshan CDW landfill in Suzhou, China, was selected as the research site, and the species composition and diversity of the spontaneous plants were analyzed. Moreover, the types of habitats and growth indexes of 8 species with high frequency and 18 species with medium frequency in the CDW landfill were investigated, and a comprehensive evaluation of growth rate and expansion capacity of the 26 species was conducted. The results showed that, herbs were the main type of the spontaneous plants in the CDW landfill. The species and quantities of the spontaneous plants in the CDW landfill were obviously fewer than those in the surrounding areas of the CDW landfill, and the Shannon-Wiener index and Pielou index of the spontaneous plants were lower compared with the surrounding areas of the CDW landfill. Meanwhile, the differences of dominant families and the distribution of origins, life forms and growth types between these two fields were insignificant. The heliophilous and drought tolerance species were widely distributed in the CDW landfill while the shade-tolerant or hygrophilous species were few. The relatively large comprehensive evaluation indexes of Elymus dahuricus, Daucus carota, Sonchus asper, Geranium carolinianum, Rumex acetosa, Metaplexis japonica, Carex breviculmis, Erigeron canadensis, Trigonotis peduncularis, Lamium amplexicaule reflected their high growth rates and strong expansion capacity, demonstrating their great potentiality in the vegetation restoration of CDW landfills as indispensable components of the nature-based solution.

On the role of water in antimony electrodeposition from choline chloride/ethylene glycol/water mixture

Through experimental research and theoretical calculation, it was investigated the effect of water and temperature on the electrodeposition of antimony (Sb) on a platinum (Pt) electrode. The plating solutions were prepared by the addition of 0.05 mol L–1 SbCl3 to the mixtures of choline chloride (ChCl), ethylene glycol (EG) and water (W) in the following molar ratio: 1ChCl:2EG (bath 1), 1ChCl:2EG:0.45 W (bath 2), and 1ChCl:2EG:1.62 W (bath 3). Furthermore, the Sb coatings were electrodeposited at 297 and 338 K. The surface morphologies and crystalline structures of Sb electrodeposits were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. In addition, to understand the interactions of Sb3+ species with the other components of the plating solution, models were created and calculated using density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM). The results of the voltammetric behaviour of Sb3+ species indicated that the reduction potential was shifted towards more positive values with increasing water content on the electrolyte, indicating that the water catalyses the electrochemical reduction of the Sb3+ species. The values of the diffusion coefficients for the Sb3+ species were calculated by applying the Cottrell equation, which increased with the addition of water and temperature increment. The water content and temperature increase affect the surface morphologies of the Sb electrodeposited coatings, which is attributed to the improvement of Sb electrodeposition rate. Moreover, Sb electrodeposited coatings were successfully obtained without adding a complexing agent, indicating that the procedure adopted for the Sb electrodeposition is environmentally friendly. The XRD results revealed the pure phase Sb films. DFT simulations indicated that the Sb-Cl interaction is stronger, which suggests the formation of Sb-Cl complexes. Adding H2O molecules favours the electron affinity of the systems, and QTAIM results suggested that this additive decreased the electron density of Sb3+ ions.

Sorption of picolinic acid by Cu(II)-containing sulfocationite KU-2-8

Objectives. To study the equilibrium distribution of components between KU-2-8 sulfocationite and an aqueous solution containing picolinic acid and Cu(II); to show the possibility of immobilization of cations of picolinic acid and Cu2+ in sulfonic cation exchanger KU-2-8; to calculate the component compositions of the equilibrium solution, in order to obtain the required ionic composition of the KU-2-8 sulfonic cation exchanger according to the selectivity coefficients of binary ion exchange, and the constants of formation of such complexes in water.Methods. The concentrations of the individual components in multicomponent solutions were calculated using the HySS 2009 program (Hyperquad Simulaton and Speciation). The calculation of the equilibrium ionic compositions of KU-2-8 sulfocationite was performed using the selectivity coefficients of binary ion exchanges and the formation constants of complexes of picolinic acid with Cu2+ and H+ cations. Experimental study of the equilibrium distribution of components between aqueous solutions of picolinic acid, copper nitrate, and KU-2-8 sulfocationite was carried out by means of the dynamic method at a temperature of 298 K. Fourier-transform infrared spectroscopy and electron paramagnetic resonance spectroscopy were used, in order to determine the ionic forms of the components contained in the sulfocationite.Results. It was shown that the equilibrium solution contains H+ protons, Cu2+ cations, LH picolinic acid molecules, protonated picolinic acid cations [H2L]+, deprotonated picolinic acid anions L-, Cu2+ complexes with the deprotonated picolinic acid anion [CuL]+, and Cu2+ complexes with two anions of deprotonated picolinic acid [CuL2]. The concentration of H+, Cu2+, and [H2L]+ cations in the solution significantly exceeds the concentration of other components at pH values from 0 to 0.5. The content of [CuL]+ cations and neutral complexes [CuL2] increases significantly in the solution, while the [H2L]+ cations disappear at pH greater than 1. It was experimentally established that the concentrations of picolinic acid and copper in the polymer phase are many times higher than the concentrations of these components in an aqueous solution. The partition coefficients are about 24 and 210 for picolinic acid and Cu(II), respectively. The calculated dependencies of the concentrations of Cu2+, [H2L]+, H+, [CuL]+ cations in the polymer vs pH of an equilibrium solution containing picolinic acid were obtained. The experimental data on the concentrations of all cations in the ion exchanger is in the intervals of the calculated compositions within the limits of measurement errors.Conclusions. KU-2-8 sulfocationite is proposed as a container for obtaining drugs based on picolinic acid and Cu2+ cations. It was shown that the selectivity coefficients of binary ion exchanges and the formation constants of [H2L]+, [CuL]+ complexes can be used to precalculate the ionic compositions of the equilibrium solution, in order to obtain the required compositions of the sulfocationite.

Development of a method for the simultaneous determination of ionic nutrients in hydroponic solutions using cation-/anion-exchange chromatography with a neutral eluent.

Nutrient availability in hydroponic solutions must be accurately monitored to maintain crop productivity; however, few cost-effective, accurate, real-time, and long-term monitoring technologies have been developed. In this study, we describe the development and application of cation-/anion-exchange chromatography with a neutral eluent (20-mmol/L sodium formate, pH 7.87) for the simultaneous separation (within 50min) of ionic nutrients, including K+, NH4+, NO2-, NO3-, and phosphate ion, in a hydroponic fertilizer solution. Using the neutral eluent avoided degradation of the separation column during precipitation of metal ion species, such as hydroxides, with an alkaline eluent and oxidation of NO2- to NO3- with an acidic eluent. The suitability of the current method for monitoring ionic components in a hydroponic fertilizer solution was confirmed. Based on our data, we propose a controlled fertilizer strategy to optimize fertilizer consumption and reduce the chemical load of drained fertilizer solutions.

ОПТИМИЗАЦИЯ РЕЖИМА 3-D ПЕЧАТИ ТУРБИННОЙ МЕШАЛКИ ДЛЯ ДИСПЕРГИРОВАНИЯ РАСТВОРОВ ПОЛИМЕРНЫХ КОМПОЗИТОВ

The design of the turbine stirrer is characterized by a rather complex shape of working surfaces and during its manufacture by traditional methods unique molds are required for each type of stirrer, increased material and labor costs are required. The use of 3D printing allows you to obtain products with a complex surface configuration, with minimal costs and which do not require subsequent machining. Analysis was carried out and selection of 3D printing type and material of turbine stirrer intended for mixing of elastomeric nanocomposite solutions components was carried out. FDM (Fused Deposition Modeling) is the most suitable type of 3D printing for solving design and technological problems in the manufacture of turbine stirrers. Plastics of the brands ABS, PLA and PETG have become very widespread in this type of 3D printing. The highest mechanical properties, chemical resistance and the lowest price of the materials under consideration are PETG plastic, which was chosen for the manufacture of a turbine stirrer designed to mix and disperse solutions of elastomeric nanocomposites. An active experiment was implemented according to the В2 plan. The samples are PETG plastic plates printed on a Flying Bear Ghost 5 3D printer. The main mode parameters of 3D printing by FDM type, which determine the strength of samples and printing performance, are: the number of concentric lines that make up the wall of the printed product and the line width. A regression model of the dependence of strength of samples made of PETG plastic on the number and width of lines in 3D printing was obtained. The optimal 3D printing mode of the turbine stirrer is set, providing high strength of the product and performance of the technology.

Smart Billing Software

The set of solutions offered by the Business Operation Support System revolves around Smart Billing Software. Because billing is the nerve centre of the company, it oversees all the important data, including product catalogues, customers, rates, taxes, financial accounting, invoices, payments, debit and credit notes, dual ledgers, support for multiple currencies, and more. You can manage any business operation involving metered charges, recurring charges, event-based charges, and ad-hoc charges with the help of Smart Billing Software's engine, which offers unparalleled flexibility in setting up any kind of product, product packages, user-defined rating structures, tax rules, and more. With Smart Billing Software, any service model and offering can be easily integrated into a single platform. It is compatible with both pre-paid and post-paid payment systems. Due to its open API foundation, Smart Billing Software is highly compatible with other BOSS products, allowing for the construction of comprehensive solutions. Smart Billing is a pre-integrated component of Xsinfosol Solutions and is one of the BOSS solutions offered by Xsinfosol.

Study of crucial factors for minimizing the roughness of chemical coatings with Ni – P and Ni – Cu – P alloys

The surface roughness of coatings has a significant impact on their functional properties and efficiency. We present the results of studying the effect of the main technological parameters on the roughness of chemical coatings with Ni – P and Ni – Cu – P alloys. The key factors affecting the roughness of coatings were determined by the Taguchi method. Parameters of the coating process were varied in the experiments: concentration of components in solution, pH, temperature, and the time of deposition. It is found that the surface roughness increases linearly with the thickness of coatings. The concentration of sodium hypophosphite and pH value have the greatest influence on the development of roughness. It is shown that the lowest roughness is observed at concentrations of sodium hypophosphite and copper salt 0.358 and 0.0012 mol/liter, pH 5.8 and temperature 90 °C. The rate of the surface roughness development for Ni – P and Ni – Cu – P coatings under optimal conditions is 0.68 and 0.97 %/μm (before optimization — 6.72 %/μm). The obtained results can be used to improve the methodology for reducing the roughness of coatings with Ni – P and Ni – Cu – P alloys and, accordingly, to improve the functionality, wear resistance and quality of coatings.

A New Fixed Coefficient Diagonally Implicit Block Backward Differentiation Formula for Solving Stiff Initial Value Problems

Stiff initial value problems in ordinary differential equations occur when solution components evolve at varying rates, posing challenges for traditional computational methods. Specialized techniques are crucial for maintaining accuracy and stability during rapid transitions, emphasizing their significance in developing reliable numerical algorithms across scientific and engineering applications. This study aims to develop a new fixed coefficient 3-point diagonally implicit block backward differentiation formula for the numerical solution of first order stiff initial value problems. The method is constructed by integrating a triangular matrix into the coefficient matrix of an existing extended 3-point super class of block BDF for solving stiff initial value problems. The selection of a fixed coefficient within the interval accompanies this integration to ensure optimal stability. The method is found to order five. Stability analysis indicates that the method is consistent, zero-stable, and almost A-stable, validating its applicability to stiff initial value problems. Implementation of the method involves Newton’s iteration, and a code in the C programming language is devised to demonstrate its effectiveness. Comparative examination of numerical outcomes with the existing 3BBDF and 3ESBBDF methods highlights the proposed method's enhanced accuracy and reduced computation time.

Affordable Housing Solutions

Affordable housing has emerged as a critical issue worldwide, particularly in urban areas experiencing rapid population growth, economic disparity, and high living costs. This research paper examines the various solutions to address the growing demand for affordable housing, focusing on strategies that balance economic feasibility, social inclusion, and environmental sustainability. The study reviews existing literature on affordable housing, explores diverse methodologies to enhance housing affordability, and analyzes case studies from different regions to identify best practices. It discusses innovative financing models, public-private partnerships, land use policies, and sustainable building practices as key components of comprehensive affordable housing solutions. The paper aims to provide actionable recommendations for policymakers, developers, and stakeholders to implement effective strategies for affordable housing.

Crystallization Kinetics of Hybrid Perovskite Solar Cells

AbstractMetal halide perovskites (MHPs) are considered ideal photovoltaic materials due to their variable crystal material composition and excellent photoelectric properties. However, this variability in composition leads to complex crystallization processes in the manufacturing of Metal halide perovskite (MHP) thin films, resulting in reduced crystallinity and subsequent performance loss in the final device. Thus, understanding and controlling the crystallization dynamics of perovskite materials are essential for improving the stability and performance of PSCs (Perovskite Solar Cells). To investigate the impact of crystallization characteristics on the properties of MHP films and identify corresponding modulation strategies, we primarily discuss the relevant aspects of MHP crystallization kinetics, systematically summarize theoretical methods, and outline modulation techniques for MHP crystallization, including solution engineering, additive engineering, and component engineering, which helps highlight the prospects and current challenges in perovskite crystallization kinetics

Crystallization Kinetics of Hybrid Perovskite Solar Cells.

Metal halide perovskites (MHPs) are considered ideal photovoltaic materials due to their variable crystal material composition and excellent photoelectric properties. However, this variability in composition leads to complex crystallization processes in the manufacturing of Metal halide perovskite (MHP) thin films, resulting in reduced crystallinity and subsequent performance loss in the final device. Thus, understanding and controlling the crystallization dynamics of perovskite materials are essential for improving the stability and performance of PSCs (Perovskite Solar Cells). To investigate the impact of crystallization characteristics on the properties of MHP films and identify corresponding modulation strategies, we primarily discuss the relevant aspects of MHP crystallization kinetics, systematically summarize theoretical methods, and outline modulation techniques for MHP crystallization, including solution engineering, additive engineering, and component engineering, which helps highlight the prospects and current challenges in perovskite crystallization kinetics.

Bifurcation and regularity analysis of the Schrödinger-Poisson equation

Abstract The aim of this paper is to present bifurcation results for (weak) solutions of the Schrödinger-Poisson system in R 3 , involving subcritical and critical nonlinearities and using the global bifurcation theorem. Furthermore, we establish the existence of unbounded components of (weak) solutions, which bifurcate from trivial solutions and from infinity, respectively. The novelties of the paper lie in the appearance of the indefinite nonlinearity and the critical nonlinear term. Finally, we also analyze the regularity result that guarantees the L ∞ -bound of the (weak) solutions of the nonlinear Schrödinger-Poisson system under consideration.

The elementary reactions for incorporation into crystals

The growth rates of crystals are largely dictated by the chemical reaction between solute and kinks, in which a solute molecule severs its bonds with the solvent and establishes new bonds with the kink. Details on this sequence of bond breaking and rebuilding remain poorly understood. To elucidate the reaction at the kinks we employ four solvents with distinct functionalities as reporters on the microscopic structures and their dynamics along the pathway into a kink. We combine time-resolved in situ atomic force microscopy and x-ray and optical methods with molecular dynamics simulations. We demonstrate that in all four solvents the solute, etioporphyrin I, molecules reach the steps directly from the solution; this finding identifies the measured rate constant for step growth as the rate constant of the reaction between a solute molecule and a kink. We show that the binding of a solute molecule to a kink divides into two elementary reactions. First, the incoming solute molecule sheds a fraction of its solvent shell and attaches to molecules from the kink by bonds distinct from those in its fully incorporated state. In the second step, the solute breaks these initial bonds and relocates to the kink. The strength of the preliminary bonds with the kink determines the free energy barrier for incorporation into a kink. The presence of an intermediate state, whose stability is controlled by solvents and additives, may illuminate how minor solution components guide the construction of elaborate crystal architectures in nature and the search for solution compositions that suppress undesirable or accelerate favored crystallization in industry.

Understanding the Interplay of the Brønsted Acidity of Catalyst Ancillary Groups and the Solution Components in Iron-porphyrin-Mediated Carbon Dioxide Reduction.

The rapid and efficient conversion of carbon dioxide (CO2) to carbon monoxide (CO) is an ongoing challenge. Catalysts based on iron-porphyrin cores have emerged as excellent electrochemical mediators of the two proton + two electron reduction of CO2 to CO, and many of the design features that promote function are known. Of those design features, the incorporation of Brønsted acids in the second coordination sphere of the iron ion has a significant impact on catalyst turnover kinetics. The Brønsted acids are often in the form of hydroxyphenyl groups. Herein, we explore how the acidity of an ancillary 2-hydroxyphenyl group affects the performance of CO2 reduction electrocatalysts. A series of meso-5,10,15,20-tetraaryl porphyrins were prepared where only the functional group at the 5-meso position has an ionizable proton. A series of cyclic voltammetry (CV) experiments reveal that the complex with -OMe positioned para to the ionizable -OH shows the largest CO2 reduction rate constants in acetonitrile solvent. This is the least acidic -OH of the compounds surveyed. The turnover frequency of the -OMe derivative can be further improved with the addition of 4-trifluoromethylphenol to the solution. In contrast, the iron-porphyrin complex with -CF3 positioned opposite the ionizable -OH shows the smallest CO2 reduction rate constants, and its turnover frequency is less enhanced with the addition of phenols to the reaction solutions. The origin of this effect is rationalized based on kinetic isotope effect experiments and density functional calculations. We conclude that catalysts with weaker internal acids coupled with stronger external acid additives provide superior CO2 reduction kinetics.