Determining the Adsorption Energetics of 2,3-Butanediol on RuO2(110): Coupling First-Principles Calculations With Global Optimizers

As climate change continues to pose a threat to the Earth due to the disrupted carbon cycles and fossil fuel resources remain finite, new sources of sustainable hydrocarbons must be explored. 2,3-butanediol is a potential source to produce butene because of its sustainability as a biomass-derived sugar. Butene is an attractive product because it can be used as a precursor to jet fuel, categorizing this work in the alcohol-to-jet pathway. While studies have explored the conversion of 2,3-butanediol to butene, little is understood about the fundamental reaction itself. We quantify the energetics for three pathways that were reported in the literature in the absence of a catalyst. One of these pathways forms a 1,3-butadiene intermediate, which is a highly exothermic process and thus is unlikely to occur since 2,3-butanediol likely gets thermodynamically trapped at this intermediate. We further determined the corresponding energetics of 2,3-butanediol adsorption on an ensemble of predetermined binding sites when it interacts with a defect-free stoichiometric RuO2(110) surface. Within this ensemble of adsorption sites, the most favorable site has 2,3-butanediol covering a Ru 5–coordinated cation. This approach is compared to that obtained using the global optimization algorithm as implemented in the Northwest Potential Energy Surface Search Engine. When using such a global optimization algorithm, we determined a more favorable ground-state structure that was missed during the manual adsorption site testing, with an adsorption energy of −2.61 eV as compared to −2.34 eV when using the ensemble-based approach. We hypothesize that the dehydration reaction requires a stronger chemical bond, which could necessitate the formation of oxygen vacancies. As such, this study has taken the first step toward the utilization of a global optimization algorithm for the rational design of Ru-based catalysts toward the formation of butene from sustainable resources.

ANALYSIS OF THERMAL EFFECTS WITH MULTI-FOCI STRUCTURING

The possibility of a thermal imaging technique for studying the setting of composite materials in the light of the paradigm of multifocal structure formation is analyzed. Since thermal violated observations are characterized by a high thermal sensitivity to temperature gradients up to hundredths of degrees, they make it possible to distinguish the temperature differences arising in the adjacent sections of the hardening binding. A technique for obtaining thermal images (thermograms) of a hardening composite binder is implemented. A series of thermograms of setting processes was obtained, for two of them a quantitative study was carried out, including the temperature gauge and the construction of several types of graphic mappings of the obtained patterns ‒ the normalized frequency of the distribution of the area of the binder for those temperatures and two types of densitograms ‒ radial and circular, allowing to visualize the structure of thermal foci arising in a binder. The hardening of binding materials is considered as a multistage exothermic process, in which hydration processes is accompanied by heating. The speed of heterogeneous processes associated with hydration depends, in turn, on the characteristics of the forming structure of binding materials. The observed thermal processes are considered as an indirect response, "shadow" of structure formation processes. The information consisting in this indirect response, however, is enough to make a number of conclusions on the nature of the emerging structure. The study revealed a high probability of the formation of foci near the macroscopic boundaries of the section (walls and bottom of the form), inconsistency of the structural processes, the occurrence of diverse foci of structure formation corresponding to temperature foci. The interpretation of the data obtained is the conclusion about formation of the regions of high plastic deformations near the boundaries of the contact of the foci. This regions are considered as a cluster of microscopic boundaries of the section, cracks and pores, which give rise to the structure of the destruction of the hardened material. The emergence of such areas is associated with nonynchronouspassage of structuring in different parts of the binder.

Phase transitions of liposomes: When light meets heat

Phase transitions of liposomes are normally studied by differential scanning calorimetry (DSC). A suspension of liposomes is subjected to an increase (decrease) of temperature and when heat is absorbed (released), the liposomes transit from a gel (liquid) to a liquid (gel) phase. This endothermic (exothermic) process takes place at a temperature called the melting temperature Tm, which is distinctive of the type of lipids forming the vesicles. The vesicles, though, also modify their size in the transition. Indeed, the thickness of the membranes decreases (increases) because carbon tails misalign (align). Concomitant with the modifications in the membrane thickness, the diameter (D) of the liposomes changes too. Therefore, when they are inspected by light, the scattered signal carries information from such dilatation (contraction) process. We performed careful experiments using dynamic light scattering (DLS) as a function of temperature to detect the size changes of different liposomes. Gaussian fits of the derivatives of the D vs T curves coincide within 1% with thermograms, which hints to the possibility of performing thermodynamic studies of lipid systems employing light.

Adsorption of Yttrium Ions on 3-Amino-5-Hydroxypyrazole Impregnated Bleaching Clay, a Novel Sorbent Material

In this work, spent bleaching clay (SBC) was treated with ethyl acetate and impregnation with 3-amino-5-hydroxypyrazole (AHIBC) that utilized as economical sorbent material. The uptake of yttrium ions from aqueous solution using AHIBC was studied under batch process as a function of pH of the solution, contact time, adsorbent dosage, Yttrium ions concentration, and ambient temperature. The adsorption equilibrium was achieved at the value of pH = 6.0 and agitation time of 60 min at room temperature. The utmost adsorption capacity of Y(III) ions on AHIBC was 171.32 mg·g−1. Kinetic, isotherm, and thermodynamic models were applied to the experimental data obtained. Adsorption follows a pseudo–second–order kinetic model, while the adsorption isotherm fits the Langmuir model. A negative value of Gibbs free energy ΔG° revealed that the adsorption of the Y ions on the AHIBC adsorbent was spontaneously in nature. In addition, the electrostatic interaction process between the metal ions and AHIBC was favorable. The negative value of ΔH° states that Y ions adsorption was an exothermic process. Desorption efficiency reduced from 97% to 80% after eight consecutive rounds.

MODELING AND SIMULATION OF THE CURING PROCESS OF EPOXY RESINS AND FIBER COMPOSITES

This study discusses simulations of the curing process in epoxy and fiberreinforced polymer composites incorporating changes in the thermal and mechanical properties of epoxy during curing at various temperatures. A coupled constitutive model that includes an exothermic process from the cross-linking, heat conduction across the specimen and deformations of the specimen from the thermal expansion and shrinkage effects is formulated. The model is used to capture the curing process in the epoxy resin. The coupled constitutive model is then integrated into a micromechanics model of fiber-reinforced composites and used to study the influence of epoxy curing on the formation of residual stresses in the composites. Furthermore, the micromechanics model is also used to predict the macroscopic properties, i.e., elastic moduli, of the cured composites. The model can then be used to understand the influence of processing parameters, i.e., temperatures and pressure, on the formation of residual stresses and their consequences on the overall properties of cured composites.

PROCESS FOR REMOVAL OF CHROMIUM ION FROM LEATHER INDUSTRIAL WASTES BY ACTIVATED PURE RICE HUSK

The removal of (Cr) ions from industrial wastage by adsorption on rice husk was investigated based on activated pure rice husk dosage, stay time, metal concentration and solution temperature. The optimum values of activated pure rice husk dosage and stay time were determined to be 0.5gm/50ml solution and 60 mins, respectively, for the adsorption of (Cr) ions. The constant for the Freundlich, D-R and Langmuir isotherms were 50%, calculated at 50 . The adsorption of (Cr) from industrial wastage was found to be exothermic. Thermodynamic parameters such as free energy change ( G°), enthalpy change ( H°) and entropy change ( S°) of adsorption also calculated and interpreted from the slope and intercept of the plots of lnkD vs I/T. The G° value decreases with rise in temperature and the negative values of H° indicate that the adsorption of (Cr) from industrial wastage was an exothermic process while positive values of change in entropy ( S°) were also observed

SN-CUO-ARABIC GUM COMPOSITION FOR RED TRACER PROJECTILE AMMUNITION POTENTIAL

<div><p class="Els-history-head">Fundamentally, tracer projectile material based on pyrotechnic composition, and where the pyrotechnic was generally composed of fuel, oxidizer, and binder. The tin (Sn) material is one of the candidates for fuel material because tin has a low melting point, so this composition can ignite at low temperature, while the copper oxide (CuO) can emit the orange-red spectrum. This study aims to evaluate the thermal and spectrum character of Sn-CuO-AG-based composition. The characterization data of these samples was evaluated by tests of morphology and phase, enthalpy change, calorie energy, and spectrum emission. Based on this data, the 17Sn-68CuO-15AG sample was emitted a strong red color too, but this sample has a high or the longest exothermic process. Furthermore, the 27Sn-58CuO-15AG sample has emitted a weak red color with medium exothermic energy. Generally, the 22Sn-63CuO-15AG is more suitable than the two other compositions for the tracer projectile composition of ammunition, this material emits a strong red spectrum and low-calorie energy.</p></div>

Removal of Murexide Dye from Aqueous Solution Using A Novel Schiff Base Tin(IV) Compound

A Schiff base tin (IV) compound was synthesized by reactions between 2-((E)-(p-tolylimino)methyl)phenol (TIMPH) and butyltin trichloride in 2:1 mole ratio in ethanol at room temperature. [SnBuCl3(TIMPH)2] was characterized by FT-IR, 1H-NMR, 13C-NMR spectroscopy, elemental analysis, and mass spectrometry. Optimization of Murexide dye from aqueous solution was performed by examining; effect of contact time, initial pH, adsorbent amount, initial dye concentration and temperature on the tin adsorbent. The highest adsorption recovery value of was 98.00% and the adsorption capacity was 248.8 mg/g at the end of 20 minutes at 100 mg/L dye concentration while the temperature was 25°C and the pH was 3. Langmuir, Freundlich, and Temkin adsorption isotherms were calculated at 25 ºC. The highest R2 value was found 0.099 for the Langmuir isotherm model. The adsorption characteristics of murexide dye showed that adsorption kinetic obeyed the pseudo-second-order kinetics, and the thermodynamic data suggested the spontaneous and exothermic process.